Dr. Stacy Sims: Female-Specific Exercise & Nutrition for Health, Performance & Longevity

Andrew Huberman: [OPENING THEME MUSIC]

Welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. My guest today is Dr. Stacy Sims. Dr. Stacy Sims is an exercise physiologist and a nutrition scientist and a world expert in all things training and nutrition specifically for women. In addition to working at Stanford and with numerous professional athletic teams, Dr. Sims has authored more than 100 peer-reviewed studies on exercise physiology. She has not only evaluated existing protocols for nutrition and fitness that are specific to women versus men, but she has also developed many new protocols that are now in practice with professional sports teams, and that can also serve people who are generally interested in fitness and longevity and in doing so, the general public. The tools that Dr. Sims shares with us today are applicable to fitness, to changing your body composition, and to overall health.

Today, we discuss how hormones and hormone cycles impact nutrition and fitness needs, specifically in women of different ages. We, of course, discuss the menstrual cycle, perimenopause, and menopause, but also female-specific nutrition and training as it relates to things independent of hormones. For instance, we evaluate the evidence that women may not want to train fasted and the reasons for that. We talk about how training might vary according to different phases of the menstrual cycle, and we discuss how women can design nutrition and training programs that are optimized for their specific needs, not just because they are women, but because they are women of a particular stage of life and women with particular goals. As you'll soon see, Dr. Sims is exquisitely skilled at explaining the human universals of nutrition and training, that is, the things that do not differ between men and women and their needs in terms of nutrition and training. But she is also exquisitely skilled at highlighting the data showing that there are specific areas of nutrition and fitness for which women and men differ, and women have specific needs. So today, you will learn what those are, and you will learn how to apply those specific protocols such that by the end of today's episode, you will be armed with a tremendous amount of new knowledge about the biological mechanisms and the specific do's and do not's that can guide you towards your female-specific health and fitness goals.

Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero-cost consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast.

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And now, for my discussion with Dr. Stacy Sims. Dr. Stacy Sims, welcome.

Stacy Sims: Thanks.

Andrew Huberman: Our podcast and I put out a lot of content about nutrition, fitness, cold exposure, heat exposure, hydration, topics that are very near and dear to your heart and for which you have a ton of expertise, but for which you have an extra degree of expertise as it relates to females specifically.

Stacy Sims: Yeah.

Andrew Huberman: So I'm excited to talk to you today because very often I will get questions in the comment section on social media or on YouTube. Was this study done in both men and women? How does it differ for men versus women? And on and on. And I rarely, if ever, have answers. But you have answers.

Stacy Sims: I have answers for you.

Andrew Huberman: Great. So just to kick things off, because this is a question I get really often. Fasting.

Stacy Sims: Oh yeah.

Andrew Huberman: Intermittent fasting. We need to distinguish between the two. Of course. Perhaps the most common question I get as it relates to males versus females is intermittent fasting, or time restricted feeding, as it's sometimes called, an eight hour feeding window, a six hour feeding window, a ten hour feeding window. Is that something that. That perhaps differs in terms of its impact and how well it works for men versus women?

Stacy Sims: Yeah, that's a short answer.

Andrew Huberman: Great.

Stacy Sims: Yeah. Yeah. So I'll put some parameters around it. Right. So if we talk about intermittent fasting, that's where you have, like the 20 hours non feeding window, or you're holding a fast until noon or after, and then we have time restricted eating. And that's the fancy way of saying normal eating where you're having breakfast and then you stop eating after, or you don't have anything after dinner. Right. So you're eating with your circadian rhythm during the day. If we look at intermittent fasting, where you're holding the fast up till noon or you're having days of really low calorie restriction, we see in active women, it's very detrimental. Unless you have PCOS or you have some other sub clinical issue. And the reason for that is we, as women, have more oxidative fibers. So we hear about all the things about fasting to improve our metabolic flexibility, to improve telomere length, to improve parasympathetic activation. But by the nature of women having more oxidative fibers, we are already metabolically more flexible than mental.

Andrew Huberman: Interesting.

Stacy Sims: Yeah.

Andrew Huberman: Didn't know that. Could you elaborate on more oxidative fibers, what that is and how it relates to metabolic flexibility?

Stacy Sims: So, oxidative fibers are muscle fibers that are more aerobic capacity. So those are the ones that you can go long and slow for a very long period of time because it uses a lot of free fatty acids. You need a little bit of glucose in order to activate those free fatty acids. So when we look, when a woman starts to exercise, she goes through blood glucose first and then gets into free fatty acid use, she doesn't tap so much into liver muscle glycogen, which is, I think, another misconception that happens. So when we're talking about fasting or fasted workouts, trying to improve that metabolic flexibility, it increases stress on the woman. And so when we're talking about overall stress, we're talking about cortisol increase, and they can't hit intensities high enough with no fuel to be able to invoke the post exercise responses of growth hormone and testosterone, which then drop cortisol. So, from an overall stress perspective, that fasted workout and holding that fast for a long period of time increases cortisol. But then when we look from, like, a hypothalamic point of view and we're looking at how the brain reads it, so we know that there's one area of kisspeptin neurons in the brain for men, but there are two for women. So the two areas are distinct, where one controls appetite and luteinizing hormone, and the other one is looking at estrogen and thyroid. So if you start having an exercise stress or a daily stress of getting up and going on with your day without fuel, you perturb those kisspeptin neurons and downregulate them. When you start downregulating them, we see that after four days, you have a dysregulation of thyroid. We have a change in our luteinizing hormone pulse, which is really important to maintain endocrine function. We'll hear this, oh, I've been fasting for so many years, and it does great for me. But the other side of the question is, well, how much better would you be if you were to actually pay attention to your circadian rhythm and fuel according to the stress at hand, and knowing that you're going to garner less stress that way? And if we're really tying in nutrition according to that profile, instead of following a fast, we see better brain improvements as well. We see more cognitive function, we see less thyroid dysfunction, and overall, a woman does much better when we're not in that fasted state. Then when you look at population research that's coming out now, they're showing in both men and women who hold their fast till noon and then have an eating window from noon to maybe 6:00 p.m. have more obesogenic outcomes than people who break their fast at eight and finished their eating window by four or 5:00 p.m. so it's coming back to the chronobiology of we need to eat when our body is under stress and needs it. Unless we have a specific issue, like obesity, inactivity, PCOS, or other metabolic conditions, then we can look at using fasting as a strategic intervention to help with those modalities.

Andrew Huberman: Super interesting. Two questions. Is there a protective effect of starting the eating window? And here I'm asking for both men and women starting the eating window at, say, 11:00 a.m. or noon and ending it a little bit later. So not a six hour eating window or seven hour eating window, but extending that to eight or 09:00 p.m. under those conditions, do you still see the obesogenic effect?

Stacy Sims: Yes, because we're looking at the way cortisol responds. We know cortisol has lots of fluctuations throughout the day, and it peaks about half an hour after you wake up. Right. So if you're having that cortisol peak half an hour after you wake up, but you're not eating, then that is that higher baseline sympathetic drive for women. For men, it's not the same. So when we're looking at that obesogenic outcome, the actual timing hasn't been tested yet to see how can we expand or contract that eating window for men. But for women, because of that cortisol peak right after waking up, women tend to be already sympathetically driven. So then they walk around more tired but wired and have a really, really difficult time accessing any kind of parasympathetic responses down the way, where if you have something really small, where you're bringing blood sugar up, then it's signaling to the hypothalamus, hey, yeah, there's some nutrition on board, then we can start our day.

So again, it has to look at that circadian rhythm and those hormone fluxes, which people don't really either understand or talk about, because all of our hormones flux through the day. And so you have to look at where's the peak of cortisol? How does estrogen flux? How does luteinizing hormone flux, progesterone, all these things that have this tight interplay. And the more we're doing the hormone research and the more we're understanding these perturbations and how important it is to fuel for it to stay out of any kind of low energy availability stance.

Andrew Huberman: Regular listeners of this podcast will know this but just to remind everybody, a sympathetic state has nothing to do with emotional sympathy. Sympathetic arm of the autonomic nervous system, which drives more arousal and alertness, and at higher levels, stress, sometimes called the fight or flight response. Parasympathetic being the other arm of the autonomic nervous system, sometimes called the rest and digest arm of the autonomic nervous system. They work sort of like a seesaw or a push pull. Pick your analogy. In any case, it sounds like intermittent fasting or time restricted feeding, unless it's very well aligned to the circadian rhythm, is not going to be advantageous for women. That's what I'm hearing. I'm also hearing that if a woman trains while fasted, so in the non feeding window, so wakes up, maybe has some hydration and trains, that's going to further exacerbate the stress response in a way that's not going to be good.

Stacy Sims: Exactly.

Andrew Huberman: And I have to imagine that if she also is drinking caffeine in order to do that training, because caffeine is a stimulant of the sympathetic arm of the autonomic nervous system, that it will further exacerbate all these issues. So this is an eye opener for me, because I've had female training partners for years. I don't eat until 11:00 a.m. I like to hydrate and caffeinate before I train in the morning, and then I like to eat starting around noon. Several of them have hopped on that schedule with me. Some of them eat breakfast first, some of them don't. They do as they choose, of course. But now I'm thinking that's probably the worst way to go.

Stacy Sims: And it gets worse as you get older, because if we're seeing as women are getting into perimenopause, which is in their 40s, and we have more fluctuation of those hormones and an increase in baseline cortisol anyway, then when you look at fasted training, it increases that cortisol drive and that sympathetic drive. And because it's at a point where you really need to polarize your training to get any kind of body composition change, not having any fuel before a high intensity workout puts them in moderate intensity, they just can't hit the intensities they need to. Same with resistance training. Like, you go in and a lot of women are now working on sessional RPE or rating perceived exertion, where you go in and say, okay, we need you to hit an eight on this squat. So you have two reps and resistance and a sessional RPE of an eight. Well, if they're not fueled, then we are seeing trends that they're missing around two to 5% of that top load. So they're not really lifting in that zone that they need to be in.

Andrew Huberman: Let's get people, sorry to interrupt. Let's get people up to speed on RPE, because this is a term that's starting to circulate more outside the physical training community into the broader kind of recreational exerciser community, which I consider myself part of.

Stacy Sims: Me too, now.

Andrew Huberman: I mean, I train regularly and have for years, but I'm not an athlete, I don't get paid to train and I, you know, and so forth. So reps in reserve, perceived effort. Let me just explain this. I think probably 95% of our listenership has never heard these terms.

Stacy Sims: Okay so if we're talking about reps in reserve, this is when you go in. And if you say eight, means you have two reps in reserve. So you finish your eight and you should be able to complete two more with a really good form and then you hit failure.

Andrew Huberman: So eight repetitions in good form and the person doing the exercise could, in theory, if they really dug in there, grit their teeth, could complete two more repetitions in good form before hitting failure. The inability to move the weight anymore in good form.

Stacy Sims: Exactly.

Andrew Huberman: Okay. But they're stopping at eight, so they have two reps in reserve.

Stacy Sims: Exactly. And so we can correspond that with your rating, perceived exertion. So if we're saying we need you to hit an eight on our scale of one to ten of a rating perceived exertion, we see it correlates with that eight with two reps in reserve. So it's a way of quantifying what you're doing in the moment for a squat or a deadlift or some other really heavy lift that you're trying to accomplish,

Andrew Huberman: As opposed to looking at, say, percentage of one repetition maximum. Saying you're going to move 70% of your one repetition maximum for six repetitions seems like that's a great thing as well. But it's a little bit more complicated because you need to know your one repetition maximum. Doing one repetition maximums can be dangerous if you're not skilled in that, especially with compound movements like squats and deadlifts.

Stacy Sims: Yep.

Andrew Huberman: Okay, so is there an across the board recommendation for most people that they should generally train their sets in good form to failure to leave a couple reps in reserve? What do you suggest for, let's say, women? But this could also pertain to men.

Stacy Sims: And then that also depends on the age of the woman. So if we're looking at the reproductive years, so, you know, 20 to 40, then it doesn't matter so much. You can periodize pretty much how normal periodization works with your mesocycles and your microcycles. So you're looking at what you're doing across a few months. What are you doing in the week? Are you lifting heavy power based training. But when we start to get to perimenopause and we're losing all the flux of estrogen, and estrogen is woman's testosterone the key driver for strength and power? We have to look at lifting heavy. So this is where we really turn women on to. We want you to do something that is two reps in reserve, three reps in reserve, because your one rep max also changes depending on what kind of training block you're doing. So we're finding that when you're talking about reps in reserve, then it allows people to lift more on the day so we can get women to get into that strength and power based type training, rather than going, let's lift to fatigue, because then it might be 20 reps. And that 20 reps doesn't invoke a big central nervous system response, which is what we want. It's more of that hypertrophy and muscle tearing. You will gain some lean mass, but not as much strength as if you were to invoke that central nervous system response. And that becomes really critical as women get older, because we need to find that external response that's going to cause the same kind of strength and power adaptation that estrogen used to support.

Andrew Huberman: Interesting. Lots to talk about in terms of exercise. But before we move on, if the bad situation is a woman fasting, drinking caffeine, and training intensely, but as you told us, not as intensely as she would be able to otherwise, what's the solution? I imagine that solution involves ingesting some fuel. What is a good example of a pre training meal, if you will? And we could put some variation on that for people with different tendencies towards omnivore or vegan or whatever, but what is the timing of that meal relative to training that works best? I'm assuming there's some flexibility there.

Stacy Sims: Yeah. I'm the kind of person gets up and is out the door within a half an hour to go do whatever I'm gonna do. So it's not like I'm gonna have a full meal.

Andrew Huberman: I've heard of people like you. Yeah. Meaning I tend to move slowly in the morning.

Stacy Sims: I wish I could, but the way my life is, it doesn't work that way. But I'm also one of the people that never really has an appetite till 11:00.

Andrew Huberman:  Okay, so we're similar in that way.

Stacy Sims: Yeah.

Andrew Huberman: So how do you square that so.

Stacy Sims: I make a double espresso at night and I put some almond milk and a scoop of protein powder in there. So the almond milk is sweetened and usually it's unsweetened but sweetened for the carb and then the protein powder for the protein. Because if I'm going to go do an ocean swim, then I need some carbohydrate and protein on board. If I'm going to just go to the gym, then I'll probably just have the protein powder and the coffee. Yes, I'm caffeinating, but I'm also getting the calories for the hypothalamus and getting more circulating amino acids. Abby Smith Ryan out of UNC did some specific work looking at carbohydrate protein before and strength or cardio, and found that if you're going to do a true strength training session, you only need around 15 grams of protein before you go to really help you get into the idea that, yes, you have some fuel on board and also increases your post exercise oxygen consumption or your epoch, so your resting metabolism stays elevated, giving you a better chance for recovery post exercise as well.

If you're going to do any kind of cardiovascular type work up to an hour, then you're adding 30 grams of carb to that. So it's not a lot of food and it's not a full meal. Other people are like, I'm starving right before I go training. Then yes, you can have your meal giving yourself about half an hour before, but it doesn't have to be major food that we're talking about. But that's just enough to bring blood sugar up and, and stimulate the hypothalamus to say, yeah, there's some nutrition coming in and then you have your real food afterwards. You have your breakfast afterwards within 45 minutes.

Andrew Huberman: As a neuroscientist, I find it so interesting that at least some of what you're talking about with this pre workout meal, and perhaps most of it relates to how ingesting those calories impacts the brain, protects those kisspeptin neurons. We'll talk more about kisspeptin, very interesting peptide, as opposed to saying, okay, you need x number of calories because you're going to burn x number of calories.

Stacy Sims: I hate that conversation.

Andrew Huberman: Which is a very different conversation here. What we're talking about is the neural aspects of being able to generate intensity. Also blunt cortisol and get the most out of training without putting the body into kind of an emergency state.

Stacy Sims: Yeah. And the longer someone withholds food after exercise. And the greater they stay in that catabolic or breakdown state, the more the brain perceives it as being in a low energy state. So the first thing to go is lean mass. When you start telling a woman that, you know, if you're going to do fasted training and or you're going to delay food intake afterwards while you're training, because the first thing that goes is lean mass, and it's really, really hard for women to put on lean mass. So once you start really nailing that and then saying, look, you just need 15 grams of protein to really help and be able to conserve that lean mass, it's a small, simple fix. People try it and they're like, oh my gosh, I feel amazing. So small little things when you're working with the whole system because I get tired. Especially around Christmas time, when you're reading all the magazines, it's like "two cookies means you have to walk for 30 minutes on the treadmill". It's like it doesn't correlate like that at all. So that's why I was like, I hate the calorie conversation because it's just not applicable, right?

Andrew Huberman: And it has its own kind of elements of being laced with neuroticism about calorie counting, and then that can drift easily into the realm of eating disorders. I did an episode about eating disorders some years ago, and as I was researching that episode, I learned that people with eating disorders, women and men, especially anorexia, become like calorie calculators. Their eyes and their brain just are constantly evaluating the caloric load of food, and it can be obviously very intrusive. It's also the most deadly of all the psychiatric conditions. So that's a long way from hopefully what we're talking about here. But there's the opportunity for drift whenever talking about calorie counting in and out. We of course, believe in the laws of thermodynamics and calories in, calories out. But I love what you're describing here as getting the brain in a mode that the brain and body are protected so that one can invest in that high intensity exercise and get the adaptations that one wants, but not send everything down this pathway of just becoming a computer, of how much am I exercising? What did I burn, what did I earn?

Stacy Sims: It's crazy.

Andrew Huberman: It's crazy. As long as we're talking about food and food intake relative to training, what is the suggested post training window in which one should either avoid or make sure they get nutrition? Meaning how long does one have after let's say a resistance training session of about an hour. Seems to me that's what most people are doing if they're investing in resistance training, maybe plus or minus what, 20 minutes and they're hitting those high intensity sets where they have maybe just one or two repetitions in reserve, maybe going to failure on a few of those sets. What do you recommend women eat after they train?

Stacy Sims: So we know that women who are in their reproductive years need around 35 grams of good protein, high quality leucine oriented protein within 45 minutes. And we see that women who are perimenopausal onwards are 40 to 60 grams because we become more anabolically resistant to food and exercise as we get older. When we look at the recovery window for food, there are definitely sex differences because we hear all the conversation of there's no recovery window. It's old science, but we look at the research of when women's metabolisms come back down to baseline, meaning that they have constant straight blood sugar levels versus men. Women it's within 60 minutes and for men it's up to 3 hours. So when we're looking at the data that says there's no window per se for getting food in, it's based on male data. So when we're looking at women we have this tighter window to stop that breakdown effect and start the reparation. So yeah, it's like when we're talking about the protein intake, it's really important not only to get that leucine content up in the muscle to start the reparation and repair, but also again to signal that yeah, we're in a building state, we're not holding that catabolic state and increasing all the repercussions that come with it.

Andrew Huberman: So women should try and get 30 or as much as 40, maybe 50 grams of protein depending on their age. Post training, within an hour of training, men seem to have a longer window. They could wait an hour, 2 hours, maybe even 3 hours before ingesting protein. What about carbohydrate?

Stacy Sims: We look at mixed, but for men it's more important because they go through their liver and muscle glycogen so much faster than women. So when we look at women we want to get around 0.3 grams per kilo of carbohydrate within 2 hours of finishing. So we look at protein and people are like whoa, that's a big dose of protein. How do I get it all in? It's like, yeah, well you can look at how we mix all of these things and you're also getting carbohydrate in with that. So that's why I say you could have your next meal after your training session. Yeah, there's a time and a place for protein supplementation, but if you're getting that real food and then you're also getting, you know, your magnesium and your potassium and your sodium and all the things that people supposedly lose, and you're able to also repair a lot better.

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At some point, there was a lot of discussion about training fasted burns more body fat. I think now most people accept that that's not the case, that perhaps the percentage of fat as fuel is increased when one trains fasted, but that overall, in terms of loss of body fat, it doesn't matter if you train fasted or you train fed.

Stacy Sims: Correct.

Andrew Huberman: Okay. I think that can't be stated enough by experts like you. That doesn't mean that if one prefers to train fasted or with a minimum of food in their gut, that they can't do that. I like to train fasted, but what I'm hearing is that women should probably ingest at least some protein, high quality protein, and maybe drink the protein in a protein shake form if they don't want to ingest solid food.

Stacy Sims: Yeah. I think the easiest way for people to understand the basic idea of what low energy is and how this affects men and women is when we are looking at a tipping point for endocrine dysfunction. For men, we're seeing that tipping point at 15 calories per kilogram of fat free mass. For women, it's 30. So when we're looking at baseline calorie needs, before you really get into that endocrine dysfunction, when you're looking at those parameters, you can see why men do better in a fasted state or a low calorie state. But for women, our intake and especially our carbohydrate needs are so much higher because we have so many other functions that are reliant on that kisspeptin, up regulation or downregulation, preferably up regulation. So when we're just talking the basic calorie needs and what we're seeing, it's that dichotomy right there of 15 to 30. And when you start telling people that, they're like, oh, okay, I get it. Is that a biological aspect? It's like, well, you could trace it all the way back where men went out to get the calories in most tribes and the women were home, and it wasn't advantageous to be pregnant under low calorie intake. That's why you have dysfunction when the calories are too low. But you can also feed forward to modern day now, and you're seeing that all this perturbance of hormone and the way we regulate hormone across the circadian rhythm requires more calories for women than it does for men.

Andrew Huberman: I know some men that basically don't eat all day and then eat one meal in the evening and they'll train in the morning. That's inconceivable to me. Within an hour or so of training, I'm hungry. Which brings to mind and what we mean when we say training. I'm a big believer in people, everybody getting, ideally, two or three resistance training sessions in per week and two, maybe three cardiovascular training sessions per week. That would be ideal. One could potentially do more, probably not a whole lot less, before you run into long term health issues that you could offset. But I think most people can fit those in. And I'm very frankly delighted that nowadays there's such a push for women and men to resistance train. That wasn't the case when I was growing up. You know, I recall taking my sister to the gym for the first time, and I think she was the only woman in the gym when we were in high school, except for a few female bodybuilders. And she said, well, I don't want to look like that. And I said, well, don't worry, you're not going to look like that. But now you go to a gym and women are lifting weights, men are lifting weights.

Stacy Sims: It's great.

Andrew Huberman: It's terrific.

Stacy Sims: I've seen the evolution. When I was 16, one of my friend's brothers was a bodybuilder, and he took us to the gym, kind of like what you did with your sister. And so both of us were like, oh, we want to beat those guys. So we got into weight training with him. Not to be a bodybuilder, but it's been like the paramount throughout all of my athletic career. Used to be I'd be the only woman on the lifting platform, and now it's like, you have to wait because there's so many women on the lifting platforms. I love it. It's great.

Andrew Huberman: Yeah, it's awesome. As I mentioned before, I've had female training partners and they kill it. It's a lot of fun to have a female training partner also, because not only is it cool to see the progress they can make really quickly, which surprises them often. I think a lot of women think that, okay, it's going to require a external androgens or it's going, you know, and what you pointed out that there are some barriers to women putting on mass quickly. I think I've noticed that strength increases, can come really quickly.

Stacy Sims: Yeah.

Andrew Huberman: Why is that?

Stacy Sims: It's a central nervous system aspect. There's a lot of, like, if we look at the culture of how a lot of us grew up, and I'm saying us, like 45 plus, right. The women were all the 90s supermodels don't show muscle, that kind of stuff, so always been gravitated to cardio. Even now, if you go to a gym and you're a new member, you're signing up for a new member and you're a woman, they'll say, hey, great. Here's all of our spin classes and our box fits classes.

Andrew Huberman: We're still doing that.

Stacy Sims: Yeah. And there's a cardiovascular machines. A guy comes in like, all right, how much do you want to put on? Here are the lifting platforms, all the, you know, the weight trainings at the back. Starting to see a shift with boutique type gyms, but that's still the commonality there. So it's still that little bit of taboo. When women start strength training, they haven't been exposed to that kind of central nervous system stress before. And the whole aspect of getting the nerve and the acetylcholine, which are little vesicles that hold the ability for the nerve to actually stimulate the muscle fiber, all that gets trained really quickly. So the more that you train it and the more muscle fibers that are recruited for contraction, you see an increase in strength really rapidly and slowly building on that for increased muscle bulk because it takes a long time for women to put bulk on, because the driver for strength training is that central nervous system. So it's great when we see higher doses, more volume. We aren't seeing huge hypertrophy. We're just seeing really good increases in strength.

Andrew Huberman: Whenever somebody, male or female, is concerned about growing too big too fast, I always remind them that resistance training is unique among different types of exercise, in that because of the blood flow to the muscle during the exercise session, the so called pump, you get a window, a transient window, but a window nonetheless, of what the hypertrophy could look like if you do everything else correctly in terms of recovery. So provided that the size of the muscle during the training session is not aversive to you, you're okay.

Stacy Sims: You're good.

Andrew Huberman: Which is unique among training. It's not like when you go running, you get a sense of being much faster. You actually get the opposite effect. You feel the burn in your lungs and the pain of hitting the wall of your limits, and then hopefully, if the adaptation takes place, then you can push past that next time. But with resistance training, you get literally a physical picture and a, and a somatic feeling for what that hypertrophy could look like.

Stacy Sims: Yeah, that's why on your physique competitions and bodybuilding competitions, they're out the back pumping before they go on stage.

Andrew Huberman: So we've been talking about training, but we haven't really spelled out what you would suggest a novice, perhaps an intermediate resistance training cardiovascular training program would look like in broad terms. I realize we don't have time here to get into all the nitty gritty details you've written about this elsewhere, and we'll refer people to those terrific resources in the show note captions, but what would you like to see women doing? And maybe we can break up the age brackets, because it sounds like this is something that is resurfacing again and again here. Women, let's say 30 and younger women, 31 to, let's say 40 and then let's say 41 to 60 and then maybe 61 and on. In terms of how many sessions of resistance training per week, is it whole body training? How many sessions of cardiovascular training and what sorts of examples could you give?

Stacy Sims: Yeah, so if we're looking at that 2020 to 30 year old, a lot of times I really try to get them to focus on the whole movement aspect first. So we phase them in. Same with older women. Phase them in, learn how to move, learn complex movements so that when you are going in to do resistance training, preferably three to four times a week, you can look at moving well. And it doesn't have to be a long period of time if you're doing to failure, which works really well when you're younger, to increase strength and a little bit of hypertrophy, you're going to have to spend a little bit more time in the gym. So it might be 45 to 60 minutes. When we're looking at doing that four times a week, you can add in a sprint interval training at the end of one of those to get that super high intensity, or you can look at putting in at the most two hit sessions from on separate days if you're training specifically for something. So if I work with a lot of endurance athletes still, and they're like, well, how do I fit it in? It's like, okay, well, we look at the quality and how that fits into your training. So if you're training for a marathon, you're training for a triathlon or, or other endurance stuff, you can take that high intensity work and put it into your training program. So ideally, we look at three to four resistance training with really good movement when we're in the younger set with too high intensities.

When we start getting into our thirties, we start having an eye to how are we actually doing that resistance training instead of just going and doing a circuit, we're really focusing on, let's do some compound movements, let's look at doing some heavier work. Let's look at how we are periodizing. So we're having six week blocks, and we're building on those blocks because we want that base foundation. So when we get to be 40 plus, we can actually go and do our power based training. If you're in your 40s, you've never done resistance training at all. Then we take between two weeks to four months to really learn how to move well, because there's a higher incidence of soft tissue injury and overall injury as we get into our 40s because of perturbations of estrogen. And ideally, when we get there, we're looking at that around three minimum three resistance training with compound movements and either one sprint interval or two sprint intervals, and one hit in a week.

Andrew Huberman: And just to remind people, compound movements, multi joint movements, squats, deadlifts, chin ups, rows, overhead presses, bench presses, etc. As opposed to isolation movements where only one joint is moving. And for everybody, in all those age ranges that you describe, are you suggesting they train the same muscle groups three or four times per week, or they do some sort of split where it's upper body, lower body take a day off, or upper body take a day off, lower body take a day off? What might work for them?

Stacy Sims: Yeah, what works for them. If you're looking for short amount of time in the gym because of busy lives, and you can split it if you're looking at, okay, well, I can allocate an hour to an hour and a half in the gym, then you can do total body with adequate rest. The key when you're younger is working to failure. The key when you're older is working heavy.

Andrew Huberman: Interesting.

Stacy Sims: Yeah. So when we're looking at working to failure, we're trying to get more of that lean mass growth with strength when we get older because it's so difficult to put on lean mass, we really want to focus on the strength component because that becomes more important when we're talking about longevity. Because if you're looking at the strength component from a central nervous system standpoint, we see it feeds forward into better proprioception, attenuation of cognitive decline. And this is the other thing that you, in neuroscience, would understand, the sex differences in things like dementia and Alzheimer's. There's some really interesting research looking at strength training and that power based stuff when we're getting into our older ages, because we get more neural growth patterns and more neural pathways.

Andrew Huberman: Even some interesting literature about emphasizing some unilateral movements as people get older, not just dual limb movements or dual limb simultaneous movements. You always want to train both sides of your body, folks. But. So if I understand correctly, younger women should train to failure, try and generate strength and hypertrophy. As women get older, they should emphasize more strength training, leave some repetitions in reserve, but train heavier. It makes so much sense, what you're saying because what we know about the nervous system as we age is that there's some atrophy, or at least some weakening of neuromuscular connections and the upper motor neurons in the brain that control the neuromuscular connections in the spinal cord out to the muscle. There's something really sticky about this idea in terms of longevity that I don't think anyone else has ever said.

Stacy Sims: No. The thing about it is men age more in a linear fashion, whereas women, we have a definitive point in our late 40s, early 50s, where all of a sudden things go to shit, where it's that perimenopausal state. And I can't tell you how many emails and DM's I get in a day from women who are like, I'm 46 or I'm 47, I'm putting on body fat, I don't know what's going on, I can't sleep. And then we say it's perimenopause. What is that? When we're looking at perimenopause, it is a huge change in the body because you're having less and less of your sex hormone circulating. More and more anovulatory cycles means no progesterone or very low progesterone. You're having a difference in the pulse of your estradiol to those flat line aspects. And because every system in the body is affected by it. This is why you see more soft tissue injuries. Like, two of the biggest things that women who are in their 40s are going to pts about are frozen shoulder and plantar fascia. Those are two really indicative issues that are happening in perimenopause. So that whole section of mid 40s to early 50s is a definitive aging point where I really tried to get women to get into the heavy lifting and get into the patterns of polarizing their training, not putting an emphasis on zone two, just really looking at how am I polarizing, how am I affecting my central nervous system, so that when they get into that one point in time of that perimenopause, their body is already conditioned for the stress that's coming. Whereas men, we see that kind of stuff happens in their late 50s, early 60s. So the soft tissue injuries, the change in body comp comes at a later time. So, yes, looking at how we're scoping our strength training, definitely something to think about in a longevity factor. But for women, there's a better indication of the timing across the ages of when you should start implementing. For men, I think you have a better bandwidth of when you should start implementing.

Andrew Huberman: For women who are not on hormone replacement therapy. And we did a previous episode about perimenopause, menopause and hormone replacement therapy. But if it comes up again and again today, that would be wonderful because these are important under discussed topics.

Stacy Sims: Absolutely.

Andrew Huberman: For women that are not on hormone replacement therapy who decide to train heavier, maybe do a bit more training volume, not train to failure, they're making sure to not let their cortisol spike too much by making sure they have some pre workout nutrition, some post workout nutrition, would they be wise to be very careful in how much cardiovascular exercise they add to that? Meaning there seems to always be this risk of over training. And as you pointed out, for various reasons, cultural reasons, historical reasons around exercise, my observation is that most women, sort of, unless they know better, default to cardiovascular exercise as opposed to resistance training. So if a woman in her 40s, late 30s to let's say 50, is doing two to four sessions of resistance training workouts per week, and they also really like cardio, or they feel they want to or should do cardio, should they be careful about how much cardio they're doing? And is there a best form of cardio? Should they, should they really emphasize the high intensity interval training? Should they avoid zone two? We should probably also define for people what zone two is if they don't already know.

Stacy Sims: So I am notorious for slamming things like Orangetheory and F45 because they market specifically to that age group of women and it's not appropriate because it's not true high intensity work. When we're looking at women who are really trying to maximize body composition, change and longevity, unfortunately, default to cardio because they think, oh, that's going to help change my body composition, it's going to help me lose body fat. It doesn't.

Andrew Huberman: Is this things like soul cycle as well? I've never done any of these, but I imagine there's a lot of spinning, a lot of moving, a lot of sweating and a lot of calories burned emphasis.

Stacy Sims: Yes, there is, but it puts women squarely in moderate intensity, where they're so used to leaving one of those classes feeling absolutely smashed that when you tell them, actually, that training doesn't work for you because it's putting you in a state of intensity that drives cortisol up. But it's not a strong enough stress to invoke the post exercise growth hormone and testosterone responses that we want to dampen that cortisol. So this is why we have that hyperbole of women who are in their 40s plus shouldn't do high intensity work. It's like, well, actually, they shouldn't do moderate intensity. They need to avoid that polarizing. Absolutely. That's what we want. We want true high intensity work, which is one to four minutes of 80% or more. Or if you're doing sprint interval, it's full gas for 30 seconds or less, and you're doing that a couple of times a week. You're not doing it every day because you need to have enough recovery to hit those intensities, truly, because those are the intensities that are going to give you those post exercise hormonal responses to drop cortisol.

When we're looking at women who are like, oh, well, I love going out for hours and hours on my bike, and I love doing my spin classes, it's like, okay, but we need to look at the big rock here. If you are looking for longevity and body composition, change and cognition and all those things, you have to polarize your training, and that has to be the focus. But soul food, like, I come from a long background of endurance. I now love riding my gravel bike on the weekends for long periods of time, which is not optimal for me, my age, that kind of stuff, for all the things that I want to see improvements in. But mentally, it's great. So when we talk about going out for that long stuff, zone two is at low conversation, and that's fine for mental health and being out in nature for optimal health and wellbeing, we don't want to do that. We want to look at resistance training as a bedrock and true high intensity work to help with body composition, change, metabolic control, insulin sensitivity, brain health, and dropping that cortisol.

Andrew Huberman: I have family members who are women who are thin because they love to walk, and they just walk a ton and they eat well and enough, but they are resistant to resistance training. And if they do pick up a weight, it's usually some very light dumbbells do a few curls, a couple tricep extensions, and aren't really leaning into the higher intensity work. I think this is pretty common. And my observation is that it's common, not because they couldn't be incentivized to do the higher intensity work. But that learning the complex compound movements, like how to squat properly or even leg press properly, deadlift properly, can be a bit overwhelming, especially when one walks into a gym. This is true for men, too. All this stuff, all this equipment, all these bodies, and these people look like they know what they're doing. Like, if I were to go into an advanced, like, kitchen or symphony and, you know, all these instruments, I don't know how to play.

Stacy Sims: Yeah.

Andrew Huberman: So what's the best line of attack for somebody who really wants to overcome this longevity barrier? Because clearly, resistance training, proper nutrition work, and the cardiovascular exercise piece is a little bit more intuitive. Walking, you do it faster. You're jogging, you do it faster. You're running.

Stacy Sims: Yeah, yeah.

Andrew Huberman: The bike, the SoulCycle class, etc. It's easier in terms of the mechanics. One can still get hurt, but it's just more straightforward. Is there a way that in the absence of a budget for a personal trainer, that somebody can learn how to do these movements and, as you said, ease into them over the course of even up to four months in a way that they can be confident that they're unlikely to get hurt and really build up their capacity to do real work that can benefit them?

Stacy Sims: Yeah, this is where I love technology, for one thing. But if we're staying really basic, I look at some of my family members, and I've gotten them started with just body weight stuff or loading a backpack with cans to add a little bit of resistance so they feel comfortable in their own house, and they might be doing lunges or squats, just keying them up of, like, wear, foot placement, and knee and that kind of stuff. So they're getting used to that kind of movement. I love Kelly Starrett's stuff with mobility. So show them, like, here's how we do some of the mobility to find where the sticking points are. And then you can either direct them to some of the programs that are out there that, like Haley happens, has some really good ones for women who are 40 plus. So does Bree and then Sonny Webster down in Australia, you can send in a video of what you're doing, and he can critique you and tell you things to do. There are other programs like that, too, so there's lots of ways of getting help if you seek it. The personal trainer is very much a stumbling block for a lot of people. And as much as I am not a fan of Planet Fitness, I am a fan of the fact that they've made it really easy for someone to walk in who's interested in resistance training. And they can go to a circuit, one of the circuit things that they have at the back, and they can start resistance training on machines, which is another level up to learning compound movements. So there's lots of ways of breaking that barrier to entry. You just have to find the motivation factor of what's going to incentivize the person to give up their time walking every day and taking time to go to the gym or taking time to do garage based stuff that's going to improve their lean mass.

Andrew Huberman: I'm a big fan of machines, especially plate loaded machines, but machines just create the close to correct or correct arc of movement.

Stacy Sims: Yeah. For your size.

Andrew Huberman: Yeah exactly. And to really spend the time adjusting the seat height, adjusting the various pins on the machine, not just the weight, in order to make sure that one gets the best range of motion. I think this is something small, but that is significant in terms of its impact. People just plop down in a machine, especially if you're working in with somebody and feel, especially beginners will feel pressured to move quickly and they won't adjust the seat height. And so it's just all wrong for them. And all it takes is a little bit of time to and ask people how to adjust the machines.

Stacy Sims: I'm also a fan of kettlebells in the garage or lighter dumbbells that you can do like thrusters or hang cleans or something like that to get the momentum and movement feeling, because that's another good learning curve for people. So, like I said, there's lots of ways that you can implement things based on someone's intuitive, like or dislike of resistance training.

Andrew Huberman: So you've mentioned polarized training. If I understand correctly, this would be a woman doing three or four days of high intensity resistance training for 45 to 60 or 45 to 75 minutes per session, and then at the opposite extreme, maybe just walking a lot or jogging a lot. So is that what you're talking about? Polarized training, as opposed to these other forms of training, where it's designed to get people sweating like crazy, breathing hard for long periods of time, but neither putting them in the landscape of inducing muscle strength adaptations and hypertrophy adaptations, nor really taxing the cardiovascular system enough to create an increase in longevity for instance.

Stacy Sims: When I talk about polarizing, I look at the high intensity strength, like, that's really hard on the central nervous system. And then we look from a cardiovascular standpoint of doing true high intensity work. So the walking is more of the recovery. So if you're going to go out and do something long, it has to be very, very easy. If you are looking at cardiovascular and you want that big sweat, then we are talking true sprint interval training. So what I have a lot of women do is a 20 minutes lower body heavy set, and then they'll go on the assault bike and do as hard as they can for 30 seconds and then recover as much as they need to to go, then do another 30 seconds as hard as they can. Most people go, oh, I can do four or five of those. After two, they're completely gassed because it's that hard of work. And that's what I mean by polarization. You have very, very low intensity for recovery, and super, super high intensity for metabolic and cardiovascular changes is what we're after.

Andrew Huberman: I'd like to take a quick break to let you know that the Huberman Lab team has launched a new podcast with host Doctor Andy Galpin. Andy is an expert in exercise science and human performance, and has long been a fan favorite on the Huberman Lab podcast. This new podcast is called Perform with Doctor Andy Galpin, and it dives into topics such as how to build muscle and strength, how to improve your cardiovascular health, and how to optimize recovery and sleep for performance, and much more. Andy is an absolutely fantastic educator and true expert on all things human performance. I know you'll thoroughly enjoy his new podcast and learn a ton of useful knowledge from it, so please check it out and give it a subscribe wherever you're watching or listening to podcasts. Now again, the podcast is called Perform with Doctor Andy Galpin.

Let's talk about the menstrual cycle and how that impacts training at the level of psychology and physiology, meaning. And of course, the two are linked. They're inextricably linked. For instance, is there a particular phase of the menstrual cycle where a woman should expect that motivation and or recovery would be more challenging?

Stacy Sims: So this is the sticky point of recent science, because we see all these research studies and meta analyses that are coming out of the sports science literature saying that there is no effect of the menstrual cycle on anything. When you look at that population, it is specifically humanoraic. Women might have a subject pool of ten, if you're lucky, twelve.

Andrew Huberman: So this is women who have "normal menstrual cycles".

Stacy Sims: Supposedly ovulating, so they have a definitive low hormone and high hormone phase.

Andrew Huberman: And this is probably because these studies are being done on university campuses with college undergraduate women.

Stacy Sims: Yes, exactly.

Andrew Huberman: Which typically is in a given age range.

Stacy Sims: Right. And they look at performance, meaning that one point in time, and we know that psychologically you can perform at any point in the menstrual cycle, unless you have something like heavy menstrual bleeding. When we're looking at a higher touch and looking not only from a molecular aspect, but also pulling in mixed methods and looking at the qualitative, we need women to track their own cycle and find their own patterns, because we know that there are times where you feel like crap and you can't push intensity. But that might be on day eight for one woman, it might be day 18 for another. From a molecular standpoint, we know that the low hormone phase, being day one, is the first day of bleeding up through ovulation, which is midway through your cycle. You have a greater capacity for pulling in and accommodating stress, physical and mental stress. So if we're looking at doing heavier loads, we're looking at doing high intensity work, we're looking at motivation, then that low hormone phase is really optimal for trying to hit a pr or trying to hit a new speed, because you can take on that stress and your immune system handles it. Your muscles handle it, your core temperature, everything handles it.

Andrew Huberman: So for most women, in the weeks before their period, they're going to feel more robust, except right up until the point of menstruation, or the inverse.

Stacy Sims: It is day one, a bleeding up through mid cycle, that I feel great. The sticky point comes, not every woman ovulates. And this is a thing when we're looking at general pop, we have lifestyle stress, we have nutrition stress. We know that women, for the most part, have four to five anovulatory cycles a year. This is where, when you're looking at that high hormone phase, we can't say you're definitively in the high hormone phase. So this is where we need women to track their own cycles and understand their own patterns. Because in an ideal world, we know that in the luteal phase, this is where we have the most change, where we have a pro inflammatory response from the immune system, we have inability to access carbohydrate as well. We have a higher sympathetic drive. So there's lots of things in there that are, aren't so fantastic for accommodating stress.

Andrew Huberman: So, broadly speaking, the luteal phase is associated with more cortisol, more kind of baseline levels of stress. Would it make sense for a woman to try and offset some of that with a bit more nutrition during that phase, a bit more, perhaps complex carbohydrate. We know that some complex carbohydrate can blunt some of the cortisol response, maybe just even a little bit more attention to eating.

Stacy Sims: Yeah, absolutely. I mean, core temperature goes up, but the whole goal of the luteal phase is to build tissue. You. So this is where we're seeing a lot of shuttling of carbohydrate and amino acids to go to build that endometrial lining. And that's the whole goal. So, yes, you need to eat more protein. You need to eat more carbohydrate. But again, the sticking point is, did you ovulate or not? So if you aren't aware of if you ovulated or not, you're tracking your own patterns, then just be acutely aware that in about the week before your next period comes, you really need to be amping up carbohydrate and protein, because that's going to help you hit intensities. It's going to kind of level that playing field, especially on days where you feel like you can really hit those intensities. You feel great, but then you go to do something and your heart rate's higher than it should be, you don't feel that that you can hit those. If you're offsetting it with some increased carbohydrate beforehand, you're going to hit it. So it's, again, it's really dialing it back down to the individual now, because we don't have enough robust research to make generalized ideas because of the nuance of have you ovulated or not? What are your ratios of estrogen, progesterone, in that luteal phase. So when we bring it back down to the general pop, it's like the best thing to do is to track your menstrual cycle over, sleep over how you're feeling, find your own patterns, and dial in your training and your days according to what your pattern is.

Andrew Huberman: How hard should a woman push through the mental and maybe even physical resistance to train less or not train during a given phase of the cycle?

Stacy Sims: It depends on how she feels. What we can't rely on are things like heart rate variability, because we know that changes with the autonomic nervous system. Change of progesterone. It's a good indication that you've ovulated because your heart rate variability tanks, but it's not a good indication of what your body can do if you wake up. I always say it's a ten minute rule. You wake up and you feel awful and you're like, I really want to do this workout, but I don't know how it's going to go. Give yourself ten minutes. If after ten minutes you can't hit those intensities or you just feel horrible, change it, drop it down, do something that's more recovery. Do something that's not going to be so taxing because we do have a limited amount of that stress acumen, of how much stress we can handle. So if you're going to try to exert it all in a high intensity workout, what do you have left over for the rest of the day? And then that compounds, because if you're always fighting it, then you're going to increase this baseline sympathetic drive because you're fighting the training, you're fighting life. So give yourself that ten minute rule. If it happens three days in a row, that's okay because it's a very short period of time. It's not going to last forever. So a lot of women have this internal conversation of, I have to do this. And it's really based on some kind of external. They think everyone's watching them, but internally, you don't have to. If you give yourself permission, you end up training better, recovering better, and getting better gains.

Andrew Huberman: On the flip side, if a woman is feeling spectacularly good, should she just really push it as hard as she can? Or is there anything about the relationship between the hormone fluctuations of the menstrual cycle and feeling really, really great that training hard can somehow disrupt the cycle? And this is actually kind of the old lore, probably myth, I would imagine that high intensity resistance training is somehow detrimental to female hormone cycles. I don't think there's any evidence for that, but I hear that from time to time. Why do you think that myth came to be? Why do you think it propagates? And what can we do to extinguish it? If in fact it's not true?

Stacy Sims: It's not true. We see it comes from a misstep in food intake, and we also see that it's a cultural influence, because if we think about how sports started, it started as a way for men to demonstrate how powerful and aggressive they are. And this is the original Olympics, right? There were no women allowed. And as we feed forward into sport and how it became okay for women to be involved at the high performance level, if a woman walks in and shows any fallibility, then she's immediately put on a lower stool, right. You can't play with the boys because you have a menstrual cycle. You're bleeding. You're a woman, you're a delicate flower. So women would walk into that professional sports space and be excited if they were amenorrheic or didn't have periods, or they trained hard enough and their period went away because then they were more like men and they could play with the boys. If you start bringing up menstrual cycle in professional sport now, as of the past about four or five years, it's okay to talk about, which is, you know what, 2020. So that myth of high intensity resistance training causing issues with the menstrual cycle, one, it's a cultural nuance for pushback against women being in that space. But then the reality is women weren't eating enough to accommodate for that stress, which then feeds forward to low energy availability, maybe relative energy deficiency in sport perturbations in all of our menstrual cycle hormones. So it's not the act of the high intensity resistance training, it's the act of not fueling appropriately for it and then getting the okay to not have your period because, yeah, now you're in with, you're training hard enough, you've lost it. You're more like a man.

Andrew Huberman: Wow, very interesting history there. Is it true then that if a woman maintains either caloric balance with her basically eating enough to support her energy output or even a slight caloric surplus, that it's unlikely that her periods will cease even if she's training very hard and very often?

Stacy Sims: Correct.

Andrew Huberman: So it basically boils down to calories in, calories out.

Stacy Sims: Fuel for the task at hand, because some people want to have a slight calorie deficit even in high training. And if that deficit is at night, away from training, maybe 150 to 200 calories, then it's going to help perpetuate body fat loss, not lean mass loss, and it's not going to interfere with recovery. It's the fueling in and around the stress, meaning the exercise stress. It's really important. But women have been so conditioned to not eat and not take up space to be small, you know, all of these socio cultural things that women are afraid to admit the fact that they want to eat and they should be eating. So this is a nuance within the fitness community that we're really trying to change and get the mindset around. You train hard, you eat well, and your body responds in kind.

Andrew Huberman: Appetite, body temperature and hormones are very tightly linked. They are far too tightly for us to disentangle all of those in a single conversation here. But as you're describing the urgent need for women to fuel enough with the proper fuels to train hard enough to stimulate the correct adaptations that they need. I imagine that the, the shift in appetite and body temperature that occurs across the menstrual cycle is also going to play into this. Meaning there will be phases of the menstrual cycle where women will be just naturally less motivated to eat enough, carbohydrate, enough protein in order to get the most out of their training. What phases of the menstrual cycle are those? So that women can pay particular attention to make sure that they're fueling enough.

Stacy Sims: Yeah. As estrogen starts to come up right before ovulation, that estrogen surge really dampens appetite. It also has an interplay with our appetite hormones, which is part of the reason why we don't have that great of an appetite. It holds after ovulation, estrogen dips, you get hungry, it comes up, and people are like, I have some cravings which are driven by progesterone because your body needs more calories, but at the same time, with the elevation of estrogen, you're not hungry. You have cravings, but you're not hungry.

Andrew Huberman: Interesting.

Stacy Sims: Yeah. So it's trying to disconnect those. It's like your appetite is something that will come back, of course, once you eat, but cravings are more of that psychological capacity of, yeah, my body needs more, but I'm not quite sure what. So to get women to understand what's happening across the board, it's always coming back to, let's fuel appropriately for the exercise. And even if you're not hungry, if you are fueling appropriate appropriately at that point in time, if you end up with less, at least you've stopped that breakdown state, that catabolic state. So we don't get those perturbations in the hypothalamus. That's my biggest concern for women is really taking care of that signaling from the brain to the rest of the body. And if we have fuel on board, even though we have appetite perturbations, and if you go do a really hard workout in the heat, you're not going to be hungry either. But if you're having a cold protein drink after that hot workout, you're taking care of that immediate need to shut down the signals that we need to break down things.

Andrew Huberman: Let's talk about one of the many third rails of discussions online, which is, is birth control.

Stacy Sims: Yeah.

Andrew Huberman: And we need to define exactly what type of birth control we're talking about, because there are so many different forms.

Stacy Sims: Yes.

Andrew Huberman: There are IUD's, there are the copper IUD's, there's the ring, there's the, you know, let's talk about oral contraceptives that are designed to prevent ovulation. So this is "the pill".

Stacy Sims: Yeah.

Andrew Huberman: So we're being, let's for now, limit the conversation to that so that there isn't confusion. Share with us, if you will, your thoughts on these, how they impact any of the things that we're talking about, or anything else, for that matter.

Stacy Sims: Can we have another history lesson?

Andrew Huberman: Please.

Stacy Sims: All right. I just gave a talk at home to some young athletes on contraception because someone might be on the depot, and if they're on it for more than two years, they get bone mineral density loss. So then the question of, okay, well, how does the oral contraceptive pill come up? How does that affect things? It's like, well, let's look at the history of it initially came from Stanford. It was funded by Katherine McCormick, from McCormick family, and a feminist activist, Margaret Sanger. But because they were women, they couldn't get in the lab. So they got a guy from Stanford to develop the pill, and he's like, you know what? We need to put in a placebo week so that women feel like they're having a bleed. So if we're looking at the three active pills and then the one sugar pill week, it was by design to make women feel like they are having control over their menstrual cycle and they would still have a bleed. But it's not a true bleed, it's a withdrawal bleed. So this becomes the confusing point for people who are on an oral contraceptive pill. They're like, I get my period. It's like, no, you don't. Because the idea of the hormones that are in an oral contraceptive pill is to downregulate your ovarian function so that you don't ovulate. So you have a whole different hormone profile from someone who naturally cycles. So this depends on the type of oral contraceptive pill you are using. For the most part, monophasic is the one that's most prescribed. So that means the three weeks of the active pill is the same dose of estrogen, progesterone, and then you have your sugar pill week or your withdrawal week, and then you start again. When we look at the repercussions of using oral contraceptive in active women, there's a higher amount of inflammatory responses and oxidative responses. So from a training standpoint, no one's done the study yet, but I would be interested in doing this, of looking at how that impacts adaptation. You do end up with a new baseline of this when you start taking the pill, but we're not really sure how that impacts, impacts adaptation. We also look at the progestin component of the oral contraceptive pill because we have four generations of progesterone. First generation was really high dose and has a lot of risk factors. Not really prescribed that much. Second generation is the most prescribed, and this is the one that people just take. It's in your IUD, it's in your OC, has the least amount of side effects. And then we have a third and a fourth generation. The fourth generation is primarily used for women who have really bad PMS or PMDD, which is your premenstrual dysphoria disorder. So significant mood issues, because that progestin has a direct effect on a lot of the dopamine receptors in the brain as well. The third generation is very androgenic. So we see that in some preliminary research, that improves speed and power by the second week of intake because it's accumulated. So when we're looking directly at an oral contraceptive pill, we can't make generalizations because you have low dose, high dose estrogen, we see that a 30 microgram dose increases hypertrophy, but not strength, because estrogen increases the satellite cell aspect. So for my power and olympic athletes, Olympic lifting athletes, that's a detriment because they'll put on muscle mass, but no strength. So we've had to look at changing their OC or getting them off. For women who have breakthrough bleeding, that higher incidence of or that higher intake of estrogen is really beneficial.

So when we look overall at how it impacts women from an athletic standpoint, it's so variable in the hormone profile that we can't make generalizations. We only look at the very high performance aspects and what's happening up there because that can make or break an athlete. So from the general touch point, we don't know enough. Like the beginning of this year, 2024, there was a study that came out looking at changes in the amygdala that happens with oral contraceptive use. It's reversible in adults, but for young girls, we don't know because their brain is developing. And unfortunately, physicians will pass out OC's as if it's candy.

Andrew Huberman: Oral contraceptives. And do you recall what the direction of the effect was on the amygdala? For those that don't recall the amygdala bilateral brain structure, meaning one on each side of your brain, literally means almond in Latin. It's almond shaped, and it's part of a larger network associated with threat detection. Sometimes it's described the locus of fear in the brain, but it's involved in a lot of other things, too, both positive valence and negative valence, but nonetheless is part of the threat detection system. Elevated levels of arousal, which is why it's often discussed in the context of fear, anxiety, etc.

Stacy Sims: It increased fear in women who were on the OC or a contraceptive pill, made them less willing to take chances. And when they went off it, they're like, well, why couldn't I do that before? So that's why they started looking at the amygdala. And when I say we're looking at young girls, and again, we don't know what's happening, is it reversible in young girls that are put on it or not because of the brain structure changes that are happening? So when we talk about an oral contraceptive pill, I want people to understand that it has a significant effect on the body, not just reproductive. We don't know enough about all the other effects. So I have parents who say, my daughter wants to go on the oral contraceptive pill. She's having irregular periods, she's an athlete, we want to be able to control it. And it's like, if there's an issue with your menstrual cycle now, it's still going to be there when you get off it. So we have to look and see what's going on here. If you're looking to get on it to control your menstrual cycle. Why? Because we know that you can have an increase in your V̇O₂ max and other anaerobic capacity when you are not on it. So you have a better top end capacity when you're not being blunted by these hormones.

And then the other conversation is, oh, my skin. It's like, well, they have really good dermatologists that can help you with that. You don't have to go on an oral contraceptive pill, but unfortunately, gps don't understand all of that. And if a girl comes in and says, I'm having irregular cycles, heavy menstrual bleeding, I want to go on the OC. See, here you go. So it is a huge conversation still be had. I put it in the same category as menopause hormone therapy because there isn't enough research to address all the population needs. And we see these big pendulum switches. So before it was like, everyone be on the OC, and now it's like, maybe not. And then it was no one beyond menopause hormone therapy, everyone should be on it, but we need to land in the middle and understand more of what's happening with these exogenous hormones.

Andrew Huberman: Is there any evidence that other forms of female contraception can be, let's just say, problematic for the types of things we're discussing today?

Stacy Sims: Like the implant in the depot?

Andrew Huberman: Or IUD. Copper IUD.

Stacy Sims: Copper IUD and the Mirena, or, you know, your progestin laced IUD. Those are what a lot of my tactical athletes will use, because it doesn't have a systemic effect on adaptation or inflammation, mood, any of those things. And it's a fit and forget. So you can put it in for up to three to five years. If you have a really heavy bleeding, it really dissipates, because the whole idea of an IUD is to thin the endometrial lining, and so then you have autophagy that takes care of the endometrial lining, so you don't necessarily have a bleed. The copper IUD is different because you do have really heavy bleeding for the first three cycles and then at weights.

Andrew Huberman: Before we got started today, you mentioned some very interesting pioneering studies on evaluating menstrual blood itself as a window into some larger themes about what's going on physiologically, maybe even psychologically. Now might be-

Stacy Sims: A good segue?

Andrew Huberman: To just touch into that. We can always return to it again later. But let me just ask it more directly. Firstly, what are some things that can be measured directly from menstrual blood that are informative for women? And it sounds like there's a new generation of at home tests that might be interesting and informative for them to think about.

Stacy Sims: Yeah, well, if you think about menstrual fluid, everyone thinks about it as a discard product, but it's a very good indicator of what's happening from an endocrine standpoint. Gives a really good indication of what's happening from an endometrial standpoint. So if you're looking at all the cytokines and the proteins and the tissue that comes from it, it's a huge indicator that's naturally discharged that we're now looking at for determining HPV. Do you have it or not? What about proteins for PCOS? Can we really identify PCOS or endometriosis?

Andrew Huberman: Can we talk about PCOS for a moment? Most people have heard of it by now. Polycystic ovarian syndrome. It's associated with typically elevated androgens. It's becoming more and more common or perhaps detected more based on better detection methods. I don't know which. The prevalence of PCOS seems to be very, very high.

Stacy Sims: It does, and I think it's a combination of both. We also see some rebound PCOS that happens when someone gets off an oral contraceptive pill. It's not necessarily true PCOS, because what's happening now, your ovaries are producing eggs that have been downregulated for so long. So under ultrasound, it might look like PCOS, but it's not necessarily true indication. The other is more and more women are starting to eat more, and so they're coming out of low energy availability. If you have more carbohydrate, you end up with greater follicular stimulation, which also shows up as PCOS. So the true PCOS, yes, there is a high incidence from a reporting standpoint, but is it that rebound where it's not having all the androgenic changes? That's still kind of up in the air at the moment, but it is a big concern for women because it is an indication that something's going on and they might have some fertility issues. We see a really high incidence of PCOS in Olympic level athletes. Athletes. Because of the higher androgenic aspect of PCOS. So better recovery time, a little bit higher baseline testosterone. So, yeah, it's a population specificity as well.

Andrew Huberman: In the 80s and 90s, there was a lot of excitement in the neurobehavioral endocrinology fields, largely based on animal literature, but then expanding into human literature, that certain forms of activities could change hormone patterns and maybe even psychology. And that makes sense on the surface of it. But is there evidence that if somebody engages in, say, high intensity training or competitive scenarios, this has been explored a lot in men, but I'm wondering if it's also been explored now in women that androgens go up. I mean, there's been these studies, I don't know how good they are of people on the stock exchange watching their stress fluctuations, measuring testosterone. I think most of those studies were done in men, but other competitive scenarios, even showing, for instance, that exogenous testosterone can increase altruism in men if men are competing for who's donating the most money at a philanthropic event, but you put them in a different scenario where it's far less benevolent in goal, and then exogenous testosterone drives competitiveness towards things that are more traditionally thought of male male competition. In other words, it's all context dependent. Is there anything that springs to mind of interesting studies as it relates to androgens or estrogens in women athletes and as it relates to exercise?

Stacy Sims: They haven't done any specific studies like that in women. We do see that under stress, the cortisol increases, and if you have an adequate response to it and your body can overcome it, then, yes, you get a boost in testosterone. For women, we see this in a lot of the night mission shift changes and tactical athletes. There is also, I guess, a lessening of circulating estrogen. So the pulse changes when we start getting to the end of a really strong training block because we're starting to have a little bit of a downregulation of our luteinizing hormone, pulse and estrogen, but it shouldn't be severe enough to cause menstrual cycle dysfunction. What we want people to do is look at the ratio of their estrogen, progesterone, and keeping track of luteinizing hormone. If they are at that point where they are going to have a really big training block, we look at preseason, during season, end of season, and people who might be at a higher risk factor for becoming amenorrheic, then we keep track that way because it is the stress component that can downregulate, not actually causing a permanent change.

Andrew Huberman: As we talk about menstruation, we should probably talk about iron stores and iron. Do women need to supplement iron given that they lose iron during menstruation?

Stacy Sims: It's interesting because we have a change in hepcidin or hepcidin, depending on which part of the world you come from, because it is increased under times of inflammation and decreased under times of iron loss. So we see a significant change across the menstrual cycle. So I tell women, if you are concerned with low ferritin, then we want you to take an iron supplement every other day, starting at the first day of your bleed, for ten days, because that's going to really allow your body to absorb it and stay on top of it after that every other day. Yeah, but you're not going to be absorbing as much of it because hepcidin starts to come up after ovulation. Again, you have a pro inflammatory response, so you have greater inflammation. Do women blanket need to supplement? No, because we see fatigue isn't necessarily just iron related. There's so many other reasons why women are fatigued. The one problem is the baseline levels for, like, ferritin. For active women, if you go in and you have a ferritin level of 20 to 25, they're going to say it's normal, but we'd rather see you up around 50. So if you are in that low end of normal, then supplementing will help you get up into that 50 and see if it makes a difference.

Andrew Huberman: If a woman is going to get a blood test to evaluate testosterone, estrogen, lipids, metabolic factors, etc. And she can only afford to do that at one point during her cycle and compare at various times, maybe every six months or once a year, even at that specific time of her cycle. Is there a best time in cycle to do that blood test?

Stacy Sims: If I'm limited to say that, then I would say five to seven days before her next period starts, so mid luteal, because then you get a good indication of estrogen, progesterone peak. Testosterone doesn't fluctuate as much as those two, so you're going to get a good idea what baseline testosterone is, and we know that there's a greater inflammatory response. So anything that's outside of the norm of that upper elevation of inflammation, you're going to be able to pick out. So, yeah, I would say if you could only do it at one point in time, that would be the time to do it.

Andrew Huberman: And if she can add a second blood test at a different phase of the menstrual cycle, where would you place that second test?

Stacy Sims: Day two of the menstrual cycle, second day of bleeding to get a really good indication of what your true estrogen level is at baseline.

Andrew Huberman: And if she measures her hormones at those two times within the cycle, do you think that's sufficient to get 75% plus of the relevant data?

Stacy Sims: Yeah, definitely.

Andrew Huberman: Terrific. Caffeine.

Stacy Sims: Yes.

Andrew Huberman: In the old days, meaning when I was a kid and not long ago, three weeks ago, we would hear these crazy statements about caffeine. It pulls calcium out of the bones. You'd hear this stuff. I did a whole episode on caffeine. I'm a big fan of caffeine, but I do warn people that if they suffer from anxiety or they're going through a particularly stressful life event, it can raise the activity of the sympathetic arm of the autonomic nervous system. You'll feel more nervous, you're more prone to panic when you're drinking caffeine. But many people love caffeine. I think 90% of the adult population of the world ingests some form of caffeine every single day.

Stacy Sims: I'm in that 90%.

Andrew Huberman: Likewise, making it the most consumed drug worldwide. Is caffeine safe for women? I suspect, based on what you just said that the answer will be yes. But are there case conditions where women should be cautious about their intake of caffeine, independent of this anxiety thing? I mean, people probably shouldn't drink more caffeine than they can tolerate psychologically. No one male, female, young, or old.

Stacy Sims: Yeah, it's more of a genetic factor than it is a sex factor. So, I mean, both men and women will be fast metabolizers. Slow metabolizers or not, have an effect that becomes the bigger rock of them. What we do find is, in that perimenopausal state, women will become more sensitive to the blood sugar fluctuations that happen with caffeine. So they're used to having coffee in the morning with something. Then halfway through their workout, they become a little bit hypoglycemic because there's changes in insulin sensitivity, insulin responses. So there's changes also in blood sugar control, and caffeine can exacerbate that. So if you are someone who's like, oh, I always have a double espresso before I go workout. And then halfway through, I'm really hypoglycemic. I'm really dizzy and lightheaded. I don't know what to do.

Andrew Huberman: Feel sick or nauseous.

Stacy Sims: Yeah. Eat some food. Eat some food with a it.

Andrew Huberman: What about sipping caffeine through the workout? You know, taking that coffee in and just having a sip between sets? Can that offset some of that?

Stacy Sims: I don't think so.

Andrew Huberman: Okay. I hear a lot that people who drink caffeine before a workout, you know, midway through, they're like, I don't feel good.

Stacy Sims: Yeah. Because they don't eat.

Andrew Huberman: For me, that just stimulates the desire for more caffeine. But. Or even, dare I say, a half piece of nicotine gum, which experimented with. But I was told, and this is why I'm not going to continue to do it. Not only is it very habit forming, it actually is such a vasoconstrictor that I was told by a dermatologist that it's terrible for skin, even if you're not getting your nicotine by smoking, vaping, dipping, or snuffing. So this big trend now toward ingesting nicotine as a stimulant and cognitive enhancer and performance enhancer, think people should at least be aware of the negative effects on skin.

Stacy Sims: Never would have known. Because I'm not a nicotine person.

Andrew Huberman: I'll tell you, that half piece of nicotine gum is, the first time you do it, it's an unbelievable experience. It's like your first real cup of coffee.

Stacy Sims: Oh, really? Wakes you up.

Andrew Huberman: Yeah. And dials you in. I recommend nobody do it because it feels that pleasant. If you like caffeine.

Stacy Sims: I like Schisandra for that reason.

Andrew Huberman: Schisandra?

Stacy Sims: Yeah.

Andrew Huberman: What's Schisandra?

Stacy Sims: It's an adaptogen.

Andrew Huberman: I should know what this is.

Stacy Sims: You should know what this is.

Andrew Huberman: Well, I'm here to learn.

Stacy Sims: Okay.

Andrew Huberman: Schisandra.

Stacy Sims: Schisandra. Yeah. So it is an adaptogenic plant. So, you know, like ginseng, siberian ginseng, maca, ashwagandha, all those buzzwords out there. Schisandra is another really well studied adaptogen. And I have friends who say it's like Adderall, where you take it and it's immediate focus and function because its main goal is to regulate dopamine, serotonin and cortisol. So it gets women and men out of that brain fog, gives them incredible focus.

Andrew Huberman: Do you use it?

Stacy Sims: Yep.

Andrew Huberman: Are you on it now?

Stacy Sims: I put it in my morning coffee.

Andrew Huberman: Okay. You just sent people down the rabbit hole.

Stacy Sims: Yeah, yeah. [LAUGHING]

Andrew Huberman: You heard it here first. Doctor Stacy Sims. I'm gonna give it a try. Because the nicotine thing is an interesting one, and there are some cognitive enhancing effects of nicotine that perhaps in people 65 and older might actually be beneficial for offsetting some forms of neurodegeneration. But that needs to still be explored and researched. Don't cut that and clip it and put it out there like so. That's happened already. Very interesting. All right. Caffeine, we both agree, is great. Schisandra.

Stacy Sims: You gotta try it. Check it out, let me know.

Andrew Huberman: All right, will do.

Cold.

Stacy Sims: Yeah.

Andrew Huberman: For reasons I still don't understand, people have associated me or this podcast with deliberate cold exposure. I like deliberate cold exposure in the form of a cold shower or a cold plunge or an ice bath, mostly for the effects that occur afterward, meaning more alertness, a kind of semi euphoric buzz that goes on a long, long time. No, I don't think it increases metabolism significantly enough to have a meaningful difference. The long lasting increases in the so called catecholamines, dopamine, norepinephrine, and epinephrine, to me, are pretty impressive, and I just like the way it makes me feel. So that's the main reason, I believe, why people do deliberate cold exposure. And every time I do a post about deliberate cold exposure, I get asked, understandably, so how does it affect women differently than men? And then I usually get questions about Raynaud syndrome.

Stacy Sims: Oh, yeah.

Andrew Huberman: Yeah. So is there a difference in terms of how deliberate cold exposure impacts women? I have to imagine the answer is yes, given what you said earlier about vasoconstriction versus vasodilation. But deliberate cold exposure. Like it? Hate it? What do you think? Do you recommend it for women?

Stacy Sims: I recommend it for open water swimmers who might experience that vagal response when they first dive into the cold. I prefer heat for women. Everyone's a responder to the heat. You get better adaptations.

Andrew Huberman: So sauna.

Stacy Sims: Yep. Sauna.

Andrew Huberman: Hot tub.

Stacy Sims: Yep. Preferably a true finished sauna. Infrared doesn't. It warms the skin, but not the core.

Andrew Huberman: Thank you for saying that. I'm not a big fan of infrared sauna. Because it doesn't get hot enough.

Stacy Sims: No.

Andrew Huberman: Yeah. You can bring an infrared light into a traditional sauna if it can tolerate the heat.

Stacy Sims: Yeah.

Andrew Huberman: But finished sauna would be, what, something between 185 degrees Fahrenheit and maybe 210 if you're really heated up.

Stacy Sims: Yeah, I'm still working on metric. Let me do the conversion.

Andrew Huberman: Oh, sorry. Yeah. You're living down in New Zealand.

Stacy Sims: Yeah. So 60 to 80 degrees Celsius.

Andrew Huberman: I need to look. Every time I've tried to do math on the fly on this podcast.

Stacy Sims: I know, it's like, okay, times nine divided by-

Andrew Huberman: Different process mode.

Stacy Sims: Yeah.

Andrew Huberman: People can look it up.

Stacy Sims: Yeah.

Andrew Huberman: Okay.

Stacy Sims: Look it up. So the thing with cold water exposure is the whole conversation about ice cold ice baths and how cold it is. It's too cold for women, because when we're looking at that severe, immediate jump into that icy cold, it causes such severe constriction and shutdown. So women do really well and get that whole dopamine response and everything. If the water is around 16 degrees Celsius, which is 55 to 56 degrees Fahrenheit, which is chilly.

Andrew Huberman: It's chilly. It's not warm.

Stacy Sims: No, it's go dive in San Francisco Bay. Right. And that is enough to offset that severe constriction survival. But it is cold enough to invoke all the changes that we want with cold water exposure. So it's a temperature nuance. That's that sex difference. And like I said, when I have open water swimmers who are going to do a long swim or they're going to do a triathlon, the water is colder. I have them do cold water exposure, especially face exposure into the cold water to get them habituated to that initial severe constriction and sympathetic activity that we don't want to happen before. A rice with heat being the true, like, true heat that we're talking about with sauna, we see a lot of metabolic changes for women, so we're having better insulin and glucose control. We're seeing a better expression of our heat shock proteins and the uncoupling and the rebuilding of those proteins, better cardiovascular responses. And then for women, as we get older and have the offshoot of hot flashes, night sweats, that kind of stuff, if you're doing heat exposure, you're sending a stronger stimulus to the hypothalamus, and you're also getting a better serotonin production from the gut, because we have 95% of our serotonin produced from the gut, which lends to better temperature control and shuts down hot flashes.

Andrew Huberman: I think some people might be confused by the idea of using sauna in order to reduce the hot flashes. So I'll just remind people that your brain has a set of neurons in the medial preoptic area that's sort of a thermostat, if you will, controlling core body temperature. And if you heat the surface of your body, your medial preoptic neurons say, oh, let's cool down the core of the body. Now, if you stay in that heat too long, you'll cook, your core body temperature will go up. But conversely, if the surface of your body is made cold, the internal milieu of your body will heat up, because those medial preoptic neurons will say, oh, this is like putting an ice pack on the thermostat, which is what graduate students and postdocs used to do in the lab side working, because it was a battle over the heater. Some people were in hot, some people ran cold. So it was always this business, in any event. So it's not that you disapprove of using deliberate cold exposure. You just recommend that women do deliberate cold exposure with temperatures that are maybe in the low 50 degree Fahrenheit range, as opposed to the really, frankly, just painfully cold for anybody, 38 to 50 degree temperatures. Is that right?

Stacy Sims: We did a pilot study looking because Wim Hof has been down to New Zealand quite a bit, and so his breathing and ice bath stuff has been making the rounds and working in the high performance. People wanted to do that, but we have few athletes that have really severe endometriosis. It's like, well, we could look at using cold exposure to help control that. And what we found over the course of this study was that if we were to do deliberate cold exposure around ovulation and then hold it for ten days over the course of three menstrual cycles. It attenuated the endometriosis. Because endometriosis is an inflammatory disease, right? So if we're looking at inflammation process and growing the tissue, if we can dampen that inflammation and create a response that learns that inflammation and dampens it, then it helps with endometriosis.

Andrew Huberman: Very interesting.

Stacy Sims: That's another avenue that we really want to take when we're looking at cold, deliberate cold exposure.

Andrew Huberman: Wow. Fascinating. As a cautionary note, if anyone is going to explore Wim Hof type methods, please, please, please do not combine cyclic hyperventilation or hyperventilation of any kind with breath holds and water exposure. Not even in the depth of a puddle. There have been drownings associated with people doing cyclic hyperventilation in various contexts. Not just related to Hoff breathing, but basically people who are not skilled and even some who are skilled, combining cyclic hyperventilation, breath holds and water in any form, cold or warm water, just don't. If you're going to do any kind of cyclic hyperventilation breathing, and my lab's actually published on this in a clinical trial, do it on dry land or don't do it at all. And if you're going to do deliberate cold exposure, limit your breathing to slow, deep breath, make sure that you're well supervised, and just stay alive, please.

Stacy Sims: Yeah, we didn't incorporate any of the Wim Hof breathing, we just incorporated the deliberate water.

Andrew Huberman: Cold water exposures, cold and temperature generally is such a potent stimulus, and it's exciting that people are starting to explore this, especially, in my opinion, the sauna work. One thing I suppose that we should discuss very briefly before we move on. Since we've been talking about resistance training, we've been talking about deliberate cold exposure. There is evidence that doing deliberate cold exposure not so much in the form of a cold shower, but in the form of a submersion up to the neck, post strength or resistance training, say in the four, but probably the 8 hours after resistance training because of the attenuation of the inflammatory response, which sounds like a great thing, it actually can inhibit some of the strength and hypertrophy gains that one would otherwise experience. So if you're going to do deliberate cold exposure, best to not do it in the 8 hours or even on the same day after resistance training geared towards developing strength and hypertrophy increases. No problem to do it first. In fact, maybe even some performance enhancing effects of doing it first. There's some athletes at Stanford doing that, but just want to throw that out there. Is there anything else you want to add to that?

Stacy Sims: Which is different from heat exposure because heat exposure, you want to do afterwards vasodilation. Yeah. Because it extends that training stimulus. And also the passive dehydration from training will stimulate greater blood volume improvements.

Andrew Huberman: Oh, interesting. So after a good weight training session, if one has the luxury of doing it, get into the sauna for...?

Stacy Sims: Up to 30 minutes,

Andrew Huberman: Make sure you're hydrating.

Stacy Sims: You want slow rehydration, because part of it is that dehydration and the decrease of oxygen at the level of the kidney to stimulate more EPO. So with more red cell production, you have natural increase in plasma volume. So it's a blood volume expander.

Andrew Huberman: So now we're getting into real performance enhancement. Is this true for men and for women?

Stacy Sims: Yep. Yep.

Andrew Huberman: Let's walk through this protocol. I like this. This has not been discussed on this podcast. So somebody does their resistance training, finishes up, drinks eight or 16oz of water with a little salt in it, maybe, and then hops in the sauna.

Stacy Sims: Yep.

Andrew Huberman: For how long?

Stacy Sims: Up to 30 minutes.

Andrew Huberman: Okay.

Stacy Sims: No longer.

Andrew Huberman: No longer, no longer. Yeah, they'll probably be a little bit thirsty in there. You're looking for a little low level dehydration, is that right?

Stacy Sims: Yep.

Andrew Huberman: Okay. The ranges that I've seen published in the Finnish studies are, as I recall, and I'll double check these numbers. 186 degrees Fahrenheit. Up to about 210 Fahrenheit. And the higher end only being for those that are heat adapted, one can cover their head with a towel and actually feel more comfortable because the brain is insulated. This surprises people. They think putting something on their head would make it excessively warm, but you actually are protecting your brain from some of the heat.

Stacy Sims: And people will put a towel over so that when they breathe, it doesn't burn to the inside of their nose and their mouth either. I'm always like, if you're going to be in and it's that hot, just move down a level on the floor.

Andrew Huberman: Yep. And this stimulates the production of more red blood cells. Okay. Which then translates to what, in terms of athletic performance?

Stacy Sims: You have an increase in your cardiovascular effort. And because you have greater amount of blood volumes, you have greater amount of pretty much blood circulating. So you have more available for muscle metabolism, heat loss. So it's akin to going to altitude. So people will go to altitude to get that blood volume boost. But not everyone responds to altitude because you have responders, non responders, over responders.

Andrew Huberman: Okay. This is why when I go to Colorado, I'm gasping for air while I do a walk. But then I come back to sea level and I feel better. My endurance is better, but some people might not experience that effect.

Stacy Sims: True. This is, I was telling the guys before we started that I've been in our sauna at home in preparation for going to Park City. Because I live at a beach town and going to Park City, I am a significant responder to altitude and I won't be able to have coherent meetings at altitude if I am not adapted. So, okay, yeah.

Andrew Huberman: So this explains why when I've gone to meetings in Colorado at altitude, some people can have a drink that first night and they're perfectly fine, even though they normally live at sea level. And I'm trying to see the stairs correctly, even though I don't drink.

Stacy Sims: Yep, that would be it.

Andrew Huberman: Very interesting. So you can use post resistance training sauna exposure to improve performance.

Stacy Sims: Yeah, you can use it post cardio as well. So anything that is giving you that passive dehydration from training, because you're not, because you will become passively dehydrated when you're training, you can't keep in as much fluid. So I'm saying passive, as in you're not able to stop that dehydration. And then you go into the sauna and you are extending that training stimulus because your heart rate is elevated, you're putting your body under stress from dehydration and the body responds in kind of. We need more blood volume. So let's jump start that.

Andrew Huberman: I love it. Logically watertight and I'm going to give it a try.

Stacy Sims: Yeah.

Andrew Huberman: What other training tricks tips do you have up your sleeve, Doctor Sims?

Stacy Sims: What you want to talk about?

Andrew Huberman: Do you have any favorites besides that? I delight in these and I know other people will as well. Do any come to mind? I mean, you've taught us about schisandra, about post training sauna exposure to improve performance by increasing red blood cell. Is there anything else that kind of springs to mind? No, no pressure.

Stacy Sims: I'm a fan of what I call the track stack that we used to use for track athletes, but then for really significant high intensity work. So track stack is kind of the idea from the old bodybuilding set where you're taking 200 milligrams of caffeine, low dose baby aspirin, but then I add beta-alanine.

Andrew Huberman: Used to be ephedrine.

Stacy Sims: I know.

Andrew Huberman: So I'm old enough to remember when they would sell it as the triple stack with ephedrine, but some people dropped dead and they took it off the market.

Stacy Sims: Yep. Hey, it came back on the market in New Zealand last week.

Andrew Huberman: Did it really?

Stacy Sims: Yeah.

Andrew Huberman: It gets you going?

Stacy Sims: Yes, it does.

Andrew Huberman: It's speedy, it's dangerous.

Stacy Sims: Yeah. But the track stack, which has beta-alanine in, not ephedrine, is really good at encouraging an extra top end effect because you're having the caffeine, you're having a little bit of the blood thin from the aspirin and then the vasodilatory properties and the carnosine aspect for muscle contraction from the beta-alanine. And so like training for gravel races in the top end sprint, you do a couple of sprint sessions with that. It's increasing your training stress during the training. So your adaptation is to that higher.

Andrew Huberman: Stress should anything be done in terms of recovery to make sure that you offset that additional stress that's achieved with this track stack?

Stacy Sims: Yeah, just making sure that you're not stacking two days in a row of high intensity work, like really making sure that you're recovering well because it is a significant stress on the body.

Andrew Huberman: What about sleep? We hear so much these days about the importance of sleep for mental health, physical health performance. I think this is a great thing, a great trend. Are there female specific requirements for sleep that vary across the menstrual cycle and or by age or just generally? Do men and women need to think about the need for sleep differently?

Stacy Sims: Yeah, part of it is the obvious, like, when you're talking about sleep temperature, right. Women and men have variations in their sleep temperature and what's optimal. So looking at that, like, you need to create an environment for you that is cool, comfortable, which is probably going to be different from your partner who might be sharing your bed. So that becomes a sticky point. We talk about the menstrual cycle. There are definitive changes in sleep architecture. We're seeing that in around the mid luteal to the premenstrual. So you know that about ten days before your period starts, significant change in your slow wave sleep, there's less of it. Latency is increased, so you have a longer time to get to sleep and you have more light sleep. So overall, you know, less of that deep recovery sleep. And this is where women tend to have more of their mood issues too, because of estrogens play with serotonin in the brain of. So we really need to nail down our sleep hygiene in that time period. So looking at things like L-theanine and apigenin and looking at your room temperature and the screens and all the things that you've talked about for the most part about sleep and sleep hygiene, super important. And then, of course, as you get older in both men and women, becomes more difficult to sleep. But we see a significant issue with insomnia in women who have really bad hot flushes and significant menopausal symptoms. And again, this has to do with lots of the perturbations from temperatures of night sweats, increased sympathetic load, not being able to get into a parasympathetic state. So this is where working with a specific sleep specialist might come into play. We can also look at using some adaptogens, the rhodiola stacked with theanine and looking at the cold temperature, getting people to use the Non-Sleep Deep Rest or yoga nidra or some other kind of meditative property that they can then access when they're in bed. So there's a lot of different things that we have to be aware of. And again, in that perimenopausal state, we see that significant change in sleep and sleep architecture and quality of the sleep. But men don't have the same thing. So women have to be a little bit more aligned with what's happening from a hormonal profile standpoint, because it does definitively affect serotonin, melatonin, and sleep architecture because of the interplay that estrogen has on the brain and the receptors.

Andrew Huberman: Makes very good sense. We'll put a link in the show note captions to some zero cost Non-Sleep Deep Rest, yoga nidras. We've put out a couple with my voice, if you prefer another voice. I'm a big fan of the ones by Kelly Boys, who's contributed to the Waking Up app. It also has terrific Non-Sleep Deep Rest yoga nidras out there. And there are others as well.

You mentioned a few supplements, theanine apigenin, which is chamomile extract, maybe let's just have a general conversation about supplements. What's your thought on supplements? How do you place them into the landscape of nutrition? They are, after all, supplements, not replacements. The word supplements, I believe, is a little bit misleading because there are food based supplements, like a protein powder. There are supplements designed to achieve a specific outcome, and then there are supplements that are designed to be more support for a bunch of things. Insurance policy. What are some of your favorite supplements in any of those categories, specifically for women, and perhaps even specifically during certain phases of the menstrual cycle? Perimenopause. Menopause. I just threw about nine questions at you.

Stacy Sims: Okay. The number one is creatine. Creatine for women doesn't matter what age, it's really important. We're seeing a lot for brain mood and actually gut health.

Andrew Huberman: So 5 grams of creatine monohydrate per day, sort of typically

Stacy Sims: Three to five.

Andrew Huberman: Three to five.

Stacy Sims: Preferably, of course, Creapure because of the way it's produced. So if you're looking at Creapure, it's the German company that produces. It uses a water  based wash to produce the creatine.

Andrew Huberman: Interesting.

Stacy Sims: Whereas others use an acid based wash. And we see a lot of side effects with the acid base wash. Like gastric distress. So people are like, oh, I'm really bloated. And I have nausea and stuff from taking creatine. I'm like, is it Creapure? Actually, no. It's like, switch to Creapure. And so they switch and they're like, oh, my gosh, I feel so much better.

Andrew Huberman: Noted.

Stacy Sims: Yeah. And then vitamin D3. Really important, especially when we're looking at all the information that's coming out from cardiovascular, muscle, brain, everything that goes with vitamin D, also with iron. So vitamin D is really important for absorbing and maintaining iron stores. So those are the two big ones. And then-

Andrew Huberman: Sorry, I just wanted to stop you for a moment. As it relates to creatine, I hear two general lines of concern. One I hear more often from women. My understanding is that because creatine brings water into the muscle, as well as supporting the phospho creatine system of the brain, the water into the muscle component means, yes, people who take creatine 3 to 5 grams per day will gain a few pounds of body weight. That's solid body weight in the form of water within the muscle. So solid in air quotes, it's water, but it's within the muscle. So they should know that.

Stacy Sims: It's not a given, though.

Andrew Huberman: Interesting.

Stacy Sims: It's not a given. There are some women on the lower dose of three that don't experience the water gain.

Andrew Huberman: Okay. And this is not bloat like water, subcutaneous water. This is water within the muscles, so it will be stored within lean tissue. And then I do hear concerns about creatine causing hair loss. My understanding is there is zero evidence for that.

Stacy Sims: No evidence.

Andrew Huberman: There is a smidgen of evidence that it might increase dihydrotestosterone levels, but it's like one study, marginal increase. And then people linked dihydrotestosterone to hair loss. And so then the conclusion people drew was that somehow creatine increases hair loss. But you're saying zero evidence.

Stacy Sims: No evidence. We see that women who start taking it midlife are complaining about it, but it's actually a progestin driven thing. We see progesterone and fluctuation. Progesterone can exacerbate any hair loss. So if women are experiencing that and they're saying, oh, it's creatine. I've read all this stuff on creatine. No, it's not.

Andrew Huberman: Okay, so we've got creatine, D3. 1000 iu's per day, 5000 iu's. I guess it depends a little bit.

Stacy Sims: Yeah. Being very close to Antarctica in the southern hemisphere in the winter, very low sunlight exposure. Looking around the 5000, same with upper northern hemisphere UK, that kind of stuff. Closer you get to the equator, the less you need. The one concern is like a day here where it's foggy and it's supposed to be sunny and people are like, great. I don't, you know, don't have to worry about going out in sun exposure. But then the next day it's bright and sunny and they're like, ooh, sunscreen. So they put sunscreen on and not getting the right sun exposure. So then again, it is a lifestyle thing. So basic is 2000 to 5000.

Andrew Huberman: Great. Okay, so we've got creatine, vitamin D3. What are some of the other supplements that you, that you take or that you, I don't know if we say suggest, but that you perhaps suggest women consider.

Stacy Sims: Yeah, so protein powder, really good, high quality. Because the amount of protein that women should be getting is often difficult to eat. So again, supplementing, not using it as the mainstay. That's one to consider. And then again, I'm about adaptogens. So looking at the different adaptogens, ashwagandha is a good one. Holy basil or Tulsi is another one. Schisandra. And then getting into some of your medicinal mushrooms. Lion's mane, Reishi. Those are the two big ones that I look to and often have women use

Andrew Huberman: If these adaptogens blunt cortisol, because certain ones do like ashwagandha, which by the way, I do think people should cycle if they're going to take it high doses because there are some issues with liver and thyroid and thyroid problems if people take ashwagandha at high doses for too long. So that's important to note. But assuming that the adaptogens are reducing cortisol levels in addition to doing other things, is there a particular time of day or night that people should consider taking them? Should they avoid taking it early in the day? My understanding was that you want a bit of that cortisol bump early in the day, but you certainly want cortisol lowered later in the day.

Stacy Sims: Yep. And I think the problem is people think that they don't want any cortisol. They think that would be bad. That would be bad. They don't understand that the body has fluctuations of cortisol throughout the day. Normal. If we're looking at having issues with sleeping and that anxiety provoke from that sympathetic drive and elevation of cortisol, let it peak in the morning after you're waking up and look late afternoon, like 4:00 when it starts to dip, to take your adaptogens, then, because then it feeds forward to being able to relax more, which feeds forward to better sleep. For something like schisandra, where you're looking for that brain focused, you can have it in the morning. It doesn't necessarily have as big an impact on cortisol that you see with something like Tulsi or ashwagandha, because schisandra is more stimulatory, the other two are more calming. I put some in my morning coffee and then in the afternoon, when I need to pick me up, instead of more caffeine, I'll use schisandra, because it gives you that boost without the effects of caffeine and it doesn't interfere with sleep. So there's a time and a place to take them. And, yes, some need to be cycled on, some need to be cycled off. But I tell women, what are your main symptoms? What are the things you're looking to control? And we can look and see what kind of adaptogens we can use and how we place them, what's the story.

Andrew Huberman: With pregnancy and training?

Stacy Sims: Yeah.

Andrew Huberman: Now, is there an official word on this? You know, assuming a woman knows that she's pregnant from the very beginning of missing a period where she's in a position to make decisions about training or not training. Training at a given intensity or not. What are your recommendations?

Stacy Sims: The human body is really interesting, and when you get pregnant, your body tells you what you can do. So we see that you have a reduction in your anaerobic capacity on purpose. Your body's trying to be protective. You do have an expansion of your blood volume, so endurance is really good, but you can't do high intensity. When we're looking at the general guidelines that are out there, they've gotten rid of the heart rate rule. They are now telling women to be as active as they can be without creating injury and without trying to make gains. So that means if you're in the weight room, you're not looking to improve, you're looking to maintain. If you're doing cardiovascular work and you have a specific class that you love to go to. Yeah, but don't beat yourself up that you can't hit that high intensity. You're going for the social aspect. You're not trying to gain fitness, you're trying to maintain. I think the very worst possible scenario is someone is super active and stops doing everything because they're afraid. Because then they get deconditioned and then they end up in a worse state than someone who was sedentary, who's now encouraged to walk during exercise. It hasn't been well researched because you can't get ethics to study pregnant women very well. So we go a lot on case studies and case study notes. And the bottom line of it all is you stay active and you can do resistance training, you can do all the cardiovascular work and your body will tell you what you can and can't do.

Andrew Huberman: I've been asked whether or not pregnant women can do deliberate cold exposure. Probably no fewer than 2500 times on social media. And I never have an answer. But I always default to the cautious answer, which is, please don't until you talk to somebody who actually has an answer.

Stacy Sims: Yeah.

Andrew Huberman: Just because it sounds like a very precarious situation. But in all honesty, I don't know. I'm just biding time there and saying, please go ask somebody who can give you a definitive answer.

Stacy Sims: Yes. So we see women who have a high risk for miscarriage that anything that they do that's incredibly stressful for the first twelve to 20 weeks will put them at a higher risk for it. So being very cautious, especially with cold, because we know that there are so many different nuances. Doing something like hot yoga when you're pregnant is not. There is research, so it's not detrimental. Yeah, because when we're looking at blood flow diversion that way, when you have slight hypoxia to the placenta and to the baby, there is a rebound effect that increases the vascularization so that the baby has better nutrients. We see this also with, like, exercise and exercise intensities. This is why people are now saying, you need to have some kind of blood flow change and increase in core temperature to create these vascular effects within the placenta to improve nutrient and nutrient delivery to the developing fetus. So heat's good. Cold I'm not so sure of.

Andrew Huberman: Probably not extreme heat.

Stacy Sims: Not extreme heat. So that's what I mean. Like, hot yoga is not going to the sauna. Hot yoga sits around 40 degrees Celsius. So what is that? Just around 100 degrees Fahrenheit? And in that situation, if you're feeling too hot, you leave, you lie down on the floor. Don't try to stay for the whole class, but it's not going to be detrimental unless you're pushing yourself too much. Again, everything in moderation, especially when you're pregnant.

Andrew Huberman: It's almost the inverse of what we know for males, which is if men want to conceive, they should avoid the sauna, because we know that heat is detrimental to sperm viability in a real way. So much so that I tell guys if they are trying to get their partner pregnant, that they should bring an ice pack into the sauna. They should insulate that ice pack. Don't put it directly on the scrotum for other reasons, but that it's a. You know that the effects of heat, the negative effects of heat on sperm are real. But there's also an interesting. It's not just a trend. There's actually some research showing that cooling the testicles leads to increases in testosterone, which is, on the face of it, kind of counterintuitive, because it turns out that it's about the vasoconstriction, causing the subsequent increase in blood flow, increased vasodilation. So the inverse of what you just said, which is that during the heating process, the hypoxia induces more vascularization of the placenta.

Stacy Sims: Yeah.

Andrew Huberman: So when talking about temperature, one always has to think about the surface of the body versus the brain response, as we talked about earlier, and then what's happening during the deliberate heat or deliberate cold versus what's happening after the deliberate heat or deliberate cold. Everything in biology is a process, not an event.

Stacy Sims: And I should make full disclosure. I started as an environmental exercise physiologist and my PhD was all in heat and heat research, so I'm a little bit biased towards heat, but I've done a significant amount of research in the hot and cold.

Andrew Huberman: Thank you for the disclosure. I see it more as an indication of real knowledge. So thank you. This is an aspect of your training I knew a little bit about, based on your publications, but I didn't realize the depth of knowledge. So we're all benefiting here, including this earlier protocol of sauna post training. You can bet a lot of people are going to start incorporating that. I think we might need to name that. I've done this from time to time, named protocols, because people are reluctant to name them after themselves. Maybe we call that the the Sims protocol or something like that. [CHUCKLES]

Anyway, your discomfort will be other people's benefit. Now seems like a good time to address some specific questions related to the age brackets that you mentioned earlier. In anticipation of sitting down with you today, I asked some different women that I know if you could ask the world expert, exercise physiology, hormones and nutrition, etc. As it relates to women. One question, what would it be? And one of the most common questions I got in the 50 and up category was, what is the most efficient way for a woman older than 50 to train for the maximum health span and lifespan benefits?

Stacy Sims: I love this question because I get it all the time. We have to turn our brains away from everything that's been predicated before to this point. So if we're looking for longevity and we're looking at what we want to do when we're 80 or 90, we want to be independently living, we want to have good proprioception, balance, we want to have good bones and we want to be strong. So this is where we look at ten minutes, three times a week, jump training. So this isn't your landing softly in our knees. This is like impact in the skeletal system. A colleague and friend of mine, Tracy Cassels, did a PhD and post, not a postdoc, but post research on this and is developing an app on it to show women how to jump to improve bone mineral density. Over the course of four months of this type of training, people have gone from being osteopenic to normal bone density. So it's a different type of stress. So if your concern is that which a lot of women do have a concern, because they lose about one third of their bone at the onset of menopause.

Andrew Huberman: Wow.

Stacy Sims: Yeah. Significantly.

Andrew Huberman: Goodness gracious.

Stacy Sims: If you don't do something as an intervention. So we see a lot of women are like, oh, I'm going to go on menopause hormone therapy to stop bone loss. Yeah, it can be a treatment, but I always look at an external stress that we can put on the body that's going to invoke a change without pharmaceuticals. So jump training, heavy resistance training, training, and sprint interval training, those are the three key things. And from a training standpoint, and then from a nutrition standpoint, getting protein. Protein is so important. When you start telling women they need to look at around 1 to 1.1 gram per pound, which is around that, 2 to 2.3 grams per kilo per day, they're like, whoa, that's a lot of protein. It is, because we haven't been conditioned to eat it.

Andrew Huberman: Two scrambled eggs. It's a chicken breast at lunch. It's a small steak at dinner, plus other things.

Stacy Sims: Right, exactly. It doesn't all have to be animal products. I mean, you're looking at all the different beans and things that you can put together, and that's the other big thing, that in order to build the muscle and to keep the body composition and state that we want it to keep going for longevity. Those are the big rocks, the sprint interval training, the heavy resistance training, the jump training, and the prey.

Andrew Huberman: I'm thinking about this, and I'm thinking about my mother, who's 79 years old. She'll be 80 at the end of June and is in good health, walks a lot, gardens, does some yoga, but does none of the things that you're describing. So, mom, please, I'm going to send her to listen to this. In the same vein, what about the women out there age 20 to maybe we make it the 20 to 40 bracket. And if we need to divide that more finely, we can. What is the most efficient way for them to train for health, vigor, and longevity?

Stacy Sims: Making things fun. For the most part, I don't want people to think that it's a chore. So if you're someone who's been told you need to run and you hate running, then don't run. That's common sense. And I say that because I see little kids in non us countries that have to run across country. And you see these kids when they're six years old and all running around the field, and they're the kids that hate running, that aren't natural runners, and then they hate physical activity for the rest of their life. So I put that in, like, when you are exercising, you want to find something that you find fun. When you're in your twenties to forties, you have more room to get away with things that might not be optimal for you when you start get older. Big rock again, is resistance training. It doesn't have to be heavy resistance training, like I said earlier, to failure. You're periodizing. If you want to do a block of Olympic lifting, go for it. If you're like, I'm not comfortable doing that kind of lifting. I want to do more machine stuff, great. But we want to make sure you're changing it up all the time to keep things moving and shaking with regards to strength and hypertrophy. And then it becomes more of, are you training for something that's enduring? Are you looking for just longevity? For brain health? We need to have some lactate production, because women, as I said at the beginning of the podcast, are more oxidative. We don't have as many of those glycolytic fibers. So what we're finding in older research is that there's a misstep in brain lactate metabolism because the brain hasn't been exposed to it, especially if we're looking at women who are being studied now. It hasn't been in a societal context to do that kind of work. The younger we are, and the more that we can keep our glycolytic fibers going by doing high intensity work, the more we are exposing our brain to lactate, the better we see fast forward to attenuating cognitive decline and reducing the plaque development of Alzheimer's. This is why women who are in their 40s plus I want them to do the sprint and the high intensity work for that lactate production, start early, because then you can take some of those type type-2B fibers that could either go more aerobic or anaerobic and make them more anaerobic aerobic. So those are the two big things for women who are younger, and then you can play around with the other things if you want to be an ultra endurance athlete. Yeah, not really ideal, but, yeah, you can do that. That's fine. You'll recover well.

Andrew Huberman: Now forgive me, because you've said it several times throughout today's discussion, but I really want to drive home a key point that I think for most people, men and women, is not obviously, but is really important. When you say high intensity, you don't mean a class or a run where you're drenched in sweat and gasping for air at the end, necessarily.

Stacy Sims: Correct.

Andrew Huberman: Let's disambiguate high intensity from what most people think of high intensity, which is a really hard workout, a tough class where they had me moving the whole time, doing a circuit, etc. What is the appropriate high intensity workout look like?

Stacy Sims: Okay, so if I talk about true high intensity interval training, if you're a runner, it's going to the track and doing sets of 400-800-

Andrew Huberman: So 400 a lap.

Stacy Sims: Yep.

Andrew Huberman: 800.

Stacy Sims: 2 laps. So you're looking at between a minute and four minutes of, of hard work at 80% or more with variable recovery. So that's why I use a track as a, as an example. So if you do one and you're like, oh, I'm going to walk half a lap and then do it again, that's adequate recovery.

Andrew Huberman: Tough.

Stacy Sims: Yeah, it's hard, right. But it's not like you're going to be there for 90 minutes, doing as many 400s as you can, because you have that variable recovery, it might take half an hour to 40 minutes max, and then you're gassed out, you can't do it anymore. If we're looking at a gym situation, I like to look at something like every minute on the minute where you might be doing ten deadlifts at moderate intensity weight.

Andrew Huberman: And it takes ten repetitions.

Stacy Sims: Yeah. So it takes you 50 seconds to complete that. Then you have 10 seconds to move to the next exercise. That might be thrusters, so you know, a squat, clean thruster, so it's a squat pulling the weight up overhead. So you're doing maybe eight of those in that minute and you might have ten second recovery. You go to the next exercise, that might be kettlebell swings and you're doing explosive kettlebell swings and you'll finish, you know, 10 seconds to go. You go to the fourth exercise, I don't know, toes to bar or some other kind of v up, some other high intensity, and then you have 1 minute completely off. So you've had four minutes of really heavy work with maybe 10 seconds to move to the next exercise, 1 minute completely off, and then you repeat that three times.

Andrew Huberman: And this is high intensity interval training. This is not what you would consider resistance training for sake of building muscle or stressed.

Stacy Sims: Correct.

Andrew Huberman: You're using these loads, these machines, the pike, you know, hanging from the bar and bring your knees up or l sit or something as a tool to get the heart rate up continually. Very different than resistance training, the way most people think about it.

Stacy Sims: Correct. So this is the cardiovascular high intensity interval training, and the subset of that is sprint interval training. And this is something that's really, really hard and people don't get it. I don't necessarily mean running, it can be whatever mode of activity, but it's 30 seconds or less as hard as you can go. So this is your nine or ten on your rating and perceived exertion, 110%. It's max effort.

Andrew Huberman: On the rower, on the airdyne bike, running, if you like.

Stacy Sims: Yeah, any of those things.

Andrew Huberman: Gear the battle ropes.

Stacy Sims: Battle ropes are big.

Andrew Huberman: So 30 seconds all out, then rest. What? 10-15 seconds, repeat?

Stacy Sims: No, you want to, because now we're looking at that top end where we want regeneration of your ATP, you know, all of that system and central nervous system recovery. So this is 30 seconds all out. Could be two or three minutes of recovery.

Andrew Huberman: Oh, nice.

Stacy Sims: Because I'm not looking at Tabata where you're 20 seconds on, 20 seconds off. Because that's not the intensity we want. We want you to go all out and recover well enough to be able to go all out again. You're not leaving anything in the tank. So those are what I mean by high intensity interval training, or when you're looking at polarizing your cardiovascular work, that's the top end. Those are the two examples of your top end. And then your recovery is that long, slow walking on another day where you're not going and doing a tempo run, you're not doing a 5k easy jog, because that puts you in that moderate intensity.

Andrew Huberman: And if I heard you correctly earlier, you are suggesting most women do one or two days of high intensity interval training plus three to four days of resistance training for sake of building strength and muscle, which looks very different. It's more warm up, do a couple work sets, you know, two to four work sets of, you know, an overhead press, two or four work sets of maybe a barbell curl, two or four sets of some dips or whatever, whatever ones, you know, personal choices. Okay, got it. Very different. Far and away different than what most people, men or women, are doing out there, which is a lot of stairmaster, treadmill, jogging, maybe some lifting for hypertrophy.

Stacy Sims: Because I look at the general consensus of what's out there in the fitness world is all based on aesthetics and body composition. And so people have this mentality of I need to be hypertrophy to get swole, and I need to do long, slow stuff on the cardio machine to lose body fat. But that isn't what we're after. We're after let's create really strong external stress to create adaptations, not only from a neural and a brain standpoint that's understanding it, but also feeding down to metabolic change. Because if you have a really significant high stress, we see epigenetic changes within the muscle that increase the amount of what we call the glut four gates. So, you know, the proteins that open up that allow carbohydrate to come in without insulin. So we're expanding that acute glucose uptake through an epigenetic change. The other thing that it does is it causes an acute inflammatory response that your body learns to overcome. And it's really important for women to do that because as we start to lose estrogen, we lose a significant anti inflammatory age. So this is why we see that increase in the visceral fat, especially when we're hitting your mid 40s onwards, is because now you have this increase in free fatty acids. And the inability for inflammation to come down. So the muscle cell is going, I don't know what to do with this. So it gets circulated to the liver, and the liver stores it as visceral fat, whereas if you do that high intensity work, it creates that change within the muscle. To understand pull that in, let's use it. Let's also bring more carbohydrate in and more glucose, and use that, which helps use free fatty acids. And it also creates a significant anti inflammatory response at the level of the mitochondria and within the cell itself, which is what estrogen used to do. So if we look at those external stresses, it's not about body comp and aesthetics per se. It's about the molecular changes that we want to invoke to get that body composition and the brain health that allow us to be 80 or 90 and independently living.

Andrew Huberman: And in terms of nutrition, you mentioned women should shoot for 1.1-1.2 grams of quality protein per pound of body weight. What other types of foods do you like to see women ingesting? So are you a fan of fruits?

Stacy Sims: Yeah.

Andrew Huberman: Great. Well, these days you sort of have to ask in these circles. Vegetables, fiber is important.

Stacy Sims: Yeah, absolutely.

Andrew Huberman: And then in terms of starches to replace glycogen, especially if people are doing these high intensity interval training sessions and the resistance training, what are your preferred sources?

Stacy Sims: Depends on who I'm working with. I have some people who love coco pops and kids series.

Andrew Huberman: Oh, I cringe at that stuff. But, you know, I prefer rice and oatmeal, and I like a really good sourdough bread with butter or olive oil, you know, guilty of that.

Stacy Sims: Yeah, but there are some people will like the ultra processed stuff. So I'm like, okay, if you really, really need it, then you can put it on top of your yogurt after training as part of your carbohydrate uptake.

Andrew Huberman: It's the only time because glute four levels are so high, you're basically pulling everything into glycogen at that point anyway.

Stacy Sims: But ideally, carbs are all the different colorful fruit and veg. And if we're looking at sweet potatoes or kumara, if you're from other parts of the world, yams, all those kinds of things, sprouted bread, fantastic quinoa, amaranth, all of those different types of things, it's just staying away from the ultra processed. And when we look at women, it's really important to have a very significant diversity in the gut microbiome. So we see there's a definitive decrease when we start to have hormonal shifts because of the way the gut bugs help deconjugate or unwrap some of our hormones and shoot them back out in the circulation. So as much fiber, colorful fruit and veg as you can. But also, it's the 80/20 rule, right? 80% of the time you're spot on. 20% is life. Because otherwise, where do we get our chocolate and our whiskey?

Andrew Huberman: And there's some data that chocolate is good for us.

Stacy Sims: It is.

Andrew Huberman: Especially the low sugar dark chocolates.

Stacy Sims: Look at is how it makes you feel. Makes you feel good, right? Yeah.

Andrew Huberman: Yeah. One has to live. And fats. Where do you like to see women get their fats from?

Stacy Sims: Again, I'll do a full disclosure. I have been vegan since I was in high school because of an incident of a field trip to a pig slaughterhouse and driving down the five. But that's my own preference. So when we're looking at fats, it can be from a lot of different sources. I prefer women to have most their fats from plant based stuff, not because I am plant based, but because of the effect it has on the body. But there is a time and a place for animal fats too. The whole fear mongering of saturated fatty acids from dairy has been disproven. So if we're looking at what kinds of fats, you want a conglomerate, but you want most of them to come from whole foods, food plant based, not from ultra processed. And then of course, you're reaching for some real butter, you're reaching for some 4% fat yogurt or something like that to complement your avocados, your nuts, your seeds and your olive oils.

Andrew Huberman: That all sounds very rational and delicious, in my opinion.

Stacy Sims: Yeah, it's too common sense. People don't do it.

Andrew Huberman: I think if people hear it from, they'll do it. I think people just need to hear it in the context of a non diet context. And you've done an amazing job today of explaining how nutrition fuels training. Training fuels changes at the level of the muscle, the liver, et cetera, that allow one to ingest more fuel. In fact, a lot of what I'm hearing is that women should probably ingest more quality fuels in order to offset these cortisol spikes.

Stacy Sims: Absolutely.

Andrew Huberman: And feel better while training and to train more, which everyone agrees, provided it's done properly, is great for us. Kind of a fun, hopefully fun question for you. If you had a magic wand and you could get all the women on earth now and going forward to make a change or changes you don't have to pick just one. In terms of nutrition, how they think about their hormone cycle, exercise, health span, lifespan, what would it be?

Stacy Sims: I think I would have everyone understand their intrinsic selves because we have been inundated so much with socio cultural rhetoric and so much external noise that women have forgotten what it means to listen to themselves and their bodies. I mean, that's the one thing that I have to reteach women to do so often. So if I could have a magic wand and have every woman understand what their bodies are saying and what their cycles are saying and perimenopause is normal, everyone's going to go through it. If you have had a menstrual cycle just to intrinsically understand what their body is, so then they have the tool to be able to implement external stressors that's going to be beneficial for them.

Andrew Huberman: Well, Doctor Stacey Sims, this has been tremendously educational for me and I know for everybody listening and or watching. You've taken us on an amazing tour of the best ways to train with cardiovascular training and resistance training, those tailored specifically for women, as well as touching into some protocols for both men and women that are immensely powerful. Talked a lot about the menstrual cycle. I get asked about the menstrual cycle and how it relates to training and vice versa so many times. And thank you for providing clear, actionable answers. And you've also educated us on caffeine supplements, including revealing some supplements that I didn't know existed, which is not a common occurrence for me.

Stacy Sims: Yeah I win. [LAUGHING]

Andrew Huberman: And many wins. Many, many wins. Thanks to you. And on and on. So just such a rich data set here, presented with such clarity and in an actionable way. On behalf of myself and everyone listening and watching, I just want to say thank you. I know you've come a very long way from the other side of the equator, not just to see us, but given that your time is so precious that you've come to visit us and share with us your knowledge, I just want to say a really deep, heartfelt thank you.

Stacy Sims: Yeah, thanks for having me. It's been fun.

Andrew Huberman: And we'll have to have you back again. Maybe we'll come to New Zealand.

Stacy Sims: You should come down. Definitely.

Andrew Huberman: Thank you.

Thank you for joining me for today's discussion with Doctor Stacy Sims. To learn more about her work, please see the links in our show note captions if you're learning from and or enjoying this podcast, please subscribe to our YouTube channel. Please also subscribe to the podcast on both Spotify and Apple. That's a terrific zero cost way to support us. And on both Spotify and Apple, you can leave us up to a five star review. Please also check out the sponsors that I mentioned at the beginning and throughout today's episode. That's the best way to support this podcast. If you have questions for me or comments about the podcast, or topics or guests you'd like me to consider for the Huberman Lab podcast, please put those in the comments section on YouTube. I do read all the comments.

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If you haven't already subscribed to our neural network newsletter, our neural network newsletter is a zero cost monthly newsletter that includes podcast summaries as well as protocols in the form of brief PDF's of one to three pages where I spell out the specific do's and in some cases do not's, but mostly do's related to things like how to optimize your sleep, how to regulate your dopamine levels. There's a protocol for neuroplasticity and learning, as well as protocols for fitness, which we call the foundational fitness protocol includes everything sets, reps, cardiovascular training. Again, all available completely zero cost. You simply go to hubermanlab.com comma go to the menu tab, scroll down to newsletter, and provide us your email. But I should point out we do not share your email with anybody.

Thank you once again for joining me for today's discussion with Doctor Stacy Sims. And last but certainly not least, thank you for your interest in science.

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