Dr. Lauren Colenso Semple (3:10)

When we look at how the muscle responds, so we look at muscle protein synthesis in response to exerc or nutrition, there are no differences. Very similar protein metabolism response, very similar growth response. The major difference, and this is hormone related, is the baseline muscularity, because during puberty, when men experience a surge in testosterone that coincides with an increase in muscle mass. So if you take an untrained adult man and an untrained adult woman, there will be a disparity in their baseline muscle mass and that is due to differences in testosterone. However, once they start training, they will gain similar relative size.

Andrew Huberman (4:00)

So not that I'm suggesting people get into competitive bodybuilding and use steroids, although some people might make that their life choice, the vast majority of people won't. But if we were to look at female bodybuilders at any point in the last 30 years or so, it's very clear that with chemical augmentation, which is typically increasing testosterone or some testosterone like derivative, that women can achieve a very impressive level of muscularity that in many ways rivals what certainly men who are not taking anabolic steroids can achieve. What does that tell us? The fact that the addition of androgens, testosterone and testosterone like derivatives, can take female musculature and make it look essentially like male musculature. Does that tell us anything interesting that informs the non steroid user, the non bodybuilder?

Dr. Lauren Colenso Semple (4:56)

Not so much, because we're talking about those supraphysiological levels and that's the real game changer. So if we think about even with men, what is the normal range of testosterone, we don't see this relationship between, oh, you know, you're closer to 900 and you are going to respond better to resistance training. So as long as you're within what, that wide normal range, there doesn't seem to be a predictability of your response to training. However, once we get into those supraphysiological levels and we're taking that exogenous hormone, then yes, we are going to develop levels of muscularity that wouldn't necessarily be possible.

Andrew Huberman (5:41)

You said something, several things very interesting. If I understood correctly, if a male is somewhere in the reference range, so typically I believe that's somewhere between 300 nanograms per deciliter and 900 nanograms per deciliter, maybe in some countries it goes up to 1200 but in any case, that a male with 400 nanogram per deciliter testosterone versus 600, it's not as if the male was 600 can make, you know, that much more muscle growth. And the same is true for women.

Dr. Lauren Colenso Semple (6:11)

That's right. Okay, so as long as you're within that broad normal range, and of course what's normal for you differs from what's normal for someone else. So if there are changes that might impact you, because now you're below what is your normal, then that can manifest in a variety of ways. But there isn't this clear kind of linear relationship where we would say, oh, let's measure your testosterone. You are going to be a hard gainer or you're going to put on mass really easily.

Andrew Huberman (6:49)

If we were to just look at people who are not chemically augmented in any way, not know their testosterone in any way, and here I'm referring to women specifically, how much individual variation is there or what's known about the individual variation among women in terms of the amount of potential to grow muscle and strength? Is it true that some women have a much greater potential to build muscle mass that's independent of their testosterone levels?

Dr. Lauren Colenso Semple (7:16)

I'd say yes, it's independent of the testosterone levels, but we're going to start with different baselines, and then it depends on the stimulus that you are using for growth. And some people are adapting to that growth stimulus to a greater extent than others. But part of that is effective, consistent, progressive training. And then part of it is arguably some genetic factors. But when we even look at the molecular level, say fiber type differences, we see adaptation in both sexes that is quite dramatic. And that tells us that both men and women have the potential for large adaptations in either direction. Whether we're saying two endurance type training or resistance type training.

Andrew Huberman (8:08)

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Dr. Lauren Colenso Semple (11:35)

Well, the circulating levels are already quite low. And one of the issues here is that the way testosterone has been measured in women for a very long time is such that the assays are not capable of detecting some of these normal low levels. So we know a lot less about those lower kind of circulation levels of testosterone in women than I think people acknowledge. But more importantly, that acute response to exercise, that increase in post exercise testosterone, growth hormone, et cetera, people used to think that was the driver of hypertrophy. And so there were all of these training styles to sort of maximize that response. And so people would promote high rep training or supersets and they'd say, oh, this is going to really maximize that response. But what we know now is that response, although acutely it's not the driver of growth long term. And so it doesn't really make sense to chase that short term response because it's not predictive of longer term adaptation.

Andrew Huberman (12:53)

Until fairly recently, women doing resistance training, especially heavy for them, somewhere between 70 and 90% of a one rep max or even a one rep max. So heavy for them was scary for a lot of women. I have women in my family and they're like, I don't want to lift weights, I don't want to get too big. This was a common statement. What do you think changed?

Dr. Lauren Colenso Semple (13:19)

I think part of it was the introduction of the bikini category in competitive bodybuilding because that was a level of muscularity that people didn't look at and say, oh, that's bulky. That was, oh, she looks good in a bikini. And so people wanted to look like that, realized that they needed to lift weights to do it. And it kind of opened up a door for resistance training being more feminine. I think that in combination with the introduction of more group fitness that had resistance training components, CrossFit, which a lot of women were drawn to, I think all of that has made women feel more empowered to lift weights and less fearful of the results. Although I think there is still a sentiment in some circles that lifting weights or lifting too heavy is going to make you huge instead of, you know, quote unquote toned. Also, if there are all of these, where are all of these bulky women? When do you walk? How often do you walk down the street and see an incredibly jacked woman? It's very, very rare. And so clearly no one is getting huge by accident. You're not getting extremely muscular without working really, really hard. And often incorporating some pharmacological help.

Andrew Huberman (14:42)

For a woman who's not currently doing resistance training, maybe we could talk to her for a second. At what age is too early for a woman to do resistance training? What does the data say?

Dr. Lauren Colenso Semple (14:59)

I think as a cultural stereotype, that at least in high school girls, the girls didn't belong in the weight room. That was certainly my experience growing up. Now I think that's shifting. And so it's not that it's unsafe, it's just that it wasn't done. And so people weren't teaching teenage girls how to lift weights. And there's a lot of advantages to that, especially if you're playing sports, because we have female athletes who are teenagers and then going into college and continuing to play their sports. And there can be not only a performance improvement, but also an injury reduction from doing some resistance training along with your sports specific training. So I think it's certainly valuable to start younger also from a habit building perspective, because I know if you're somebody who has gone decades without ever doing a lot of structured exercise or without ever lifting weights, it can feel kind of daunting and intimidating to learn the new skill. That said, we know that you can gain muscle anytime, even if you start at 70. So it's not that it's ever too late to start, but if we start earlier, we are building muscle in the way that you're building a savings account or a retirement account. Because if we're not lifting weights and if we're not physically active, then we do start to lose muscle with age and later in life, it does become a problem.

Andrew Huberman (16:31)

I wonder if resistance training should be taught earlier. It doesn't sound like it should be avoided for young girls, is that correct?

Dr. Lauren Colenso Semple (16:39)

Yeah, I mean, I think if we see a young kid doing a barbell squat, there's something kind of jarring about that. But think about all the kids we see all the time on the monkey bars essentially doing pull ups or muscle ups and developing a lot of upper body strength. And certainly young gymnasts have been doing that for a very long time. So it's not that there isn't any sort of resistance training going around or happening in childhood. It's just not the structured training that we think when we talk about lifting weights.

Andrew Huberman (17:14)

That's an excellent point. And it makes me realize that probably early in development, boys and girls are doing resistance training at the level of pull ups and monkey bars and all the rest to the same extent, maybe even the girls a bit more. If the boys are all playing video games or like, I don't know, who knows? But then there's a drop off because of this. What really is just a cultural stereotype that boys are going to go to the gym and girls aren't. Although that seems to be changing. That's a bit of the sociology around resistance training in young girls. What about a woman in her teens, 20s, 30s or older, who's just never done formal resistance training, perhaps has done other forms of exercise? How should she think about starting resistance training? We could break this down into days per week, sets and reps, et cetera. But what's the general contour of a really good starter program for a woman at essentially any age?

Dr. Lauren Colenso Semple (18:14)

Historically, I think women have been told that exercise is for weight loss. It's really important that we start to shift that narrative because resistance training isn't about being smaller, it's not about the number on the scale. So we want to think about getting bigger, about growing muscle. And in order to do that, we need to challenge the muscle in a way that is a sufficient stimulus for growth. So if we think about a full body training program, we want to target all of the major muscle groups and a challenging load will differ depending on the exercise and the muscle groups that we're targeting. And we can train in low, moderate or high rep ranges. But we need to train close enough to failure, meaning if we can only do 10 and not an 11th, that's failure. So we can stop at maybe eight or nine and that's an appropriate stimulus. But if we finish that set of 10 and we could easily do another 10, then that load is too light. So making sure that we are doing a full body training program targeting all the major muscle groups, that we're using appropriate loads and we're progressing over time because what you'll be able to do, whether it's load or number of repetitions, this month will change next month and.

Andrew Huberman (19:40)

The month after you mentioned full body program. Does the entire body have to be trained each session or could somebody use a so called split, like you know, chest and back one day rest legs, the next day, rest shoulders and arms, calves, some ab work, stretch, repeat, that sort of thing.

Dr. Lauren Colenso Semple (20:00)

If you're only going to train two or Three times a week. I think it's better to do a full body session because you're hitting all those major muscle groups at an appropriate number of times per week. If you want to train more often than that, it does make sense to split it up. So if you're training four days per week, I would do, you know, maybe upper body, lower body, upper body, lower body. If you're training five days or six days per week, then we might split it up even more the way that you suggested. And there are also options depending on your personal goals. And so if we're thinking about muscle growth for overall health, then maybe we're not doing as many exercises like accessory type exercises. But if we're thinking about changing the physique with resistance training, then we might tailor the program to your goals and preferences and work a little bit more on those muscle groups that are important to you.

Andrew Huberman (20:57)

For sake of example, then I'll just try and build a structure around what you're saying. Let's say a woman decides to do a Monday, Wednesday, Friday, whole body workout each time, take the weekends off. Obviously the days that it starts could shift, but due to schedule or other things, sometimes it's a Monday, Friday, sometimes it's a Monday, Wednesday, sometimes they hit Monday, Wednesday, Friday. Seems like a reasonable framework. Would you suggest training the entire body all three or in some cases two days per week, using the same exercises to target the same muscle groups each time? Meaning if she squats on Monday for her quads and of course also for other muscle groups, you know, hamstrings and glutes are in, lower back are going to get hit too. But should she squat again on Wednesday and Friday, or do you recommend varying the movement per muscle group?

Dr. Lauren Colenso Semple (21:48)

It's an option to do either. I think it's. There's an element of personal preference. If you're working on improving squat strength, then you probably do want to squat more than once per week because it practicing the movement is important. But if we're talking about muscle growth, then we have a lot of options. And so you can do barbell work, you can do machine work, you can do dumbbells, and we can break it up if you wanted more variety by saying, okay, Monday your lower body exercises are going to be a squat, and on Wednesday we'll do a good morning and we'll work more of the posterior chain, or Friday, maybe we'll do more of a glute dominant exercise and we'll do some hip thrusts. And so I think it depends how many exercises you're doing in a session and then how long the workout's going to be before we decide how we're going to split that up. And so you could do a more quad dominant movement, like a squat, a lunge, a leg press, a step up and also do more of a glute hamstring dominant movement like a good morning or a stiff leg deadlift and do both in the same session. Or you could split those up and have more of a quad dominant day and a more hamstring glute dominant day.

Andrew Huberman (23:11)

Got it. I'm gonna drill down a little bit more into specifics because I anticipate that's what people will want. And it's probably the first time we've had somebody so well qualified to get into these specifics about resistance training on this podcast specifically for women. Although you're going to tell us later that the words specifically for women is dangerous language. We'll get back to that. Okay, so let's assume two or three days per week, whole body workouts. One could vary or keep the exercises per muscle group the same. How many work sets after a sufficient warmup? And when I think of warmup, I'll take the liberty here and you can tell me where I'm wrong. I think, okay, a light set to kind of remind yourself what the mechanics are. Get some blood flow going, See if anything feels like it might need another light warm up set and just kind of like a stretching out. Then a moderate set, like 50% of your one rep max, something where you could do 10 to 15 reps, but maybe you do seven or eight or maybe even a little heavier and then move to the work set. The work set that's taken within to failure or within a rep or to just shy of failure. How many work sets after a sufficient warmup for that muscle group?

Dr. Lauren Colenso Semple (24:22)

At least two. I prefer three. You could do four. Beyond that is probably overkill.

Andrew Huberman (24:30)

And that's assuming one exercise for that muscle group for the entire workout. So for three to four sets per muscle group per workout, each muscle two to three times per week, with the.

Dr. Lauren Colenso Semple (24:43)

Understanding that many exercises work more than one muscle group. So if I'm doing a leg extension, then I know I'm specifically working the quads, right? But if I'm doing a leg press or a squat, then yes, I'm working the quads, but I'm also working the glutes. And you can kind of say, well, is that a half a set for the glutes? Is that a full set for the glutes? And same thing. If we're doing a bench press, yes, you're working your chest, you're working your delts, you're also working your triceps. So is that a full set for the triceps or is it just a tricep push down that I'm going to consider a set for the triceps. It gets a little bit murky when we think about exercises that work multiple muscle groups. But I think if we focus on those compound movements, the bench press, the squats, the deadlifts, then we should think in that range that we're doing at least two, preferably three, but beyond four, probably unnecessary.

Andrew Huberman (25:40)

Well, at three workouts per week, you know, it's, you know, that's getting anywhere from, you know, nine to 12 sets for the quads. That's, that's a fair amount of work. If one were to collapse all of that into a single workout, that's, that's a lot of quad work. What sort of rest intervals between sets?

Dr. Lauren Colenso Semple (25:55)

I prefer autoregulation for rest. I think if you have strength specific goals, meaning you're really working on a one rep max deadlift, let's say in order to repeat that type of performance, you will need longer rest, maybe four minutes, five minutes, it depends, right? But for an average gym session, using some machines or using some dumbbells, then two minutes is probably fine for most people. And once you've been training for a while, you'll know when you're ready. But if it makes you feel better to set the timer, then I'd say two minutes for most exercises, maybe three minutes for something like a squat or deadlift.

Andrew Huberman (26:45)

Is there anything of value that can be done during the rest period other than rest and change the weight? Of course.

Dr. Lauren Colenso Semple (26:51)

If you want to maximize time efficiency, then we might consider agonist antagonist supersets. So when you look at somebody doing a bench press or chest press and then instead of resting for the two to three minutes and then doing the next set, they go and they do a row. And so you're going back and forth and you're, you're pairing a push and a pull and that doesn't seem to interfere with adaptation or even acute performance, the same way it would if you didn't rest in between your straight sets of bench press. So that can be a really viable way to train, especially if you are crunched for time.

Andrew Huberman (27:34)

So maybe a bench press or some other press type movement, dumbbell incline presses, whatever she selects, and then move immediately from there to a pull down and then wait out the remainder of the rest interval and then do another superset, that sort of arrangement.

Dr. Lauren Colenso Semple (27:49)

Yep.

Andrew Huberman (27:50)

Super. Setting or doing an exercise that normally you would rest two or three minutes between and instead resting a minute, then going. Doing the antagonistic muscle and back also prevents getting lost in your phone because you're on task. You know, it's amazing how much longer workouts get when one starts texting or paying attention to other things. And the switching back of focus from exercise to phone is. I don't know, I don't know any good studies on this, but it can't be healthy.

Dr. Lauren Colenso Semple (28:18)

Yeah, There are also studies about stretching in between or doing some sort of active recovery type work in between. We don't have enough data to say that's necessarily beneficial. But I think if people are thinking I don't want to sit and rest and do nothing, then the superset or even a circuit type of structure is probably a better way to go.

Andrew Huberman (28:43)

What about pushing past failure? Some assisted reps, AKA forced reps, done in reasonably good form so injury isn't a risk. Drop sets where you immediately lower the weight and get a few more reps after failure. Are you a fan of these so called intensity techniques?

Dr. Lauren Colenso Semple (29:00)

I think forced reps we're not getting much benefit from other than can be fun if you're working with a training partner. Drop sets are a good kind of finisher because they can, especially if you're doing a cable type exercise. I'm not, I'm not going to say drop sets are better than straight sets, but it is a way to add some kind of variety into especially the last set of, of a workout. Um, or if, if you're doing exercises that are just more conducive to drop sets like a bicep curl or a leg extension or something that's really easy to immediately drop the weight and go to the next. So it's not better, but it's certainly a tool and it fits into that time efficient strategy.

Andrew Huberman (29:55)

For the longest time I thought time under tension and moving the weight really slow was a value. I know that everyone should control the weight so that you don't get injured. No dropping the weight and swinging it back up and this kind of thing. But assuming that the weight is under control, meaning momentum isn't doing most of the work, you're being careful to protect your form and posture, et cetera. Is there a best rate of movement for the resistance? Should we emphasize the lowering phase, et cetera?

Dr. Lauren Colenso Semple (30:24)

There's always going to be a harder part of the movement and an easier part of the Movement. So we should move the weight as quickly as we can during that difficult phase and then control on the easier phase. But trying to intentionally slow down either direction is not particularly advantageous. Especially if we think about, like standing up from a squat. We want to stand up from the bottom of the squat as quickly as we can under load. If we have a lot of loads of, we're not going to stand up super fast, but we should be thinking stand up because if we don't, we're less likely to be able to complete that repetition.

Andrew Huberman (31:07)

I think this is a really important point that most non muscle physiologists, exercise physiologists, have not been trained on. But I'm hearing more about this these days. That trying to move the weight as fast as one can, under control against resistance should be the mindset inside of the set. Is that correct? Did I want to make sure I'm not contorting your words at all?

Dr. Lauren Colenso Semple (31:28)

That's right. And when you think about doing a set of 10, right, by the time you get to 7, 8, 9, the weight is already moving more slowly. You're starting to grind it out because it's getting more and more challenging. And so if you are using a load that that is appropriate, then the rate, the time it takes for you to complete that rep will inevitably get a little bit longer. But that's not something you're doing intentionally.

Andrew Huberman (31:58)

Got it. Getting really granular here. But I get asked these questions all the time. And as it relates to women's training specifically, you'd be amazed that people are coming to me for that. But almost certainly so that I could ask you, partial repetitions and isometric holds, do they have any value?

Dr. Lauren Colenso Semple (32:16)

The problem with doing partial repetitions or even playing with tempo is that it's really difficult to, to replicate consistently. And so I mentioned earlier that we want to progress over time. And if we're standardizing the range of motion and we're standardizing the exercise and we're standardizing the tempo, then it's easy to say, okay, I'm using two and a half more pounds this week. I've progressed. If we're playing around with all of these variables and, and then we're trying to add load, it starts to get a little tricky because you're saying, I know I'm using more load, but am I cutting the range of motion short in order to lift more? Am I speeding up the reps in order to lift more? So we want to introduce fewer variables to make sure that we are progressing, whether it's a replacement or load repetition ranges.

Andrew Huberman (33:22)

Earlier you said getting close to failure or going to failure is the critical component, but within a pretty broad range. Do you think it's necessary to limit oneself to certain repetition ranges? On the order of a workout, the week, the month, a phase of the year, are repetition ranges between three and five compatible with repetition ranges? You know, other muscle groups are the same in the same week, 10 to 15. I mean, I think there's a lot of kind of vagueness around this for women and for men, you know, you hear, oh, low reps get you strong, but don't grow muscle and then hear higher reps. As long as you go to failure, they'll grow muscle. And that's all fine and good, but no one really has ever said clearly how to vary this stuff in a way that allows for the best progress. And I realize that's a lot to ask you to tackle in one answer, but you have the mic. What are your thoughts on repetition ranges and how to vary them?

Dr. Lauren Colenso Semple (34:25)

And when we used to think, and they used to teach all the personal trainers this, there was a strength endurance continuum such that you're doing one to five reps and you're building strength and then you're doing something kind of moderate range up to 12 and that's hypertrophy. And then beyond that 12 to 20, that's in muscular endurance. And our understanding of that has evolved. Certainly if you're training for maximal strength, I. E. A one rep max, then you need to be training in those lower rep ranges because that is a sports specific training. And so it's not that if you do sets of 10, your one rep max won't get stronger, it will. But to maximize your one rep max, then we need to do some very high load, very low rep training. If the goal is hypertrophy, we have way more flexibility because we do see similar growth. Whether you are training in those high load low rep ranges or the lower load high rep ranges and anything in between, provided that we train close enough to failure. However, we need to think about overall volume because that's very important for growth. If we're doing sets of three, we're going to need to do a lot of sets of three to accomplish the same overall volume that we would get by doing sets of eight or ten.

Andrew Huberman (35:58)

That last point, I'm so grateful you said that. I used to hear the late Charles Paul Quinn say this, that if you're going to use higher repetitions, let's say between 8 and 15, which for me seems like high Repetitions you can, I don't want to say get away with, but you could do two or three sets per muscle group or per exercise and maybe two exercises for a muscle group. Whereas if you're going to train in the 3 to 6 rep range, you might need to do eight sets of and because typically one rests longer in between sets when with heavier loads. Those are two very different workouts. One is actually much more efficient than the other, even though it gets you something slightly different. I'm sure people are wondering, and I know you don't want to bias people's choices, but do you have a favorite repetition range for you for your level of experience these days? I mean, what do you typically select?

Dr. Lauren Colenso Semple (36:49)

I typically do something in the 6 to 12 depending on the exercise. But I think some exercises are fun to do 15 reps of and some are not. So I think if you're doing something like face pulls for your rear delts or leg extensions, I would never say, yeah, do a set of three. But if you're doing squats, I don't want to do a set of 20 squats ever. And most people don't. So I think we can, for most people say, all right, somewhere in the kind of 6 to 12 ish is a good sweet spot. If you're new, I'd say go 8 to 12 because we want to get really comfortable with the movement pattern. And so if you're only doing sets of four or sets of five, then you're not repeating the movement enough to get really proficient with the technique. So I'd love for those people to start in a moderate rep range. I think also if you go beyond that, then there's more of a chance of kind of form failure and injury risk. And so we want to be really proficient in the moderate rep range before we start exploring those lower or higher rep ranges.

Andrew Huberman (38:13)

Do you think it's valuable for women to vary the repetition or men to vary the repetition ranges, like week by week? Like, okay, this week I'm gonna train six to 10 reps on everything, or I'm going to go three to five reps on everything for three weeks. Then I'm going to switch to six to eight for three weeks, and then I'm going to go, you know, 10 to 15 for three weeks and then repeat. Is there any known value for hypertrophy and strength training to doing it, sticking with one thing and then systematically varying every, say, three weeks?

Dr. Lauren Colenso Semple (38:46)

You can do it that way. I prefer to combine it into the week. So if, let's say we're doing squats twice a week, then let's do a lower rep set day and a moderate rep set day. And you can do that for all of your kind of main compound lifts. And that adds some variety, but also means you have the data to make sure that you're progressing in each of those replacements rep ranges kind of simultaneously. Whereas if we were to do sets of six for three weeks and then move to sets of 12, then I don't really have that anchor point for am I making progress because now I'm doing the that lift in another rep range.

Andrew Huberman (39:38)

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Dr. Lauren Colenso Semple (41:35)

Yeah, I think it's an equal opportunity game. You know, we really need to make sure that form is dialed in and that you have a spotter or training partner, if appropriate, depending on the lift that you're doing. Because if you're doing high rep deadlifts, for example, you do have more opportunities to lift the weight in such a way that you just tweak something. And sometimes if people are doing those lower rep, heavier sets, they're more likely to kind of take that moment, reset, lock in and then perform the next rep. And it's a bit easier to rush the set and not kind of force yourself to reset and focus on those form cues when you're using a load that doesn't require you to do so.

Andrew Huberman (42:31)

Thank you. Yes. Recently there was pretty avid debate online about heavy weights versus not heavy weights, especially for older folks. And since now I'm 50, I place myself in that category. I'm a big fan of low repetitions, but not three or less. But let's just say some of my peers feel that that's super dangerous not to Recommend, you know, 5 to 8 repetition range. It could be that some people are just better at quote unquote, locking everything in and getting really focused and doing a proper set when there's fewer repetitions than. And some people might be great. I realize that doing 20 repetitions of stiff legged deadlifts and every repetition is just beautiful. But isn't there the idea that some of the smaller supporting muscles can fatigue as a set goes on and make one susceptible to injury? Is that, or is that just gym? Is that just like jock science?

Dr. Lauren Colenso Semple (43:27)

No matter what, we need to make sure that we're appropriately warmed up and that we're using proper technique. So if you try to go do a one rep max or a set of three and you're not properly warmed up, I'm concerned, sure. But assuming all else is equal, then depending on the exercise, we also have to think of overall systemic fatigue, even fatigue. On the cardiovascular system. If you're doing 30 squats, you might be out of breath before your legs give out. And that can introduce another mental challenge to the set.

Andrew Huberman (44:06)

Excellent point. I hadn't considered that. I also don't enjoy 20 repetition squats, although on the belt squat I'm finding some, let's just say some personal growth through them. Mental, personal growth. It's a whole different thing to do high repetition leg work. It's like a. And it is very cardiovascular. Speaking of which, I think most people Nowadays, men and women understand that cardiovascular exercise is important as well. And I realize that term pisses off the endurance athletes because what is cardiovascular exercise? I'm talking about something that you can repeat for six minutes or more continuously, gets heart rate elevated, and so on. I think most people think of this as cardio. How do you recommend scheduling cardio with the two or three day per week resistance training? Does it matter if somebody does it before or after their weight training on a given day? Can they do it on the same day? Would they be better off doing it on other days? What are the guidelines?

Dr. Lauren Colenso Semple (45:08)

So the concept of kind of the interference effect or issues with concurrent training come from the idea that you have both endurance training goals and resistance training goals, and that if you perform those too close together, that the endurance training might blunt some of that hypertrophic adaptation. We see that could be true if you're doing very high volume work and you're stacking it very close together, assuming your hypertrophy or strength is the goal, then we would want to perform that first and if possible, separate them by at least several hours. But we really don't run into the true interference effect type results unless we're doing tons of training and you know, you're doing your sprints before you do your leg workout. I would avoid that. I think we also need to think about whether we have endurance training goals or we're just trying to be fit for health.

Andrew Huberman (46:20)

Most people listening to this probably would like to get stronger, probably would like to add muscle to specific muscles and maybe have it in mind, and we'll get here in a moment, to not deliberately not add muscle to other muscles and to be what they consider lean enough and that want to be fit. I always think of the general life requirements, like you want to be able to carry your suitcase or bag and if you have to run for the plane, that you can do it without coughing up a lung, pick things up and not get injured. Sprint if you need to play a game of Frisbee or soccer or volleyball, a pickup game at the picnic or something, go for a hike maybe with a kid on your back, maybe with a backpack if you don't have kids. I think these sort of like just ability to go out on a Sunday and take a long hike with a pack without having to train for it. The ability to sprint for the plane without dying when you arrive there. These kinds of things to me are the real life metrics. I feel like that's what most people want. And then of course, some people want to run marathons and be powerlifters and you know, Alex Honnold just scaled a tower in Taipei without any ropes. So you know, there's a huge range. But I think what I described, I think is where most of us are at. What do you think most women are at?

Dr. Lauren Colenso Semple (47:39)

Lifting weights is so important because we don't have a lifestyle fun equivalent activity. But I don't think we all need to be going for a jog or spending an hour on the elliptical if we prefer playing tennis or going for bike rides with friends or going for hikes or something that is physically active and enjoyable and that we will be more likely to do consistently. So there is an element of that that can be really freeing for people because they think, oh well, then I don't need to worry about adding these structured cardio sessions in my week. I'm just going to do those outdoor physical activities with friends that I'm enjoying and also benefiting from.

Andrew Huberman (48:33)

What are the data on walking? I've heard 7,000 steps or so per day is a good number to shoot for. I heard that the 10,000 number was just kind of thrown out there the same way that eight hours of intermittent fasting was just kind of thrown out there. We'll get back to that. How important and helpful is walking for women in particular?

Dr. Lauren Colenso Semple (48:52)

I like to think of walking as something you can do that is not structured exercise. And so we're not thinking about meeting a step count necessarily. You can do that. But people who focus on something like step counts usually do so for a few months and and then stop because being kind of obsessive about tracking that metric gets a little old. And it's important to think not only about hitting one target, whether it's, you know, minutes of exercise per week or step count or heart rate goal, but what are we doing for the other hours in the day? So I think somebody who isn't active at all going from doing very few steps to getting it up to 4, 5, 6,000 steps, yes, we're going to see a huge benefit. But if you're somebody who is physically active in a variety of ways and you are moving throughout the day, not necessarily focusing purely on steps, then that metric of step count is a little bit less useful because we are getting in that overall activity that is going to be beneficial for health.

Andrew Huberman (50:09)

So what I'm hearing is if a woman is in the gym two or three days per week, lifting the way that you described, and has some outdoor or indoor social sport type activities that she enjoys, there's no need to Specifically, add cardio unless there's an endurance goal or a sprint competition goal. Is that right?

Dr. Lauren Colenso Semple (50:31)

Yeah, and I think a lot of people are adding cardio for, for weight loss goals, and that is a bit of a fool's errand because the fat loss that we will get from just adding exercise is pretty disappointing relative to the fat loss that we will see when we adjust our nutrition.

Andrew Huberman (50:52)

What about getting up toward max heart rate for sake of the dreaded VO2 max? No, I don't say dreaded. I mean, I just think it's funny because, you know, five years ago no one was talking about heart rate variability and VO2 max. I mean, again, I'm not trying to inject male fitness or my routine into it, but by virtue of what I've learned in the course of the podcast and also what I enjoy, I make it a point to get on the Airdyne bike or some other thing I can do at max effort or close to it without getting injured and do 32nd sprint. 32nd rest. 32nd sprint for at least once a week, ideally twice. I'm assuming, and you tell me you have the credentials here, I'm assuming that by getting my heart rate way, way up for a couple of minutes each week, that I'm doing myself some benefit separate from my resistance training. Is that true or is it because I see, I mean, I'm not a calorie counter, kind of an intuitive sense of what I need, but I see at the end of those workouts it says I burned 100 calories, which is, you know, I, you know, I walk, I eat 100 calories of blueberries in one pass by the blueberry basket. So I'm not trying to do it for caloric burn sake.

Dr. Lauren Colenso Semple (52:05)

Yeah. The value of the really high intensity stuff is time efficiency. So if we look at those adaptations to endurance exercise, or if we're going to just say cardio broadly, then you can get those by doing more long form, moderate intensity. You can also get those by doing higher intensity for shorter amounts of time. So it's not that it's magic in terms of the adaptation, but you're able to get more bang for your buck because you're doing that higher intensity and you don't need to do it for quite as long.

Andrew Huberman (52:43)

Let's talk about the somewhat barbed wire topic these days about variations in hormones as they relate to the menstrual cycle and training requirements. There's a lot of assumptions about this. There's a lot of conjecture, and I do believe there's also A lot of outright fabrication. Not because anyone necessarily wants to mislead, but I don't think anyone has spent as much time with the data on this as you have. So should women train differently depending on where they are in their menstrual cycle?

Dr. Lauren Colenso Semple (53:19)

The short answer is no. The conversation around the menstrual cycle is good. I think it's good that we're talking about it. It's good that people feel comfortable discussing it with their coach. The unfortunate shift of because you have a menstrual cycle and because hormones are fluctuating, you need to change how you are exercising is way too simplistic and doesn't align with the data that we have. So instead of worrying about whether you're in this phase or that phase, or whether estradiol is high or low, I would really focus on how you feel. Train hard, train consistently, train progressively. If at some point in your cycle you experience menstrual symptoms or fatigue or a lack of motivation that you relate to menstruation, then having an option to skip a workout or adjust the exercises that you're doing for that workout or do another form of exercise that day is completely fine. Not saying you have to grind it out, push through, but you are not less capable that day because you have your menstrual period or because the hormone profile has shifted in one direction or another.

Andrew Huberman (54:43)

There's a broader conversation around this, I think, about when to push through internal resistance, either just kind of general malaise like one doesn't feel well or didn't sleep well, whether or not one is feeling run down. Maybe we can kind of tuck that into this conversation about ways to vary training or not vary training according to phase of the menstrual cycle. Let's say somebody is not feeling as rested as they normally do or would like to. And I say that because people assume you need eight hours of sleep, right? One might need eight, they might need ten. I'm fine on six and a half to seven. I prefer eight, but actually six and a half to seven, I'm good. Five, that's a whole other issue. So should women push through a day of a workout if they got maybe an hour or two less than their normal ration of sleep that they need, or are they putting themselves in some sort of danger if they do that?

Dr. Lauren Colenso Semple (55:43)

There's no danger. You might feel worse. But subjective measures of performance are different often from objective measures of performance. And that goes for the menstrual cycles, symptoms and other factors as well. So you might go in and Deadlift the same weight as last week and you'd say, wow, this feels really heavy or the weight's moving really slow this morning, but you're still lifting it so objectively, the performance was the same. It struck just your experience of what it felt like differs. It feels harder today. To your point, that can be the case for a variety of reasons. We can be underslept or we are jet lagged, or we're stressed about something work related and feeling distracted. There's a lot of reasons why we don't have a 10 out of 10 workout every single time we go to the gym. So I think there's an argument to be made to, yeah, push forward, just do it anyway. Even a subpar workout is better than no workout at all.

Andrew Huberman (56:55)

In your experience and observation, do you think that women who take up resistance training enjoy it on average? Do they tend to enjoy it or do they tend to enjoy the feeling afterwards? How do you feel about resistance training?

Dr. Lauren Colenso Semple (57:12)

I think it's particularly powerful for women because, and I alluded to this earlier, there's a history of marketing ineffective programs to women or encouraging them to constantly switch it up. Try this new group fitness class or try this new at home video workout, and they never really see the results that they are hoping to see. And so you're just program hopping and disappointed and feeling like I'm putting in all this work, I'm doing the thing and I'm not seeing results. When you stick to a good resistance training program for long enough, not only do you start to see results in the way that your body looks, because muscle growth can change your body composition and can change your physique, but you also have this empowering feeling of progression over time. I can get stronger, I can do more. And that keeps you coming back. It's really motivating. So I think that can be really powerful that you feel like you're getting something out of what you're putting in and you're more likely to stick to.

Andrew Huberman (58:17)

It long term for anyone. But since we're talking mainly about women's resistance training today, do you think there's value to spending two or three weeks, maybe less, maybe more, just learning movements properly before getting into the whole business of progressive overload?

Dr. Lauren Colenso Semple (58:37)

Yes, because the problem is you start to see, oh, I can do more than I did last week, and then you think, oh, well, this is linear. Right. And so you think, I can add £10 every week forever. It doesn't work like that. So inevitably you end up training, or many of us have trained in such a way that we injured something, tweaked something, form failed because we got so focused on just lifting more weight, lifting more weight, lifting more weight. So I agree that a slower progression could be better, but that's also the power of just trying to add another rep instead of trying to add weight week in and week out.

Andrew Huberman (59:22)

We're all told we just kind of like need to exercise. And there's examples of how to do movements. But it'd be wonderful if there was kind of like getting the basics. Like a sprinter doesn't just go sprint. They learn how to do all these drills and move into it. And some of these things are complex. And it's not just about avoiding injury. It's about getting the most out of the exercise over time. That's kind of how I'm thinking about this.

Dr. Lauren Colenso Semple (59:45)

I think it's also making sure that you are using proper technique and full range of motion, because that's one of the other things that is often the first to go when we really try to load up and load up and load up. And you see this with people squatting and benching all the time. They're just adding another plate, but then cutting the range of motion short to accommodate that additional load. And so that's not really progressive overload because you changed your range of motion. So I think, especially if a lift is technically demanding something like a hinge, you no deadlift. Good morning. For a lot of people who've never done that movement pattern, it can be really difficult to just develop that kinesthetic awareness of where am I in space? Am I bending my knees too much or not enough? Am I starting to round my upper back? And when you can really understand the proper form, then you know how to load it.

Andrew Huberman (60:46)

If a woman just feels lousy at one particular phase of her cycle, and that's a consistent month to month thing for her, and she doesn't want to train during that time. It sounded like there's no issue with that. That you're not suggesting that women push through that necessarily. That they. We're on the West Coast. That they honor their feelings is how people speak out here. That they honor their feelings as opposed to push against the sense like, this is just a tough time to do this. But you're from New York and you're giving me this look now where that makes it. People are just listening. Lauren's looking at me like, yeah, that sounds like, I don't know, but I don't want to put words in your mouth. What are you thinking?

Dr. Lauren Colenso Semple (61:32)

Well, I'll tell you this. We have survey data looking at how many people report experiencing menstrual symptoms, things like cramps and low back pain, lack of motivation, irritability. And 75, 80% of women report feeling those symptoms and none of them report changing their training in response to those symptoms. Not to say that you shouldn't, but typically, at least where the data shows, it's not that common that people are overhauling their training even in response to menstrual symptoms. That said, most people experience them for one or two days. So we're only talking about skipping or adjusting one, maybe two workouts. So I, I don't feel that strongly about it either way. I think, you know, it's up to you. And like I said, there will be a variety of reasons within any given month why we show up to the gym and we don't feel our best. And some of those days, again, for a variety of reasons, we might decide to make some adjustments and other days we might just decide to push through. And both are completely acceptable.

Andrew Huberman (62:46)

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Dr. Lauren Colenso Semple (64:37)

The majority of these studies are on folks taking combined oral contraceptive pills. So this wouldn't apply to something like a hormonal IUD or there's a patch that people are using now that it's more modern take. But there is enough data at this point to say when it comes to strength hypertrophy power, we're not seeing combined oral contraceptive pills move the needle in either direction. And there were appropriate hypotheses to say, oh, maybe this could be detrimental or maybe this could be beneficial, or. But what we see, similar to the influence of the endogenous hormone fluctuations, which are quite substantial, if those aren't affecting performance or exercise induced adaptations, it's not that shocking that the hormonal contraceptives wouldn't move the needle to a great extent either.

Andrew Huberman (65:34)

Yeah, it's an excellent point. I mean, if one just looks at the plot of estrogen levels or progesterone levels across the different phases of the menstrual cycle is these are enormous differences, likewise for testosterone and other hormones in women. And you're making the point that hormone based pill contraception is making changes in hormones of at least that magnitude. And so there's no reason to expect that it should impact at least ability. I can think of motivation to train ability somehow, like if it relates somehow to contractile ability of the muscles or tendon, tendon strength or something, and then the actual adaptation. So it sounds like none of these things block the adaptation to exercise, the increase in muscle size or strength or both, is that right?

Dr. Lauren Colenso Semple (66:25)

That's right. I would say if you're just starting a contraceptive pill, some people have symptoms and side effects, some of which are kind of attenuated over time and some of which are not, and you need to switch to something else. So you might for a short term, because that pill is not a good fit for you, then there could be some short term influence in that sense. But on the flip side, a lot of people go on a hormonal contraceptive because they have really severe menstrual symptoms and then that can be helpful in relieving that pain. And so then you might be willing to go to the gym more frequently during the week where you have your menstrual period. So I think we can think about those kind of practical implications. But in terms of just the hormones themselves and the fact that we're downregulating the endogenous hormone production by introducing these synthetic hormones, that doesn't seem to impact performance or adaptations to exercise.

Andrew Huberman (67:27)

What, if any, are the really good data around the relationship between perimenopause and menopause and the hormone changes that tend to occur? Let's assume without hormone replacement therapy for the moment. And training, should women change their training as they enter perimenopause? Menopause?

Dr. Lauren Colenso Semple (67:44)

There's no reason to change your training because we still want the same adaptations. We want to increase and maintain muscle muscle size and strength. We want to reduce fall risk and fracture risk, maintain bone density. And so resistance training is going to be a really key component of an exercise program for somebody pre and post menopause. I think the idea that somehow the hormonal changes would influence muscle are really tied to that same thought process that cycle syncing is based on. And so it comes down to this hypothesis that there is this relationship between estrogen and muscle. And so if estrogen is declining with menopause, then that would have some effect on muscle. But we don't see that. We see age related muscle loss that is exacerbated by physical inactivity. But you look at lean mass across the menstrual, across the menopause transition, and that in and of itself isn't accelerating the loss of muscle.

Andrew Huberman (69:00)

I think for understandable reasons, there's this correlation that people draw between hormones and muscle. And since resistance training is more kind of muscle oriented in people's minds anyway, I mean you got tendon and bone, et cetera, than cardiovascular training. It's a silly thing, but we kind of make that association there. See all these things around women's fitness. It's like, should training change during different phases of the menstrual cycle? Because after all, menstrual cycle is hormones. Hormones affect how one feels, but also muscle. Here we are back to muscle. The changes in muscle size and strength as one ages, in my understanding, are just as much a function of atrophy of nerve to muscle connections, the strength of those as they are some drop in hormones. And I think it's never really been stated out loud. So I just want your thoughts on this. Do you think that if people Understood that a lot of muscle and strength loss is inactivity, as you said, and inactivity brings a weakening of the nerve to muscle connection. That it might help us get away a little bit from this idea that everything about muscles is hormones and everything about hormones is muscle, that they're equally important. I really realize I'm leading the witness here a little bit, but I'll just out you. Your father's a neuroscientist. How important is the nervous system and the changes that the nervous system normally undergoes as one ages important here? Is that what we're trying to do, or are we trying to offset some of that?

Dr. Lauren Colenso Semple (70:29)

It's important too, because we need to maintain those connections for all movement patterns. Right? And so when we see long periods of physical inactivity, think immobilization or bedrest. The rate at which you lose muscle is shocking. It's really, really dramatic. And so we know that is a very extreme model of atrophy that we want to avoid. But there are other versions of that. In just daily, kind of sedentary life, you're not on bed rest, but. And you're not technically immobilized, but you're moving so infrequently that you are exacerbating muscle loss. And even if you are just physically active, even if you're not lifting weights, you're much more likely to maintain that muscle. But once you stop being physically active, then we run into a lot of problems.

Andrew Huberman (71:28)

If more people understood the neural aspect of all this exercise stuff and muscle and how that relates to fitness and brain health, I think it would help men and women kind of get around this thing that you mentioned earlier. It's just kind of hovering my mind that so much of the way that fitness has presented exercise has been presented to women is around weight loss. And now the conversation seems to be changing. It's about longevity, it's about maintaining muscle, it's about maintaining brain health and not getting injured. And so it's. It seems like it's morphing slightly.

Dr. Lauren Colenso Semple (72:01)

I think that is missed in resistance training because we just think about it at the muscle level. But when we think about motor unit recruitment, that is a neural pathway, and we need all of those to stay intact to perform any kind of motor function. And so when we are lifting weights, we're not exclusively building muscle. And that's why we see tendon adaptations, bone adaptations. Everything is connected. And it's also why if you're somebody who is aging, but you're physically active in a way that requires A certain type of coordination, maybe it's pickleball, that that is really helpful as well. I think the idea that you have to go to the gym is intimidating for some people because a lot of women in their minds think that they're going to be the only woman in the gym, that's less and less true. But in my experience, it's still, the weight room is still probably a male dominated section of the gym. I think the biggest fear is not knowing what to do. And machines can be a really good place to start if you're somebody who doesn't want to work with a trainer and is a little bit nervous about trying to self teach those movement patterns with barbells or dumbbells. A lot of commercial gyms these days have a circuit of machines and you can start there and kind of get comfortable with those movement patterns, get comfortable with what is challenging, what is close to failure, and then progress to some of these other exercises and equipment.

Andrew Huberman (73:47)

Yeah. When I've tried to encourage female family members to weight train, like, I don't want to go to a gym. Like, why not? They're like, I like my yoga class, I like Pilates, I like going for hikes. What do you think are some things that women could do to sort of lower those barriers for people, starting with group fitness?

Dr. Lauren Colenso Semple (74:07)

Because even though most group fitness classes are suboptimal from the perspective of a sound resistance training program, it gets you into the gym, it gets you feeling comfortable, it will teach you some of those movement patterns that we've discussed. And then maybe after class, you and a couple of friends that you've made in class can go and try out a couple of machines and so you can kind of ease into it that way. And people gravitate towards group fitness because it's social and you have an appointment because you have to be there at a specific time. So that can be another good kind of entry point to get you going to the gym without feeling overwhelmed by exercises you're not sure how to perform or equipment that you're not sure how to use.

Andrew Huberman (74:57)

In terms of the relationship between hormones, menstrual cycle and training, I know I'm staying on this, but it comes up, I mean, you've. On social media, I mean, I don't know what percentage of questions that you get on social media relate to hormones and training as they relate to one another.

Dr. Lauren Colenso Semple (75:13)

It's a lot. I think now more than ever you're just seeing more and more of this messaging pop up. And with the menstrual cycle it's not only about exercise. I see the way you should eat differently due to cycle phase, the way you should work differently, the way you should socialize differently. There are all of these messages that are saying you need to kind of overhaul this aspect of your life to align with these phases.

Andrew Huberman (75:43)

Is there any evidence that resistance training can help ameliorate some of the symptoms of the negative symptoms of certain phases of the cycle that women might be experiencing? In other words, do they often feel better by training during the most difficult phase of their cycle? Has that ever been demonstrated?

Dr. Lauren Colenso Semple (76:02)

Not with resistance training specifically, but with physical activity? Sure, it can definitely help because you, if you have something like cramps, then just kind of doing something to increase blood flow, even if it's going for a walk, can be helpful. And it also kind of gets your mind off of it so you're not actually sitting there kind of focusing on the fact that you're uncomfortable. And it depends on the person. But I think some sort of physical activity can be beneficial and that's something that, that you should consider exposing. Exploring whether it's resistance training or anything else.

Andrew Huberman (76:40)

What about the nutrition aspect and the menstrual cycle?

Dr. Lauren Colenso Semple (76:45)

The nutrition data is pretty poor because as is most nutrition data, it's kind of self report. And so we're saying observationally, people tend to eat a little bit more in this phase versus that phase on average. But based on self reported food diaries, does that mean that you should change caloric intake or protein intake or carbohydrate intake? We don't have the data to support any of that. And a lot of it comes back to this theory that you have a kind of an anabolic phase or a catabolic phase. And so that extended from oh, you should focus on more resistance training during this phase to oh, well then you must need more protein in this other phase. So what kind of started as a hypothesis about anabolic and catabolic states has twisted into changing your exercise program and changing your diet, among other things.

Andrew Huberman (77:50)

I spoke to a couple different women prior to sitting down with you today because I needed data from actual women as opposed to my ideas about what they might be thinking. Right. Or what I see online. Right. These are people I'm close with and I believe they were honest with me. And for the, it wasn't an enormous poll. This is not an official study, but I heard something at least three times out of the five people I spoke to. And it was this. I know I should lift weights, but I feel like I get enough muscle training from my Pilates or yoga. And I said, yeah, but couldn't those things be really different than resistance training? And the answer that I got back was similar in several cases, which was, yeah, but my Pilates teacher, she looks awesome and she has tons of Energy and she's 10 years older than me and I want to look like her, so I'm going to do Pilates. And I said, well, do you, does she lift weights? And she said, no, she just does Pilates. And I said, well, I wonder if she would like, did gymnastics when we were younger. And then pretty soon I'm now the guy having this like conversation, trying to essentially negotiate something. I have no interest in negotiating, but it gave me a window into something that I think might be pretty common, which is that we all look at somebody and what they're doing and we go, oh, like that seems like a look that is reasonable and attractive and I would want that. And they seem to be like kicking butt in life and happy and I'm going to just do that. And so what do you say to women who perhaps think like they're as muscular as they want to be now doing Pilates and walking and maybe doing some other activities, but they're not doing resistance training? Is there some reason why they should be motivated to also resistance train?

Dr. Lauren Colenso Semple (79:40)

What you're describing is very common and unfortunately for the vast majority of people, they then go and do the exercise class or follow what this person eats in a day and they never end up looking like that person because we have genetic factors, nutritional factors, exercise factors, and sometimes no matter what, we're not going to have the body of this other person. But Pilates is particularly guilty of promising these dramatic changes in body composition, position and that if you do this class that you're going to get toned. You're, you're going to increase your muscle mass and get these long lean lines or you'll look like a dancer. And so we're, when we, we use that word, which we don't, toned. But when people use it, they mean increase muscle size and decrease body fat. And the most effective and efficient way to accomplish that is through resistance training to increase muscle size and through nutritional adjustments to decrease body fat. Even if you're happy doing the Pilates and walking right now. And I'm not saying give that up because I'm a fan of all physical activity that people enjoy. But it is not sufficient resistance, it's not progressive resistance to stave off that age related muscle loss that I mentioned. All we need is two 20 minute workouts per week, full body resistance training to make a pretty powerful impact on trying to attenuate some of that decline and losing muscle mass, increasing fall risk, fracture risk, all of those downstream health effects that lead to an existence of in your 80s or 90s that is not very functionally independent. We don't want that. And so if we know we can implement this and it's not that much of a time investment, it's not that much of a financial investment, it's kind of a no brainer.

Andrew Huberman (81:51)

I'm so glad you mentioned the genetic piece because genetics are huge when it comes to, you know, lean mass to non lean mass body ratio. People don't, I mean obviously people over consume calories, they're going to gain weight. Some people more quickly than others perhaps. But it's such a big factor. It seems to me that so is someone having done strength and speed sports when they were younger. You look at someone who is a gymnast, a sprinter, a pole vaulter, a competitive tennis player, you got a lot of speed, height, movement. And I noticed even when they just do yoga or something in their 30s, I know this because as a graduate student, as you know, right in your, when I was in my 20s and then a postdoc in my 30s, you know, I was exercising less. And the people around you are exercising less, they're just doing experiments all the time and studying all the time. And some people just seem to stay really fit through that. And you go like what do you do? And they're like, oh, I just like these days I just do yoga. Did you play a sport in high school? Yeah, I was like, you know, D1 soccer gymnast. And I do think that people who play these competitive sports early in life, they hold on to a certain amount of musculature. Now maybe there's a selection bias that led them to be a D1 athlete combined with training. Right. So they were kind of had genetics that then they built on. But what I'm, I feel like these situations are very misleading. And with men it tends to be misleading where somebody is extremely muscular and lean. I think of my friend Nassima. He does a podcast with Mark Bell. Seema is completely steroid and TRT free. He really is. I believe him. And actually to speak to your earlier point, his testosterone, he's shown his charge is somewhere in like the mid fives. The guy is like, his muscle density is insane. He walks around with 8% body fat, he's a terrific athlete, et cetera. He has genetic gifts that he's built upon with very hard work. So I can't look at him and say, oh, I'm going to just do what he does, right? The parallel in women's fitness. And I don't want to discount the women out there who want to be very, very muscular. But let's just consider the averages here. They might look at their Pilates teacher and she might have been a gymnast who was also slightly genetically gifted and now can just do that. And no one talks about this. And it really contorts people's thinking and people are trying to figure out what to do, what to eat, et cetera. So I'd love for you to elaborate on this a bit more if you think it's appropriate. But like, no one acknowledges this.

Dr. Lauren Colenso Semple (84:23)

I share your hypothesis about the activity you do as a kid. Even if you don't become an elite athlete, I think that is something that does kind of stick with you. And let's say you were a child gymnast and then you pick up lifting in your 20s. I see women develop that upper body strength a lot more easily because I think they were doing that in childhood. The genetic variability is huge because it's the structure, our bone structure, our muscle insertions, the size of our waist. There are certain things that we can't change. You can't change your shape. Yes, we can gain fat, lose fat, gain muscle, lose muscle. But some people have naturally broader shoulders or have delt insertions that mean they have that look of these capped shoulders, or they just don't carry a lot of body fat on their arms or on their legs. And so the way that where we tend to store fat or distribute that fat varies from person to person. The place in which we lose fat, first and last, will vary. And often when you compare yourself to somebody with a very different structure, perhaps they have a metabolism that allows for them to maintain a certain body weight or a certain body fat at a really comfortable caloric intake. Whereas for you to maintain that certain level of body size or body fat would require a very uncomfortable, unsustainable level of caloric intake. And that is just is what it.

Andrew Huberman (86:24)

Is in the old days of fitness. Meaning when I started in the 90s, it's not old days, but here I am. There was this idea of ectomorph, endomorph and mesomorph. We don't hear that anymore. Ectomorph being very thin, long, sinewy muscles, small joints, quote, unquote, hard gainer. There was mesomorph, which is the kind of more muscular, somewhat lean perhaps. And then There was the endomorph idea, somebody carrying a lot of excess body fat kind of idea. Is that just completely irrelevant now in terms of picking training programs? Have we just really landed in a place where it's all about, hey, listen, if you're a endomorph, you're eating more than you should. There's muscle under there. Perhaps if you're an ectomorph, you're just, you know, maintaining a very low body weight. You need to lift more and eat more. Is there any reality to this?

Dr. Lauren Colenso Semple (87:16)

I could be wrong, but I think those labels and those descriptors don't even come from any sort of physiology research or framework. I think they come from psychology, which makes no sense given that we're using them to describe how one might explain, to adapt to training. You can say, oh, if you're somebody who is kind of skinny, maybe you can expect to be a hard gainer. But sometimes that's not the case at all. You see teenage boys that were kind of skin and bones and lanky, and then they start lifting and they blow up.

Andrew Huberman (87:57)

Oh, I didn't wait, I raised my hand as you said, I didn't blow up. But I mean, I was a 6:1, 150 pounds. And in my first year of training, I think I put like, like 25, 30 pounds of. Maybe it wasn't all muscle, but that didn't continue. It definitely can happen. But I also knew guys that when we finished junior high school, they were like, built even though they had never touched a weight. They were like my bulldog Costello, who had these huge forearms. He never touched a weight. It was just, you know, so I do think the genetic variation piece is huge.

Dr. Lauren Colenso Semple (88:28)

There's also the height component too, though, because if you think about, if you are five six and you have, you know, the same kind of relative muscle mass as somebody who is 5 11, you are going to look way more muscular than the tall counterpart. So if the person who's 511 or 62 wants to look really muscular, they're gonna have to put on a lot of mass because they're taller.

Andrew Huberman (88:55)

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Dr. Lauren Colenso Semple (91:34)

I'm glad you bring up the data piece because in some of these conversations, there's a lot of extrapolation of a potential mechanism that's not where we lean. When we develop our recommendations about exercise and nutrition, we need to look at the data in the population of interest, humans measuring the outcome. We are interested in using the intervention that we're discussing. So in the case of fed and fasted state training, this has been looked at long on longer term studies of consistent fasted state training, not just an acute bout of fasted state training. And the muscle growth and fat loss adaptations to exercise are the same in men and in women. And there was a school of thought that fasted training might be beneficial for fat loss, like 2012 maybe. And everyone was doing fasted cardio thinking it was going to accelerate their fat loss because they were exercising in a fasted state and oxidizing more fat because they were fasted acutely. Turns out that acute fat oxidation or fat oxidation post workout isn't meaningful enough to offset the rest of the metabolism throughout the day such that you don't lose more body fat long term. Now the pendulum has kind of swung in the other direction and the argument is that if you're training fasted, you're going to gain fat or lose muscle. And that doesn't make a whole lot of sense either because when we wake up in the morning, we ate dinner last night, right? We have stored glycogen and most resistance training sessions aren't extremely glycogen depleting anyway. So unless we're going to do some really long form endurance training, in which case, yeah, it's probably wise to have something to eat beforehand to fuel that that long session. The decision to train fed or fasted should be based on personal preference.

Andrew Huberman (93:55)

Do you have a personal preference?

Dr. Lauren Colenso Semple (93:56)

If I go in the morning, I always train fasted. If I go later in the day.

Andrew Huberman (94:03)

I've eaten caffeine before. You train always for the just general alertness or also performance enhancing effects of caffeine?

Dr. Lauren Colenso Semple (94:16)

I notice more the general alertness, but it's probably, probably hard to separate those. I think we see more performance benefits if you go from being caffeine naive and I am not. I'm very habituated at this point, so I'm probably not seeing that many performance benefits. But yeah, I definitely feel it when I don't have caffeine pre workout.

Andrew Huberman (94:42)

90% of adults in the world drink caffeine every day. And it turns out one of the hardest things to do about running a study on caffeine is getting people to not drink caffeine for like two weeks to do a washout because otherwise you end up studying caffeine withdrawal versus people who are continuing to drink caffeine. I spend a lot of time with this literature and it's a maddening literature. I'm right there with you. Total caffeine addict. And I'm cool. I'm Andrew. I'm a caffeine addict, you know, and proud of it. So if you were going to ingest food before you train, and given that most resistance training sessions are not glycogen depleting, which you said, is there any advantage to having some starchy carbohydrate before resistance training that's independent of glycogen? Is there any value to eating a given food before training?

Dr. Lauren Colenso Semple (95:37)

Might make you feel better. You might feel like you have more energy, you might feel better in the gym. Other people feel like they have GI issues if they eat too close to a workout and so that's they prefer to eat afterwards. So I think if you are someone who wants to experiment with both, then have at it. But for resistance training, the composition of the meal you're eating pre workout is very unlikely to be used as fuel in that workout.

Andrew Huberman (96:11)

Really?

Dr. Lauren Colenso Semple (96:12)

Well, if we are eating right before we train, then we still need to digest and absorb those nutrients. So I guess it depends what it is that we are consuming. If you're consuming, you know, one of those liquid packs that people consume during a marathon. Do you know what I mean?

Andrew Huberman (96:32)

The goo packs? Yeah.

Dr. Lauren Colenso Semple (96:34)

So that's like really fast generating. But if we're going to have some oats or something, then if I'm eating my oats and going to the gym, I'm probably not using that as my fuel for that workout.

Andrew Huberman (96:51)

What about post workout nutrition? For many years there were all sorts of ideas. You have a unique opportunity to store more glycogen. To this day, I still have some fruit and some starch and a protein drink after I train. Does it matter if it's in the first 30 to 90 minutes? In terms of the adaptation, this is all independent of hunger and kind of what makes one feel better. I'm just thinking in terms of recovering more quickly to be able to train again, get back to work and do other things.

Dr. Lauren Colenso Semple (97:24)

So the training is the stimulus for the adaptation or muscle growth. If we're talking about resistance training and then the nutrition or the dietary protein can kind of optimize our results from that stimulus. And there was once a school of thought that there was this anabolic window and it was very narrow and you needed to slam that protein shake the second you left the gym. Or why did you even Bother lifting that day. It turns out that post resistance training, that window that elevated protein synthesis is long lasting. We've measured this and see that it's still elevated even 24 hours after your session. Not that I'm suggesting you wait 24 hours to eat, but this indicates that whether you're eating within 30 minutes or three hours, that's not going to affect the extra extent to which that dietary protein can support your muscle adaptations.

Andrew Huberman (98:28)

I saw a study, I think it was about a year and a half ago that asserted that post resistance training, and I forget how long they waited post resistance training, but some period of time after resistance training that men and women can assimilate up to 100 grams of protein, whereas previously we thought that one could only assimilate 30 grams of protein per feeding. Whatever became of the 30 gram limit? And how does exercise impact the amount of protein one can and perhaps should ingest?

Dr. Lauren Colenso Semple (99:00)

Well, when we think about the protein that we're actually able to absorb and utilize for muscle adaptation, it's a different question of, you know, how much can we consume and absorb? Because not every, all of the protein that we consume is going straight into the muscle. So it's not that we should worry so much about maximizing per meal protein so much as per day, per week, consistent protein intake and that will again support the adaptations from the stimulus that we're getting from our training, but the idea that we're somehow gaming the system with timing or dosing, it's really, we need to kind of pull back the lens and think more. Big picture of, okay, if I'm aiming for this overall protein intake, then practically it probably makes sense for me to split that up into a couple of meals. So what does that look like? And then can I do that consistently?

Andrew Huberman (100:12)

Creatine is really big these days. Everyone's talking about creatine. It seems creatine has been around a long time. What can it do for muscle and strength? What do we know it can do for brain function? And is there anything different about the creatine women should take or the amount of creatine women should take or when they should take it? I'm not familiar with this aspect of the creatine literature at all all. But I hear about creatine just about every day.

Dr. Lauren Colenso Semple (100:44)

Yeah, it's having a renaissance. But for women it's still the same. It's just creatine monohydrate often packaged in gummy form, which you should be careful about because gummy supplements often don't contain the dose that they claim to contain. Someone actually analyzed a bunch of creatine gummies, top selling brands on Amazon and some of them contained virtually no creatine.

Andrew Huberman (101:13)

Really?

Dr. Lauren Colenso Semple (101:13)

Yeah. So be careful about the gummies. They're often they spray the gummy with the kind of solution on top afterwards. And so it can. Anyway, I would go with a powder form of creatine monohydrate over a gummy. It can get you an extra rep or two in the gym or cut a second off your sprint. We're talking adaptations of that nature. It's very safe, it's well studied. And so if you're somebody who is training and you're interested, then I think it's worth taking. And the kind of standard recommendation would be 5 grams per day. And if you're not exercising, I really wouldn't bother taking creatine. It's not going to, to just increase muscle mass when you don't have the stimulus for muscle growth. So this is an appropriate supplement for people who are exercising. And the claims about brain health I think are premature because the data that we have today are people in some kind of a deficit. So they were Alzheimer's patients, they were clinically depressed and also taking SSRIs. They were undergoing extreme sleep deprivation, they had a traumatic brain injury. This is really interesting literature, but I think it's been repackaged to tell people that you're getting some sort of cognitive boost with creatine. And that's not the same as, oh, this could be helpful for these clinical populations with some sort of potential creatine brain creatine deficit.

Andrew Huberman (103:05)

It will increase creatinine levels on a blood chart, is that right? Often it will, yes, because that will spike into the quote unquote red zone. It'll spike high. Is there any. My understanding is there's no reason to be concerned about that. If that spike of the creatinine levels are because of taking creatine.

Dr. Lauren Colenso Semple (103:24)

That's right. And you just need to tell your physician that you're taking it because otherwise they likely would be concerned. But that's. It's normal. That's just breaking down creatine.

Andrew Huberman (103:34)

And is it still true that the long term data show no danger of taking creatine on the order of 5 grams per day for years? Is that still true?

Dr. Lauren Colenso Semple (103:44)

That's still true. I mean, it's one of the most studied supplements out there.

Andrew Huberman (103:49)

What's your take on the various forms of creatine? Monohydrate is the most typical form, but I see a lot of different versions. There's a. I think it's a. Well, I won't name brands, not because I'm trying to hide that, because I can't remember, but some people want more water drawn to the muscle and less subcutaneous water. Is there any evidence that it can be directed that way by way of the form of creatine?

Dr. Lauren Colenso Semple (104:17)

No. I mean creatine monohydrate is definitely the most studied form. And so people are trying to introduce these with the kind of claim that somehow it would be better or that you won't bloat as much. I've seen that particularly marketed to women. But it doesn't really end up working that way way because just because it's, it's breaking down more in your liquid, right. It doesn't mean that it's absorbed differently when you actually consume it. So even if you were to just dry scoop creatine and just chase it with water, the results are the same as if you blend it up until there's literally no bits left in the glass.

Andrew Huberman (105:01)

For two scientists to have an I have a friend who told me kind of conversation is a little bit non scientific, but I have a friend, she's a woman, she started taking creatine, she started resistance training, not in that order. And she's getting great results and loves it. And she's totally into the fact that now she can do three full range pull ups. And it's just awesome to see her progression and hear her excitement around it. She was fit before, now she's just really charged up about this. And she said she was reporting her experience. She said, you know, when I take pictures, 5 grams of creatine, I feel like it kind of makes me blurry. Like there's a lot of subcutaneous water I hold. Then when I take three, that doesn't happen. This is a more general question that I have about how to deal with people's individual experience. I mean, you never want to argue with somebody's individual experience. I believe her. She knows her better than anyone. And yet my understanding is that there's no data to support that. So I'm asking you about creatine, but thematically I'm asking you as a scientist who's online dealing with questions all the time, who has her own individual experience, how do you want people to think about a situation like that for creatine, but for anything. Hey, when I. Some people say I take creatine and I lose hair and you're like, oh, there's no evidence of that. But then they go, no, I Think my hair falls out. What do you do? How do you specifically deal with that?

Dr. Lauren Colenso Semple (106:30)

Well, I think some people are online for others to validate their own personal experiences. And in that situation you say, I respect your experience and you walk away. There are other people who are online with genuine questions sometimes because they've heard that this was their friend's experience or they've seen another post post about it and they're actually open to the information. And those are the people that are worth the time investment to connect with because they're genuinely interested in the science and interested in learning and it's not about proving them wrong, because that's a losing battle.

Andrew Huberman (107:12)

There is another phenomenon, not just online, where there's a lot of distrust in formal academic science nowadays. There are a lot of reasons for this, social media being one of them, but this was building up for a long period of time. And I think as a woman in this area of research and public education, I think it's tricky when we look back 25 years and we were told, oh yeah, if you work out with weights, put on muscle, but then it all turns to fat if you stop, like, you know, if you take creatine, it's going to destroy your kidneys, you know, it's going to mess up your hormone cycles, especially if you're a woman, and it's going to mess with pregnancy. Like, are there any things that you hear circulating now that you would like to see explored in a formal, rigorous way because you think they could really help clarify and help people.

Dr. Lauren Colenso Semple (108:03)

I think we don't understand a lot about these body composition changes that some women experience and others don't through the menopause transition. And one of the, the big complaints that a lot of women have is this kind of redistribution of body fat or preferential growth of body fat in the midsection. And you could speculate that it's the estrogen receptor related, perhaps, but we don't have human data to support that. And whenever you make a claim about estrogen specifically or loss of estrogen, then you have to think, well, if it's only that, then it should be everybody who experiences it, because post menopause you're on the same boat, right? And so it has to be more complicated than that. And most things, as, you know, physiologically, it's rarely just one thing and that one thing can explain. So I think that deserves more exploration. And I think we need to do a better job with science communication because unfortunately, the Internet is sort of taking it by storm. And on one hand, I'M thinking it's cool that there's this interest in science that people want that PubMed ID and people are asking for data. But the flip side of it is that not everybody has the tool or the skill set to interpret the full paper. And so then people are using science as a way to cherry pick or to promote a message that isn't really reflective of the literature as a whole. And, and that's really challenging for the confused woman on social media, for the fitness coach or personal trainer who is trying to help that woman out, and for the scientist who looks around and says, hey, this is sort of weaponization of science because you're not being true to the literature. That said, an individual study is not designed to tell any one person exactly how to eat or how to train or how many steps to take or what supplements to take. So yes, we need to be evidence based. Yes, we need to be honest about what the science says, what we do and do not know. But of course there's going to be a component of individualization when you actually make decisions about what behaviors to engage in.

Andrew Huberman (110:58)

Spectacular answer. I would love to see the study that you described done. Is it possible to look at receptor distributions in adult humans using some imaging technique? Or do you have to biopsy fat and muscle from the midsection to get a sense of estrogen receptor density and saturation?

Dr. Lauren Colenso Semple (111:15)

The biopsy would be the way to go. And that biopsy is even more uncomfortable than a muscle biopsy. Ouch.

Andrew Huberman (111:23)

Yeah. Wouldn't it be wonderful if there were imaging techniques that would allow people to go into a scanner and you'd get distribution of estrogen receptors, distribution of testosterone receptors and saturation, how many bound? It'd be wonderful. These, I mean, medical imaging can get us there, I think. Hopefully.

Dr. Lauren Colenso Semple (111:40)

Yeah. I mean, it would be really powerful because even when we think about any biopsy study, we're taking 50 to 100 milligrams of tissue out of a single muscle or site and then making a lot of extrapolations based on this tiny amount of tissue. We're saying, is this representative of the whole muscle? Is this representative of other muscles in the body? If we're doing a pre post design, then when you go back in, is it possible that the adaptations along that same muscle could vary slightly? So there's a lot of limitations to what is a very cool, very valuable technique. But I think when we talk about a biopsy and what we're getting from that, we do need to acknowledge that we're making a lot of assumptions based on that tiny amount of tissue.

Andrew Huberman (112:36)

Earlier you said that where people store fat has a genetic component. So as uncomfortable as the experiment might seem to people, is it fair to say if you want to know where you have a propensity to store fat, look at your parents, Maybe.

Dr. Lauren Colenso Semple (112:53)

But there are lifestyle considerations certainly that go along with that. So I think genetics is our starting point, but it doesn't dictate our end point. And so if you have parents who have never really paid attention to their diet, have never really engaged in sport or structured exercise or resistance training, then how they fare through the aging process does not have to be the same experience for you.

Andrew Huberman (113:27)

I'm just trying to think of how the sight of fat storage would be encoded genetically, I'm guessing, like more adipocytes at certain locations. And of course, there's a male female difference. There tends to be a male female difference that presumably depends on androgen and estrogen receptors. But I'm not an expert in that issue specifically.

Dr. Lauren Colenso Semple (113:52)

Some would hypothesize that, though, there's a kind of reproductive advantage to having more fat around the hips. And so then across the menopause transition, when you no longer have that reproductive function, then that explains the reason why you would start to gain more fat around the midsection and lose fat around the hips. Do we have the data to support that? Not really. This is more kind of looking back at evolutionary biology and kind of trying to piece things together as to why it might be the case. That said, not all men have what we would say, male pattern fat distribution, and not all women have what we would say is female pattern fat distribution. So, yes, you're right that there's a tendency to have one or the other, but it's not necessarily a one size fits all.

Andrew Huberman (114:52)

Speaking of hormones, let's talk about the most barbed wire hormone of them all, which is cortisol. I won't belabor this conversation with this because I've said it many times before, but you want high cortisol in the morning. It's why you wake up in the morning. You want your cortisol low at night before you go to sleep, in the last hours before sleep. That sets you up for a lot of great things. And that's true for men and women. But cortisol and women and women's fitness has become like a real hotbed of misinformation. It's the first time I've ever used that word on this podcast. Misinformation. It's such a loaded word. But I think it's appropriate here because you hear all the time, if you stress, your cortisol goes up, people will say, if you cold plunge, your cortisol goes up. And if your cortisol goes up, you're gonna, you're going to get moon face and you're going to store body fat around your midsection, which is true if somebody has Cushing syndrome, which is pathologically high levels of cortisol. But please clarify, educate.

Dr. Lauren Colenso Semple (116:00)

Yeah. And you hear, oh, never do zone two training because of cortisol, don't do high intensity training because of cortisol. And so then you're stuck with these women who are thinking that any intensity is bad because of cortisol. As you said, this is real manifestations of Cushing syndrome that are being kind of twisted to say, hey, are you a little stressed? Have you gained some fat around your midsection? It must be cortisol. So it's a really compelling pitch to people usually to sell them some ineffective cortisol reducing supplement which we don't need and they don't work. If you actually have chronically elevated cortisol, then you need to be treated with medication, not some natural supplement. So I think the important point here is that those cortisol increases are normal and necessary. It's also necessary for blood pressure regulation, blood glucose regulation, that's important for exercise. And those acute fluctuations are not contributing to fat storage or inability to lose fat.

Andrew Huberman (117:18)

Yeah, presumably in the population of people who try and self soothe with eating excess calories when they're stressed, that the correlation just becomes to them obvious. But it's like cryptic correlation as we call it. Right. Because two things are happening. They're stressed and they're eating more and more. And yes, their cortisol is probably elevated, so it all hangs together rationally. But the food part is never really discussed. How being stressed causes some people to eat far less and how being stressed causes some people to eat far more, in particular unhealthy foods. So I feel like the real world puzzle pieces kind of fit together at the level of kind of perfect storm of people thinking that cortisol is the culprit, forgetting what cortisol does to eating when food is most likely. I don't like to call food a culprit, but in this instance I think it's appropriate.

Dr. Lauren Colenso Semple (118:11)

Well, I think that is not an exciting message that makes you feel like, really? So if you say, oh, you know, what's your diet look like? We as humans, we want a different answer. We want to look for something else to, to blame. And so the flavor of this year, or maybe the last couple years, has definitely been cortisol. Maybe we'll move on to blame a different hormone in 2026.

Andrew Huberman (118:41)

Just as supplements go through broad trends, hormones go through broad trends. Neurotransmitters. Like, a few years back, it was all oxytocin. Everything was oxytocin. Then it was serotonin. Dopamine had its big moments, and then now it really does seem to be like, cortisol's the thing. And I'm only being half facetious. I mean, I love that people are interested in this stuff and they want to learn, I think can't give them so much detail that they dissolve into a puddle of their own confusion. And yet the oversimplification can be tough.

Dr. Lauren Colenso Semple (119:15)

And Cushing's syndrome is not very common. It's typically a manifestation of somebody who's taking a lot of stuff, steroids, and then you're ending up with this chronically elevated cortisol as a side effect. And so it's not the case that everybody on the Internet actually has Cushing's syndrome and should be concerned and needs to go see an endocrinologist. It's more the case that people are, again, borrowing from some of the side effects of Cushing's Syndrome and then kind of tugging at people's vulnerabilities and desires to change their body composition and saying, it's not your behaviors, it's not your lifestyle, it's your cortisol.

Andrew Huberman (120:02)

As you and I both know, a good, solid resistance training session of about 30 minutes to an hour will triple or quadruple circulating cortisol levels. I think if people understood that, they might look at cortisol a little bit differently. How do you think people should feel when they finish a workout? I know that might seem very subjective, but it's something that we can all get in touch with, because I know that if I train for an hour, 75 minutes, feel great. If I push hard past 90 minutes in the gym, I'm pretty depleted for a while. And oftentimes that leads to less progress and minor, you know, I think more susceptibility to infection and things like that. Is it reasonable to assume that cortisol is somehow involved? Is over training at the level of an individual workout a real thing? Most importantly, how should people walk out of the gym feeling, assuming they're sleeping well and the rest of their life is in order?

Dr. Lauren Colenso Semple (120:59)

I think most people are not at risk of overtraining. I think, especially your average female population. I think women there are issues with female athletes certainly. But I think there's a lot of concern about needing recovery or inflammation that's probably overblown because true over training we get red flags that would manifest in other ways. So you would have difficulty sleeping or you would feel sore for days and really under recovered or under the weather and, and those might be some signs that you're really overdoing it. But I think it's probably not an issue for most people. But I think some days it depends on when we're training, what time of day we're training and that might dictate your personal decisions for how hard to push and how long to train. There are some people, if they train in the evening then that disrupts their sleep and there are other people who when they train in the morning and feel like that's a great start to their day really pushes energy and productivity for the rest of the day.

Andrew Huberman (122:15)

Are you a morning trainer or an evening trainer?

Dr. Lauren Colenso Semple (122:18)

I prefer mornings. I'll go in the afternoon, I won't go in the evening. I don't like it. What about you?

Andrew Huberman (122:25)

I used to train in the afternoon evenings when I was in college and then over the years I've just shifted to training in the morning. I would like everyone to ask themselves the following question. If you train at different times of day, does it impact your energy the rest of the day? Because what I've found, and this is less about my experience, the reason I like to prompt people's questions about themselves is if I do resistance training before say 10am, I have more energy all day long. If I do it somewhere around noon 2pm I just. Afterwards I'm just beat and I like to think that I'm, dare I say, riding the morning cortisol wave and I'm collapsing whatever cortisol I'm getting from my training into that and I just feel really good. I don't like to train after 2pm Because I like to drink a lot of caffeine before I train and it messes up my sleep. I do not like to train uncaffeinated. So that's the biggie for me. But in college when I was more of going to sleep at midnight 1am and sleeping until, you know, 8 or 9 because I could afford to do that, I'd go to the gym at night and it's also when it was social and I think some of those factors change over time.

Dr. Lauren Colenso Semple (123:40)

Yeah, I think one thing to keep in mind for people is if you are used to training at a certain time of day and Then you switch it, particularly if you transition from late afternoon or evening training to morning training. You might switch see a kind of hit in performance initially, but that should resolve in a couple weeks.

Andrew Huberman (123:59)

Cardio I'll do whenever because I don't need caffeine to do it, but I prefer caffeine to do it. Prefer caffeine for most things. What are your thoughts on hormone therapies that are not replacement? And I'm not talking about blasting anabolic steroids, I'm talking about because this is happening now in mass with women because of the understandable interest in hormone replacement therapy for perimenopause, menopause, estrogen therapy, testosterone therapy. So for a woman who feels like, hey, like they're feeling less vigor, their sleep, muscle, et cetera and they get, it's very easy nowadays to find a doctor to prescribe them estrogen or testosterone cream or injection and they're like I feel awesome. I talked to someone the other day, I'm taking this, I think it's progesterone. I have to be I a progesterone. And she said I feel awesome. The progesterone thing fixed my sleep. I have so much energy, I'm up in the morning. She's like I feel like I did in my 30s. It's now we're not talking supplements, talking prescription drugs, but none of them had a measurable deficiency. They're just giving some what I call hormone augmentation. And the language gets tricky here. They're just augmenting their hormone level. So they're going from whatever they were to higher and they are thrilled about it. I don't know that they're not creating other issues but I think we're going to see tons of this in the years to come.

Dr. Lauren Colenso Semple (125:23)

Menopause hormone therapy, as you said, is not intended to replace because you're not supposed to have the same hormone levels after menopause as you did pre menopause. So the goal there with these estrogen based therapies is really to target symptoms, not to treat to a hormone level. And there's a wealth of data that this can be really effective for symptom management which has a ton of downstream effects. So we don't have good data to suggest that it is going to attenuate the loss of muscle mass or increase muscle mass. But if you're somebody who is suffering with hot flashes and poor sleep and night sweats and then you can get some relief from that, then certainly you're more likely to be adherent to your diet. Or going to the gym with greater frequency and feeling better. And so we can't discount the ability to lean on some of these to improve the way that you feel. The testosterone conversation gets a little bit trickier because right now it's really only kind of proven to be effective for low sexual desire, low libido in women. And so there are a lot of people who are experimenting with it for other reasons. But we need to remember that the testosterone levels that people are using or should be using for, for this kind of supplement are fairly low because you're trying to treat to low normal. And then if you start to go beyond that low normal, then we can get a lot of those unwanted side effects that we would get if we were taking testosterone for the bodybuilding purpose. And so you might see voice deepening or unwanted hair growth or. So that's typically why if you're a woman, you'd only want to use this in really low doses. And we don't have the evidence to say that low dose is going to do anything for muscle. And it's probably not worth the risk to take the high dose when you could just lift weights.

Andrew Huberman (127:48)

When you could just lift weights. Thank you for entertaining that somewhat tricky question because I think we're in a whole new self directed medical care landscape, meaning even if people are working with doctors, they can generally find a doctor to make them feel better, even if it's not dealing with the specific issue.

Dr. Lauren Colenso Semple (128:13)

We need to be careful with the hormone therapy conversation though, because the data to date doesn't support the use of it for preventing cognitive decline or preventing cardiovascular disease. And there's a lot of messaging out there that is sort of telling women if you don't take hormone therapy, you're doomed. And that's not accurate. And some women can't take hormone therapy. So we need to kind of hold two truths where this is really powerful and can be really effective for symptoms. Perhaps down the road we'll learn that it has these other benefits or it could go the other direction, we don't know. But prematurely making claims about all of these benefits, that it's going to improve your lifespan, increase longevity, prevent disease, that's not accurate. And women need to understand that something can be really valuable but not a panacea.

Andrew Huberman (129:21)

Or do you feel isolated because you won't join this hey, things are different for women message?

Dr. Lauren Colenso Semple (129:28)

Well, if it were true, I would say it. I mean, when I got into this field, of course that was a question. That was one of the, the major questions that I had and at the time, there were reasonable hypotheses to explore. And as scientists, we test those and then we look at the data and we form our opinions based on the data. As a woman, if I honestly thought there were things we should do differently to optimize our results, of course I would be doing them myself and telling other women to do them too. But the narrative that women need a sex specific program or nutrient timing guidance or a particular intensity of exercise or rep range or all of makes women feel like they're being spoken to and being considered and they're part of this community instead of, oh, you know, just do what your boyfriend does or what your husband does, or so the narrative is very much, we know this works for men, but women are not men. And so obviously women need something different. The data says men and women respond to exercise very similarly. I think the fitness space is so saturated that a lot of people think they need to kind of reinvent the wheel or that message that you and I have discussed, which is, you know, consistent, effective, progressive training, that's not exciting enough, that doesn't give you the edge, and so you need something else. And that something else is often misinformation or something that just over complicates everything. But when it's more complicated, people are convinced that you know something they don't. That's why misinformation spreads.

Andrew Huberman (131:44)

I don't think it could be made any clearer and I appreciate your directness about it. The scientist in you, the person who looks at data, comes absolutely clear in that statement.

Dr. Lauren Colenso Semple (131:57)

And I'll say this, when I explored menstrual cycle phases, yes, I was interested in would there be differences in these different hormone profiles? But the other reason, the more exciting take home from the fact that there was no difference, is one of the biggest reasons why we don't have as much data in female participants is because of the challenge associated with standardizing the testing and the training and the recruitment. For people with equal length phases and standardizing ovulation timing and excluding people who are on contraceptives, it adds in a whole study on top of a study. And so if we don't have to do that anymore, think about all the research we can do in women or in mixed sex samples or in combined people on and off contraceptives, especially for sports science labs, with fewer resources, they can be part of that mission to do more research in women. If we don't have to work, worry about what was a huge barrier historically.

Andrew Huberman (133:10)

There are more funds now being directed towards studies that include Women or are solely directed at women's health and fitness. Having not come through science through that portal, I'm curious about how experiments are done in terms of resistance training and muscle growth and strength increases. I'm familiar with some of Brad's work and your work, do you think it replicates the gym well enough? I'm not being critical. I just, you know, I've seen studies where it's like, oh, you know, leg extension, you know, and then you're like looking at 1 rep max on the curl or. I'm not saying you guys did those studies, but a lot of times I think untrained subjects who then, you know, train for eight weeks doing something and it, it's hard for me to know if it really carries over. It could, I mean, I ran a lab where we used VR to study stress. You'd say, well, is that real? It's better than just showing people pictures on a screen. But it's not like real life stress. We had a falling thing and people think they're falling. We actually had people fall physically in the lab thinking, because the visual world's going up in VR, but it's not like falling off a building. So are the studies of resistance training that one can do in a lab, gym, lab, do you like them? Are you satisfied with what's there in a lot of cases?

Dr. Lauren Colenso Semple (134:35)

Well, I've been involved in those more real world gym like program studies. And with that increase in ecological validity, you sacrifice some of the measurements that you can do, you take away some of that really tight control or within subject designs where you're having one leg perform one protocol and another leg perform another. So I think there's a time and a place for both. But if we want to look at molecular signaling, if we want to do these tighter controls where we just to want, want to know that there was a sufficient exercise stimulus, and it's not necessarily about the fact that it was a leg extension versus a real world leg training program, then those are better. Because that kind of a study is not designed to say, and therefore everyone should do unilateral leg extensions. It's designed to say under these conditions with this hormone profile or with this infusion of nutrition, then what happens to protein synthesis? And that can be powerful and controlled in a way that a lot of the more translational exercise science studies are not. So I think both are important, but it really depends on the research question as to which is the most appropriate design.

Andrew Huberman (136:19)

How long have you been training?

Dr. Lauren Colenso Semple (136:20)

14 years, something like that.

Andrew Huberman (136:22)

So with that caveat what is, people are going to want to know what is your general routine now and how much does it look like or differ from what you described earlier?

Dr. Lauren Colenso Semple (136:36)

It's definitely changed over the years. I went through phases of really trying to maximize strength and I got injured a lot. And then when I've been in phases of doing data collection, I've had to really scale back from my training because your schedule is not your own. And now I'm at a point where I like more frequency, so I tend to go more often, but I'm not necessarily for really long sessions. So I go for a half hour, sometimes 45 minutes. But I like to go more frequently because then I feel like I'm better at kind of keeping up with the habit. And so right now I do a split of an upper body push, an upper body pull, and a lower body and. And I just kind of rotate through that.

Andrew Huberman (137:30)

So do you take a day off after six days of that? So push, pull legs, push, pull legs, take a day off.

Dr. Lauren Colenso Semple (137:36)

Or sometimes I'll do push, pull legs and take a day off and then push, pull legs and take another day off. I'm not as kind of strict with it because it does depend on my weekly schedule, but that rotation kind of allows me to always be able to go in and pick up where I left off.

Andrew Huberman (137:52)

And you're doing the sets presumably the way you described before? Getting close to failure or going to failure?

Dr. Lauren Colenso Semple (137:59)

Yeah, I will typically get close to failure. Occasionally I will go to failure. It kind of depends on the exercise. I think if you're doing something particularly machine based, then going to failure is pretty risk free. Either the weight moves or it doesn't.

Andrew Huberman (138:15)

And cardio, in addition to that, dedicated.

Dr. Lauren Colenso Semple (138:18)

Cardio, I will do some, but not regularly because I tend to be physically active, hiking with my dogs and I prefer to be outside if I can, getting my physical activity than, you know, on a StairMaster on an incline treadmill. But I'll do it if the weather is bad.

Andrew Huberman (138:44)

I think the routine you just described sounds really doable. The routine you described earlier sounds really doable. Do you think mobility work is important for women or men, dedicated mobility work?

Dr. Lauren Colenso Semple (138:58)

Not really, because I think if you are doing full body training through a full range of motion, then as you are warming up with those lighter sets and making sure that you are moving through your full range of motion, you're already getting that built in mobility work. So if it makes you feel good, then great. But I think a dynamic general warmup versus a specific. Let's do some of the target, exercise with lighter loads and move through that they can be equally effective.

Andrew Huberman (139:35)

I want to make sure I double click on something you said earlier. You said the long term outcomes of these hormone replacement therapy studies on women do not show improvements in cognition, et cetera. My understanding of that large data set was that women who started hormone replacement therapy as they entered menopause fared better than those that didn't. But those that started it after menopause, it didn't turn out well. Maybe I'm not up on the latest of these.

Dr. Lauren Colenso Semple (140:08)

Well, it depends which outcome you're interested in. But one of the biggest issues historically was in the early 2000s, Women's Health Initiative was doing a set of studies looking at hormone therapy. It was older versions of hormone therapy, but ultimately the goal was to evaluate the utility of that estrogen based hormone therapy for, for reduced risk of cardiovascular disease. And they stopped one of the trials early because they saw that it wasn't reducing risk and that perhaps it was going in the other direction. And so they couldn't ethically continue the trial. But the media had a field day with this and kind of twisted things. Then the message to the public was that hormone therapy causes heart disease, hormone therapy causes cancer. And it took a lot of years to really unpack that, to say, okay, what does the data actually say? What was that study designed to assess? Because it's one of the largest data sets to date on all sorts of outcome measures. But what it doesn't say is a blanket statement. Hormone therapy is terrible for this person or for that reason, or here is when everyone needs to start it. Because to your point, there were people who were a variety of ages and menopause status. So there's work that has come out since looking more specifically at outcomes like muscle mass, bone density, cognitive health. And then there's also trials that are more observational in nature or cross sectional and saying, can we look at this to identify some patterns that we could then go investigate in a clinical trial. And there is a tendency to kind of jump the gun and say, well, based on this potential pattern, then it looks like there might be this health benefit. And then the message gets misconstrued into if you take it, you'll never get Alzheimer's or you'll never get dementia. And that's not an appropriate representation of the data.

Andrew Huberman (142:48)

I'm just curious. So deliberate cold exposure, Yay. Nay, Meh. Depends.

Dr. Lauren Colenso Semple (142:55)

Depends. I think the most compelling benefits are probably the kind of mental clarity and psychological well being as opposed to the physiology zone. Two, it's fine. It's certainly necessary with long term endurance training goals, but if you prefer higher intensity or other forms of moderate physical activity, then do that instead.

Andrew Huberman (143:22)

Weight vests skip.

Dr. Lauren Colenso Semple (143:24)

Really?

Andrew Huberman (143:24)

I'm surprised. Please tell me more.

Dr. Lauren Colenso Semple (143:26)

Because weighted vests are being marketed to women as an alternative for resistance training. Walking with a weighted vest. And so walking with a weighted vest is not going to improve muscle or bone. It's not the appropriate stimulus. So if, if you want to use the vest to maybe do some squats or lunges or jumping exercises, then that might be an appropriate use case for it. But just going on walks with a weighted vest is not a substitute for resistance training.

Andrew Huberman (144:02)

Arm hang test as an indirect measure.

Dr. Lauren Colenso Semple (144:05)

Of longevity, I would skip that. I think we have a lot of data in grip strength because grip strength is really easy to measure in clinical settings in people who have never actually exercised, including people who are on bed rest. So we know there's a relationship between grip strength and, you know, quote unquote longevity because grip strength is a proxy for overall strength. So instead of worrying about testing or training grip strength, we should be focusing on doing our full body resistance training.

Andrew Huberman (144:34)

Jumping up onto or off of things specifically to get a longevity or safety effect.

Dr. Lauren Colenso Semple (144:41)

I'd rather incorporate some sort of balance training into your resistance training session. So we could do that through unilateral exercises or through something like a walking lunge. And then we're making sure that we're kind of working in full ranges of motion in different planes of motion, because that way if we have good balance and we have our strength and muscle mass and we're able to coordinate that movement, then if we start to fall.

Andrew Huberman (145:09)

We'Ll also be able to catch ourselves dedicated abdominal work. And if it's a yes, what's your favorite recommendation?

Dr. Lauren Colenso Semple (145:18)

Any kind of abdominal exercise is not going to burn off your belly fat. So if you want to hypertrophy your rectus abdominis, then you need to treat it like any other muscle group and load it it progressively. But I think most women who are doing hundreds of crunches are hoping that it's going to make them leaner, not that it's going to grow their abs.

Andrew Huberman (145:47)

Favorite exercise that you don't see people doing that they might want to try with the appropriate instruction. Just like a fun one that you like.

Dr. Lauren Colenso Semple (145:58)

I like a single leg RDL Romanian deadlift. And you can hold on to something. And so you're getting kind of a good glute and hamstring on a single side. And you can also Incorporate a kind of balance component into that. If you don't want to hold on to something for stability, I like to put one of those barbell pads on a low bar in a squat rack. So then you can put the top of your foot on the pad and. And it's more comfortable than putting your foot on the bench.

Andrew Huberman (146:31)

And do you hold the dumbbell on the side that's doing the work or on the side with the leg back when you do those?

Dr. Lauren Colenso Semple (146:41)

You can do it either way. I prefer to hold it on the same side.

Andrew Huberman (146:47)

Last question. Is there anything that's been scientifically shown to accelerate recovery from resistance training, not just move out soreness, although if it does that, great. But to accelerate recovery, meaning to get you from the stimulus to the adaptation more quickly?

Dr. Lauren Colenso Semple (147:02)

A lot. To attenuate soreness, but to accelerate the adaptation. If you want to accelerate recovery, then you're potentially compromising adaptation. So ice baths are a perfect example of that. You know, you're getting more recovery, but you're possibly blunting the hypertrophic stimulus. So same with NSAIDs.

Andrew Huberman (147:32)

Same with NSAIDs, yeah. They will block hypertrophy because they reduce inflammation.

Dr. Lauren Colenso Semple (147:37)

Right. And we want that inflammation at least, you know, short term.

Andrew Huberman (147:41)

Well, Lauren, Dr. Colenso Semple, this was amazing. First of all, thank you so much for coming here and talking with us with the audience today. Thank you for being a rational, scientific voice online. I will say with a high degree of confidence that what you described before, that it's very hard to get attention for the basics and for what's known in a landscape where other things seem to lend favor. I think there's been a lot of that now, and I'm confident that you're going to be the signal in a lot of noise so that things invert. And it's a wonderful thing that you're doing what you're doing. I really appreciate the clarity of your answers. And I also have to say I really appreciate your Instagram, et cetera. Are there other things that you're doing now that people can find you?

Dr. Lauren Colenso Semple (148:35)

Yeah, I write a monthly research review with three other PhDs, Eric Trexler, Eric Helms, and Michael Zordos. And we release that, like I said, monthly. And it's all sorts of topics in health, fitness, wellness, and we kind of break down the latest science and give you actionable take homes. So if you're someone who likes the deep dive into the science and also wants to know in the context of the literature as a whole, what should I do then? Check out mass research review.

Andrew Huberman (149:08)

Great. All right, we'll put a link to that also. Well, thank you so much. Definitely come back when there are more data to discuss. I'm sure it won't be long and it'll be interesting to see how the landscape changes. But like I said before, thanks for being the signal in the noise. Appreciate you.

Dr. Lauren Colenso Semple (149:25)

Thank you.

Andrew Huberman (149:26)

Thank you for joining me for Today's discussion with Dr. Lauren Colenso Semple. To learn more about her work, please see the links in the show. Note Captions if you're learning from and or enjoying this podcast, please subscribe to our YouTube channel.

Dr. Lauren Colenso Semple (149:37)

Subscribe.

Andrew Huberman (149:38)

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