#588: Menstrual Cycle "Syncing": Do the Claims Hold Up to Evidence? – Expert Panel

Hello, and welcome to Sigma Nutrition Radio. My name is Danny Lennon. You are very welcome to the show. If you are a new listener, then welcome. Hopefully you enjoy this and many more episodes into the future. And if you are a regular listener to the show, then thank you for rejoining for another episode. A few months back, I had the chance to play the role of presenter at an event called the Inside Advantage, which was hosted by Optum Nutrition. It was held at the McLaren F1 Performance Center in the UK. It was a really excellent day of various different panel discussions and insights from a host of experts, some of which you will hear from today. And I was fortunate enough to be presenting or playing the role of moderating these panels and introducing some of these experts and putting questions to them on a whole range of different topics, one of which we're going to take a look at today. Before we get into any of today's actual content for the episode, I just want to give it a thank you to Optum Nutrition for putting on an event and for taking an interest in actual evidence-based education. And a particular and big thank you to Kriina Tobin, who coordinated things, who organized the whole thing, who put in a huge amount of work to make it the success of what it was as well as the team that did that alongside her. So it was great to be a part of that and I thoroughly enjoyed the experience. And in addition to that, I want to give a thank you to Kriina and the team for allowing us to use some of the audio from those discussions here on the podcast. And so what you're going to hear today is some of the discussions that took place on the day. And so the listeners of Sigma Nutrition can get access to those. If you'd like to watch a high quality video of a number of the sessions that happened on the day, they are now available on the Optum Nutrition website. I will put a link to that in the description. So if you click through there, you'll be able to find a few more of the discussions that happen and some of the videos to go with that. Like I said, I'll link to that in the description box. Now, today's episode that you're about to hear includes some of the sections from those conversations where I was joined by four people, many of you who will already be familiar with, Professor Kirstie Elliott-Sale, Professor Stu Phillips, Professor Shona Halson and Dr. Eric Helms. Indeed, they've all been previous guests on this podcast. And so in the episode page, I will add links to their episodes or I'll put a list of them. Or, of course, you can go back and search through the archive of episodes on whatever app or platform you're currently listening on. And you can find those episodes with those experts. If you want an individual one. But very briefly, as a reminder, we have Professor Stu Phillips, who is Professor of Kinesiology and a Tier 1 Canada Research Chair and Skeletal Muscle Health at McMaster University. And his research is primarily focused on the impact of nutrition and exercise on human Skeletal Muscle protein turnover. And he's also keenly interested in diet and exercise-induced changes in body composition. Then we have Professor Kirstie Elliott-Sale, who is Professor of Female Endocrinology and Exercise Physiology at Manchester, Metropolitan University, where she leads the Center of Excellence for Women in Sport. And her research focuses on key questions in female athlete physiology, including menstrual cycle effects, hormonal contraceptive use, pregnancy and postpartum exercise interventions, musculoskeletal health, and relative energy deficiency in sport. We also have Professor Shona Halson from ACU's School of Behavioral and Health Sciences. She was the head recovery physiologist at the Australian Institute of Sport from 2002 all the way up to 2018. And it's been part of three Olympic campaigns with the Australian Olympic Committee. And her research focuses on recovery, fatigue and sleep. And in particular, she has an interest in maximizing recovery and monitoring and improving sleep in elite level athletes. And then finally, we have Dr. Eric Helms, who is a senior research fellow at Auckland University of Technology and the strength and conditioning lab manager at the Sports Performance Research Institute, New Zealand. And academically, he focuses his research on physique and strength sports, specifically looking at training and nutrition with this emphasis on long-term sport careers healthistically integrated with life. He's also a coach and educator with 3D muscle journey, as well as being the co-founder and author for the Mass Research Review. And if you want more information about Mass, I'll put a link in the description box for this link now. And in our episode today, we're going to be taking a focus in on female performance and recovery across two main areas. Let's say two categories of claims that are often made around female performance. And we're going to take a look at what the evidence might say in relation to those and what conclusions people can come to and try and get rid of some of the confusion that can pop up around this topic. So first of all, in the first half of this episode, we're going to hear us taking a look at some of the various claims that come up around the so-called menstrual cycle syncing of training and nutrition. So you've probably seen some of these very confident prescriptions online about how women should lift heavy in a certain part of their menstrual cycle, or when in other parts where they're not going to be able to adapt to training, or when they may need to radically change their diet based purely on their cycle phase, and a variety of other claims related to this concept of cycle syncing. So we're going to try and unpack where these ideas come from, what underlying physiology tells us, and then more importantly, what the current evidence does and does not support. And so this will hopefully include things like discussion around symptoms, individual variability, the difference between auto-regulating training based on how you feel versus following rigid template that is tied to hormone graphs or other textbook physiology. Then in the kind of second half of this episode, we're gonna take a turn and look at some of the persistent points of confusion that relate to muscle growth, protein intake, and recovery in female trainees and athletes. So things like, do women need fundamentally different protein strategies to men? Are women actually at a disadvantage in terms of their ability to gain muscle mass? What are the actual drivers of hypertrophy and recovery, independent of some of the social media narratives and buzzwords around things like bulking and fears around protein and weights, et cetera? So we're gonna take a look at a variety of these across these discussions. For those of you who are Sigma Nutrition Premium subscribers, there are detailed study notes to accompany this episode. So they're gonna include a breakdown of the main concepts we discuss, useful definitions, reference to different papers that may come up as well as useful diagrams and so on. You can access those via the link in the description box where you're listening right now, or directly over on sigma nutrition.com. So with that context set, let's get into it. So this is myself in conversation with professors, Kirsty Elliott Sale, Stu Phillips, Shona Halson, and Dr. Eric Helms at the Inside Advantage event hosted by Optum Nutrition. Enjoy. (upbeat music) So, Racer Elliott Sale, if you'll help me out here, can you maybe talk about some of the typical hormonal changes that occur across the menstrual cycle and some of the useful terminology that people might be aware of? So what you're looking at are two hormones, estrogen and progesterone, and these two hormones fluctuate across the menstrual cycle. Estrogen almost on a daily basis and progesterone more so on a weekly basis. Now you might be wondering, whether it's the menstrual cycle and progesterone more so on a weekly basis. Now you might have heard that every menstrual cycle is 28 days long, or once a month, you know, it lasts a month. But actually we know that some menstrual cycles are short as 21 days and they can still be healthy, or they can be as long as 35 days and still be healthy. Now the other thing to note about the menstrual cycle is, we love to divide it into specific phases, and we do so by, the phases are based on different concentrations of these hormones. So for example, in phase one, estrogen and progesterone are low. In phase two, estrogen is very high, progesterone is low, and then in phase four, I can count, I know I've skipped three, but in phase four, progesterone is high, and there's a secondary peak in estrogen. The reason why I didn't mention phase three is it's a bit of a transition phase, and actually we're mostly interested in the bigger, the significant changes. So hopefully you love seeing from this particular figure that the menstrual cycle is not static, so it is a very dynamic process. It is not 28 days, it can be for some women, some of the time, but not all women all of the time. So what I really want you to take away is it's highly variable, the cycle length is variable, and the phases are not at a fixed point. Lots of variability to consider. Fantastic. First of all, when it comes to recovery, one of the things that sometimes gets mentioned is the potential role of some of these hormones, and the changes within them or even claims around, is there differences between sex as based on some of these hormones in terms of people's recovery? Do we have evidence around this, and what is the current state of the evidence? Yes, I'm going to sound like I'm just repeating myself, but no, there's no evidence to suggest that recovery is different across different phases of the cycle, nor that women or men require different recovery strategies to optimize their performance. So there's a little bit of evidence, like we know that in the luteal phase, there might be a decrease in heart rate variability and increase in heart rate, but for us, that's just the way I interpret that, is that it doesn't mean we need different recovery strategies. It just means that if you want to train these things as part of your training program, that you might need to take that into consideration. But now, there's no really good, solid evidence. I admit, there hasn't been many studies, but there's also no good evidence to suggest that you will recover differently at different phases of the cycle. One of the things you wanted to get to is this concept of cycle thinking, which is incredibly popular, and people have seen a variety of different claims about this. Professor Phillips, first could you maybe define first what this is, what people are typically referring to when this term cycle thinking is used? Yeah, cycle thinking refers to changing your training according to the phase of your menstrual cycle. I think that there's various sort of definitions that are out there, lots of different opinions on this. I think one thing that we can't discount is that women definitely experience different symptoms throughout their cycles, and one woman is not like the next woman with respect to how you might feel about training, your motivation, how training might make you feel. But there's certainly no one way to do it, and I think that's what sort of cycle thinking has branded itself as, is that you are more anabolic, and so predisposed to gaining muscle and you're stronger during your follicular phase, and then you are catabolic and weaker during your luteal phase. Now some women may feel that way, and I won't discount that, but from a physiological standpoint, there's actually no evidence to suggest that there's much difference. In fact, some women find it exactly the reverse, so I think that the notion of trying to sink cycles and the fact your training that way is going to be tough to get a physiological basis more, but feeling wise, there's some evidence behind it for sure. And we'll certainly spend some time talking about some of those symptoms, as well as training itself. But if we turn to nutrition just briefly before we move on, some other claims people may hear that Professor Phillips relate to, differences in what nutrients may be needed, or best handle at different times, and you need to radically change dietary strategies for athletes at different times, because you may be speak to some of that and what evidence we have. The changes in hormones, even though they are obviously quite distinct and result in very different physiological states, from a nutritional perspective, again, there's probably even less evidence to suggest that nutrition should change from one phase of the cycle to another. So there was a group that attempted to look at all the literature in this area and synthesize it and really came away with what we don't have a consensus. There's nothing that appears to be a trend that's coming out. So I don't think that there's any evidence to say you should do this in this phase and this in this phase, and that's the same for all women. So I think that actually at CL put it really, really well, is no one woman has the same cycle as the next woman, and even a woman from cycle to cycle can be different as well. So with all of those things considered, I think it would be hard to put hard and fast recommendations, nutrition wise, for sure. And so Professor Elliott-Sailer, can you maybe talk about where some of these things come from in that does the role of these different hormones have an effect on, say, training? Where did we first start to suggest that there could be an impact that they're playing a role on, either recovery or performance? Where does that sort of come from? Oh, good question. I think for such a long time, we never spoke about some of these female specific considerations. So we often hear people say the menstrual cycle was a taboo topic in sports. But I think we've maybe that pendulum swing effect. And now, where it's come out of hiding, we didn't talk about it. It's sort of become the everything. And so I think we need to sort of course correct. And so you were asking me, you know, what do these hormones do? You know, what's the rationale that sits behind possible changes in performance? So first and foremost, I always need to remind athletes, practitioners, everybody that these two hormones are reproductive hormones. So their primary function is to prepare the body for pregnancy. So that's their primary function. That's what they're there to do. Now they have a whole host of secondary functions related to health. So again, these hormones have roles in cardiovascular health, bone health. So we talk a lot about estrogen and bone health cognition. So they're traveling to lots of other places in the body for these secondary health roles. And then we have to think about what's left over or what's available for these other sort of performance effects that we're now starting to think about. And theoretically, we have estrogen and progesterone receptors pretty much all over the body. So theoretically, there is a biologically plausible pathway, but we don't have research data that says, actually, it goes to the muscle and it causes you to be weaker or stronger. So the research evidence for the direct physiological effect is lacking. There's not a lot of evidence. And the evidence that we have is a real mix bag in terms of quality. Just like Professor Phillips said, I'd like to just highlight there are indirect possible effects, I think, on performance. Two of the main ones, or maybe we'll go for three if that's okay. So one is around the physical act of bleeding. So as female athletes menstruate as part of the menstrual cycle, again, caused by the change in the hormones, some female athletes are distracted by that bleeding or they're anxious about it. So whether they're anticipating it might come in the middle of an event or they're already menstruating and they're worried about potentially leaking into their uniform and obviously that could be possibly embarrassing for them. So if you're anxious, if you're distracted, that could impact upon your performance. So that could be an indirect way. The second way is very much around the symptoms, like Professor Phillips said. And just to really need to make the point that it's not all women who have menstrual cycle symptoms, it is some but not all. So again, I think we just need to be careful that we don't imply that every female athlete is going to be impacted. I know many who are not. And if you have menstrual cycle symptoms, there's a clue here. It's called a menstrual cycle. So the symptoms would be cyclical. And if they're cyclical, then you can anticipate when they're coming, okay? And if you can anticipate when they're coming, you could adapt your training based on that, okay? So auto-regulation, my Professor Phillips, been around since the 1940s, not a new concept. Men, do it, women can do it, okay, that's fine. But if you know they're coming and if they have a negative impact on your performance, why don't you get ahead of that and mitigate against those negative symptoms? So I think that's another indirect way. And then the last one is around perception. There's a lot of noise on social media telling female athletes. They'll win in this phase, they'll lose in that phase. They'll get injured in another phase. And actually, we know the perception sometimes shapes reality. So again, we just need to be really careful about the narrative that we're putting out to female athletes. So a little bit of nuance there, but from a physiological point of view, no direct link that we've seen yet. But maybe some indirect ones that need some consideration. Yeah, and to build on some of those indirect impacts. And as you know, on an individual level, some of these things will be playing a role around the perception of a, if you have the perception you are going to train worse, then that's probably going to have some sort of impact. But also noting those individual differences and being able to apply them and modify your training, is not the same as saying everyone else needs to follow this particular structure, or at this point, you are going through experience it this way. So I think that really gives people a lot to work with. One of the things Professor Halson that comes up is, while sometimes there might not be some direct effects, do we see differences in things like impacts on sleep across a menstrual cycle with changes in hormones that could then have knock on effects on things that recovery? Yeah, so there's been a little bit of research in non-athletes. And we sort of decided a few years ago to try and answer this question in athletes. And we've done probably three projects now looking at sleep across the menstrual cycle. We used the Queen of Female Physiologies gold-standard measurements for the menstrual cycle, which is Professor Kirstiel herself. We used gold-standard measurements of sleep, looking at lots of different devices, and we really didn't see anything. Sleep didn't change across the menstrual cycle. We measured the hormone concentrations, the hormone concentrations weren't related to sleep. But like everyone else on the panel has said, the one thing that was related to slightly disturbed sleep in some participants was when they had higher symptoms. And that's essentially all we saw. I'm moving forward in this space, so it's obviously we can't forget that as women age, hearing menopause and menopause, we know there are people find that their sleep is really disturbed and of course in pregnancy. From that regard, I expect to see issues with sleep that across a normal menstrual cycle, very, very few issues. Professor Phillips, one of the things that creeps into these conversations when different hormones are mentioned or related differences between men and women in response to training or nutrition, for example, is that there are distinct differences in how they should train and how they will adapt. And that being the main difference as opposed to all the other factors that could be playing a role that are probably more important variables to look at on an individual athlete basis. Could you maybe speak a bit to this and explain some of the things that maybe is misplaced in where people are putting more of their focus? Yeah, that's a great question. I think for a long time, the focus in what was it that drove muscle gain and strength gain and weightlifting and resistance training in particular was around testosterone. And just the casual observation, men are bigger, broader. They have more muscle. And wow, that's, of course, that's testosterone. That's true when boys and girls go through puberty, always get a pubertal surgeon to testosterone, they gain muscle, they get bigger. And that's an advantage that they probably retain for their entire life. But we now have a number of studies in men and women training beside each other in parallel comparisons between studies that show that actually women gain relatively speaking. They start with generally lower muscle. The same amount of muscle is men. And in fact, in some studies, it may even favor women in terms of the amount of strength that they gain. So I think that puts a pretty big nail in the coffin that it's all driven by testosterone, because, of course, women have 10 full, less testosterone than men. And at the same time, it shows you that the physiological response is dictated as much probably by the amount of effort that's put into the training as by the hormonal environment. Professor Elliott, say, of course, you've done a huge amount of research in this area. But you've also been involved on the practical application side with elite-level sport across some of the most well-known athletes in teams in this country and beyond. Can you maybe talk to your experiences with some of those conversations you would have had with those athletes to try and get past maybe misconceptions or concerns they had related to these type of issues? Absolutely. A couple of different examples I could give you. So first is around what they're seeing on social media. And so I spend a lot of time debunking, demystifying some of those things. And the social media is great. And I think I heard Professor Phillips say that. But the content can be engaging, it can be capturing, and actually quite compelling. So it's easy to buy into that. And then I turn up a little on me. And I don't really speak like an influencer. I speak like a scientist, and I'm trying to convince them that the opposite is true. So that's often where the conversation starts, trying to walk back some of that stuff that they've seen that isn't evidence-based. Then there's some interesting conversations around menstrual cycle symptoms. Now I know we've spoken about this a couple of times. But one thing that I think maybe is spoken about less is the big shopping list of menstrual cycle symptoms. So what I mean by that is I'll often go and work with a new athlete. And I'll tell you about your menstrual cycle symptoms. And for those who have them, it comes to list. And I look at that, and I go, OK. So how do you know that these are related to your menstrual cycle? And they're like, oh, I'm a girl, and I have a menstrual cycle. And these things are bad, they suck. So they're menstrual cycle symptoms, right? So what we do is we ask them to make a note, a diary of their symptoms across three consecutive cycles. It's really simple signs. It's not even signs. We overlay all the symptoms. Do they occur at the same time? Are they cyclical? So I'm going to go back to what I said earlier. And often, a lot of those menstrual cycle symptoms that were being attributed to the menstrual cycle are not cyclical. And so therefore, we start to look, if the scattergun, we think, OK, what else could it be? And we've had some other examples. We saw one athlete whose headaches were linked to dehydration, bad hydration strategy. And so actually, by doing the simple exercise, we can get rid of often a lot of symptoms that were perceived to be the menstrual cycle ones. The multidisciplinary team, quite often, the nutritionist has got great fixes for lots of these things. And then when we get down to those maybe one or two that are cyclical, then again, it's about being proactive. Do you need to change something to your diet or to your training program? So that's probably where I spend a lot of my time that that's sort of the conversations. And then I guess, lastly, we do. We talk about performance and their own performance. And we're always keen to hear their experiences. So you know, lived experiences are super important. But again, sometimes they need help navigating that. So you could say, I won in this phase. So this is my winning phase. But you might also have had great sleep. You'd just come back from a break. All these things, you'd optimise your nutrition. So that cause and effect, it's going to be rare. It's just one thing. So we talk about and we navigate their lived experiences. And I remind them that actually, while we may not have a lot of research evidence, it's almost a good thing. They have the freedom. Medals have been won and lost on every day of the menstrual cycle. PBs have been set. So I think giving them that freedom to think about, what are their lived experiences? How do we position that amongst everything else? But knowing that actually, whilst we're waiting for this great evidence to come through, that they don't have to be too limited and constrained in their practice, they can go out and win in any day. Fantastic. And maybe to wrap this up with our concept of cycle syncing, Professor Phillips, from what everyone has said and from what we know from the current evidence and some of the misconceptions that are out there, can you maybe give us what is it we should take away about this concept of having a very prescriptive ability to plan training and nutrition based on cycle? I would have to think after listening to all of this is that there are some women who definitely need to take a break at certain times and because they're symptoms, but train according to how you feel. There's nothing that is specific to one phase. That's called auto regulation. It's been around for over 50 years. Men do it to the whole idea that, you know, if you have a bad night's sleep and you're not ready to for a big day of training, then it's not a big day of training. So maybe that's the better way to look at this rather than one phase is better than the other. So one of the myths you referenced earlier, Professor Phillips, was around this concept of protein well make women bulky, quote-unquote is the common word that's thrown around on social media or this idea that this is in some way even a problem. Can you maybe just revisit some of what you discussed in that myths and myths conception piece but maybe add a bit of context for us? Yeah, I mean, I think that there are certain sports and you could look at certain positions within certain sports where bulk per se, so mass per se, is a good thing. American style football is an example where offensive and defensive linemen, they're just big human beings and it doesn't matter as much about how much muscle or how much fat they have. So they're just in it for bulk. But I think that most people probably realize is that those guys lift a lot of weights. Similarly, if you look at women playing in the rugby world cup which we've got going on right now, there are some women in that sport. They are bigger because they lift weights. They're strong as well. So I think there's a distinction between just getting bigger and bulking between what you gain is muscle and that's a phenomenon driven by lifting weights. It's not a phenomenon driven by protein or all. And we'll dive into some of those mechanisms. But first, first of all, it's sale. One of the things I think is worth heading off is, I think most people now will have an appreciation that in a lot of studies, and particularly in sports science, we have maybe traditionally an under-representation of female participants or studies that maybe are female only. However, there's sometimes this extreme position then people see pop up in line of, there's no studies in women whatsoever. Can you maybe tell us what the actual state of the evidence is? - I think we are living proof on the stage that there is some research being conducted in this area. I think we've all conducted studies on this particular topic. So I feel like that's a little lazy. I understand why people say I'll come back to that in a second, but it is lazy. There are studies that have been conducted looking at women. I think looking at women could be unpicked further. Is it that you are interested in different phases of the menstrual cycle? Are you interested in hormonal contraceptive users? Pregnant athletes, older master athletes who are maybe perimenopausals. When people say I'm interested in women, I obviously like which type of woman. So that's what I mean. They were quite different in our profiles. So let me go back to when I said I understand why people say there's no evidence. What they should actually say is there's a lot less evidence in women. Would they have historically been overlooked, particularly in sports science? Again, I'm not a sociologist, but I think maybe we could even consider that from a supply and demand. Look, I think it was in 1902, don't quote me on the exact year. 1902 Olympics in Paris, 2% of the participants were women. Fast forward, as Professor Phillips said, we've reached parity now. So last year, 2024 in Paris, we got parity in participation. So it's taken more than 100 years to go from that 2% to 50%. So maybe we could argue that sports science has been built for more traditionally, investigating men, but there were more men taking part. It doesn't make it the right thing to do, but I think we're starting to turn our attention there. So one more nuance, all about the nuance today. So there is less evidence, maybe on a supply and demand. There's less evidence, maybe, because there's been a women or two complicated. We're not complicated. We're really interesting. So there's less evidence, but here's the last bit of nuance. Is that I'm very open. I'm excited to see the new evidence coming through, but we really need high quality evidence. So when it comes to research, using women as participants or studying female athletes, it's underfunded. And so you try and do a lot on a little. And I think we've got to be careful not to do low quality work, because for the practitioners in the room, you want high quality data. Data that the scientists are saying, it's robust. It's credible. It's trustworthy. And you should change your practice based on that. And so if we just do more of any quality, then we're not giving you what you need. So I think we need more. And we need that more to be high quality. One thing that Professor Phillips mentioned earlier was around that men and women have the, basically, same ability to build muscle. Dr. Helms, can you maybe speak to some of the evidence we have on this, to this concept, and maybe fill in some of those gaps of, well, how do we distinguish that? What evidence we're basing that on? Yeah, we've actually got a pretty robust set of evidence on this. There was a 2020 meta-analysis. And then there's a more recent one in 2024 meta-analysis. It's just when we take all of the trials on a given topic, put them together, and we then try to get a summary statistic of that. And this is really important in the field of sports nutrition and sports science, because we don't have the funding, like Dr. Sales talking about, of the medical field, where you might have a multi-site 10,000-person study, and you can get a very robust estimate of the data. We have 10-person studies, and we can kind of cobble that together. But there's actually some really big data sets. There's one particular study on resistance training. That's called the famous study, which is some ridiculous acronym. It was done in the 2000s, still data coming out from it. And I think collectively now it's got about 1,300 participants or so. And they looked at the percentage changes in muscle mass, and that's actually included in the meta-analysis. That's just one of the studies. So what we see is exactly what we've mentioned before, while you see absolute higher levels of muscle mass gained in men compared to women in terms of kilograms of size, or a mass, the relative change, the percentages, are actually quite similar when you look at things. And we do see an interesting phenomenon if we want to talk about strength, where the lower body strength percentage changes are quite similar between men and women. But upper body strength, on average, actually, increases more in women. Then the question is, going back to your sociological comment as why? And even when we do research on untrained participants, it doesn't necessarily mean that not having performed resistance training puts you at the same state when you live in society. So is it a true sex difference? Or is it a systematic difference between what we would classify as an untrained man or woman? So for example, in the US, in the famous study, they observe this, different rates of strength gain. For the longest time, and still to this day, much different participation rates in high school of sport. And back when the participants who were in the 2000s were participating in this study, the 2/3 to 75% rates in women versus men. And importantly, in the States, American football, strength conditioning was the first sport that really embraced-- sorry, football is the first sport that really embraced strength conditioning. And football, you're getting it off the ground, you're standing up, you're pushing, you're pulling. There's much more upper body involvement. And they're actually training with weights. So even though you're an untrained participant 10 years later, when you are in the study, you're probably going to see some systematic differences between the men and women who are quote unquote untrained. So when you are untrained and you start training, you make faster initial gains, neuromuscular adaptations, you learn the skill. And if you take a whole bunch of people and some of them, oh, yeah, yeah, I still lived in high school. Or I used to play football. I did pushups, that kind of thing. That's enough to see some kind of systematic difference when you have these big data sets. But is that a true sex difference? Is that because of estrogen? Is that because testosterone? Probably not. I can't prove to you that it's not. But I can say that in terms of the actual potential to put on muscle mass, very similar percentage changes. And not to pull us off topic, but there's a kind of similar discussion going on now in the injury and rehab world, right, around injury rates within female athletes. And it's maybe not a sex difference, but rather the general physical preparedness before that of the exposure because of society to different sports and so on earlier. So there's something that aligns with as much you were saying. And it even happens when later in life, we don't have parity in the workforce. There's something like 20% of manual laborers are women and 80% are men. So as a researcher, you have to set parameters for-- I'm recruiting trained or untrained participants, and that means X, Y, and Z. But you typically can't go. And I'm not recruiting manual laborers. Actually the famous study did. They specifically said we're not recruiting people who have resistance training like jobs, which they didn't define, which bothers me as a researcher. But I'm like, oh, that's cool. They try to control for that. So you have to be aware of these nuances. Because if we're going to say something as important as there are these fundamental differences between men and women, then therefore they should train differently. And we're going to increase the varied entry, make it more complex in a world that's already quite complex, confusing, and overwhelming us with information. You better have damn good reason to do so. One of the things that was mentioned earlier, I think, by Professor Phillips, was around this concept that, well, if someone just starts consuming lots of protein, it's not going to magically cause someone to gain a lot of muscle. So there's a bit to unpack here. And maybe I'll start again with you, Dr. Helms here. Can you maybe let us know from the overview level, if it's not just drinking more protein, can let me gain muscle, what are the actual drivers of muscle growth? Yeah, so at a high level for a practitioner or a lifter, it's like what you do in the gym. And then if I want to speak to it from the researcher perspective, it's how does that actually connect to the muscle physiology. And I won't do that to you. So what we're going to do is we're just going to talk about what are the main things in the gym. And it's two, two big things. It's how hard are you training, which we would define as proximity failure? Not necessarily how heavy you lift. But did you take the given load you're working with? And in that set, did you get to the point where-- you know, I probably could have only done a few more reps. And then OK, that's a unit set of training. How much of that did you do? So it is volume and then effort. If we want to define effort as proximity failure, there are two big training variables in the gym that results in hypertrophy long term. Fantastic. Professor Phillips, if we talk about protein as being part of that recovery process or a building muscle, again, another area where there's lots of strange claims of people of comor cross, that may be there's specific types of protein supplements that are for women versus men, or they need different amounts of protein purely on a sex-based difference. Can you always speak to some of the things that you may be of comor cross have been asked about and how you can maybe set the record straight on some of them? Not a marketing person, but I understand the phenomenon is known as pink washing. So we take male products and we repackage them and sell them to women and put them in pink packages. Because, of course, women like pink things. But I think, again, if you've listened to everything that we've said this afternoon, the same rules apply relative to basically body weight, or if we had a measure, maybe relative to muscle mass, all of the recommendations we've made around protein would be exactly the same for women as they would be for men. I realize on social media that there's a big push right now for women and paramanopause to consume more protein. But I can say, again, unequivocally, that there's no evidence to suggest that their protein needs would be any different than a man going through that same age range in their life. So between 45 and 55, where about 95% of women go through menopause. So it's basically, it's age, how much you weigh, and then you've got the requirements. They're exactly the same. First of all, if we return to some of your experiences with athletes, and maybe the concerns they come to you about, or questions they ask you about, that maybe relate to how they are training, or how they're going to consume protein, or their overall quality of diet, relating to some of these issues around muscle, what are some of those that you most commonly have to address with them? And how do those conversations tend to go? I'm going to go back again. Sorry, I'm a bit like a broken record. Most of the conversations hinge around a phased-based approach. How should I train based on my phases? What should I eat based on my phases? And maybe I'll take this answer in a slightly different direction. Obviously, I showed you the figure at the start of this particular segment. And those hormones are fluctuating sometimes daily, sometimes weekly. And it's difficult to navigate that. I can't tell on any given day what my estrogen concentration is. I can't tell by looking at a female athlete what her progesterone concentration is. So a lot of the time, we have to break it down and show them how they might navigate their menstrual cycle. So we tell them about they should make a note on the calendar how often they bleed. So that gives them phase one. They could look at how, if they're consistently ovulating, and that gives them phase two and phase three. And then if they really can do this within the applied setting, they can look at their progesterone concentration to see about phase four. And so by doing that, that allows them to navigate through the cycle. And that way, then you can start to test things against those phases. Because if you don't measure these things, you don't know what phase you're in. And then obviously can't make that decision about your performance or about your nutrition. I would say that the conversation usually starts with, if you do this, it will give you really good information about your health, because we know if you ovulate, that means you've got good, high, peaking, and estrogen. And we know that's good for bone health cognition and so on. If you've got good progesterone, maybe flipping that and looking at fertility, it's good for the lining of your wound. So we reframe the conversation into this gives you great information about your reproductive health and your general health. It allows you then to navigate the phases. And then, and only at that point can we start to test your performance once we know for sure that you're in these particular phases. And usually by the time we get to that point of the conversation or that point of the journey that we're on together, we make these measurements. And I can tell you, in 25 years, I have not seen a consistent or universal response or consistent within an individual that every time she hits that phase, this is her muscle strength. So there's no consistency there within an athlete. And I don't see it as a universal response. So when I take in 10 women as a sample, they're not all having the same response. So those conversations are around navigating the cycle. What information do you get about your health and then checking your performance against that? One of the things that everyone accepts is that there's individual differences in training response. But sometimes what can occur when we note something where there may be some type of sex-based difference is that that's the only thing that's focused on as opposed to the individual athlete where there's other factors more important. One of the things you said Dr. Helms might be a good example of this where you noted, we do see evidence where with upper body strength, relatively speaking, women may see greater gains in upper body strength. And for a while, there was almost people taking that information and saying, any female athlete I have, I need to give them much higher volume of upper body training than any male athlete that I have, as opposed to thinking about, well, other ways that we typically, for all athletes, determine if they suit low-moder or high-training volumes. Can you maybe speak to some of what was going on and maybe some context for a better way to make decisions for your athletes? Absolutely, and you just have to think through, well, why don't we see a difference in lower body strength? And then we look at female participation rates and what sports they're doing, it's volleyball, basketball, track and field. It's sports where there's a lot of jumping and running and all of us walk around. So there's a certain training age in the lower body that's maybe a little more similar between the sexes. So this is one of those things where it's like, is there a true physiological difference? There might be, there could be, through puberty, a different distribution that persists so that you have more capacity to build muscle or strength than the upper body because of the relative distribution of muscle mass, but even then, it comes down to individualization. Auto-regulation, coaching, what it is, is seeing what's in front of you and making a change. And you're more likely to make an error by making an assumption about how someone's going to respond and actually being reactive and having a monitoring system in place, what had to do that, on an individual basis. Every good coach, every good sports scientist, every good high performance program, it is an integrated iterative back and forth process where we try something, we see how it goes, we bring it back, and we had an Olympian on stage talking about that process. You can't wait until you have the meta-analysis when you're at that high level and you do need to care about the singular piece of data that matters. It's not the summary statistic of the population. It's what happened on Tuesday, what happened on Wednesday. How did I feel about it? And then what patterns and cycles do I have? So ultimately, any good coach is creating systems. An auto-regulation, I think sometimes, gets talked about as intuitive training. It's good to have intuition and body awareness. I think that's the mark of a high level athlete, but auto-regulation is a systematic approach to individualizing your training. It's if you're based on objective markers or at least quantitative markers of something subjective that are reliable. Ultimately, to answer your question, you need to make decisions based upon the athlete in front of you, independent of their sex. Knowing that their sex will impact some of these things. So if you have an athlete with a menstrual cycle, that's going to go into that sheet. It's going to look a little different. You're going to run that data if they don't have a menstrual cycle. Then you're probably not going to ask about PMS sometimes. But it doesn't mean that you wouldn't have the exact same process with different inputs to get the output. Yeah, those things will emerge from that process that coaches should have in place, regardless. So as we wrap up this section, maybe I'll turn to each of you for your maybe key takeaway from what we've discussed about this. I'll start with Professor Phillips, and we'll work down. So a key takeaway you want to make sure people really take from what we've discussed. Yeah, I mean, I hope that one of the key takeaways is that given we've got gender parity now, and women's sports is on the rise just about everywhere. We've got a professional ice hockey league in Canada, which is the only sport Canadians care about. Athletes can achieve great things. And it's a great time to be around as a researcher to see the research rising up in this area. And hand on heart, we thought, for a lot of years, we didn't include women because the menstrual cycle was a barrier. We're beginning to see that that's not the case now. So good times lie ahead. Fantastic, Dr. Helms. Yeah, make sure that you have a system. Every good coach has a monitoring practice in a way of giving the individual the best possible way of being the best version of themselves. And while we all are very different from our sex, to our ethnicity, to our age, to our height, to our genetics, we don't want to make assumptions about that, but rather have a system to respond to how those things play out in the environment. And Professor, are these two? I've got two quick ones. So I think firstly, we've zoomed in on the menstrual cycle and how that might affect our ability to train or watch we should eat. And I think we should zoom out. And I'm going to add to Dr. Helms. And I'm going to call that the gendered environment. I think that gendered environment is probably the big header. And let's come out. Look at that. And we don't need to zoom in quite so much. And the other thing I was going to say is, we have said menstrual cycle over and over again today. And what we haven't said is, depending on which country you live in, which sport you work with, sometimes maybe only a third of your female athletes will have a menstrual cycle. So we do need to broaden as well our sort of conversations and our knowledge around the other ovarian hormone profiles, like hormonal contraception, pregnancy, menstrual dysfunctions, menopause, and so on. So yeah. (upbeat music) So that is our episode for today. I do hope that you enjoyed it. And remember, if you want to get even more insights and video footage from some of the insider advantage event, you can find a series of those videos on the Optum Nutrition website. I'll link to those where you're listening right now. In addition to that, if you want to convert your podcast listening into an even more potent learning tool, then check out our Sigma Nutrition Premium membership. As a premium member, you will get detailed study notes to each podcast episode. So for example, with today's episode, you'll be getting notes on all the concepts that were covered, explanations of some of the key terms, diagrams to illustrate certain points, and having a resource that allows you to both understand the content a bit more deeply, as well as then to be able to revise and remember the key points that were discussed. So if you want to see that, as well as all the other extras you get with a premium membership, click the link in the description box to this episode or head over to sigmanutrition.com. Thanks for listening in and hopefully you join me for a future episode. Take care.