Evidence Strong
Menstrual cycle effects on strength gains: debunking the myths with Lauren Colenso-Semple
this paper was important and I'm glad that it is kind of getting some attention from coaches and fitness enthusiasts because there are people out there who are making these recommendations to alter your training around the menstrual cycle are saying all this kind of phase-based training is all a one-size-fits-all and make sure that that you were really in the phase that you were intending to be which is pretty complicated and at this point just probably really unnecessary seven reviews were assessed by you in terms of quality and heterogeneity you have concluded that we don't have evidence to say the menstrual cycle phase will influence acute gains that's right what we don't have is evidence to suggest that objectively your performance is worse because of your menstrual symptoms there's sort of a difference between yeah you know i don't i don't feel well i didn't feel like i had a great session today but as long as they are kind of what would be considered normal for you then your ability to or propensity for muscle growth and strength gains are the same all right laura and welcome to evidence strong show it's my pleasure to have you if you could briefly introduce yourself sure i'm finishing up my phd at mcmaster university stu phillips is my supervisor and before coming to mcmaster i got a master's degree in exercise science from the university of south florida with bill campbell and my undergraduate work is in psychology and nutrition and in addition to my academic background i also have several years of coaching experience and so i i'd like to kind of keep a hand in the that element of of coaching and practical application and remember that the translational side as as well as of course um all the work i do in the lab what what sport are you coaching sorry not sports um more just resistance training uh for the most part my my clients were just kind of recreational exercises who wanted to learn how to lift weights well and and wanted to get stronger and build muscle excellent okay so i invited you to talk about the paper title current evidence shows no influence of woman's menstrual cycle face on acute strength performance or adaptations to resistance exercise training so let's start with the goal the study and why did you do it one of my goals in pursuing my graduate education has been to kind of further the area of research in women in with a resistance training area because as i'm sure you may have discussed before on your podcast there's a lack of for every research in women and for many many years kind of the young healthy men were the go-to population for for exercise science research one of the reasons that women are often excluded and that population of choice is young men is because women with menstrual cycles have fluctuating hormones throughout the month and so there's an assumption that these hormonal fluctuations could potentially impact exercise performance acutely or resistance training induced adaptation so you know how much muscle you grow how strong you get over two three months let's say and because that is it's sort of an unknown people tend to shy away from studying women because having to kind of standardize when you would test when you would train so that everyone was training according to a certain phase of the cycle it would be very complicated from a research perspective you know so here we are and there just really isn't as much work done in that population but the reality is like i mentioned it's it's really an unknown at this point so there's a few studies out there but it has not been studied extensively and so the question whether this matters or not is a really important one because if it doesn't matter then we can start including men and women in the same study and we don't have to worry about when their cycles started or what phase they're in or you know whether estrogen is high or progesterone is low we can just have people exercise if it does matter then we can create some kind of guidelines for researchers to implement that accordingly so you know in either way it will further the research that can be done in women the the purpose of the paper was an umbrella review and so it's essentially a review of reviews but we also dive into some specific key papers and we aimed to look at both acute strength performance that could be a single exercise about you know how many repetitions can you do how much weight can you live how much power can you generate in a single session or a single bout of exercise and we also looked at the evidence around the longer term adaptation so the strength that you gain or the muscle that you gain after doing a a resistance training program over a generally two to three month period i think we covered why the paper was needed and um you touched a little bit on the design so not everyone knows what umbrella review is you explained where it is but now how technically you go about collecting your studies and how you decide which ones are included which ones to discard and so on this was an umbrella review which is essentially a systematic review of meta-analyses and and systematic reviews so it sounds a little bit complicated but it's essentially the the purpose and structure of an umbrella review requires the researchers to be systematic in their literature search and instead of a narrative review where you can kind of pick whatever papers you'd like to make your point a systematic review needs to kind of thirdly step by step review all of the relevant literature as a whole and then we can kind of dive into the methodological quality of the papers and the findings but it really allows us to take that kind of holistic view um as opposed to in some narrative reviews you'll kind of seek them the authors taking the researcher conclusions at face value and if we're going to be rigorous and and think critically as scientists we really need to critique each other's work and make sure that we're doing things properly from a statistics perspective and we're doing things properly from a study design perspective and you're one of the challenges when you try to do a meta-analysis or a systematic review is that you're kind of pulling together studies that attempt to answer the overarching research question but they're generally never designed exactly the same way so we would refer to this as heterogeneity and that might mean that the populations are slightly different or the exercise test wasn't the same or the duration of the training study was different and so it means that you know it would be ideal if we could just compare ten studies and they all did exactly the same thing but that's never really the case so we need to take the literature you know as it is bring together the the papers that are relevant to our research question as systematic reviewers and then look at the methodological quality the fine things and make our own conclusion based on the the totality of the evidence as it stands today we were looking at papers that assessed menstrual cycle phase and acute exercise performance and long-term exercise adaptations and they needed to be a meta-analysis or a systematic review so not individual studies there were enough meta-analyses and systematic reviews and out there that we were able to you know conduct a thorough search for our analysis once we we've done our search and we've pulled together the papers and we've made sure that you know we thoroughly searched the appropriate databases then we start going through the papers and pulling out their findings and then also assessing their methodological quality and then we can kind of take it a step further and if the authors pointed to certain higher or lower quality individual studies then we can go and we can look at those papers as well and that's what we had to do for the kind of chronic adaptations because there are so few papers that it that part of the question really isn't ready for a meta-analysis because there just needs to be more work done honest it could you explain how you decided on the quality because you said that was the part of decision-making process sure yeah so we use a kind of standardized assessment they called amstar and essentially it goes through and it looks at potential risk of publication bias it looks at the overall rigor of the methods and so you kind of give a score if you will for each item on that list and then we can say okay you know this is of low moderate or high quality so before we dive into the results could we just go briefly through the menstrual cycle so we on the same page in terms of the phases and how it goes and i'll say this just up front we're talking about women who are naturally cycling or have a menstrual cycle and so this would exclude women who are postmenopausal and women who are on any kind of hormonal contraceptive if you're on a hormonal contraceptive you don't have the kind of cycle that i'm referring to here there are uh we would say on average a cycle is about 28 days in reality there are people who have shorter cycles than that there are people who have substantially longer cycles than that and so we'd kind of say that um you know that can range from maybe 21 days to 35 days but average we would be looking at a 28 day cycle and the hormones that we're primarily referring to here are the ovarian hormone so that's estradiol and progesterone and then luteinizing hormone comes into play when we talk about ovulation so at the beginning of the cycle so when menstruation starts all the hormones are low now during the first half of the cycle which we would refer to as the follicular phase we see progesterone remain low but estradiol starts to increase and then it gets to its sort of highest peak mid cycle again that that varies between people but after estradiol peaks we tend to see ovulation and that is a pretty short but high spike in luteinizing hormone after ovulation we're in the second phase or the luteal phase of the cycle and we have an increase in progesterone up until kind of mid cycle and then it starts to slowly decline and then we also have another kind of increase in estradiol but it never gets as high as its original re-obulatory peak so we would say estrogen and progesterone are on moderately high during the luteal phase and then both hormones levels slowly decline and then that's the end of the cycle and we start all over again okay could we just clarify where we start and when we finish in terms of how we count which is day one and which is day 28 day day one would be the beginning of the follicular phase and then if you were to ovulate on day 14 then day 15 would start your luteal phase and then that would go until you get your next period on average a cycle is 28 days in length and on average a person with a 28 day cycle will ovulate on day 14 so right in the middle but there's a huge amount of variability here not only in people's cycle lengths but in their phase lengths as well and so it's absolutely possible to have a 28 day cycle and ovulate on day 20 which would mean you have a very long follicular phase and a pretty short luteal phase it's also fairly common to have inconsistency from cycle to cycle in terms of cycle length phase length timing of ovulation that can vary as I said substantially between people but it can also vary within that one person from cycle to cycle so maybe this month it's 30 days and next month it's 25 days or this month ovulation is on day 12 and next month it's on day 16 some people are very consistent but there's a lot of variability there and so that makes it challenging from from a research perspective for sure if you're really trying to capture everybody in your trial during one phase the easiest way to do this is to try to test people during the early follicular phase because you know you know when you start your menstrual cycle when you get your menstrual period then that's when the follicular phase starts so that's an it's an easy one to to detect and identify if you're looking for the late follicular phase um or the mid luteal phase then we really need to determine the timing of ovulation because the late follicular phase will be prior to ovulation and the mid follicular phase will occur after ovulation so one of the of the shortcomings of a lot of the work in this field is that researchers have not properly identified the timing of ovulation in their participants and instead they've just made the assumption that since on average a cycle is 28 days and on average ovulation occurs on day 14 let's just say everybody is in their follicular phase for two weeks and everyone is in their luteal phase for two weeks instead of actually determining whether they are or they aren't and as i said if you make that assumption for that person who actually doesn't ovulate until day 20 then you're just not answering your research question so one of the of the goals of the paper was also to really highlight the methodological issues in this body of literature and encourage researchers moving forward to use better practices to really make sure that we're being thorough in cycle tracking leading up to the trial and during the trial and then also identifying the timing of ovulation and the hormone levels and so doing blood work if you can ovulation can also be identified using urinary reactive strips and that they pick up that spike in luteinizing hormone it's also important to actually measure the hormone levels throughout the cycle or at least throughout the phases in which you're you're doing your tests because then you can really demonstrate that yeah on average people do follow the this pattern of hormonal fluctuation but everybody is a little bit different and if your ovulation is later in the cycle then everything i described is going to be kind of shifted over and so you'll have a longer time spent with that increase in estradiol during the follicular phase because you have a longer follicular phase so all of this individual variability that i'm describing makes this challenging because when we do research we're looking at a group level averages and one of the biggest take-homes from you know really diving into this literature is that the inter-individual differences are overwhelming and it we really just can't look at this as out one size fits all kind of cookie cutter solution for women so interesting we're very very complicated so i think we're ready to hear what have you found what were the results of the review sure so in terms of acute performance we really didn't find that there was substantial evidence to conclude that cycle phase will predictably influence your exercise performance when it comes to resistance changing exercise performance so to be clear this is people who are lifting weights we're not including kind of aerobic exercise in this conversation and there's one amazing meta analysis that we included in our paper uh the the first author is McNulty they found that perhaps there was they they referred to it as kind of a trivial effect for the the early follicular phase but because the of the quality of the the papers looking at this question and because of the variability that i just described they concluded that you know we we really are not in a position to make any kind of recommendation because there needs to be more high quality work done in this area and they are also when i say high quality i mean people really kind of using these best practices because we're trying to lean on results from studies that may have not used methods appropriate to answer the research question and so that's very tough right because if they say oh we found a difference but i look at the paper and i say well you don't really you didn't look to see if they were actually in the phase you thought they were then that to me i can't put a lot of weight on that finding because we don't know if they really answered the research question it is is sort of the the issue there when it comes to the long-term adaptation so the muscle growth and the strength gains as i mentioned early in our conversation there are very few studies that have looked at this and i can imagine one of the major reasons is the tremendous challenge that it would that it would be and we concluded that because of the quality of the evidence again we're not in a position to make any kind of broad recommendations and that at this point coaches and athletes should be looking at this on an individual basis again i i go back to the kind of methodological flaws here there is a pretty widely cited study that reported that training in the follicular phase was preferable for strength and muscle growth compared to training in the luteal phase the issue that i highlight in in that paper is that they did not use at the gold standard methods of detecting ovulation and measuring serum hormones and doing the cycle tracking and we really need to see that study design repeated but the issue here is that people have really kind of clung on to this one paper and then the narrative has become oh uh follicular phase is better there's something kind of magical for muscle growth or strength about estradiol because like i said you know that that's the hormone that is is high or the flip side of that is oh there must be something terribly catabolic and um problematic about progesterone when it comes to muscle and there's so much mechanistically even that we just don't understand about about the the actions of of those hormones when it comes to muscle but when you you when you go back and you think about the number of days that we're talking about high estradiol in a given cycle and then remember that i also said estradiol is moderately high in the luteal phase as well so we're talking about kind of net similar levels of of estradiol and the narrative that oh well the luteal phase is bad because progesterone is somehow counteracting those potentially positive effects of estrogen we just have no evidence to back that up even in animal models like we had nothing and so there's so much more work to to be done here and you know from a kind of scientific perspective i would love to to learn more i hope we we'd continue that work to really enhance our understanding of the role of of these hormones so just to understand what was the extent of the review you mentioned one meta analysis you include how many did you end up working with there were seven that we included these are reviews seven reviews with meta analysis so like combining the individual studies and trying to analyze them seven of these were assessed by you in terms of quality and heterogeneity so these were good enough to include they were relevant to the topic to the research question and after looking through seven of these you have concluded that we don't have evidence to say that their menstrual cycle phase will influence acute gains and for the long-term gains we have two little studies to even be concluding that's right when you say good enough i just want to clarify when the studies that we included they are criteria our inclusion criteria which we determined before we even did the literature search so an example of something that might not be appropriate would be the influence of menstrual cycle phase on thermal regulation or endurance exercise so those kinds of meta analyses would not be appropriate for for what we were looking at because it was just resistance exercise and then the the other kind of piece of this that we did not include is the influence of hormonal contraceptives because that's kind of a separate question those are exogenous hormones and what we're talking about with the menstrual cycle is fluctuations in the endogenous hormones that we produce and i want to be careful with with the language here um it we said the evidence is insufficient and so as a scientist i keep an open mind i'm absolutely willing to to change my mind should there be more high quality work done in this area that the indicate that these short-term hormonal fluctuations are important but i think that this paper was important and i'm glad that it is kind of getting some attention from coaches and fitness enthusiasts because there are people out there who are making these recommendations to alter your training around the menstrual cycle are saying oh this kind of phase-based training is all a one-size-fits-all and as i mentioned throughout this conversation repeatedly there's so much variability between people that if i gave you a phase-based training program and i have no idea what your cycle length is or what your phase lengths are or when you ovulate then uh you're not even doing phase-based training necessarily um so in order to to implement this you would need to track your cycles track your ovulation um and make sure that that you were really in the phase that you were intending to be which is is pretty complicated um and at this point just probably really unnecessary um but you know i think it's really important to kind of get this message out there because i am familiar with these these programs are influences who who are making these recommendations the last thing that i touched on in the in the paper but it's kind of come up more since is the influence of menstrual symptoms on on performance and it hasn't really been studied very much um in a kind of objective way there's a lot of surveys that have of assessed athletes and said you know do experienced menstrual symptoms what are they when do you experience them and the overwhelming majority of of women report that they do experience symptoms the most common ones are like abdominal cramps they generally experience those symptoms either um right before their period or maybe in the first few days there is a certain perception that those symptoms could influence your exercise performance which makes sense right if you're not feeling great then um maybe the training session just doesn't feel as good the same way if you were really tired or if you were a bit sick um and you just don't feel that you had as productive a session what we don't have is evidence to suggest that objectively your performance is worse because of your menstrual symptoms so there's sort of a difference between yeah you know i don't i don't feel well i didn't feel like i had a great session today but maybe you lifted the target weight for the target reps and on paper you had a fine training session so those are two those are kind of two different questions but when we look at the research of um where they did testing in the early follicular phase we need to be mindful of the fact that testing during the late luteal or early follicular phase is around that time where the majority of of women do report experiencing some symptoms and so even that kind of subjective data is is not generally collected and so i hope in future research that's another thing that that the researchers will consider and some some data that they would collect and even you know it's just self-report right but um it would be it would be good to know because it's a different question to say um is there something about these hormone levels changing from day to day week to week that is physiologically influencing our ability to exert muscular force or build muscle or build a strength over time that's a different question than to say when i have menstrual symptoms is my performance affected because i don't feel well and so i think we do need to make that distinction but certainly as an athlete or as a coach that's something that that you would want to keep in mind and have an open dialogue about and then you know you can make some adjustments as needed to one or two training sessions in the in terms of Olympic weightlifting there are some studies for example how sleep deprivation influences performance in Olympic weightlifting and what seems to be happening is that the mood and enjoyment of training goes down but the actual maximal performance so one repetition maximum does not right so maybe it's similar in this situation that the symptoms are unpleasant but actually they don't impair the maximal performance and in Olympic weightlifting that would be the goal to lift the most in snatch and clean and jerk so a very specific goal to achieve in terms of performance so you know as long as you can perform eddyomax within you can feel miserable for the rest and it's totally fine it's it's one thing to say oh if if you're not feeling great you can adjust your training session but of course if you are a competitive athlete and you need to perform that day uh and you don't have control over that the competition is where when it is and if your your cycle starts and you know you're probably gonna suck it up and compete anyway it's interesting because the survey data that reports i think over 75 percent of of women say that they do experience regular menstrual symptoms and that they do perceive that it negatively impacts how they feel or their performance in the gym but very few of them reported making any kind of changes to their training accordingly um and so i and and you know that i think the flip side it's actually that sometimes exercise at even like a light to moderate intensity can make people feel better when they have things like abdominal cramps from the menstrual cycle so there isn't a lot of hard science to go on but i think it's something worth bringing up when we're talking about the real world implications of of the influence of of the menstrual cycle because i think experiencing those kinds of symptoms is tangible whereas i don't know when my estrogen is highest i don't feel it throughout my my cycle and and so the influence of menstrual symptoms on how you feel in the gym is something that is very tangible for for an athlete and and it's something they can explain to their coach and it's something that you can kind of make adjustments or not as needed and i think it's it's important to kind of distinguish that from what we primarily talked about in the paper which is the idea that there's something about high estradiol or low estradiol or something about high progesterone that is positive or negative for for performance and so i do like to separate the two but i think it's important to bring up the menstrual symptoms because they're clearly so prevalent and of course if you are a high level athlete and you really want to do everything to dial in your performance then perhaps it's worth at least documenting in your training log when your cycle starts and just being aware of whether it's a subjective thing that you just don't feel as well when you start your period or if there is actually something going on where the numbers are dropping when you get your period and if that's the case then perhaps there's some kind of modification that you would want to make to a training session or not you know i think that's it's really up to the athlete and coach thank you that's that's some good advice so the goal would be to pay attention for some time figure out how it applies to you as an individual and then maybe from if you notice that some symptoms are common you can prepare for them ahead of time or make some adjustments maybe in self care or how you come to the session or what you bring or what you need to keep yourself feeling more comfortable and having less symptoms i wouldn't necessarily predict that you would need to make any adjustments or that you would even see trends but if you wanted to to log that and track that just you know for your information or for your coach's knowledge then i don't i don't see any harm in doing so at all uh you know i think that it just it depends on whether it it seems appropriate for that particular athlete one thing i will notice with my clients who who track is that uh it's very common for body weight to go up during the uh like first week of the menstrual cycle so if you are having somebody who's tracking their their body weight consistently and you see uh kind of an increase in scale weight around the the onset of menstruation i would kind of throw out that data when i'm looking at like weight loss trends or things like that because it's not um it's not a real increase in in body fat it's usually just you know a artifact of water retention okay that's an important point because olympic weightlifting is um weight class contested sports so um any fluctuations regarding body weight are applicable and important and sometimes young people so that's maybe one case where having awareness where an athlete is before the competition in terms of where they are in the cycle may be useful to expect things like 2 kilograms more just because they're starting the period yeah no absolutely i actually i have a client who is competing in a powerlifting meet on saturday and i spoke to her yesterday and we were looking through her kind of weight trends and she is exactly what you just described you know it's like about a 2 kilogram weight increase but i also know that that only lasts for a couple days and so we won't need to take that into account for her saturday weigh-in but you know of course if it had been last saturday then it would have been something that we would have to consider for sure any other considerations or usefulness or the results of the review the athlete should be thinking about or the coach you know i i think that you know in the absence of additional evidence that that indicates otherwise we need to be viewing the the menstrual cycle as just come one other factor that if it has an influence it's probably very minor um perhaps it would apply to to some individuals but in broadly speaking and in terms of just making kind of practical recommendations i actually think it can be more harmful than helpful to tell women to completely overhaul your program based on your menstrual cycle phase because you're you're thinking about you know potentially half the month either doing lower volume or not listing at all and the recommendations are kind of all over the place but usually it involves doing less during your luteal phase and you know i just think that you're potentially hindering your progress if you do that and without good reason i really think that i would shy away from doing any kind of programming around cycle phase until we have a substantial amount of high quality events indicating that you know otherwise and where people can find you if they want to learn more about your research or what do you do or conduct you where should either go so if you're a scientist then i'm on research gate that's where i post all of my papers i'm also on social media at loren cs1 on instagram i'm on twitter as well and so feel free to send me a message if you have any questions and i will continue to share my research on social media and i'm also a writer for the research review mass or monthly applications in strength sport so you can check out some of my reviews of of the latest research on exercise and nutrition at stronger by science dot com slash mass awesome thank you so so much and see you the next time You You