I recognise the irony in what I’m going to write about. I’m a male coach. But I’m also a post-graduate researcher investigating factors influencing substrate utilisation in women that take part in endurance type events. And the women I coach often ask me: should I be training more in line with the obvious fluctuations in physiology that appear to happen across my menstrual cycle?
At present there is no simple answer to this question. Menstrual cycle (MC) and associated hormonal fluctuations vary from woman to woman. And with that, so does its impact. It is this variability in terms of hormonal concentrations across the cycle, variability in terms of the length of cycle and variability of the impact of MC on Woman in sport (McNulty et al. 2020) that makes this question so difficult to answer at the individual level. So often, as with other things, the answer is, it depends.
Most of us reading this blog will be aware that historically, research in the field of exercise and nutrition sciences are male dominated in terms of the participants. Females are rarely recruited due to the variability of MC and our inability to account for it. Therefore exercise and nutrition recommendations for female athletes are largely based on the existing literature attained in males. The uncertainties this leaves us with are obvious.
Don’t get me wrong, there have been many female Olympic Champions crowned on the back of training protocols derived from coaches implementing male-based research programmes. However, can we do better? Can we get closer to answering my athlete’s key question: “Should I train to my menstrual cycle?” Especially as technology becomes more and more innovative? I believe the answer is — absolutely.
What is the menstrual cycle?
Ok, let’s not jump the gun here. Before any woman attempts to train to her cycle she needs to understand it. At a minimum, she needs to log her cycle length from the start of menses, through her MC and back to start of menses (Figure 1). This is the starting point. By continually logging cycle length and changes in cycle length, cycle length can be established (approximately 28 days +/-). When this is completed across a season, alongside training load, or nutrition and lifestyle, we can begin to get a clearer picture into the individual aspects inherent with the individual, and whether training is impacting her cycle (or not).
Figure 1. Schematic of a 28 day idealised menstrual cycle & hormone fluctuations. (McNulty et al. 2020)
Remember MC is a recurring cycle. It’s like a vital sign. If it’s lengthening in terms of days and weeks, then something like training load or nutrition might be causing this to happen and should be addressed through advice from a medical professional before the MC disappears altogether or the athlete breaks down.
For women in sport who want to take it to the next level, you have tools like the Mira fertility analyser. This small hand held urinary analyser combined with app and platform can track your cycle with lab grade accuracy. The Mira gives concentrations of Oestrogen (E3G a metabolite of oestrogen), Progesterone (PdG a metabolite of Progesterone), luteinizing hormone and follicle stimulating hormone within 16 minutes and uploads the data to the app.
Is there a better MC phase to train at?
When we consider contrasting research such as that conducted by Frandsen et al. (2020), they state that MC doesn’t affect maximal fat oxidation across the cycle. However, reviews such as that by Oosthuyse & Bosch (2010) suggest that hormone concentrations might affect performance, substrate utilisation, core body temperature and other factors. Therefore, it’s easy to see why the individualised data the Mira can provide would be extremely insightful for many women in sport. Any individual female athlete won’t care as much about the generalized group findings of these studies, as they will about how their cycle affects them.
In saying that, sometimes as athletes we want someone else to interpret the data for us. WE JUST WANT TO TRAIN. Unfortunately, that platform doesn’t exist…………….. YET. What if we could use all the real time high quality MC data our Mira hand held device supplies, and combine that with a top end smart training platform like “Athletica”. I know some of you right now are saying “I know a platform that already collects and uses this data” but let me be clear. The individualised nature of collecting personal hormone concentrations in conjunction with your personal training data leads to a training plan unique to you at that point in time. In 4, 6 or 8 weeks, your personal data may have adjusted, and so should your plan. Assuming that MC is the same for every woman, and only the length of the cycle differs, is very basic. Within every MC are unique hormonal fluctuations and concentrations that can and do change and need to be accounted for. After all, if all MC’s were the same, with only variations in the length of cycle, then every woman attempting to get pregnant would be successful every time they tried…………. Not the case.
Athletica, where science is applied to practice, is already an established platform for endurance athletes, where training smarter not harder is the ethos. In our newest initiative, Athletica will join forces with Mira to bring a female specific training study experience. A link to understanding the autonomic balance of the MC-training load axis was also critical, and to this end, we are also grateful to be joining forces with Marco Altini of HRV4Training to access daily morning HRV for this research effort. Moving forward, Athletica, Mira and HRV4Training intend to run a pilot study where the data collected by Athletica, Mira and HRV4Training will be combined and analysed to gain insight towards maximising the training response across the cycle for female athletes (Hackney, Kallman & Aggon. 2019). That means female athlete participants will receive MC hormone concentrations, MC length and other subjective data stored alongside her training data (load and load response markers). Data will be analysed to assess if MC and training load (and response) are working in synergy or antagonistically.
So, all the pieces of the puzzle are in place;
Athletica + Mira + HRV4 Training = individualised female specific training pilot study
Now, I will ask that question one more time.
Q: Women in sport: Should she train to her menstrual cycle?
A: Each woman in sport should be aware of her menstrual cycle when training, aware of its length, aware of hormone concentrations and aware how MC and training data affect each other — or at least using a platform that could do this for her………………… because MC is variable, its changing and so is its impact.
Note: I, Eoin Molloy have no commercial or financial affiliation to Athletica, Mira or HRV4 Training. I simply use their tools, realised they are incredibly reliable and accurate and said wouldn’t it be amazing if they worked together……………… So, I made it happen.
1. McNulty, K. L., Elliott-Sale, K. J., Dolan, E., Swinton, P. A., Ansdell, P., Goodall, S., … & Hicks, K. M. (2020). The effects of menstrual cycle phase on exercise performance in eumenorrheic women: a systematic review and meta-analysis. Sports Medicine, 50(10), 1813-1827.
2. Frandsen, J., Pistoljevic, N., Quesada, J. P., Amaro-Gahete, F. J., Ritz, C., Larsen, S., … & Helge, J. W. (2020). Menstrual cycle phase does not affect whole body peak fat oxidation rate during a graded exercise test. Journal of Applied Physiology, 128(3), 681-687.
3. Oosthuyse, T., & Bosch, A. N. (2010). The effect of the menstrual cycle on exercise metabolism. Sports medicine, 40(3), 207-227.
4. Hackney, A. C., Kallman, A. L., & Ağgön, E. (2019). Female sex hormones and the recovery from exercise: Menstrual cycle phase affects responses. Biomedical human kinetics, 11(1), 87-89.
About the author
My name is Eoin Molloy. I am a husband to a fantastic wife, father of three beautiful and amazing girls, coach, coach developer and generally interested in the application of science to practice across sports. In 2017 I completed my BSc Degree (1:1) in Sports Coaching & Performance @ Waterford Institute of Technology, Waterford, Ireland as a mature student (42 at the time). I then went on to complete a Post-Graduate Diploma in Performance Nutrition (with distinction) at the Institute of Performance Nutrition, UK. At present I am completing my PhD studies under the supervision of Dr Maria Murphy Griffin and Professor Michael Harrison at the South East Technological University, Waterford Campus, Ireland. Our area of interest is “factors influencing substrate utilisation in women who take part in endurance type events” with a focus on train low or fasted exercise regimes and the effects hormone fluctuations associated with menstrual cycle could impose on lipid and carbohydrate oxidation.