Understanding your physiology: “Women are Not Small Men”

It is common knowledge that hormones have a powerful effect on energy, sleep, mood and many other aspects of body function. It is also well understood that women’s cycles are biphasic, meaning hormone levels change. However, it is much less discussed in regards to the impact physiology has on female performance and training for endurance and strength sports.

As a physiotherapist I remember just one lecture that discussed the effects of the menstrual cycle on ligaments and greater ACL injury risk during a specific phase. If hormone levels affect us at so many levels why don’t we talk about the physiological differences between men and women? To best tackle this subject let’s start with what actually happens in the menstrual cycle. 

Menstrual Cycle Basics

As women, estrogen and progesterone levels fluctuate throughout our cycle which impacts a wide range of our physiology. By definition, our cycle begins with the first day of bleeding “day 1” the cycle typically lasts anywhere from 25-36 days depending on individuals. 

Three Phases: 

  • Follicular (before egg released)
  • Ovulatory (egg released)
  • Luteal (after egg release)


Phase Impacts

The follicular phase is marked as the first day of bleeding which has been described as the time a woman is “most like a man” in terms of low oestrogen and progesterone. This may lead to increased pain tolerance, improved ability to tap into stored energy (carbohydrates), and higher time to fatigue. This is the time where women should aim to hit higher intensity training and optimise their recovery after. 


During ovulation, estrogen will rise to the highest level which can impact the body’s ability to store carbohydrates and may lead to feeling a little flat, especially for endurance events. 


Luteal phase comes just before your next period. This is when estrogen levels stay high and progesterone joins it. Bloating and fatigue can often be cited at this time. During this phase, hydration becomes important with an increased body temperature and elevated progesterone levels contributing to sodium loss. 

Sounds reasonable but what can you do with all that information? 

One of the best things you can do is to track your cycle! There are many easy to use phone apps available free of charge, such as, Clue and Flo. This is by no means a recommendation to never participate in a sport event during a specific phase. Rather an opportunity to understand your physiology and best support it with nutrition and hydration.The research is still developing and individuals should compare by understanding their own experience.

Dr. Stacy Sims, MSc, PhD served as an exercise physiologist and nutrition scientist at Stanford University where she specialized in sex difference in performance. She has extensive resources for those interested in learning more, including her book, ROAR.

Our in house dietitian Bella can also assist with nutrition for sporting performance. Read her bio here.

~ Ashley Jones

Hausswirth, C., & Le Meur, Y. (2011, October 1). Physiological and nutritional aspects of post-exercise recovery: specific recommendations for female athletes. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/21923203.

Burdick 05/17/2017, A. (2018, October 11). Are You Fueling And Training Like A Small Man Vs. A Woman? Retrieved from https://www.womensrunning.com/2017/05/health-wellness/stacy-sims-roar-fueling-small-man_75111.


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