The affects of menstrual cycle on sports performance
Just like Dr. Stacy Sims says “women are not small men”. Of course we aren’t, we have physiological differences, so why on earth are female athletes being offered generic advice on how to fuel for performance?
The research is biased
Turns out, there is a plethora of research out there when it comes to sports performance for men, but when it comes to women in sports…… crickets.
Can we even assume that we can just apply all the research done on male athletes, on female athletes?
Personally, I think it would be naive to believe that, but then again I am a woman so I have my own biases.
Regardless of my personal opinion, I hope that this blog will answer some of the questions you might be asking yourself as a female athlete like:
How do I optimise my performance during PMS
Why am I hungrier than normal during my period?
Is it normal to feel this tired when my period is here?
How should I eat during the different phases of my cycle?
Should my training look different in the different phases?
Understanding the menstrual cycle
The menstrual cycle is typically 21-35 days long and is characterised by 3 main phases:
The early follicular phase, indicated by low oestrogen and progesterone
The ovulatory phase, indicated by high oestrogen and low progesterone
The mid-luteal phase, indicated by high oestrogen and progesterone.
Frustratingly for many women, when progesterone levels go up, our bodies may compensate with increase aldosterone, which means that we often experience more feelings of water retention, bloating, bleh-ness (if that is even a word), and often leaves us craving salty food….. ya know like Doritos.
*Image source: Meignié et al 2021
Even though the purpose of all these hormones is so that we can create little humans in our bodies, it unfortunately means that on a monthly basis, we are faced with challenges that affect our physiological systems including cardiovascular, respiratory, metabolic and neuromuscular.
You can imagine what this does to our overall performance.
As athletes, we depend on those marginal gains, so being able to push our bodies on demand becomes challenging when our hormones are spiking up and down every month.
How does the menstrual cycle affect how we use and store energy?
In the follicular phase of the menstrual cycle (the first half of the cycle), we use less fat for energy, require more carbohydrates so that we can convert it into muscle glycogen, use less protein as energy, and our resting metabolic rate is as per the status quo.
In the luteal phase (the second half), things change a little. We use more fat for energy, require less carbohydrate and convert less to muscle glycogen, we use more protein for energy and our resting metabolic rate increases slightly.
*Source: Wohlgemuth et al 2021
Should I modify my training to suit my menstrual cycle?
While it may be tempting to reach out to event organisers and ask them to wait until your period is gone before commencing the marathon, it might not be realistic.
However, it may be beneficial to fuel properly for events so you can recover better and fuel enough for those marathons or throwdowns.
One study found that endurance athletes experienced a 10% more time to exhaustion, and higher glycogen repletion during the luteal phase, in other words, athletes were able to refill their glycogen tanks quicker, and took longer to feel depleted during the luteal phase.
Another study found while our energy output and performance is influenced by our cycles, an increase in glucose can greatly help minimise the effects often experienced during the follicular phase.
Increasing the right amount of carbs at the right time of your cycle can dramatically decrease your recovery time, help you perform better, and feel less sloshy during those yucky days in your cycle.
Specific sports and the menstrual cycle
As of current data, research suggests that the menstrual cycle doesn’t impact strength and power performance.
One study tested female athletes on their 1 rep max squat through out all three phases of their cycle and found similar results throughout all of the phases. The research looked at force, velocity, power and loads equivalent to their 20,40,60, and 80% of their 1RM and found that there was no change across all 3 phases of the cycle.
Given the changes in how fat, protein and carbs are utilised by the body during the follicular and luteal phases, the menstrual cycle seems to impact endurance performance more than resistance performance. This is further impacted by the increase of estrogen and progesterone.
However, if like me you’re not convinced by the research because sometimes you’d rather sleep than deadlift, remember that this is just research and each person is unique in their needs.
Ultimately, the authors of this research said it perfectly…
“Indirectly, other aspects of the menstrual cycle may influence both endurance and strength/power activities. Specifically, sex differences in fatiguability, thermoregulation, and body composition should be considered.”
Some geeky research
A recent study in 8 trained females with regular periods reported that muscle damage and inflammation following 90 min of running were substantially greater during the follicular phase compared to the mid-luteal phase.
So really….Nutrition and exercise recommendations should consider phase of the menstrual cycle to maximize performance and recovery, especially since recovery can be a little slower during the follicular phase.
Calorie intake during menstrual cycles
It has been well documented that female athletes are constantly under fueling. Failure to eat enough has been linked to disruptions to menstruation, performance, and bone mass, potentially increasing the risk for injury and osteoporosis.
This is exacerbated by the fact that athletes often increase training volume as a method of adjusting body composition and the desire to enhance performance.
As stated earlier, an increase in metabolism of fat and protein is common during the luteal phase, which is often accompanied by greater calorie expenditure, and possibly appetite.
So ladies, if you’re reading this and thinking, does this mean I should eat more? The answer to that question is a resounding YES!
If you’re constantly feeling like you have to control your food cravings during those days coming up to your period, my friend, that is your body telling you, you need to eat.
This however, is not an excuse to raid your kids’ snack cupboard and spend 48 hours bingeing on chips and chocolate.
Basic eating habits still apply:
Eat when you’re hungry
Stop when you’re full
Eat slowly
Choose your foods mindfully
A little bit of self compassion goes a long way. By giving yourself permission to eat what you want to reasonable amounts, you might even find that those cravings disappear.
Remember, restrictions lead to over indulgence, so allow yourself to eat the things you love.
Conclusion
While research does suggest that your menstrual cycle can affect your performance, there is no need to change the way you train unless you felt the need to.
As an athlete you will understand your body better than your coach so if training is feeling heavy and strained, look into better recovery, increase carbs and maybe lower training loads.
Ultimately, there is no one size fits all approach since we are all different.
Did you find this article helpful? Comment below!
Resources
Campbell SE, Angus DJ, Febbraio MA. Glucose kinetics and exercise performance during phases of the menstrual cycle: effect of glucose ingestion. Am J Physiol Endocrinol Metab. 2001 Oct;281(4):E817-25. doi: 10.1152/ajpendo.2001.281.4.E817. PMID: 11551860.
G. A. Brook, C. M. Donovan. Effect of endurance training on glucose kinetics during exercise. https://doi.org/10.1152/ajpendo.1983.244.5.E505
Wohlgemuth, K.J., Arieta, L.R., Brewer, G.J. et al. Sex differences and considerations for female specific nutritional strategies: a narrative review. J Int Soc Sports Nutr 18, 27 (2021). https://doi.org/10.1186/s12970-021-00422-8
McNulty, K.L., Elliott-Sale, K.J., Dolan, E. et al. The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Sports Med 50, 1813–1827 (2020). https://doi.org/10.1007/s40279-020-01319-3
