Hormones Matter—Period

How your menstrual cycle affects performance (and how you should fuel)

Kristen Arnold is a sports dietitian, cycling coach and elite bike racer.

By Kristen Arnold MS, RDN, CSSD

Are there certain times of the month when you feel like you’re on fire and then other times you feel like a load of bricks? You are not alone! Most individuals who have female reproductive organs have a menstrual cycle. That menstrual cycle impacts many aspects of our physical and mental health, and performance.

First thing’s first--let’s talk about the various phases of the menstrual cycle and what is happening to the body during each phase. Days one through seven, known as the early Follicular Phase, is characterized by low estrogen and progesterone levels. Estrogen and progesterone are the two main hormones analyzed for their effects on performance and physiology. In a 2020 study published in the Journal of Sports Medicine, 140 athletes were asked about their perceptions of how their menstrual cycle affects performance and fitness. A statistically significant number of participants said their best performance of the month happened immediately after days five to seven of menstruation (Solli et al 2020). Studies show that during this phase, athletes have better neuromuscular coordination, breathing rates, and heat tolerance. There are also studies showing athletes have lower perceived exertion, and easier access to glycogen (stored carbohydrates) (Oosthuyse 2010).

The late Follicular Phase is characterized by a rise in estrogen, which leads to better access to glycogen compared. Other effects of high estrogen and low progesterone include better access to fatty acids (stored fat for energy) in the muscle, decrease in protein catabolism, increase in ability to complete aerobic exercise, better breathing rates, and a higher pain threshold (Oosthuyse 2010). Athletes may also have heightened high aerobic capacity (think 3-10 minute efforts).

A bike racer with science cred!

And last but not least is the Luteal Phase, or high hormone phase. In this phase, both estrogen and progesterone are high. This phase is typically around days 20 to 24 of the cycle. There is a significant increase in expression of a hormone called arginine vasopressin, which causes water retention, labored cardiac output, and higher breathing rates. This leads to a decrease in heat tolerance and the ability to get nutrients to muscles as well as clear out waste in the muscles. There is also an increase in the muscle’s ability to store glycogen but not access it, higher protein catabolism, and an increase in fatty acid oxidation. What does this all mean? Studies show that athletes may have decreased performance in short duration type exercise in the Luteal Phase. And with specific nutrition strategies, the impact of this phase on performance can be decreased to no negative effect at all (McNulty 2020).  

Every body is different. While we have research to start to explain the intricate physiological processes affected by the menstrual cycle, each athlete has their own unique experiences related to how hormones affect their life and exercise.

 That said, here are my tips for managing the menstrual cycle:

Track your cycle and consider tracking some or all these factors each day which may be influenced: mood, exercise duration and intensity, perceived exertion during exercise, cravings, food and drink, menstrual flow, daily energy levels, cramps or other symptoms, sleep quantity and quality, heart rate variability, body temperature. Start to observe patterns related to each factor and where you are in your menstrual cycle. Don’t forget to write it down!

Prioritize foods with anti-inflammatory properties seven days before you start menstruating and during menstruation. Some things to incorporate: ginger, garlic, turmeric, sardines, salmon, kale, arugula, berries, sweet potatoes, quinoa, brown rice, steel cut oats, avocadoes, almonds, chia seeds, tart cherry juice.

Consume 45-90g of carbohydrates and drink 16-32 ounces of fluid per hour during all activity over 60-90minutes.

Sip on a beverage with sodium and carbohydrates 30-60 minutes before all activities when you are seven days out from menstruation and during menstruation.

Perform light to moderate exercise to alleviate symptoms during menstruation.

Consider working with a Registered Dietitian who specializes in sports nutrition and has experience working with athletes who have female reproductive organs to fine tune your unique needs.

Be kind to yourself and know that having a menstrual cycle is crucial to performance and a healthy body and mind.

Kristen Arnold MS, RDN, CSSD is a registered dietitian with a private practice specializing in sports nutrition for women, a cycling coach with Source Endurance LLC, and a national-level road racer with Wolfpack p/b Jakroo. She is passionate about enhancing the performance of women through food and activity as well as riding all kinds of bikes.