Updated: Nov 8, 2020
As more and more research is being done on female athletes exclusively, we are finding, unsurprisingly, that it is optimal to train them differently than their male counterparts. This is largely due to hormonal fluctuations throughout the month, rendering female’s bodies more likely to adapt to certain stressors at different times in the cycle.
First, let’s review hormones and how they fluctuate throughout the menstrual cycle.
Hormones are chemical messengers that are released into the blood to regulate physiology and behavior. They are produced in the pituitary gland of the brain, adrenal glands, pancreas, thyroid, and reproductive organs. The pituitary gland is also known as the “master gland”, as it produces the hormones that regulate the other organs. Together, the pituitary gland and the organs it controls are called the Endocrine system.
The endocrine system controls the majority of bodily functions, such as digestion, metabolism, sleep, reproduction, growth and development, mood, respiration, and temperature regulation, among other functions. To describe it more directly, the endocrine system is the king/queen of the body, and affects all aspects of physiology.
As a review, the menstrual cycle consists of three phases: follicular phase, ovulation, and the luteal phase. As you can see from the graph below, we have predictable fluctuations in the reproductive hormones throughout the cycle, as the body prepares for potential child bearing.
I’ll spare the middle school health class details and get right to what this means for your training. When you’re in the low hormone phases-- during your period and the days that follow-- your physiology is most like that of a man’s, and the body is primed to make gains in strength and endurance. Therefore, day 1-14 of the cycle is the best time for high intensity work, whether that be endurance exercise or weight training. Conversely, the high hormone phase is when lower intensity training and rest/recovery are more favorable. For those that play team or field sports, there is evidence to support reduced reaction time, neuromuscular coordination, and manual dexterity during the menstrual and premenstrual phases. This is why it is also hypothesized that female athletes are more likely to sustain injuries, such as ACL tears, during these phases.
Another consequence to note during the menstrual and premenstrual periods is that the increase in estrogen and progesterone causes a cascade of signaling throughout the body that increases blood pressure. In response, the body decreases plasma volume of the blood in an effort to decrease the workload of the heart. This reduced blood volume can result in dehydration and decreased training performance. Therefore, hydration before, during, and after your workout is even more critical than normal. It is also important to note that resiliency to heat stress is decreased during this time as well, so anticipate summer runs to be particularly difficult.
As we all know, menstruation can cause a host of other symptoms, however these are the training and sport specific ones I wanted to call attention to. The bottom line is that the first 14 days are more favorable for training gains, and the second 14 or so days are less favorable. I also want to make it clear that this does not indicate that you can only train for half the month. Rather, it means to schedule the most rigorous workouts in the first 14 days of your cycle, and to factor in more recovery for the remainder of the month. Being cognizant of these changes will help you understand why a workout didn’t go as well as expected, or why you’re more fatigued than normal. It is yet another pertinent reminder to avoid beating yourself up on poor training days, as our bodies are so different from day to day.
Keeping track of your cycle can help you anticipate these times so that you can sync training cycles with the other cycle. There are a number of apps that can do this for you, and some even provide suggestions of what extra support your body may need in that phase. Garmin connect added a period tracking feature earlier this year, which is nice because then the period day data is right next to where workouts are uploaded, for Garmin users.
I know, I know, there’s an elephant in the room. What if you are on some sort of contraceptive? The type of contraceptive (oral, implanted) will impact hormonal fluctuations differently, and will change the body’s response over the course of a month. This is a topic outside of my scope of practice, but be aware that this article is less relevant for you, and if this topic is a concern, to talk to a physician about it.
Finally, I cannot write an article about this topic without mentioning this very important fact: if you are a female athlete who is not on a contraceptive, and you do not have a period every 21-35 days, you are NOT a healthy athlete. This is extremely important from not only a performance and injury prevention perspective, but also that of overall health. This is a symptom of RED-S (or Relative Energy Deficiency in Sport), which is a constellation of symptoms that result due to low energy availability. Loss of menstrual periods indicate that there is a mismatch between energy consumption and expenditure. This is a topic that is crucial to share with your physician.
On a happier note, these fluctuations in hormones are actually superpowers for female athletes. The performance boost of the low hormone periods allow our bodies to make big jumps in fitness. It is not, I repeat, IS NOT a limiter to your performance. In fact, I think that there is enormous untapped potential for female athletes. The more we learn to harness this process, the faster and stronger we can become!
Keep going, you got this!
Kacy Seynders, PT DPT
Roar: How to match your food and fitness to your female physiology for optimum performance, great health, and a strong, lean body for life, Dr. Stacy Sims, PhD