These days I love a good overview of the menstrual cycle. 

We learned about this particular cycle at the onset of puberty but do we truly understand what the phases and hormones mean? 

The truth is: female sex hormones affect A LOT. Especially when it comes to exercise. 

Body water regulation, metabolism, recovery, thyroid function, core temperature, our stress response, neurotransmitters, and even building muscle, just to name a few. So, keeping close tabs on our hormones and where we are in our cycle as we train and recover can dramatically affect our progression as athletes. 

I am going to go over the menstrual cycle with a focused lens on the hormones, estrogen and progesterone.

Your cycle is broken down into two phases: the low hormone phase and the high hormone phase. 

A typical menstrual cycle is 28 days in length, but this is certainly not the case for everyone.

Day 1 begins with the onset of your period.

As  you can see from the graph below, from days 1-14 estrogen is slowly rising and peaks prior to ovulation while progesterone is considerably low. This is your “low hormone phase.” 

After ovulation, estrogen and progesterone are both on the rise until the onset of your period when they are cleared by the liver and the gut.

TIP: Supporting your liver and gut during your period is a great way to ensure those hormones are cleared. If not, there may not be a clear signal to your brain (the hypothalamus) to start your cycle! 

I like to incorporate foods such as broccoli sprouts (chock full of sulforaphane), cruciferous vegetables (broccoli and cauliflower), and fruits high in ellagic acid (blackberries, strawberries and walnuts). 

Thermoregulation

Progesterone is considered thermogenic. As progesterone increases, your core temperature can rise 0.5 degrees Celsius 10 days prior to period. That may not seem like a lot but when you are training, heat thermoregulation is key and progesterone makes it harder.

Estrogen acts on the kidneys and increases fluid retention. You lose access to about 8-10% of your plasma volume when estrogen is high, again making it harder to thermoregulate during exercise.

TIP: Ice can be your best friend for lowering your core body temperature. This may not be convenient for those trail running in a desert but if you have a solid buddy who can meet you at mile 10 of a long run…I’d hold onto them. 

Eating ice as opposed to dumping it on your skin is key. That icy beverage or chunks of ice you ingested uses some of your body heat and is the fastest way to drop your core temperature. 

Hydration 

Progesterone also competes with aldosterone (a hormone in charge of plasma blood volume by way of sodium). When progesterone rises, sweat during exercise tends to be on the saltier side. If you lose more sodium, you are at risk for hyponatremia and thus need to replenish those stores.

TIP: Keep tabs on your hydration during the high hormone phase. Contrary to popular belief, plain water does not necessarily hydrate you. In order to transport water out of the small intestine and into cells, you need help from a little sodium and sugar, but just the right amount. Too much sugar and that water won’t be going anywhere. In fact, it will pull water into the GI tract and further dehydrate you.

According to exercise physiologist and nutrition scientist Dr. Stacy Sims, the optimal hydration solution looks like this:

Per 8 ounces of fluid:

- 3-4% carbohydrate solution (about 8 grams) of a glucose and sucrose combo 

- 180 - 225 mg sodium 

- 60 -75 mg potassium 

(For reference, an 8 ounce serving of Gatorade has 16 grams of sugar and suboptimal sodium and potassium content...a big thumbs down). 

A quick and easy homemade hydration beverage looks like this:

- 20 ounces of water 

- 1/16th teaspoon of regular table salt

- 1 teaspoon maple syrup (perfect glucose-sucrose combo)

- squeeze of lemon for a bit of potassium 

Building Muscle & Fatigue

Progesterone also increases protein breakdown. If you want to get stronger and build lean muscle, then protein within 30 minutes of your workout is important in the high hormone phase. There is more leeway during the low hormone phase (about 90 minutes after exercise).

Estrogen & Progesterone both cross the blood brain barrier and can contribute to central nervous system fatigue.

TIP: Over the past year, I started utilizing BCAA’s (branch chain amino acids) around my training (before and after). The BCAA Leucine in particular is great for muscle repair. In addition, BCAA’s can attenuate help offset some of that fatigue.

Oral contraceptives raise levels of estrogen and progesterone 6 to 8 times from baseline while also down-regulating endogenous sex hormone production which can contribute to the struggles of transitioning off of birth control. While this isn’t an anti-birth control article, every woman should choose the birth control option that works best for them. If natural family planning is an alternative that you haven’t heard much about, I would encourage you to look into it! 

A new training model…hear me out!

What I am about to propose will probably scare some of you out there…but I am going to do it anyway. 

What if we adopted a new training approach based on our menstrual cycle?

A 3 week on, 1 week off training model where, in the 5-7 days prior to your period, you deload. You do yoga, you focus on self-care and paying particular attention to what your body needs. 

No you will not find this on a generic 50K training plan designed by a man based on research in a male athlete population. 

But what if you saw improvements in other areas of your life? Sleep? Moods? Cravings? Or even weight loss? We are trained to believe we need to keep up with the boys but the truth is our physiology is different. Working with your physiology as opposed to against it is key. 

That deloading week can potentially be a time to focus on things we love other than training hard. Trading a Saturday morning long run for a walk with a friend to the farmer’s market or perhaps volunteering doesn’t have to equate to a setback. You may actually come back even stronger. 

If you are interested in learning more I would certainly check out the book, “ROAR” by Dr. Stacy Sims. I was lucky enough to have Dr. Sims give a couple of guest lectures in my Sports Nutrition course and it completely changed my outlook as a recreational female athlete.