Friday, February 26, 2016

A Chat with Aunt Flo: How Does the Menstrual Cycle Affect Training

Over the past year, I've gotten really interested in hormones and cycles and all that fun (okay, sometimes annoying) lady jazz.  After being introduced to the concept that our hormonal fluctuations due to our menstrual cycles can affect our athletic performance, I got hooked on understanding my own cycle.  

As our cycle progresses, our hormone levels fluctuate, which means different things for how we need to fuel our bodies, how we recover, how we tolerate heat, and how we perform overall.  Estrogen levels begin to rise about 5-6 days post-period and around 12 days after the period, estrogen peaks, which is coupled with the beginning of a rise in progesterone.  The highest hormone levels of both estrogen and progesterone occur about 5 days before the period.  If we consider the typical cycle to be about 28 days, that means the second half or weeks 3 and 4 are the "high hormone" phase. This Training Peaks article describes the phases and their effects in greater detail.

Fueling and Hydrating During Your Cycle

I was initially introduced to the concept of hormone fluctuations effect on performance by Osmo Nutrition.  Dr. Stacy Sims, the founder of Osmo, created the Osmo line precisely because women have different hydration needs from men based on their hormones.

During our cycle, the variations in estrogen and progesterone mean that our ability to process carbs and protein change.  When estrogen levels are low, in the first half of our cycle, we need more carbs for optimal performance.  When estrogen levels are high, women tend to conserve glycogen stores and use more fat for fuel.  This makes the second half of our cycle the prime time for endurance activities and means we don't require as many carbs, though we may need to supplement with carbs to reach higher intensities.  

Additionally, women may not experience the same results as men on an extremely low carb diet, because when women go into a carb deficit, our body starts to go into a more masculine reproductive state and we begin to conserve fat. At certain times during our cycle, this means that we need to ensure that we are getting enough carbohydrates to prevent menstrual dysfunction. See the full explanation on the Osmo blog

Now, I've been attempting a higher fat-lower carb diet for a while now, trying to teach my body to use its fat stores more efficiently, but I definitely don't shy away from carbs, particularly for refueling post-workout.  For women especially, that 30-45 minutes after a workout is done is critical for refuelling and repairing our body.

Women are more predisposed to hyponatremia during the this phase as well because progesterone increases total body sodium losses.

Training and Racing During Your Cycle

This article from Breaking Muscle "breaks" it down in terms of what hormone fluctuations might mean for training (it's mostly focused on non-endurance training, so I've adapted somewhat below). 

In the early stages of your cycle, you will see the greatest benefits from doing high intensity workouts, think intervals or speed work at the track.  

For optimal performance, you'd want to be in a low hormone phase (so the first 2 weeks post-period) on race day! 

On your day of ovulation, you could see breakthrough performances.  Head out for a time trial or do a test set at the pool. Just be careful around this time as the increase in estrogen (peaking at ovulation) can interfere with collagen synthesis and neuromuscular control, meaning our bodies can be more prone to injury. Fuelling and hydration needs are also critical here. 

In the later part of your cycle, you will benefit most from long, steady aerobic training and / or rest!  If you're using a 3 week on / 1 week rest cycle for your training program, think about planning your rest week in the week before you get your period.  The day or two pre-period can be a great time for yoga or low-intensity exercise. Then as your period starts, your body will begin to normalize and will actually be ready to get back to work! 

Now, in my time as an athlete I have heard of women using their birth control to specifically alter their cycle in order to be prepared for key events (e.g., who wants their period on teh day they do their first Ironman?)  From what I understand, this can be fine; however, I highly encourage you to consult with your doctor well in advance of your event if you are curious about this option (think at least 6 months out). 

Every BODY is different, so how well do you know yours? And can you use your own cycle to your advantage?

How well do you know your cycle? 

Wouldn't it be great to have some help in tracking your cycle? Well, there's an app for that!  One of my Team Coeur teammates, Katie, shared a video with us recently about the Clue app.  Clue is a scientifically based app for tracking your cycle.  With the app, you can track not only your period and PMS, but also things like: your sleep patterns, digestive health, exercise, moods, energy levels, bowel movements, appointments, sexual activity / desire, skin health, cravings, whether or not you took your birth control, pain, etc.  After one full cycle, Clue can provide you a helpful analysis, because it gets smarter as you use it.  (The app creators point out that you should not be using Clue as a method of birth control.)

Addressing the Female Triad

As endurance athletes, we have a higher chance of experiencing irregular periods or lack of period caused by high training loads - amenorrhea.  We are also at risk of developing the Female Triad - disordered eating, amenorrhea and osteoperosis.  These three combine to have significant negative impacts on performance.  Please talk to your doctor if you think that you are experiencing any of the three.  

Tracking your cycle can be a useful tool for us female athletes.  Knowing our bodies is one step to maximizing our performance!

Disclaimer: I am not a doctor or a health professional in any sense.  Please talk to your doctor about your reproductive health, including any abnormalities, as well as the fact that you are an athlete! 


  1. Great post! I did a lot of research on this a couple of years ago as I was training hard to try to qualify for Boston. It's actually odd how little information is out there on our cycles and how little most women know about their own bodies! After researching I definitely paid more attention and found that what you explained above was right on!

    1. That's great that you found that it made a difference with your training once you started paying attention. It is something that seems so obvious once you find it, but definitely not much attention is paid to it by coaches and athletes alike.

  2. Once you get more in tune with your cycle it also helps to understand how you're feeling for no (previously) apparent reason!

    A few years back (after having my kids) I discovered the Diva Cup. It's a menstral cup (in leiu of tampons) and I can't recommend it more highly esp. for active ladies! I want to go peddle them to high school girls and change their lives as early as possible!

    PS Love your blog. I was at Worlds in Chicago too and am still waiting for the motivation to return for this coming season! I've been focussing on more "active living" type activities vs training this winter. I've also discovered and love orienteering! I recommend it if you at all like trial running!

    1. Ah yes, I'm definitely keeping track of my cycle because of the emotional roller coaster that comes along with PMS.

      My boyfriend wants to get me into orienteering this year. It sounds like so much fun!! So cool that you've gotten into it. I'm definitely a fan of the "active living" approach. It's fun to take the pressure off of training, but still stay fit and have time to try new activities!