Do you feel like your menstrual cycle affects your training and performance? Why is it so important for every runner to maintain their monthly cycle? Menstrual cycles and training are an important topic that is thankfully getting a lot of well deserved attention at the moment.

Back in November, Mary Cain’s New York Times story reopened a conversation in a widely public forum that highlighted a culture and norm that is pervasive within the running community: that thinner means faster. She highlighted her experience as a high level athlete who lost her period for three years and broke 5 bones during that time. While there are many important issues to highlight surrounding Mary’s experience, I would like to use this section to highlight the importance of having your period and what that means for training and racing. Training and racing as a woman looks different depending on where you are in your cycle. It can bring stress when you know you’re due for your period but a major race is coming up. Or you might feel a sense of relief that you’re past your period and you can train and race without having to worry about the extra cramps, bloating, mood swings, etc. Dr. Stacy Sims, is the author of “ROAR”, an excellent book helping readers understand how to match their training cycles and fueling physiology as a female athlete, and says it best: “Don’t be afraid of racing on your period,” says Sims. “It is a great time, physiologically, to hit the high-intensity demands of racing.” Below I will highlight about the importance of menstruation for female athletes:


Everyone, athlete or not, should be getting their period every month. When you miss having a period, it’s a clear signal from your body that something is off (calorie deficit, stress, lack of sleep, hormone imbalance, etc…). This is your body speaking to you and telling you something needs to be adjusted. (Caveat: if you have a hormonal IUD like the Mirena, Kyleena, Liletta, or Skyla, you may not get your period regularly. In that case you should work with your primary doctor to make sure you can track your health in other ways!)


There is an age old myth that says that it’s ok to not get your period if you’re an athlete. The myth can also say that getting your period means you are building up fat stores which is viewed as a negative/fail. This is a false myth but one that is extremely common and destructive amongst female athletes.


What is LEA? Low Energy Availability is when your body does not have the energy required to maintain the current level of activity over both short and long periods of time. The exact value of energy needed to maintain your health will vary between individuals, but a very clear clinical warning sign that your body is experiencing LEA is the disruption or absence of your period. When the body is in a state of LEA, the body can:

  • Attempt to conserve energy in the form of slowing bone turnover increasing the risk of bone stress response (stress reactions/fractures)
  • Attempt to slow production of reproductive hormones, slowing your adaptation to exercise and potentially affecting reproductive health long term
  • Experience an overall inability to adapt to training and improve performance levels due to ongoing injuries, illness, fatigue, poor mental health, etc..)


What is RED-S? Relative Energy Deficiency in Sports is a syndrome in which disordered eating, menstrual disruption and decreased bone density are present. LEA is the driving force behind RED-S.

It’s definitely time to demystify and destigmatize the women’s menstrual cycle and what it means for athletic performance. @drstacysims drops endless knowledge and guidance in her book ROAR. Mood swings, GI issues, headaches, cramping...she explains it all and offers many recommendations for how to manage the highs and low phases of the menstrual cycle. I highly recommend it! Listed below are a handful of facts and tips to help you get started and gain a better understanding of how you can work with your menstrual cycle to optimize training and racing:

  • The average menstrual cycle is 28 days long
  • A cycle is broken up into two, 14 day phases (high and low hormone phases)
  • The low hormone phase is day 1-14 (during your period and directly afterwards)
  • The high hormone phase is day 15-28
  • Your cycle starts on the first day of your period (day 1 of your 28 day cycle)

Low Hormone Phase (During and right after your period):

  • You are physiologically at your strongest on day one of your period, technically making it the best day to race! “Don’t be afraid of racing on your period,” says Sims. “It is a great time, physiologically, to hit the high-intensity demands of racing.
  • While training and racing on your period you are more likely to have a higher pain tolerance, experience higher perceived energy levels and more likely to recover faster

High Hormone Phase (before your period):

  • The week before your period, you might be left feeling a little unfit and discouraged - be patient, it will pass!
  • Add a little extra recovery when needed and tailor your training to your bodies needs
  • Be open to having clear dialogue with your coach regarding how you feel during this phase to ensure you adapt and adjust training as neededYou have a higher rate of muscle breakdown from harder training efforts and it can be harder to make and maintain muscle during this period of time
  • Your blood is thicker and harder to pump through your body, making exercise feel more challenging

Finally, @drstacy sims makes it clear that “Barring prohibitively painful cramps or a higher than normal amount of bleeding, there’s no reason menstruation should stop someone from racing.” Women have been winning gold medals before, during and after their periods for decades! The most important thing to remember is that it is incredibly important to focus on maintaining a regular menstrual cycle as an athlete. For both your current training and racing goals as well as life outside of running, remember to listen to the signals your body is giving you - it is the smartest tool/coach you have!

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