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As they say, anything can happen race day, and it does, including starting your period. But as we know, this is the 21st Century, not the 19th Century – women have learned that it’s perfectly fine to be physical active while having a period and women do it all the time. But did you know that your menstrual cycle may affect your training and racing goals as well as hitting that PR in your performance? To understand how your menstrual phases may change the training of your hard workouts and racing experience, or expectation, let’s have a quick review of the wonders within women’s reproductive cycle to gain insight as to how the menstrual cycle can affect endurance performance.
A typical menstrual cycle is twenty-eight days and first day of menstruation marks day one of the twenty-eight day cycle. Menstruation can last for 5-7 days and the twenty-eight day cycle is broken into two phases. The first phase is the follicular phase (1-14 days) and the second phase is called the luteal (14-28 days).
During the follicular phase, estrogen is the dominating hormone. As estrogen reaches a certain level for a certain period of time, luteinizing hormone (LT) surges and ovulation begins. It is during the follicular phase that the body’s basil temperature is lower than that of the luteal phase. A concern for some women during menses is that their iron levels decrease (drop in hemoglobin and hematocrit). But there is not enough evidence showing menses will cause anemia.
The luteal phase (day fourteen to twenty-eight) is primarily controlled by the hormone progesterone and it is the progesterone that is responsible for raising the body temperature; blood volume increases while core temperature rises. During the luteal phase, the female body or stores glycogen and tends to promote fat utilization and therefore may be important to slightly increase your carbohydrate needs during training because carbohydrate (glycogen) use is spared. Race nutrition wise, if your race falls during this part of your menstrual cycle, you may also need to slightly increase your carbohydrate during this time as well, since the body is sparing glycogen, the likelihood for low blood sugar may be greater and may decrease a women’s performance. And you got it, this is also the time when you tend to feel bloated, like you are carrying extra weight, and that it’s slightly more difficult to manage heat.
Understanding how your body responds to the effecting changes of your hormone cycle can help you be better prepared, if at least not more accepting, of how your body is responding during training and racing.
Dorette "Coach D2" Franks