The period problem: does menstruation make females more vulnerable to injury?

Because menstruation is the visible sign of the female reproductive cycle, it’s natural to assume women should take it easy during this time. However, new research calls this thinking into question. 

More and more young girls are encouraged to play sports. Many of them continue to pursue active and competitive lifestyles through adulthood. For instance, nearly half of the athletes expected to participate in the 2020 summer Olympics (held in 2021) are women⁽¹⁾. Yet, researchers have largely ignored the question of how the menstrual cycle affects performance and injury rates. 

The menstrual cycle

A typical menstrual cycle for women (who are not taking hormonal birth control (HBC)) lasts 21-34 days. Each cycle starts with the first day of menstruation and lasts until the first day of the next period. There is much variability in period cycles depending on hormonal levels, the use of HBC, and the athlete’s age. 

Ovulation, the moment the ovaries release an egg, occurs mid-cycle and divides the cycle into phases. The follicular phase comes before ovulation, and the luteal phase occurs after (see figure 1). The late follicular phase starts three days preceding ovulation and extends through ovulation. Estrogen levels build during the follicular phase and peak during the late follicular phase at amounts nearly ten times higher than at the start of the cycle.