How menstruation affects athletic prowess is poorly understood

separated first from fourth place in the women’s 100 metres freestyle at the recent Tokyo Olympic Games—a race where the winning time was 51.96 seconds. In light of this and similar facts, it is not surprising that elite athletes are constantly searching for ways to get even 1% better. To that end, they hire strength coaches, nutritionists and sports psychologists. And lately, some female athletes have been trying a new tack: working with menstrual-cycle coaches.Good data concerning the effects of menstruation on athletic performance are scant. However, according to four studies conducted in 2020 on more than 250 athletes from a range of sports, more than half of sportswomen believe their performance fluctuates with the phase of their menstrual cycle. In particular, many said they suffered in the weeks immediately before and during menstruation. World-class performers like Fu Yuanhui, a Chinese swimmer, have spoken openly about this, too. And female athletes also report distraction and worry about bleeding while actively menstruating, a matter which made the news recently when a group of activists protested about the all-white dress code at the Wimbledon tennis championships.