It's very much understanding how your body's working so you can tailor your nutrition optimally and athletes do it to improve performance.

他们非常了解你的身体是如何工作的，这样你就可以优化你的营养，运动员这样做来提高成绩。

Behind the scenes are a series of hormonal controls that fine tune the body's internal workings to make menstruation start or stop during those 28 days.

表象之下，这一切都是由人体激素进行调控的，激素精密地控制着身体内部的运作，在这28天里控制经期的起始。