Science

There's a body of research going back at least 40 years, with scientists asking whether hormonal shifts in women influence strength, fatigue and recovery.  Over time, that research has filtered into gyms and social media, often simplified into rules like "take it easy during your period" or "push hard mid-cycle." The menstrual cycle is a monthly rhythm of hormones. During the month, two key hormones, estrogen and progesterone, rise and fall, shaping how many women feel, move and recover. Fitness professionals often divide the cycle into four stages:  Week one: during menstruation, also known as the bleeding phase or "period" Week two: days leading up to ovulation  Week three: after ovulation  Week four: before the next period begins And depending on where you are in your cycle, ...