A full 75 percent of women regularly opt out of exercise when on the rag. Get back in action by coercing your fluctuating hormones to help, not hinder, your workouts. Just follow these week-by-week recommendations from Anate Aelion Brauer, M.D., assistant professor of obstetrics and gynecology at NYU School of Medicine and Stacy Sims, Ph.D, exercise physiologist at the University of Waikato in New Zealand.
Estrogen and progesterone are at rock bottom, prompting bleeding—and the cramps that come with it. But: That same dearth of hormones increases your pain tolerance and helps your muscles recover more quickly. So even though you'd rather curl up in the fetal position, it's worth hitting the gym: A boot camp class won't feel as tough as usual.
Strength training right now means bigger gains in muscle mass, possibly due to rising testosterone levels. Do some kettlebell squats or crush it at CrossFit, but try to be mindful of your knees. For unclear reasons, surging estrogen levels (which prep the uterus to host the next egg) may lead to more frequent ACL injuries.
When you ovulate (usually around day 14), your estrogen peaks, causing your body to use fat, which is slower to release energy than carbs, as its primary power source. That metabolic shift will make steady-state workouts easier, so if you're training for a race, plan your long runs for this week.
Your lady parts are prepping for the big event with a major hit of progesterone. Cue: crying jags during commercials and bloating (fun!). If you can pull yourself off the couch, do it. Experts say there's no physiological reason you can't work out hard right now, but if you're not up to it, try a brisk walk or Pilates class.
This article originally appeared on Women's Health.