Why? Well, the period-related shift in hormones can cause connective tissue to get lax, says body performance and injury expert Rami Hashish, PhD. “That increases your risk of sustaining a major injury, like an ACL tear, during that time,” he says. Essentially, softer ligaments allow your lower limbs to move out of alignment more easily (think of twisting a knee or rolling an ankle).
Data backs up his assertion: According to a review of 17 studies on menstrual cycle effects on the body published in 2017, athletes who have a period, like skiers for example, tend to experience ligament-loosening during the follicular phase, which is the first of four phases of the menstrual cycle, starting on the first day of a menstrual period. And the risk of injury may return in the later part of that phase (a few days post-period), too, according to a study published in March in Frontiers in Sports and Active Living. Researchers found that among a group of 113 professional women soccer players, muscle and tendon injury rates were 88 percent higher in that phase than in any other.
Right around your period, it may be smart to avoid high-impact workouts involving side-to-side motions—especially if your body’s not well-conditioned to them.
With this in mind, Dr. Hashish says right around your period, it may be smart to avoid high-impact workouts involving side-to-side motions—especially if your body’s not well-conditioned to them. So basically, if you haven’t ever tried HIIT, now might not be the best time to dive in. And if you are a HIIT regular, you can partake if you’re feeling up to it—just be extra mindful of your posture while in motion (keep knees positioned over toes) to prevent unnatural pivots or twists, says spinal and orthopedic surgeon Gbolahan Okubadejo, MD, FAAOS.
Interestingly, the effect of your menstrual cycle on your metabolism may support going easy on the exercise during a period, too. It likely rises a bit in the luteal phase, which is the couple weeks before your period, says Sridevi Krishnan, PhD, a nutritional biologist at the University of California-Davis. “We see an increase in body temperature then, which is an indicator of higher metabolic activity,” she says. And that’s when it makes sense to ramp up the intensity of your workouts (again, this is a couple weeks pre-period), in order to reap the biggest reward from your high-functioning metabolism. In this way, you’ll also effectively offset the slow-down experts recommend once your period hits.
Also, during that pre-period, metabolism-pumping phase, you may feel hungrier, says Dr. Krishnan. In which case, go ahead and eat a little more. “A study on a menstrual cycle-focused diet had participants consume an extra 100 to 200 calories during that phase in the form of dark chocolate, and found that they actually sustained or lost weight,” Dr. Krishnan adds.
How to eat and exercise during your period
Dr. Krishnan recommends reaching for nutrient-dense foods in the lead-up to your period to provide energy and satisfy hunger. That means high-protein options, as well as anything containing oleic acid (like avocados, olives, almonds, or cashews), which triggers the production of a fullness-inducing endocannabinoid in the body.
And, yes, the experts do still recommend some exercise during your period, if you’re feeling up to it. Gentle yoga, Pilates, jogging, and swimming are all great low-impact options, says Dr. Hashish. “I also suggest stability work, focusing on the core and the gluteus medius, that big fan-shaped muscle on the sides of your hips,” he says. “Increasing strength there will help you retain better control of your lower limbs and resist injury.”
And if you really, truly just want to get your sweat on, don’t deprive yourself. By taking the appropriate precautions and pre-workout preparations, you can safely HIIT any day of the month. Listen to your body, first and foremost, warm up well and use proper footwear, says Dr. Okubadejo. “Cardio releases endorphins, which can help get rid of prostaglandins, the chemicals produced during a period that cause fever, pain, and muscle contractions,” he says. And the endorphins will of course boost your mood, too.
Want inspo for low-impact cardio workouts? Check out the video below:
That said, it’s also important to note that you should listen to your body, adds Dr. Okubadejo. “If you feel really exhausted, you may want to take a day or two off from exercising, or just engage in light exercise such as going for a walk or short hike.”
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