How your period can affect your exercise performance, according to a doctor

a photo of a female runner on a beach
(Image credit: Getty/Igor Emmerich)

I’ve run four marathons, but I’ve never stopped to think about how my hormones, or my menstrual cycle, would affect my performance on race day. In fact, for the past 10 years, I’ve taken birth control pills back-to-back to skip bleeds, not wanting to deal with my cycle and my training.

Yet, after I sat down to listen to Dr. Carrie Jones, Head of Medical Education at Rupa Health, a consultant and educator on the topic of women's health and hormones with more than 20 years in the industry, I realized where I’d been going wrong in my training — and what I needed to do. 

Speaking on a panel of female experts, Dr. Jones explains the importance of taking into consideration your menstrual cycle and hormones when training.  Because of this, certain sessions should be modified to minimize the risk of injury mid-cycle, Dr. Jones says.

It turns out I’m not alone in my naiveté — a 2019 study conducted by researchers at St Mary's University in Twickenham, England, analyzed more than 14,000 female Strava members. 72 percent of women said they have never received any education regarding exercise and their menstrual cycle. 

But why is it important? Read on to find out why all women, whatever they are training for, should be tracking their cycle. 

Note: This interview was conducted before the overturning of Roe vs Wade. If you are worried about the security of your period tracking app, here's what a cybersecurity expert said about keeping your personal data private. Alternatively, here's how to track your period without using an app. 

How do a female’s hormones affect her performance? 

“Men have testosterone, that's their big hormone," Jones said. "Women have estrogen, progesterone, testosterone, and cortisol — our stress hormone as well as a thyroid hormone, we have glucose and insulin. All of these hormones are like best friends, and they play well together. 

So if one of our hormones is off, then it the ripple down effect is across all of them. So you can't just be like, 'Oh, I had a really bad night's sleep last night, no big deal. I'll just drink extra coffee and be fine,' because it depends where you are in your cycle. It depends how your glucose and insulin are doing. It depends, like how bad was your sleep, which affects everything else in the body. And then you go out and train. So all of them, all of the hormones in a female’s body can affect her performance.” 

Why is it important for women to be tracking where they are in their cycle? 

“I think it was in 2016, the U.S. Soccer Olympic Soccer Soccer team decided to take on their cycle and train specifically for their cycles and where they were and it’s so important," Jones said.  "All humans have a 24-hour cycle — our cortisol works in 24 hours, so we get up in the morning when it’s high, and our cortisol level drops throughout the day to allow us to sleep at night. Men have an extra boost during the 24-hour cycle because they get testosterone, which is higher in the morning. For women, our cycle changes every single day. So every single day, our hormone shifts a little bit, so we have to use that as our superpower. 

I’ll give you two examples. When we are leading up to ovulation, which is generally in the middle of our cycle when we release the egg, our estrogen shoots really high, it's supposed to — it has to — but it also makes our ligaments lapse. So we're not good at HIIT, we're not good at box jumps, we're not good at quick pivots and we're more at risk for injury, especially to our knees."

If you know about you where you are in your cycle, it's only going to make you an even better rock star.

“The second example is if when we get past ovulation and we get close to our period, but our progesterone is high. Our progesterone is our nurturing, everything's-gonna-be-okay hormone. It's our nesting hormone. But it also makes us clumsy. So if you've ever noticed you’re close to your period, and you drop stuff, you break stuff, you run into walls, you trip, it’s because of progesterone — that's one of the effects it has on the body.

Now, if you know this about this hormone cycle, you can train to it. If you’re at a time when your estrogen is high, don't do box jumps, don't do quick pivot spreads, do other things. If you know you're close your cycle, you're going to really, really, really practice the clumsy things — you're going to practice going over hurdles, or the fine motor skills for your sport, so that if you compete during this time of your cycle, you'll be way better than anyone else. Because you've been practicing not being clumsy with your progesterone at its highest. So if you know about you where you are in your cycle, it's only going to make you an even better rock star.”

a photo from the Under Armour panel with Dr Carrie Jones

(Image credit: Under Armour)

What do you say to athletes who, for example, get worried about getting their period the night before a marathon? 

“Well, hopefully, I'm talking to them ahead of time, just like you, and I can get them to start tracking and trying to figure out where they are in their cycle so that when they get to the actual marathon day, they can be like, ‘I’ve got this because I'm going to do what I did last month, or the month before that. I know what I'm doing. I know I need extra magnesium. I know I need extra electrolytes. I know I need more sleep and to take better care of myself.’ 

“If we know where we are in our cycle, we can train to it. The female body is designed around reproduction. Whether you want to get pregnant or not — that's not the point. The body is like just in case, just in case, every single month. When you are in that second half of the cycle, getting close to your period, your body goes into protection mode — ‘I'm going to give you extra water weight, I'm going to make you hungrier, I'm going to make you tired, I'm also going to raise your temperature up a little bit so you're going to need to cool down more when you work out. I'm gonna make you slower. I'm gonna make you clumsier.' If you know this, as an athlete, you can switch your mentality and then train for it. You can take extra supplements, extra electrolytes, or an extra nap.”

A photo of Dr Carrie Jones at the Under Armour event

(Image credit: Under Armour)

What about birth control — how does this come into play? 

“So birth control, there's hormonal and non-hormonal," Jones said. "The only non-hormonal actual birth control is the copper IUD. A lot of women really like it because it doesn't have hormones, so you still will get your period, for other women it makes her cramps heavier, and her period heavier. With hormonal birth control we have the IUD, we have birth control pill, and then we have a ring. 

"Some women do great on birth control. They love it, their bodies love it, they compete, everything's great. Other women don't do so well with birth control. They feel terrible, they get mood swings, gut problems, they gain weight, they get mid-cycle spotting, and so on. And so, it’s so important to try to figure out whether the birth control you use is the right route for you. 

“The second thing is, once you started, you’ve got to give yourself a runway as an athlete. Because if you're going to get side effects, and you got a major competition coming up in two weeks or a month, you really don’t want to mess with your training schedule. For example, if you try to add a birth control pill or get an IUD inserted, and you absolutely hate it, it could affect your performance."

The myth is that you get your period and your race is ruined.

Remember, you don’t have to fight through negative side effects. I would never have a woman suffer for three months because why would anyone want to deal with three months of depression, breakthrough bleeding, or gas and bloating? It's about tweaking and finding what's right for you.”

Do your hormones follow the same pattern on birth control? 

"When you take birth control pill, the pill takes over and shuts down the connection from your brain to your ovaries," Jones said. "So it shuts down your estrogen, it'll shut down your progesterone and then by default, it doesn't shut down to testosterone but it increases what's called a binding globulin to go over your testosterone. So with the birth control pill, the actual hormones that your body produces flatline, so you will look like what we call week one of your cycle all the time and flatline."

What is the biggest myth or misconception about hormones and female performance?

“The myth is that you get your period and your race is ruined," Jones said. "You can use your menstrual cycle and your hormones as a superpower, you just need to know where you are in your cycle. And then just don't forget your other hormones — don't forget cortisol, which is your stress hormone, don’t forget your sleep hormone, don't forget about your blood sugar, your insulin. Know that as women, we are just really tied way more together, I think, than men. 

"So if you're feeling off, it's going to be an off day across all your hormones. So take really good care of yourself — get good sleep, eat good food, don't skip meals, hydrate, use electrolytes, stretch or do a longer cooldown. And then the next day, you’ll just be that much further ahead of the person next to you on the start line.”

Jane McGuire
Fitness editor

Jane McGuire is Tom's Guide's Fitness editor, which means she looks after everything fitness related - from running gear to yoga mats. An avid runner, Jane has tested and reviewed fitness products for the past five years, so knows what to look for when finding a good running watch or a pair of shorts with pockets big enough for your smartphone. When she's not pounding the pavements, you'll find Jane striding round the Surrey Hills, taking far too many photos of her puppy.