How Hormones Impact Distance Running in Women (and How to Stay Healthy)

Before I begin, please note I’m not in any way a doctor! I am just a woman who’s been running ultras like a crazy person since 2009. Over the years, I’ve learned a ton about how my body works (mostly through trial and error, but also through plenty of chats with doctors and other runners). One of the biggest lessons? Hormones matter—a lot. They affect how we feel on runs, how we recover, how we fuel, and even whether we stay injury free.

When I first started racing ultras, I didn’t think much about my cycle or hormones. I figured if I just trained hard and ate decently, I’d be fine. But after years of ups and downs, those mystery fatigue weeks, random injuries, and even iron issues, I realized hormones were quietly influencing everything.

Running is as much a science as it is an art, especially for women. And once you start paying attention to hormones, you can actually use them to your advantage instead of constantly feeling like you’re fighting your body.

The Menstrual Cycle and Running

The menstrual cycle has four main phases: menstrual, follicular, ovulatory, and luteal. Each one brings changes in estrogen and progesterone that can affect energy levels, hydration, and even injury risk.

For example, in the luteal phase (the week or two before your period), I’ve always felt like my legs are made of bricks. Easy runs feel harder, and workouts just don’t click. Then suddenly, around ovulation or during the follicular phase, I feel lighter, faster, and like I can run forever. Once I realized this pattern wasn’t just “in my head,” it changed how I trained.

If you start tracking your cycle, you might notice similar trends, and being aware of them makes it a lot easier to give yourself grace on the tough weeks and lean in on the good ones.

Hormones and Injury Risk

Here’s something most of us don’t hear about until we’re already sidelined: estrogen fluctuations can impact ligament laxity. Basically, during certain phases of your cycle, your joints might be slightly “looser,” which can increase injury risk (think ankle rolls or knee tweaks). On the flip side, when estrogen is low, like if your cycle is irregular or missing, it can mess with bone density, raising your risk for stress fractures. I’ve seen this firsthand, and it’s one of the reasons I take cycle health so seriously now.

Bottom line: paying attention to your hormones and fueling well isn’t just about performance, it’s about staying in the game long term!

Energy, Nutrition, and Recovery

Hormones also affect how your body uses fuel. During the follicular phase, your body tends to use carbs more efficiently, which makes it a great time for harder workouts or speed sessions. In the luteal phase, your body leans more on fat for energy. That can be useful in ultras, but it also means you may need more calories overall, and you might notice you overheat more easily.

I used to beat myself up when my paces felt harder than they “should” during certain weeks. Now, I just accept that my hormones are part of the picture. I eat a little more, hydrate better (especially with electrolytes), and ditch the watch to give myself permission to run effort based instead of chasing the clock.

Recovery is another big piece. Higher progesterone levels in the luteal phase can make inflammation worse, which explains why sometimes I bounce back slower from long runs. That’s when I prioritize extra sleep, foam rolling, and sometimes swapping a run for a hike or strength session.

Red Flags to Watch For

If you’re consistently missing periods, feeling extreme fatigue, getting repeat injuries, or struggling to recover, those aren’t things to push through. They can be signs of Relative Energy Deficiency in Sport (RED-S), which happens when we don’t fuel enough for the training we’re doing. I’ve had stretches where I thought, “I’m training hard, so of course I’m tired,” but in reality, I wasn’t fueling enough. Once I fixed that, everything - from mood to recovery - improved. Don’t ignore the signals your body is sending!

Tips to Stay Healthy and Strong

• Track your cycle and notice patterns in energy and performance.

• Fuel properly, with enough carbs and protein to support your training.

• Prioritize recovery—sleep, mobility, hydration, all of it.

• Don’t brush off missed periods. They’re a sign something needs attention.

• Work with a coach, doctor, or nutritionist if you’re struggling with consistency, energy, or recovery.

  
  

Takeaway

Hormones don’t have to be a roadblock in your running journey. In fact, once you start tuning into them, they can actually become a secret weapon. By paying attention, fueling well, and adjusting when needed, you can train smarter, stay healthier, and ultimately run stronger. The longer I’ve been in this sport, the more I’ve learned that running isn’t just about miles, it’s about balance. Listen to your body, work with your hormones instead of against them, and you’ll set yourself up for success not just in your next race, but for years of running to come!

Resources:

I bought this book many years ago, and I have frequently referenced over the years. I highly recommend anyone who wants to understand this topic better: ROAR by Dr. Stacy Sims