Hormones, Your Cycle, and Sports Performance: What Every Active Woman Should Know

This article was written by guest contributor and Health Advisory Board member, Dr. Sarah E. Hill PhD, Evolutionary Psychologist. 

If you've ever wondered why your hormones and athletic performance seem impossibly linked — why some training days feel effortless and others feel like you're moving through concrete — you're not imagining it. The answer is rooted in your menstrual cycle, and it's something most sports science has largely ignored.

In this guest post, Dr. Sarah E. Hill, research psychologist, evolutionary scientist, and author of This Is Your Brain on Birth Control & The Period Brain, breaks down what the science actually says about how your cycle affects training, recovery, and injury risk — and what you can do about it. Dr. Hill's work sits at the intersection of female biology, hormonal health, and performance. What follows is her expert take.

Training With Your Cycle: What the Science Actually Says

You show up. You put in the work. But if you've ever had a training session that felt inexplicably hard -- legs heavy, motivation nonexistent, effort through the roof -- when nothing in your schedule had changed, your menstrual cycle may have had something to do with it. And if you've ever had the opposite experience, a workout where everything clicked and you felt like you could go forever, that might have been your cycle too.

Most active women are never taught that their hormones can impact their performance. Instead, we're taught to push through, stay consistent, and treat our bodies like a fixed variable. But your body is not the same on day 3 of your cycle as it is on day 18. Understanding why can change how you train, how you recover, and how you feel about the days when your body seems to be working against you.

A Quick Rundown of Your Cycle

In case you are new to the ins and outs of your menstrual cycle, here is a quick summary of the important points.

Your cycle has two main phases, separated by ovulation. The first -- the follicular phase -- begins on day one of your period and runs until you ovulate around the midpoint of your cycle. Estrogen dominates here, rising steadily until it peaks just before ovulation. Most women feel their best during this window: energy is higher, mood is more stable, and the body is generally primed for effort.

After ovulation, the luteal phase begins and lasts until your next period. This is when progesterone takes over. Progesterone's evolutionary job is to prepare the body for a possible pregnancy, which means it's running an energy conservation program. Core body temperature rises slightly. The nervous system shifts toward a more cautious, lower-arousal state. For many women, this is when training feels harder, motivation dips, and recovery takes longer. Not because anything is wrong, but because the biology of this phase is fundamentally different.

As I discuss in The Period Brain, these shifts are happening everywhere throughout the brain and body, including muscle tissue, connective tissue, the cardiovascular system, and the brain regions that regulate energy, motivation, and stress response. Which brings us to what the research actually says.

What the Science Shows About Hormonal Effects on Performance

First, let’s talk about the limits on what we actually know about women’s hormones and their effects of performance. Women represent only about 35% of athletes studied in sports performance research. So, most of what we know about training load, recovery, and adaptation was generated in male bodies. Female athletes are often operating on guidance that was never designed for them.

This being said, there is evidence that suggests that our cycles may matter for athletic performance, with the follicular phase being related to performance advantages and the luteal phase with some disadvantages.

For example, one 2024 meta-analysis found meaningful effects favoring strength during the late follicular phase, and estrogen supports fat oxidation during exercise, potentially making your body more efficient at burning fat for fuel. That said, a major 2023 McMaster University review found no significant influence of cycle phase on strength performance overall. The honest answer: effects are real but modest, and individual variation is enormous.

There is also evidence suggesting that the luteal phase can make things more challenging for women. Progesterone interferes with glucose uptake during exercise, making it harder for muscles to access fuel during high-intensity effort. It raises resting core temperature, accelerating heat stress, which is a real concern for endurance athletes. And falling estrogen in the late luteal phase is associated with decreased serotonergic and dopaminergic activity, which is why perceived effort climbs and motivation tanks in the week before your period.

This doesn’t mean that you shouldn’t train during the luteal phase. It just means that you might want to take extra steps to work with your hormones at this time, prioritizing recovery.

What Does Prioritizing Luteal Phase Recovery Look Like?

This is where the conversation gets practical. Recovery that actively supports the parasympathetic nervous system -- the "rest and digest" branch that counters stress – pays higher dividends during the luteal phase more than at any other point in your cycle.

For example, practices like non-sleep deep rest (NSDR) – yoga nidra, guided body scans, structured relaxation protocols – bring the nervous system into a deeply restored state without requiring actual sleep. Research suggests NSDR can reduce cortisol, accelerate motor learning, and restore energy levels in ways passive rest doesn't. Twenty minutes of NSDR in the luteal phase may do more for your next session than an extra set of intervals.

Vagus nerve stimulation is another tool worth adding. The vagus nerve is the main pathway of the parasympathetic nervous system, and its activation is associated with lower heart rate, reduced inflammation, improved mood, and faster recovery from stress. Slow diaphragmatic breathing, humming, cold water exposure, and meditation all stimulate it. Wearable devices like OhmBody now make targeted vagal stimulation more accessible and consistent. During the luteal phase, when your nervous system is already running a conservative program, these tools can help you recover more fully between sessions and better manage the emotional weight this phase often carries.

One More Reason to Pay Attention: Injury Risk

Female athletes tear their ACLs at two to eight times the rate of male athletes. Hormonal fluctuations appear to be part of why. Estrogen at high levels around ovulation increase ligament laxity, making connective tissue less stable under load. Research in elite female footballers found muscle and tendon injuries were approximately twice as common during the late follicular phase when estrogen peaks. This is a week to be thoughtful about explosive training, warmup quality, and how hard you push to failure.