Do Women Really Need to Train Around Their Menstrual Cycle? What Science Actually Says

For years, fitness influencers and even some coaches have told women to “train with their cycle.” The advice usually goes something like this:

Lift heavy after your period, take it easy before it, and rest more when your hormones are “against you.”

It sounds empowering. Almost scientific.

But when you dig into the actual evidence, that narrative falls apart.

In reality, the belief that women must alter their training based on menstrual phases isn’t backed by solid data. It’s a modern remix of an outdated, sexist idea; one that subtly tells women they’re fragile, unstable, and biologically limited.

A Little History: The Old Pseudoscience in New Packaging

The idea that women are weaker during certain times of the month is more than a century old.

In the early 1900s, scientists coined the term functional periodicity, claiming that women experienced regular dips in performance and cognition because of menstruation.

The logic was simple and deeply flawed: “If women bleed monthly, they must also be less capable monthly.”

Psychologist Leta Hollingworth was one of the first to call nonsense on it. Her research showed that women’s motor skills, intelligence, and focus stayed consistent regardless of their cycle phase.

But bad ideas are hard to kill. Especially when they sound compassionate.

Today, cycle syncing sells the same concept in pastel colors: “Honor your hormones.” “Work with your body.”

It sounds empowering, but it quietly reinforces the same narrative; that women are biologically too unstable to train consistently.

What the Research Actually Shows

When you look at the data, the “train by your cycle” idea starts to crumble.

A 2020 meta-analysis published in Sports Medicine reviewed 78 studies involving thousands of women and concluded that performance differences across menstrual phases were trivial.

On average, women performed about 1–2% lower in the early follicular phase (the days around menstruation) compared to other phases. For perspective, that’s roughly the difference between training slightly dehydrated versus fully hydrated. Noticeable on paper, but irrelevant in practice.

The authors also emphasized that most studies were low quality:

• Over half didn’t verify hormone levels with blood tests (they relied on cycle-tracking apps or self-report).

• Many used tiny sample sizes (sometimes fewer than 10 women).

• Most examined a single workout or short-term outcome, not months of training or adaptation.

So, yes, your hormones fluctuate. But in practice, their effect on strength, power, or endurance is so small it gets lost in the noise of daily life: sleep, stress, nutrition, and recovery all have far larger impacts on performance.

In fact, a 2023 review in Frontiers in Sports and Active Living concluded that “current evidence shows no influence of menstrual cycle phase on strength performance or adaptation to resistance training.”

That means whether you’re squatting heavy on day 3 or day 23, your muscles adapt the same.

The Real Difference Lies in Belief, Not Biology

This is where psychology enters the picture.

If you believe you perform worse during your period, or that you should feel tired and weak because someone told you so, you’re more likely to experience exactly that.

That’s the nocebo effect: when expectation alone lowers performance.

One study in Sports Medicine found that around 70% of female athletes perceive a negative impact from their menstrual cycle, but objective data (force output, endurance, jump height) shows no consistent decline.

That disconnect between perception and physiology reveals something powerful: belief can override biology.

In other words, it’s not your estrogen that’s making you weaker, it’s your expectation.

Your brain sets the ceiling for effort. If you expect poor performance, you subconsciously reduce effort, coordination, or motivation just enough to prove yourself right.

When that happens month after month, your “cycle syncing” turns into a self-fulfilling prophecy.

The irony is thick: the movement that claims to empower women to “train smarter” often ends up teaching them to limit themselves. Not because of hormones, but because of mindset.

Consistency Beats Cycle Timing Every Time

Hormones fluctuate, sure, but so does stress, sleep, hydration, and mood.

And none of those stop you from training consistently.

Physiologically, the fluctuations in estrogen and progesterone mainly affect things like thermoregulation, glycogen use, and water balance, not your ability to lift a barbell or complete a run.

Even where differences exist, they’re small: endurance metrics (like VO₂max) vary less than 2% across phases, and strength tests (like 1RMs or jump height) vary less than 3%. Those are statistical blips, not training barriers.

Yet skipping workouts because of your cycle compounds into weeks of lost training per year. Enough to erase months of progress.

The body adapts to consistency and overload, not caution. The bigger risk is undertraining, not hormonal fluctuation.

Auto-regulate when you truly feel off, but don’t let your calendar convince you that your physiology is fragile.

Birth Control: The Ultimate Myth Buster

Here’s where the “cycle syncing” theory really collapses.

If cycle phases truly determined performance, then women on hormonal birth control, who have flat, stable hormone levels all month, would have completely different training responses. Right?

But study after study shows they don’t. Whaaaa?!

Women on the pill have a steady hormonal profile with no natural estrogen or progesterone spikes. The “phases” are synthetic, your body isn’t swinging through the same hormonal highs and lows.

Yet when researchers compare these women to those with natural cycles, they find no difference in strength gains, muscle growth, or endurance capacity after weeks or months of training.

That’s the smoking gun.

If eliminating hormone fluctuations doesn’t meaningfully change performance, then the fluctuations themselves probably weren’t the issue.

Some research even suggests oral contraceptive users have slightly more stable recovery and less perceived fatigue, not because they’re superior, but because their hormones are predictable.

In either case, performance outcomes are virtually identical.

So, when influencers claim “you need to train with your hormones,” ask them this:

“If that’s true, why do women on birth control, who don’t have natural cycles, make the same progress as everyone else?”

They won't know what you're talking about, they won’t have an answer, or they will scramble B.S. together to save face or double down.

The Power of Mindset Over Menstrual Myths

The psychological impact of this belief system can’t be overstated.

When a woman hears repeatedly that her hormones dictate her capacity, she begins to expect limitation.

That expectation drives behavior: skipping sessions, lowering the bar, labeling normal fatigue as “hormonal.”

And the pattern becomes self-fulfilling.

“I’m weaker this week” → “I train lighter” → “I see slower progress” → “See? My hormones are holding me back.”

But the evidence shows the opposite: women who train consistently through all phases not only make equal gains, many report feeling less symptomatic over time. Regular training improves hormonal sensitivity, pain tolerance, and mood regulation.

It’s an inoculation effect: staying active may actually reduce the very symptoms people use as a reason to skip training.

The truth is simple and freeing:

Your hormones fluctuate, but your capability doesn’t have to.

So What’s the Takeaway?

Science doesn’t support the idea that women need to plan their workouts around menstrual phases.

At best, there are tiny, inconsistent fluctuations that pale in comparison to the effects of sleep, diet, stress, and consistency.

If you’re on hormonal birth control, those fluctuations are largely gone, yet your training outcomes remain the same. That alone debunks the entire “cycle syncing” premise.

So the next time someone says, “Don’t train hard, your hormones are high,” remember:

It’s not your hormones holding you back, it’s the belief that they do.

Train smart. Train consistently. And stop giving power to pseudoscience dressed as self-care.

Exceed Your Limits.

 

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References

• McNulty KL et al., Sports Medicine (2020). “The Effects of the Menstrual Cycle on Exercise Performance.”

• Wikström-Frisén L et al., Frontiers in Sports and Active Living (2023). “No influence of menstrual phase on resistance training adaptations.”

• Elliott-Sale KJ et al., NSCA Strength & Conditioning Journal (2023). “Evidence for Periodizing Strength and Endurance Training Based on Menstrual Phase.”

• Brown N et al., Sports (2024). “Cycle Phases and Perceived Athletic Performance.”

• Elorduy-Terrado et al., MDPI (2025). “Systematic Review on Hormonal Fluctuations and Female Training.”

• Janse de Jonge XA et al., Scand J Med Sci Sports (2021). “Hormonal fluctuations and athletic performance: A critical review.”