should you actually be cycle syncing your workouts?

A confession to start: this article exists because of a LinkedIn post.

Professor Kirsty Elliott-Sale is the GOAT of female exercise physiology research. She runs the Centre of Excellence for Women in Sport at Manchester Metropolitan University, has spent her entire career studying how hormones influence women's bodies in sport, edits the European Journal of Applied Physiology, and advises the FA. If you've read anything credible about women's bodies in sport in the last decade, you've probably read her work.

A few days ago, she posted a back-and-forth on LinkedIn calling out the cycle-syncing trend. The problem is, LinkedIn is basically the last place a twenty-something woman whose feed tells her to align her squat day with her oestrogen is ever going to see it.

Prof Kirsty isn't on TikTok or Instagram. Most working researchers aren't, because their day jobs are already a lot. Which is sadly rather tragic for the sporty girls. So, we're here to do the work… because what she said deserves to land with the people whose feeds are full of pastel cycle-syncing infographics.

Your menstrual cycle has four rough chapters. The follicular phase is roughly the first half of the cycle, when your body is preparing to release an egg. Ovulation is the moment your ovary actually releases that egg. The luteal phase is the second half, when your body is either prepping for pregnancy or winding the cycle down. Your period is technically the start of the next cycle.

Your hormones shift across all of this. Oestrogen rises and falls, and progesterone does its own thing in the second half. Cycle syncing is built on the idea that those hormonal shifts are big enough, and predictable enough, that they should dictate how you train.

In 2020, Prof Kirsty's team ran the largest analysis on this question to date. They gathered 78 separate studies on cycle phase and exercise performance in naturally menstruating women, and pooled them into one big analysis. (That's called a meta-analysis, basically a study of studies, designed to find the real signal once you stop cherry-picking single papers.) It was published in Sports Medicine.

When they ran the numbers, the effect of cycle phase on performance was trivial. The quality of most of the underlying research was also poor. There was no good basis for handing every menstruating woman a training plan based on what part of her cycle she was in.

In 2023, a research group at McMaster University in Canada teamed up with Prof Kirsty to ask the same question specifically about lifting weights. They got the same answer, and published it in Frontiers in Sports and Active Living. Their headline finding was that programming resistance training around cycle phase is not an evidence-based approach.

Then in late 2024, the same group went a step further. They actually measured something called muscle protein synthesis (the biological process of your muscles repairing and growing after you train them, basically the engine behind every strength and toning goal you've ever had) across the follicular and luteal phases. They wanted to know if one phase was a better window for muscle growth than the other.

What they found, published in the Journal of Physiology, was that both halves of the cycle were equally good for muscle growth, with no meaningful difference between them.

In July 2025, Prof Kirsty stood up at the FIFPRO Women's Sport Strategic Summit during the UEFA Women's Euros and said it on the record. The menstrual cycle is a vital health marker for women, but it doesn't solely dictate how women train, compete, fuel, or get injured.

If you've ever done an intro exercise science unit, you've been taught the principles of training. They're the rules of how the body actually adapts to exercise. There's specificity, which is the rule that you get better at what you practise. Progressive overload means you have to gradually do more over time to keep adapting. Reversibility is the use it or lose it rule. Individuality, recovery, and variation round out the list.

Nowhere in those foundational rules, from the original textbooks to the most recent international position statements, does menstrual cycle phase appear as a programming principle.

Underrepresentation of women in sports science research is real, and we'll keep having that conversation. But the actual answer to why cycle phase doesn't appear in the principles of training is much more boring: the evidence for phase-based programming driving real adaptation just isn't there yet.

Plenty of women have genuinely disruptive menstrual cycle symptoms. We're talking cramps that double you over, heavy bleeding you can't predict, migraines, gut issues, fatigue, and nausea bad enough that getting to the gym isn't realistic.

If your body is doing all of that on day one, slogging through 6x800m at 5K pace that morning is going to be rough. Backing the session off, dropping the load, or swapping it for something easier is completely reasonable.

That practice already has a name. It's autoregulation, and it's been a feature of strength and conditioning since roughly the 1940s. Every good coach uses it, and male athletes use it constantly. The basic idea is to adjust your training based on how your body is showing up on the day, rather than letting a calendar app tell you in advance how your hormones are supposed to make you feel.

Autoregulation and cycle syncing aren't the same thing. Autoregulation looks at the actual athlete in front of you on the day and adjusts. Cycle syncing takes a generic plan, slaps a phase label on it, and sells it back to you in pastel.

If your symptoms run on a schedule, you can see them coming and actually do something about them before they wreck your training week.

There’s iron status that can be monitored (especially if your periods are heavy), pain management options that actually work, nutrition and hydration tweaks that can soften the worst days, contraceptive options that genuinely change how some women experience their cycles, and pelvic health input that most women have never been offered. There's also proper clinical care available if your symptoms are seriously interfering with your life.

The goal is to figure out what's actually going on in your body, treat it properly, and reduce the symptom load so you can train the way you want on any day of the month, day one included.

That's a much more useful strategy than the one your For You page is selling you, because it treats your cycle as health information you can act on.

When yet another pastel reel tells you to walk on day one because your nervous system can't handle anything more, what it's really saying is that your body is too fragile to be trusted. The cycle-syncing trend convinces you that your body is uniquely complicated and that you'll mess yourself up without the right protocol, app, or supplement. Which is a wild thing to be told about a body that's been running this exact cycle on its own since you were about 12.

You deserve better than that. The research is catching up, and your training does not need to be at the mercy of an algorithm that's trying to sell you something. Train to evidence-based principles, and treat the cycle data you collect as health information.

Listen to Prof Kirsty over the algorithm. You can train on any day of the month.