The WattPlan Podcast · Episode 48 · 9 min
The menstrual cycle and training: should you plan around your phases?
Next episodes: How often should you take a recovery week? · How much sleep does a cyclist need? · What does two weeks off the bike really do?
Read the transcript
James. This is the WattPlan Podcast and I'm James. I squeeze WattPlan in around family and work, grab the odd podium, and read more sports science than is sensible. Today's question comes from riders in our own inbox and from half the women's cycling groups online. Should you plan your training around your menstrual cycle, hard sessions in one phase, easy in another? Lyra, our AI research voice, has read the meta-analyses, and every study is linked in the show notes.
Lyra. The pooled evidence says no, not from a chart. The biggest meta-analysis found performance only trivially lower during the period itself, and no difference worth planning around between the other phases. What does change training is symptoms, and those vary so much between women that the research itself says the sensible approach is a personal one, built on your own data rather than anyone's chart.
James. Trivially lower. What does that actually mean in numbers? Because trivial to a statistician and trivial to a rider on day one aren't always the same thing.
Lyra. McNulty, Elliott-Sale and colleagues, in Sports Medicine in 2020, pooled 78 studies that had tested performance in two or more phases of the cycle. Across the 51 with usable data, performance in the early follicular phase, the days of the period, was lower than in the rest of the cycle by a tiny margin, and the uncertainty around it included zero. The largest difference anywhere in the cycle was still trivial. And they graded the quality of the evidence as low. [1]
James. So the phase-based plans people are selling are built on what, exactly?
Lyra. On studies the field now distrusts. Janse de Jonge and colleagues reviewed a decade of menstrual cycle research in 2019 and found that only 44 percent of studies measured oestrogen and progesterone at all. So many of the women counted as being in a given phase may not have been, and some won't have ovulated that cycle. The authors want calendar counting, ovulation tests and blood hormones together before a study can claim anything about phase. Very few of the studies behind those plans meet that. [4]
James. Hang on though. I know riders who feel genuinely awful for two days a month. Are you telling them it's in their heads?
Lyra. No, and the research doesn't either. How a ride feels and what the power meter records are different things. The meta-analysis measured performance on tests, and the symptoms that make a ride feel awful are a separate question, which the survey work answers. Both can be true at once. A rider who feels terrible on day two and tests the same on the turbo isn't imagining either half.
James. So the feeling is real, the power is fine. That's almost more annoying, because you can't point at a number and say that's why.
Lyra. It's also where the practical answer lives, because the feeling is what takes sessions out of the week. Bruinvels and colleagues surveyed 6,812 exercising women through Strava, 1,350 of them in the UK and Ireland. Mood changes or anxiety were reported by about nine in ten, tiredness by 86 percent, cramps by 84 percent. The more symptoms a woman had, the more likely she was to miss or change a session, or miss an event. [3]
James. Right, so symptoms, not hormones, are the thing to plan around. What about the pill? A lot of riders are on it, and I've heard people say it flattens everything out.
Lyra. Elliott-Sale and colleagues did the matching meta-analysis for oral contraceptive users, 42 studies and 590 women. Users might perform very slightly below naturally menstruating women on average, but the effect was most likely trivial, most studies were low quality, and performance was steady across the pill-taking and withdrawal days. Same conclusion. No general guidance, individual approach. Which contraception to use is a question for you and your GP, not for a podcast.
James. And what do actual female cyclists say about all this? Because meta-analyses are one thing, and a wet Tuesday on the turbo with cramps is another.
Lyra. Burnie and colleagues interviewed 20 competitive female cyclists this June, from club riders to elite. Their experiences were all over the place in which symptoms, how bad and when. Nearly half had irregular cycles now or in the past, which the riders themselves put down to low body weight and under-eating for the training. Most had mentioned it to their coach, usually just a note that a period had started, and most wished they knew more. An irregular or missing cycle in a rider who trains hard is a GP question, and under-eating is one thing a GP will want to rule out.
James. Let's make it practical. If you're new to this and you've just started structured training?
Lyra. If you're new to this, train by the plan unless a symptom, not a date, says otherwise. The one thing worth doing is tracking your period start and your worst days alongside your rides, in any app or a notebook, for three or four cycles. Then look. If a pattern shows up in your own power or sleep, plan around it. If it doesn't, you're free.
James. And if you train with power?
Lyra. If you train with power, you've got the data to answer the question for yourself, and that's exactly what the research asks for. Compare your hard sessions across a few cycles. And when a hard day lands on a bad day, swap it with an easy day rather than skipping it. In WattPlan you can swap any upcoming workout with another day on the Plan page, and it checks the week so you don't end up with hard days back to back. Or tell the Coach you're wiped out and want today as a rest day, and it moves things for you.
James. And if you race? Because race day doesn't move.
Lyra. If you race, the pooled evidence is good news. Measured performance barely moves across the cycle, so a race landing on day one isn't the disaster it feels like, and the main job is managing the symptoms, sleep and fuelling around it. Plan the logistics, the kit and the warm-up, and ride the race you trained for. And eat enough. The riders in the interviews who had irregular cycles put them down to under-eating for their training, and under-fuelling is a bigger threat to a season than any phase.
James. Surely WattPlan should just have a cycle setting and shift things automatically though? That's what people expect from an app now.
Lyra. It doesn't, and given the evidence it shouldn't pretend to know which phase does what. What it does is plan around what you tell it. If you tell the Coach about your cycle, it plans the training around that, it treats anything medical as a question for your GP, and it never opens a conversation by bringing up a health matter you mentioned before. The pattern worth keeping is yours, not a chart's.
James. What can't the research tell us?
Lyra. Quite a lot, in both directions. The meta-analyses rate their own studies as low quality, most didn't verify phase with blood tests, and the samples are small. So a real but modest effect in some women can't be ruled out, and neither can no effect at all. Almost none of the performance studies are in cyclists. The symptom survey was self-report from app users. And the one randomised trial of a phase-based plan had fourteen women in it and found no difference, so that's a lead, not an answer.
James. So this week. Train the plan, track my period and worst days next to my rides for a few months, swap rather than skip when a bad day lands on a hard one, and eat enough.
Lyra. And trust your own data over anyone's chart. After three or four cycles you'll know whether there's a phase that costs you sessions. That knowledge is the plan.
Lyra. The full article and every study we mentioned are on the WattPlan blog, linked in the show notes. And if you've enjoyed this, follow the WattPlan Podcast wherever you're listening, so you don't miss the next one.
James. And if you want a plan built around the time you've actually got, get WattPlan on the App Store or Google Play. Thanks for listening.
Voices produced with ElevenLabs. James's voice is a clone of his own, Lyra is an AI voice, and James reviews every episode.
Training through the menstrual cycle does not need a phase-based plan. A 2020 meta-analysis of 78 studies found performance only trivially lower in the early follicular phase, an effect size of -0.06, and rated the evidence low. Symptoms matter more. In a survey of 6,812 exercising women, 86% reported tiredness and 84% cramps, and more symptoms meant more changed sessions.
Does the menstrual cycle affect cycling performance?
Measured on a test, barely. Kelly McNulty, Kirsty Elliott-Sale and colleagues pooled every experimental study they could find that tested performance in two or more phases of the menstrual cycle, 78 studies in all, and published the result in Sports Medicine in October 2020. Across the 51 studies with usable data, performance in the early follicular phase, the days of the period itself, was lower than in the rest of the cycle by a median effect size of -0.06, with a 95% credible interval of -0.16 to 0.04 that crosses zero. The largest difference in the network analysis was between the early and late follicular phases, at -0.14 with an interval of -0.26 to -0.03. Both effects count as trivial, and the authors graded the quality of the evidence as low, at 42%, because of small samples and poor cycle verification.
Their conclusion was that no general guideline on training across the menstrual cycle can be formed from the evidence, and that a rider should take a personalised approach based on how her own performance moves.
Why do riders feel worse at some points in the cycle?
Because how a ride feels and what the power meter records are not the same thing. The meta-analysis measured performance on tests. The symptoms that make a ride feel worse are a separate question, and a rider who feels terrible on day two and tests the same on the turbo is not imagining either half.
The scale of the symptoms is what makes this matter. Georgie Bruinvels and colleagues surveyed 6,812 women of reproductive age who used Strava and were not on combined hormonal contraception, 1,350 of them in the UK and Ireland, for a paper in the British Journal of Sports Medicine in 2021. Mood changes or anxiety were reported by 90.6%, tiredness or fatigue by 86.2%, stomach cramps by 84.2% and breast pain by 83.1%. The more symptoms a woman had, and the more often, the more likely she was to miss or change a training session, with an odds ratio of 1.09 per point of their symptom index, and to miss an event or competition, at 1.07. Symptoms are what take sessions out of the week, whatever drives them.
What the studies found
| Study | Who was studied | What was measured | Key number |
|---|---|---|---|
| McNulty 2020, meta-analysis | 78 studies, 51 pooled | Performance in the early follicular phase against the rest of the cycle | Effect size -0.06 (95% CrI -0.16 to 0.04), evidence quality low |
| Elliott-Sale 2020, meta-analysis | 42 studies, 590 women | Oral contraceptive users against naturally menstruating women | Any difference most likely trivial, performance steady across the pill cycle |
| Bruinvels 2021 | 6,812 exercising women, mean age 38 | Symptom prevalence and effect on training | Tiredness 86.2%, cramps 84.2%, more symptoms meant more changed sessions (OR 1.09) |
| Kubica 2024, randomised trial | 14 moderately trained women | 8 weeks of polarised training tailored to the cycle against a regular programme | No difference on any measure |
| Janse de Jonge 2019, methods review | Menstrual cycle studies 2008 to 2018 | Whether studies verified cycle phase with hormones | Only 44% measured oestrogen and progesterone |
| Burnie 2026 | 20 competitive female cyclists | Interviews on the cycle and training | 45% had irregular cycles now or in the past, 73% had told their coach |
Should you plan training around the phases of your cycle?
Not from a chart. The evidence for scheduling hard sessions in one phase and easy ones in another rests on studies the field itself now distrusts. Xanne Janse de Jonge and colleagues reviewed a decade of menstrual cycle research in 2019 and found that only 44% of the studies measured oestrogen and progesterone at all, so many of the women counted as being in a given phase may not have been, and some will have had cycles with no ovulation. They recommend three methods together, calendar counting, urinary ovulation tests and blood hormone measurement, before a study can say anything about phase. Few of the studies behind the phase-based plans meet that standard.
Our view at WattPlan is that the menstrual cycle is a reason to track your own pattern, not a reason to move your interval sessions by the calendar. If your own data shows that the first two days of your period cost you power or sleep, that is worth planning around. If it doesn't, the pooled evidence says you are free to train as the week needs.
Does the pill change any of this?
Elliott-Sale and colleagues ran the matching meta-analysis for oral contraceptive users, 42 studies and 590 women, in the same issue of Sports Medicine. Users may perform slightly below naturally menstruating women on average, but the effect was most likely trivial, 83% of the studies were of moderate to very low quality, and performance was consistent across the pill-taking and withdrawal days. Their conclusion was the same as McNulty's, that the evidence does not support general guidance either way and that an individual approach fits better. Which contraception to use is a question for you and your GP.
What do female cyclists themselves say?
Louise Burnie and colleagues interviewed 20 competitive female cyclists, 3 elite, 7 sub-elite and 10 club riders, for a paper published on 2 June 2026. Their experiences ranged widely in which symptoms they had, how severe and when. 45% had irregular cycles now or in the past, which the riders themselves put down to low body weight and eating too little for their training. 73% had spoken to their coach about it, though usually no more than a note on the training programme that a period had started. Most said they lacked knowledge about the cycle and how to manage its symptoms. An irregular or missing cycle in a rider who trains hard is a question for a GP, and the riders' own explanation is one of the things a GP will want to rule in or out.
How to adjust the plan in WattPlan
WattPlan has no menstrual cycle setting, and given the evidence above it does not pretend to know which phase is which. What it has is a plan you can bend to the week you are having. On the Plan page, a Swap button on any upcoming workout changes places with the day you pick, and the week is checked so hard days don't end up back to back. In the Coach, "I'm wiped out, make today a rest day" or "swap Tuesday and Thursday" moves the sessions for you, and you can ask it to cut the week's volume or put in a recovery block of easy days. If you tell the Coach about your cycle it will plan the training around what you have told it, and it treats anything medical as a question for your GP. It also never opens a conversation by raising a health matter you mentioned before.
The pattern worth keeping is your own. Note the days you swap or skip and the reason, and after three or four cycles you will know whether there is a phase that costs you sessions, which is the personalised approach the research asks for.
What to do this week
- Keep training by the plan unless a symptom, not a date, says otherwise. The pooled evidence gives no reason to protect a phase.
- Track your period start and your worst symptom days alongside your rides for three or four cycles, in any app or a notebook, and look for a pattern in your own power and sleep.
- When a hard session lands on a bad day, swap it with an easy day rather than skipping it, and let the week stay whole.
- Eat enough for the training. Riders in the 2026 interviews linked their irregular cycles to under-eating, and an irregular or absent cycle is a reason to see your GP.
- Tell your coach, or the Coach, what you want planned around. Most riders in the interviews had mentioned it only in passing, and most wished they had known more sooner.
What the research can't tell you
The evidence is weak in both directions. The meta-analyses rate their own studies as low quality, most did not verify cycle phase with blood tests, and the samples are small, so a real but modest effect in some women cannot be ruled out, and neither can no effect at all. Almost none of the performance studies are in cyclists specifically, the symptom survey relied on self-report from app users, and the interview study had 20 riders. The one randomised trial of a phase-based plan, by Claudia Kubica and colleagues in 2024, put 14 moderately trained women through eight weeks of polarised training, half of them with the harder sessions moved into the mid and late follicular phase, and found no difference on any measure, though much of the control group's training happened to line up with the cycle anyway. One trial of 14 is a lead, not an answer.
Sources
- The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis, Sports Medicine
- The Effects of Oral Contraceptives on Exercise Performance in Women: A Systematic Review and Meta-analysis, Sports Medicine
- Prevalence and frequency of menstrual cycle symptoms are associated with availability to train and compete: a study of 6812 exercising women recruited using the Strava exercise app, British Journal of Sports Medicine
- Methodological Recommendations for Menstrual Cycle Research in Sports and Exercise, Medicine and Science in Sports and Exercise
- Female cyclists perceived effects and experiences of the menstrual cycle on training and performance, PLOS ONE
- Effects of a training intervention tailored to the menstrual cycle on endurance performance and hemodynamics, The Journal of Sports Medicine and Physical Fitness