Menstrual Cycle and Training

Root Physical Therapy

Clinical Note — No. 10

Women's Health

Train the load,
not the phase.

Cycle-based programming has been sold hard and studied thinly. A six-month study of elite female weightlifters found that phase on its own didn't change strength — but that it interacted with training load in a way that's more useful than any calendar rule.

Georgetown, Seattle11 min readEvidence-based

Written by the Doctors of Physical Therapy at Root Physical Therapy — on-site inside Root Strength, Georgetown. Dr. Lorrainne, DPT leads our women's health and pelvic health care. If your training and your cycle are interacting in ways you can't work out, book an assessment — no referral needed in Washington.

Over the last few years, cycle-based training has gone from a niche idea to an app category. Lift heavy in the follicular phase, back off in the luteal, treat the four weeks as four different training environments. It's an appealing story, and it fills an obvious gap — sports science was built overwhelmingly on male participants, and women have been handed male programmes for decades.

The problem is that the confident advice arrived well ahead of the evidence. So a study published in the Journal of Science and Medicine in Sport this year is worth attention, because it did something the field has largely avoided: it tracked real athletes through real training over six months rather than testing them once in a lab.

One

What the study actually did

Eight national-level female weightlifters, average age 25, were followed for six months. They tracked their cycles with diaries and daily temperature measurements — 24 of 32 possible cycles were recorded completely, with an average length of 27 days. Saliva samples every two days across three months confirmed normal hormonal cycling, which matters: a lot of cycle research assumes phases from calendar dates without verifying that ovulation actually occurred.

Back squat performance was measured with an inertial sensor during their normal training rather than in separate test sessions, and subjective recovery was captured with a validated recovery–stress questionnaire.

The Design

Figure 01

8

national-level weightlifters, followed for six months of ordinary training

24

of 32 possible cycles fully recorded, average length 27 days

3

months of saliva hormone sampling every two days, confirming normal cycling

Eight participants is a small sample — and it's small in the way that matters, because individual variation in cycle response appears to be large. Read this as a well-executed study of a few athletes, not as a definitive answer. Its value is in the design and the direction it points, not in the precision of the numbers.

Two

What it found

Two findings, and the second is the interesting one.

First, the main effect: menstrual cycle phase on its own did not significantly influence back squat strength or perceived recovery. Across the six months, knowing which phase an athlete was in told you very little about how she would perform or how recovered she would feel.

Second, the interaction: during moderate training weeks, strength performance was significantly reduced in the late luteal phase — compared both with the early follicular phase and with low-load training weeks. The phase alone did nothing. The phase combined with a particular training load did something.

Where the Signal Appeared

Figure 02

Phase One

Early follicular

Days ~1–7

Begins with menstruation; oestrogen and progesterone both low. The comparison point in this study — and the phase against which late-luteal strength was reduced.

Phase Two

Late follicular

Days ~8–14

Oestrogen rises toward ovulation. Popularly framed as the "lift heavy" window — a claim this study does not support as a general rule.

Phase Three

Early luteal

Days ~15–21

Progesterone rises after ovulation. No consistent strength effect emerged here in this cohort.

Phase Four

Late luteal

Days ~22–28

Hormones falling toward menstruation. The one place a signal showed up — and only during moderate training weeks.

Phase lengths vary between individuals and between cycles; the day ranges above are indicative for a 28-day cycle rather than fixed. This is precisely why calendar-based programming is fragile — it assumes a regularity that most cycles don't have.

The phase didn't predict performance. The phase plus the load did.

Three

Why an interaction is more useful than a rule

A main effect gives you a rule: always do less in this phase. An interaction gives you something better — a place to look.

If phase only matters in combination with a certain training load, then the phase isn't really the problem. The total demand is. The late luteal phase appears to reduce the margin an athlete has available, so a moderate week that would ordinarily be absorbed comfortably shows up as a performance decrement instead. Change the load and the effect changes with it — which is exactly what happened in the low-load weeks.

The authors' recommendation follows directly: menstrual phase by itself does not warrant systematic restructuring of strength programmes. Prioritise training load management and individual readiness; use cycle tracking to flag the late luteal phase during moderate weeks for closer monitoring; and make small, short-term adjustments in volume or recovery rather than wholesale phase-based programming.

The reframe

Cycle tracking isn't a programming instruction. It's a monitoring variable. It belongs in the same category as sleep, life stress and training history — context that helps you interpret a session that felt harder than it should have. Treated that way, it earns its place. Treated as a calendar that dictates your loading, it substitutes a population-level generalisation for information about you specifically — which is the opposite of individualisation, even though it's marketed as individualisation.

Where the evidence is limited — stated plainly

Eight athletes, one sport, six months. That's a strong design applied to a small sample, and it cannot rule out meaningful effects in individual women — the study measured whether phase predicted performance on average, not whether any particular athlete has a consistent pattern. The wider literature on menstrual cycle and performance is also genuinely mixed, with much of it relying on calendar-estimated phases rather than confirmed hormonal profiles, which is one reason the findings have been so inconsistent. If your own tracked data shows a clear, repeated pattern across many cycles, that's evidence about you, and it's worth acting on.

Four

What to actually do

A Sensible Approach

Figure 03

I

Track, but track alongside training load

Cycle data alone answers almost nothing. Cycle data next to what you actually did that week — sessions, hard sets, sport volume — is where the pattern in this study appeared. Log both or neither; one without the other produces a correlation you can't interpret.

II

Flag the late luteal phase in demanding weeks

This is the specific, evidence-supported action. Not "deload in the luteal phase" — rather, when a moderate-to-hard week overlaps the late luteal phase, watch that week more closely and be readier than usual to make a small adjustment if performance or recovery drops.

III

Adjust small and short, not structurally

If an adjustment is warranted, the evidence supports trimming a little volume or adding recovery for a few days — not rebuilding a training block around a calendar. Structural changes should be driven by your goals and your capacity, which is the same argument we make in our note on readiness versus preparedness.

IV

Treat your own data as the strongest evidence you have

Group averages describe groups. If you've tracked several cycles and see a genuine, repeating pattern in your training, that's a finding about you and it outranks a population mean. The discipline is distinguishing a real pattern across many cycles from a story built on two bad sessions.

Underneath all four: the variables that most reliably determine how a training week goes are still sleep, fuelling, life stress and total load. Those explain more of the variance in most weeks than cycle phase does — and unlike cycle phase, you can change them.

Five

When the cycle itself is the signal

There's a much more important cycle-related finding in sports medicine than which phase to squat heavy in, and it gets far less attention. A missing period in an athlete is not a convenience or a sign of being fit. It's a clinical finding.

The IOC's 2023 consensus on Relative Energy Deficiency in Sport identifies menstrual dysfunction as a key indicator of low energy availability — a state that damages bone, endocrine function, immunity and performance, and which we covered as one of the four things most often mistaken for overtraining. If you're training hard, eating less than the work requires, and your periods become irregular or stop, that combination needs proper evaluation rather than tracking.

See a physician about

These warrant medical assessment rather than a programming adjustment:

Periods that have stopped or become irregular

Periods that have never started by age 15

Pain severe enough to stop you training or working

Unusually heavy bleeding, or bleeding between periods

A stress fracture, or repeated bone injuries

Unintentional weight loss alongside hard training

Worth knowing about

FIFA launched a Female Health and Performance Project this year — 30 online modules across 13 topics including female physiology, menstrual health, pregnancy, postpartum, menopause, nutrition, recovery and injury prevention, pitched at audiences from the general public through to specialists. It exists precisely because training methods have historically been built on male-centric research. If you want to go deeper than a single study, that's a substantially better starting point than an app's marketing copy.

Six

The bottom line

The honest position is that we don't yet know enough to programme around the menstrual cycle with confidence, and the confident advice currently circulating is running well ahead of the data. What this study adds is a useful correction: phase alone didn't predict strength or recovery, but phase interacting with training load did.

Which means the actionable variable is the one you already control. Manage the load, track the cycle as context, watch the late luteal phase a little more closely when the week is demanding, and treat a disappearing period as a medical question rather than a training one. That's less satisfying than a colour-coded calendar. It's also considerably more likely to be true.

The Short Version

• Cycle phase alone didn't affect back squat strength or perceived recovery across six months in elite female weightlifters.
• The signal was an interaction: strength was reduced in the late luteal phase specifically during moderate training weeks.
• Phase doesn't justify restructuring a programme. The authors recommend managing load and individual readiness instead.
• Use cycle tracking as a monitoring variable, not a programming instruction — and log it alongside your training load or it tells you nothing.
• Adjust small and short when needed — a little volume or extra recovery, not a rebuilt block.
• Eight participants, one sport. Strong design, small sample, and individual variation is likely large.
• A missing period is a clinical finding, not a training adaptation. Get it evaluated.

This article provides general educational information and is not medical advice or a substitute for individual assessment. Menstrual irregularity, absent periods, severe pain, or unexplained bleeding should be evaluated by an appropriate healthcare provider.

Training that accounts for your physiology.

Dr. Lorrainne, DPT sees women's health and pelvic health patients on-site at Root Strength Georgetown. Private treatment rooms, a full gym next door, no referral required in Washington, most major insurance accepted — and we verify your benefits before scheduling.

Book an Assessment

Keep Reading — Root Physical Therapy

Rectocele — What It Is, and What Actually Helps Pelvic Health Before and After Birth You're Not Overtrained. You're Under-Recovered. Readiness Is the Wrong Question. Preparedness Is the Right One. How Much Training Is Enough? The Dose-Response Evidence

Sources

1. Schatz P, et al. Interactions between menstrual cycle, training load and strength performance in elite female weightlifters. Journal of Science and Medicine in Sport. 2026;29:833–840.
2. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine. 2023;57(17):1073–1097.
3. Bruinvels G, Burden RJ, McGregor AJ, et al. Sport, exercise and the menstrual cycle: where is the research? British Journal of Sports Medicine. 2017;51(6):487–488.
4. Kelly MK, Bowe SJ, Jardine WT, et al. Heat adaptation for females: a systematic review and meta-analysis of physiological adaptations and exercise performance in the heat. Sports Medicine. 2023;53:1395–1421.
5. Kruczek K, Rebelo A, Gabbett T, Nowak M. The readiness–preparedness bias: recalibrating monitoring logic. Frontiers in Physiology. 2026;17:1855985.
6. FIFA. Female Health and Performance Project — educational modules on female physiology, menstrual health, pregnancy, postpartum, menopause, nutrition, recovery and injury prevention. 2026.