Strength changes at most trivially across the menstrual cycle in women with regular cycles
Interpretation
Blagrove et al.'s meta-analysis of 21 studies found no significant strength differences between early follicular, ovulatory and mid-luteal phases (g ≤ 0.35, I² = 0%), and McNulty et al.'s 78-study meta-analysis found only a trivial early-follicular dip in performance (ES -0.06). Colenso-Semple et al.'s umbrella review reached the same conclusion. Graded moderate rather than strong because evidence quality was rated low, phases were often estimated rather than confirmed, and participants were mostly young non-athlete women.
Practical implication
Female triathletes don't need to schedule strength testing or heavy sessions by cycle phase; adjust for symptoms on the day instead. Evidence is mostly in non-athletes with regular cycles and doesn't cover perimenopause.
Sources
3 sources, independently verified.
21 studies comparing early follicular, ovulatory and mid-luteal phases found no significant differences in maximal voluntary contraction, isokinetic peak torque or explosive strength (all p ≥ 0.26; Hedges g ≤ 0.35; I² = 0%). Strength minimally altered by cycle hormones, with methodological shortcomings noted.
78 studies: performance might be trivially reduced in the early follicular phase compared with all other phases (ES -0.06, 95% CrI -0.16 to 0.04); largest difference early vs late follicular (ES -0.14). Evidence quality low; large between-study variation; general phase-based guidelines can't be made, so a personalised approach is recommended.
Umbrella review of 5 reviews (rated low to moderate quality): scant, low-quality and inconsistent evidence of phase differences in strength, performance or hypertrophy; premature to conclude hormone fluctuations matter. Key training studies had problems (ovulation unverified; a 0.2 kg lean-mass change within DXA error). Recommends individualising training and tracking cycle and symptoms rather than phase-based programming.