The Effect of Hormonal Contraceptive Use on Skeletal Muscle Hypertrophy, Power and Strength Adaptations to Resistance Exercise Training: A Systematic Review and Multilevel Meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of experimental training studies
PubMed 37755666 · doi:10.1007/s40279-023-01911-3
What was done
A systematic review and multilevel meta-analysis searched PUBMED, SPORTDiscus, Web of Science, and Embase through July 2023 for experimental studies comparing skeletal muscle hypertrophy, power, and strength adaptations to resistance exercise training between hormonal contraceptive users and non-users. Methodological quality was evaluated using the Tool for the assessment of study quality and reporting in exercise, and data were synthesized with a multilevel maximum likelihood estimator model.
What was found
Eight studies with 54 effects and 325 participants met inclusion criteria; all evaluated oral contraceptive pills (OCPs). OCP use showed no significant effect on: - Muscle hypertrophy: effect size 0.01 (95% CI [-0.11, 0.13], t = 0.14, p = 0.90) - Power: effect size -0.04 (95% CI [-0.93, 0.84], t = -0.29, p = 0.80) - Strength: effect size 0.10 (95% CI [-0.08, 0.28], t = 1.48, p = 0.20)
Why it matters
These results indicate that oral contraceptive pill use does not meaningfully impair or enhance muscle strength, power, or hypertrophy adaptations to resistance exercise in females.
Limits
The total evidence base is small (8 studies, 325 participants), leading to wide confidence intervals, particularly for power. All included studies examined oral contraceptive pills, so findings cannot be generalized to other hormonal contraceptive formats such as injections, implants, or hormonal intrauterine devices.