The Effect of Monophasic Oral Contraceptives on Muscle Strength and Markers of Recovery After Exercise-Induced Muscle Damage: A Systematic Review

Context: Oral contraceptives (OCs) manipulate hormonal fluctuations of the menstrual cycle and affect physical performance. Most investigations on the effect of OCs on physical performance did not discriminate between different types of OCs. Thus, the effects of monophasic OCs (MOCs) - the most common type of OCs - on muscle strength and recovery from exercise are largely unknown. Objective: To examine the effect of MOC use on muscle strength and markers of recovery after exercise-induced muscle damage (EIMD) in premenopausal women. Data Sources: Electronic databases Embase, PubMed, SportDiscus, and Web of Science were searched for studies examining the effect of MOCs on acute muscle strength and recovery. Study Selection: Keywords applied for the study selection were oral contraceptive* AND muscle strength or oral contraceptive* AND muscle damage. Study Design: Systematic review. Data Extraction: A total of 104 studies on muscle strength were identified, of which 11 met the inclusion criteria. Concerning recovery, 51 studies were identified, of which 4 met the inclusion criteria. Results: Of the 11 studies included, 10 showed no effect of MOCs on acute muscle strength. Of the 4 studies on recovery, 2 found a greater decrease in muscle strength, and 3 found higher creatine kinase (CK) levels after EIMD in MOC users than in nonusers. The included studies were all rated with moderate-to-serious risk of bias. Conclusion: These findings suggest that MOCs may impair recovery from EIMD as indicated by lowered muscle strength and elevated CK levels. There is insufficient evidence to conclude whether MOCs acutely affect muscle strength. Moderate-to-serious risk of bias in studies makes interpretation challenging.