Purpose: This study aimed to investigate whether maximal oxygen uptake, strength, and power parameters are influenced by the timing of oral contraceptive (OC) pill intake - specifically 1 versus 24 hours before testing. Methods: Twenty-nine trained young females using monophasic second-generation OCs participated in a crossover design study. Following test familiarization, participants completed a physical test protocol 2 times during the active OC pill phase: once 1 hour after OC intake and another at 24 hours after OC intake, in randomized order. The protocol assessed balance, push-up endurance, agility, handgrip strength, jump height, flexibility, and maximal oxygen uptake. Psychological well-being was evaluated using a questionnaire prior to testing. Test conditions were standardized for time of the day, energy intake, and exercise within 24 hours preceding the test. Hormone levels were analyzed in serum and saliva collected at the time of testing in a subsample. Results: Balance stand time was shorter (median difference: 1 s [interquartile range: -3.3, 0.7], P = .021) and handgrip strength higher (mean: 0.8 [2.1] kg, P = .044) when the OC was taken 1 hour before testing compared with 24 hours before testing. No significant differences were observed for push-up endurance, agility, jump height, flexibility, and maximal oxygen uptake between the 2 test days. Conclusions: The findings suggest that the timing of OC intake may acutely influence specific physiological parameters related to physical performance, such as balance stand and handgrip strength. Future studies involving OC users should consider standardizing OC intake to account for potential hormonal effects on performance outcomes.
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