Oral Contraceptive Use Does Not Influence The Response To Contraction-induced Muscle Damage

Eccentrically-biased exercise induces skeletal muscle damage and repair through skeletal muscle stem cells referred to as satellite cells (SC). The response to damaging contractions may be affected by endogenous or exogenous synthetic sex steroid hormones, such as those from oral contraceptives (OC); however, the effect of OC use on the response to damaging contractions remains unknown. PURPOSE: We sought to characterize the effect of OC use on skeletal muscle damage and the subsequent SC response to eccentric contraction-induced damage versus women who were not taking OC and were normally cycling (NC). METHODS: Thirty-two healthy young females (21 ± 3 years [mean ± SD]) underwent 300 maximal eccentric leg extensions on an isokinetic dynamometer, and measurements were made prior to and at 0 h, 24 h, 48 h, and 72 h after muscle damage. Skeletal muscle biopsies were collected from the vastus lateralis. Serum samples were collected to determine concentrations of creatine kinase (CK). Strength (maximal voluntary contraction) and soreness (visual analog scale) measurements were also collected. RESULTS: There were no significant differences between NC and OC groups in the SC response, with no changes in SC abundance detected across time (NC: 6.6 ± 3.4 Pax7+ cells/100 fibers, OC: 7.1 ± 2.6 Pax7+ cells/100 fibers; p > 0.05). CK increased (p < 0.05) in both groups up to 72 h post-damage with no differences between groups (NC: 278 ± 172 U/L; OC: 357 ± 221 U/L), and a loss in strength was observed immediately post-damage in both groups and remained until 72 h, also with no differences between groups. CONCLUSION: NC and OC users experienced similar strength loss and demonstrated no difference in CK release or SC mobilization in response to damaging contractions.