Abstract
BACKGROUND: The study aimed to examine the impact of combined oral contraceptive pill (OC) use on patellar tendon (PT) adaptation to resistance training in young women. METHODS: Fifteen users of OC (28 ± 3 years) (OC group) and 17 eumenorrheic non-users (32 ± 5 years) (NOC group) performed heavy resistance training of the knee extensors over a period equivalent to three menstrual or pill cycles. Maximal isometric strength of the knee extensor muscles, PT cross-sectional area (CSA), tensile stiffness, and shear wave velocity (SWV) were measured before and after the intervention using combined ultrasonography and dynamometry. RESULTS: The training period increased maximal isometric strength in both groups (≈11%, P < 0.001) with no significant interaction with OC use (p = 0.965). Likewise, a small yet significant increase in proximal tendon CSA was observed (1.5 ± 1.6% for both groups, main training effect P < 0.001) without any significant interaction with OC use (p = 0.267). Tendon tensile stiffness also increased significantly (18.9 ± 26.3% in the OC group and 28.2 ± 35.1% in the NOC group, main effect: P < 0.001) but was not significantly affected by OC use (interaction effect: p = 0.428). Tendon SWV measurements yielded similar results, indicating a main effect of training (+12% on average, p = 0.024) but no significant interaction with OC use. CONCLUSION: These findings suggest that OC use does not affect the increase in PT CSA and mechanical properties following short-term resistance training in young untrained females.