Eccentric Knee Extension Torque Differs Across Menstrual Cycle Phases in High-Level Female Athletes

Abstract

Purpose: Eccentric knee extension torque is essential to athlete performance and knee joint stability. Female athlete performance and knee injury rates differ across menstrual cycle phases. It is unknown whether female athletes’ eccentric knee extension torque differs across menstrual cycle phases. The purposes of this study were to determine whether eccentric knee extension torque differed across menstrual cycle phases in high-level female athletes and to examine the associations between sex hormones and knee torque. Methods: Twenty-one female collegiate athletes participated. Athletes’ isometric knee flexion torque, isometric knee extension torque, and eccentric knee extension torque were assessed on an isokinetic dynamometer in the early follicular phase, late follicular phase, and mid-luteal phase. Menstrual cycle phases were determined by counting menstrual cycle days, urinary ovulation test results, and serum hormone analysis. Linear mixed-effects models were used to determine whether knee torque differed across menstrual cycle phases. Pearson correlation coefficients and Spearman rank order tests were used to establish the associations between sex hormones and knee torque. Results: Eccentric knee extension torque differed across the menstrual cycle (P = .025, N·m/kg, P = .042, N·m) and was greater in the mid-luteal phase versus the late follicular phase by 0.32 N·m/kg and 20.5 N·m. Isometric knee torque did not differ across cycle phases (Ps > .475). When controlling for body fat mass, testosterone was inversely associated with isometric knee extension torque (r = −.509, P < .001) and eccentric knee extension torque (r = −.315, P = .026). Conclusions: Sex hormones may exert a small effect on eccentric knee extension torque in high-level female athletes.