Changes in Neuromuscular Performance Throughout the Menstrual Cycle in Physically Active Females

Context: In the United States, an excess of $1 billion is spent annually on anterior cruciate ligament (ACL) repair surgeries/rehabilitation programs in varsity female sports. Research has indicated that female athletes may be 2 to 10 times more likely to sustain an ACL tear than their male counterparts. Objective: The purpose of this study was to analyze the neuromuscular changes in females during different phases of the menstrual cycle. Design: Observational Cohort Setting: Laboratory Participants: Fifty (50) physically active college aged females (25 on oral contraception) were recruited to participate in three separate visits throughout one menstrual cycle. The groups were similar at baseline. Intervention: Visits coincided with follicular, ovulatory, and the luteal phase of the cycle. At each visit, participants had their blood drawn to assess for estradiol, progesterone, and relaxin levels. Along with blood measurements, isokinetic quadriceps strength at 60°/sec, 180°/sec, and 300°/sec, and knee joint laxity were measured at each visit. Main Outcome Measures: Isokinetic quadriceps strength, KT- 1000 measurements, blood assays. Results: Isokinetic peak torque at 60°/sec was significantly lower during the follicular (151.6 ± 26.8 NM) than during the ovulatory phases (157.5 ± 27.1 NM,