Neuromuscular performance and the menstrual cycle

Abstract

Women athletes are more likely to tear their anterior cruciate ligament than their male counterparts. The female athlete has a complex system of steroid hormones that are continually changing. These sex hormones that fluctuate throughout each month may influence knee injuries, specifically the anterior cruciate ligament. The increased incidence in women is thought to be multifactorial, a combination of structural, anatomical, or biomechanical factors. The NCAA has reported that 75 percent of anterior cruciate ligament injuries are non-contact in competitive jumping or pivoting sports. In this study, the effects of the menstrual cycle on neuromuscular performance were investigated. Fifteen healthy females with regular menstrual cycles completed the various tests of this study for three phases of the menstrual cycle. All females were categorized as moderate or vigorous exercisers from an activity questionnaire. This study used a repeated measures experimental design; therefore, each participant served as her own control. The participants completed a series of two tests, including functional balance and fatigability.

Each series was completed during three different phases of the menstrual cycle: menstruation, follicular and luteal. The participants used ovulation kits to predict the luteal phase. These phases were then verified through blood tests at each exercise session. The reaction time and balance test was performed with a BOSU wobble board placed on a force plate. A force platform was utilized to collect center of pressure data from the wobble board. The fatigue test protocol consisted of the participants performing in a pre-fatigue functional test, fatigue protocol and post-fatigue functional ability test. The functional test protocol consisted of two trials of four single-legged hop drills. It was hypothesized that all of the functional tests would have the greatest neuromuscular performance during the follicular phase of the menstrual cycle, and for all of the tests to have differences between the pre- and post-fatigue trials. However, there were no significant differences in the functional tests over the menstrual cycle. There were differences in fatigue in the forward hop and figure eight tests, but the affect of fatigue on performance did not differ across menstrual cycle phases.