Investigating Female Athletes’ Balance Using Center-of-Pressure (COP) Derived Displacement and Velocity Parameters

Abstract

A realization of how specific exercises relate to balance performance is important for a wide demographic of individuals. Maintaining active and healthy living is particularly important for balance-impaired individuals (e.g., otherwise healthy individuals recovering from injury, fall-prone elderly, and stroke survivors) whom are interested in improving their balance for function in daily life. However, balance performance is also important for persons that are unimpaired (e.g., athletes). How balance performance may be improved as a result of, and in relation to, various athletic activities and exercises is a common question. Further, how certain activities can be used to prevent injury is an ultimate goal. Our objective was to compare standing balance in 3 unimpaired groups (i.e., female track & female tennis collegiate athletes and female non-athletes). To assess static balance, participants performed stance variations increasing in difficulty-level, utilizing a wide or tandem stance (increasing or decreasing support base) and eyes-open or eyes-closed (limiting or providing visual cues), while standing on a forceplate walkway. Through the recorded ground reaction forceplate-based, center-of-pressure (COP) position time series, we extracted velocity and displacement parameters that aided in identifying differences between the above groups. Our general findings were that anterior-posterior (AP, or front-to-back) COP displacement and velocity measures for female track athletes were unchanged relative to the (baseline) female non-athletes. However, mediolateral (ML, or side-to-side) measures, which have previously been shown to be associated with fall-risk, showed observable differences in displacement and velocity parameters, particularly for the female track athletes. Specifically, the female track athletes were better able to control their ML COP velocity in eyes-closed, wide, and eyes-open tandem conditions compared to non-athletes. However, tennis athletes had difficulty balancing in situations where eyes were closed (vision eliminated) and feet were tandem (base-of-support decreased) which was made apparent by the increases in all AP and ML COP-derived parameters. We interpreted this finding as the female tennis athletes were trained to rely heavily on visual cues (e.g., hand-eye or eye-body coordination), and also their balance may be more focused on maintaining their center-of-mass stability and body orientation, as opposed to COP per se. Our study lends new insights as to how various types of athletic activities, and reliance on vision in athletes, impacts balance performance in un-impaired females.