College Tennis Players Demonstrate Asymmetry During Single-Leg & Double-Leg Countermovement Jumps

Abstract

Assessing bilateral asymmetry can help identify risk of injury in sport. More accurate assessments of risk can be acquired if sport-specific asymmetry is known. That is, some sports may evoke a certain asymmetry while others do not. PURPOSE: The purpose of this study was to determine whether or not bilateral asymmetry exists among NCAA Division I male tennis players performing single leg (SL CMJ) and double leg countermovement jumps (DL CMJ). A second purpose was to determine how often an asymmetry was present in the same leg during SL CMJ and DL CMJ. METHODS: Nine NCAA Division I male tennis players (20.5±1.5yr; 76.3±6.4kg) performed SL CMJ and DL CMJ on a force plate (1000Hz). Two SL CMJ were performed on each leg. Peak power was calculated using ground reaction force data. Asymmetry was then determined between the less and more powerful legs. Next, participants performed six DL CMJ. Two jumps were performed with both feet on the force plate and two jumps were performed with each foot on the force plate and the other foot off. This technique allowed for the assessment of bilateral asymmetry during DL CMJ and the relative contribution of each leg to the peak vertical force produced by both legs. Paired t-tests assessed the presence of bilateral asymmetry during SL CMJ and DL CMJ. Finally, we determined the frequency by which asymmetry existed on the same leg during SL CMJ and DL CMJ. RESULTS: During SL CMJ, there was an asymmetry of -3.1±3.0% between the less and more powerful legs (2381±286W vs. 2477±267W; p=.003). During DL CMJ, an asymmetry of -5.2±2.5% was observed between the weaker and stronger leg (879±73N vs. 926±62N; p<0.001), which accounted for relative contributions of 48.6±0.6% and 51.4±0.6% to the total double-leg effort, respectively. Remarkably, asymmetry occurred in the same leg during SL CMJ and DL CMJ in 8 out of 9 of the cases (89%). CONCLUSIONS: NCAA Division I men’s tennis players demonstrate asymmetry during SL CMJ and DL CMJ, and the asymmetry was present on the same side during SL CMJ and DL CMJ. These results can be used in future research, to determine the risk of injury when a tennis player has an asymmetry beyond the normal values observed in the sport. These results can also be used to guide rehabilitation and to make decisions about return to play after injury.