Vertical Jump to Assess Knee Function

Reactive strength index (RSI) is a frequently used metric for evaluating sports performance. RSI is an indicator of how efficiently an individual may perform the stretch-shortening cycle (SSC). Previous research has demonstrated RSI is strongly related to change of direction and acceleration speed (Byrne et al., 2017).

Utility of this measure is gaining ground outside the sprint and power circles and into other areas including endurance performance and rehabilitation. In a recent systematic review and meta-analysis in Sports Medicine researchers found endurance performance was significantly associated with RSI (Jarvis, Turner, Read & Bishop, 2021). Additionally, a study just published in the British Journal of Sports Medicine found single leg vertical jump performance (both jump height and RSI) were significantly lower in the involved versus uninvolved limb for athletes returning from anterior cruciate ligament reconstruction surgery (Kotsifaki et al., 2022). 

The practical applications of this research should influence how athletes are guided in terms of incorporating jump training for the endurance athlete and using RSI as a critical evaluation metric for performance and for safely returning the athlete to the playing field.