Relationship between vertical stiffness and soft-tissue injuries in professional Australian football

Abstract

Soft-tissue injuries are common in Australian football. Recently, literature has identified non-modifiable and modifiable risk factors, including vertical stiffness (K_vert). However, limitations regarding measurement frequency and duration exist; thus, further information is required about the role of K_vert as a modifiable risk factor for injury. This study examined the seasonal variation in K_vert and its relationship to soft-tissue injuries in professional Australian football. The mean K_vert and bilateral asymmetry were assessed and compared between injured and non-injured players. For the seasonal analysis, 56 players were tested across two seasons with no variation in bilateral asymmetry evident (p= 0.33). While there were generally no changes in K_vert, the value from the end of the second pre-season revealed 5% lower values than the mean of two seasons (p= 0.02). Considering the injury analysis, 21 lower-body soft-tissue injuries were recorded from 18 participants. No differences were recorded for mean K_vert between the injured and non-injured groups (p= 0.16-0.76). When assessing K_vert asymmetry, the injured group displayed a 4.5% higher value than the non-injured group at the end of the pre-season test (p= 0.03) but not at other time-points (p= 0.16-0.99). Higher K_vert bilateral asymmetry measures after the pre-season appear to be related to lower-body soft-tissue injury in professional Australian footballers. Medical and conditioning staff should consider this measure when trying to mitigate the onset of injury or identify at-risk players.

Keywords: Australian Football League; Spring-mass model; asymmetry; injury.