Assessment of lower limb symmetry: differences during isometric and stretch-shortening cycle tasks

Assessment of limb function asymmetry is of interest to practitioners due to its role in return to play guidelines and reported links to injury. Dynamometry is one of the most commonly used methods of assessing muscle function, but the mode of contraction used is different to the stretch-shortening cycles experienced during real-life activities. The aim of this study was to compare measures of limb function asymmetry during isometric and stretch-shortening cycle tasks and investigate agreement between the methods. Different between-limb effect sizes were observed between limbs dependent on test used, with different ranges of asymmetry observed. Agreement between methods was very poor. These results show the importance of assessing asymmetry in a condition that is as similar as possible to the task of interest.