A simple method for measuring waveform joint symmetry during running

Healthy populations are often assumed to have near identical movement patterns while asymmetry is commonly associated with pathology. Many current measures of symmetry are limited to discrete events, or involve high level mathematics that do not translate well to a clinical setting. The proposed Average Symmetry Index (ASI) is a simple method for assessing side-to-side differences throughout a waveform. Side-to-side joint kinematics were measured in three uninjured adolescent runners and ASI was compared to the previously established Symmetry Angle (SA). ASI-based measures of symmetry were found to have strong agreement with the SA-based measures of symmetry. Further study is warranted to identify clinically relevant thresholds for asymmetry, as no values currently exist that relate to performance and pathology.