The reliability of biomechanical variables collected during single leg squat and landing tasks

Introduction: The aim of this study was to determine the within- and between-day reliability of lower limb biomechanical variables collected during single leg squat (SLS) and single leg landing (SLL) tasks. Methods: 15 recreational athletes took part in three testing sessions, two sessions on the same day and another session one week later. Kinematic and kinetic data was gathered using a ten-camera movement analysis system (Qualisys) and a force platform (AMTI) embedded into the floor. Results: The combined averages of within-day ICC values (ICCSLS = 0.87; ICCSLL = 0.90) were higher than between-days (ICCSLS = 0.81; ICCSLL = 0.78). Vertical GRF values (ICCSLS = 0.90; ICCSLL = 0.98) were more reliable than joint angles (ICCSLS = 0.85; ICCSLL = 0.82) and moments (ICCSLS = 0.83; ICCSLL = 0.87). Discussion: This study demonstrates that all joint angles, moments, and vertical ground reaction force (GRF) variables obtained during both tasks showed good to excellent consistency with relatively low standard error of measurement values. These findings would be of relevance to practitioners who are using such measures for screening and prospective studies of rehabilitative techniques