The repeatability and comparison of lower limb biomechanics between suspension, step-off and vertical jump landing tasks.

Research investigating landing biomechanics has used various tasks to ensure consistent/comparable conditions. This study examined repeatability of three landing tasks (suspension, step-off and vertical jump) and compared lower limb biomechanics between tasks. Twenty recreational athletes performed five trials in each task while 3D motion and ground reaction force (GRF) were recorded. Intraclass correlation coefficients (ICC) showed excellent repeatability in all landing tasks for peak knee kinematics and vertical velocity of the centre of mass (COM) at ground contact (ICCs: 0.92 - 0.98), good repeatability for vertical and posterior GRFs (ICCs: 0.72 - 0.86), but vertical jump landings had poor repeatability for sagittal plane knee kinetics (ICCs = 0.34 for peak extension moment and 0.27 for peak anterior shear force). Repeated measures ANOVA showed vertical and anterior-posterior velocity of the COM at ground contact to be significantly different between landing tasks (p < 0.001). Peak knee flexion angle was less in vertical jump landings compared to suspension (p = 0.003) and step-off (p < 0.001). Peak knee kinetics and GRFs were greater in step-off compared to suspension and vertical jump landings (p < 0.045). These findings suggest different landing types may not be directly comparable and landing task selection should be based on variables of interest and sports-specificity.