Effect of Asymmetry on Biomechanical Characteristics During 180 degrees Change of Direction.

Thomas, C, Dos'Santos, T, Comfort, P, and Jones, PA. Effect of asymmetry on biomechanical characteristics during 180 degrees change of direction. J Strength Cond Res XX(X): 000-000, 2020-The aim of this study was to explore the effect of asymmetry on biomechanical characteristics during two 180 degrees change of direction (CoD) tasks (505 and modified 505 [505mod]). Fifty-two male (n = 24; age = 22.1 +/- 4.8 years; height = 1.78 +/- 0.06 m; body mass = 76.9 +/- 10.8 kg) and female (n = 28; age = 19.1 +/- 1.7 years; height = 1.67 +/- 0.06 m; body mass = 60.4 +/- 7.4 kg) team-sport players were recruited for this investigation. Three-dimensional motion data using 10 Qualisys Oqus 7 infrared cameras (240 Hz) and ground reaction force (GRF) data from 2 AMTI force platforms (1,200 Hz) were collected to analyze penultimate contacts (PEN) and final foot contacts. A series of repeated-measures analysis of variance were used to examine for differences in each dependent variable. Significant differences existed between dominant (D) and nondominant (ND) limbs for knee abduction angle (KAA) during 505mod (p = 0.048), while significant differences existed for peak horizontal and vertical GRF (vGRF) (p < 0.001) during 505. For both tasks, the PEN involved significantly greater peak vGRF, hip flexion angles, hip extensor moments, knee flexion angles, and knee extensor moments, but lower average vGRF, horizontal GRF, and peak ankle extensor moments. For 505, the ND limb involved significantly greater peak vGRF, but the opposite was revealed for peak horizontal GRF. For 505mod, the D limb involved significantly greater KAAs. Finally, there was a significant interaction (group x limb) for peak horizontal GRF ratio during 505. For both tasks, there was no interaction or main effects for time to completion. Therefore, it appears asymmetry influences GRFs and KAAs, but not completion time during 180 degrees CoD in team-sport players.