Balance training enhances motor coordination during a perturbed sidestep cutting task

Study Design Controlled laboratory study. Background Balance training (BTR) may improve motor coordination, however little is known about the changes in motor coordination during unexpected perturbations to postural control following BTR. Objectives To study the effects of BTR on motor coordination and knee mechanics during perturbed side-step cutting maneuvers in healthy adults. Methods Twenty-six healthy men were randomly assigned to a training group (TG) or control (CG). Before BTR, subjects performed unperturbed, 90° side-step cutting maneuvers and one unexpected perturbed cut (10-cm translation of a moveable platform). The TG subjects participated in a 6-week BTR program while CG participants followed their regular activity schedule. Both groups were re-tested after a 6-week period. Surface electromyography was recorded from 16 muscles of the supporting limb and trunk, as well as kinematics, and ground reaction forces. Motor modules were extracted from the EMG by non-negative matrix factorization. External knee abduction moments were calculated using inverse dynamics equations. Results BTR resulted in a reduction of the external knee abduction moment (33 ± 25%, p<0.001, ŋp(2)=0.725), and increased the activation of trunk and proximal hip muscles in specific motor modules during perturbed cutting. BTR also increased burst duration for the motor module related to landing early in the perturbation phase (23 ± 11%, p<0.01, ŋp(2)=0.532). Conclusion BTR resulted in altered motor coordination and a reduction in the knee abduction moment during an unexpected perturbation. The previously reported reduction in injury incidence following BTR may be linked to changes in dynamic postural stability and neuromuscular control. J Orthop Sports Phys Ther, Epub 23 Sep 2017. doi:10.2519/jospt.2017.6980.