Dynamic balance adaptations in response to bound arm walking.

Asymmetrical arm swing, due to post-surgical bracing or upper limb loss, has been associated with an increased risk of falling in the community. Falls are the leading cause of non-fatal injuries in the United States, many of which occur during walking. Bilateral arm binding has been associated with poorer stability in response to trip perturbations. However, the influence of unilateral arm binding on reactive strategies has yet to be investigated. This study aimed to determine the influence of unilateral arm binding on reactive balance during perturbation recovery in healthy individuals. Ten able-bodied individuals walked on an instrumented treadmill for two steady-state and twelve perturbed walking trials per condition (i.e. with and without non-dominant arm binding) while kinematic and EMG data were collected. Whole body angular momentum range (Lrange) were averaged, and EMG data were integrated (iEMG) across the middle ten steady-state strides and the first five post-perturbation strides per trial. Arm binding generated greater transverse plane Lrange during both steady-state walking and perturbation recovery. Deltoid activation of the bound arm was less during steady-state walking and perturbation recovery than that observed on the same limb during unbound conditions. The findings from this study provide insights into the dynamic balance of healthy individuals and highlight the importance of clinicians screening their patients for underlying conditions that could negatively influence gait and balance prior to prescribing upper limb bracing or casting to unilaterally restrict upper limb motion.