Biomechanics of balance recovery by handrail grasping

While public transportation continues to grow in relevance, few ergonomic and biomechanical studies have examined passenger safety, especially related to falls from standing, and the role of handrail grasping in balance maintenance. In this thesis, I examined forces from upper limbs (from a load cell), lower limbs (from a force-plate) and muscle responses (from EMG) involved in balance recovery during simulated vehicle acceleration and deceleration pulses. Subjects stood (forward or sideways) on a platform holding a handrail in two different positions (shoulder height and overhead). A linear motor accelerated the platform at high and low perturbation magnitudes. Hand configuration, perturbation direction and perturbation magnitude influenced hand forces, COP displacement and muscle activation. Forward stance while holding the handrail at shoulder height increased the musculoskeletal demands of balance maintenance. Improved knowledge from this project should help guide the design of safer vehicles.