The biomechanics and neural control of manual wheeling : an exploration of cutaneous reflexes

There are many health complications resulting from manual wheelchair use after spinal cord injury (SCI). Biomechanical and neural control components are critical in teaching wheelchair skills and developing efficient wheeling strategies. Thus, the overall goal of this thesis was to gain a comprehensive understanding of the biomechanics and neural control underlying upper limb movements during manual wheeling. A) Many studies examining the biomechanical and physiological characteristics of manual wheeling have examined able-bodied subjects, however, it is unknown if this data can be applied to manual wheelchair users (MWUs) with SCIs. Thirteen able-bodied subjects and 9 MWUs participated in this study. Kinetic, kinematic, and electromyography (EMG) data were collected while subjects wheeled for several minutes at a self-selected cadence. The MWUs demonstrated different wheeling strategies, significantly larger wrist range of motion, larger average forces, larger percentage of the wheeling strategy spent in propulsion and larger push angles. These differences may be key in developing effective wheeling strategies. B) The neural modulation of upper limb movements during manual wheeling was investigated by examining reflex responses to cutaneous nerve stimulation. Cutaneous reflexes from the superficial radial nerve were elicited while subjects wheeled for several minutes at a self-selected cadence. Subjects also performed a symmetrical arm cycling task at the same cadence while receiving nerve stimulation. EMG was recorded from 6 upper limb muscles. The data were divided into cycles and then all cycles were divided into 8 chronological bins. All reflexes occurring from stimuli in a specific bin were averaged together for each individual and then reflex averages were determined for the able-bodied and MWU groups. No significant differences were found in the amount of reflex modulation between the groups, but there were significant differences between tasks in the early latency response of the triceps brachii and the middle latency response of the posterior deltoid. There was also a significant correlation in the amplitude of the early latency reflex of the triceps brachii between amount of modulation and years of manual wheeling experience. Manual wheeling, like arm cycling and walking, demonstrates examples of both phase dependent and task dependent reflex modulation.Education, Faculty ofKinesiology, School ofGraduat