Biomechanics and Motion Analysis

Wheelchair Propulsion to Reduce the Risk of Injury and Improve Propulsion Efficiency

Principal Investigator: Kenton R. Kaufman, Ph.D.
Project Coordinator: Brian Kotajarvi — kotajarvi.brian@mayo.edu

This study is designed to investigate two aspects of wheelchair propulsion. The first aspect is the relationship between time-related longitudinal changes in propulsion performance, biomechanics, and the risk of musculoskeletal injury. The second is to study the potential of a novel biofeedback training paradigm in optimizing the learning of safe and effective propulsion techniques. Our results show that the only variables that change with experience are cycle frequency and time. Specifically, the cycle frequency decreased and cycle time increased. Since the push time remained the same, this implies that the amount of time spent in the recovery phase of propulsion has increased. The reasons for this finding are conjectural at this time. This may be an attempt to minimize the metabolic cost of propulsion by conserving energy during the cycle, or possibly this gives the user additional time to choose the trajectory of their push stroke.

Subjects with paraplegia have completed biofeedback training to assess its impact on the following propulsion variables: propulsion moment, mean FEF (fraction of effective force or FEF), maximum FEF, cycle time, push frequency, velocity, push time, and push angle. Data suggest that visual feedback has not been beneficial in improving efficiency. This finding was not what we expected. However, recent work by another group of investigators (Groot, S., et al 2002) that was published after we began our study also found a lack of benefit in the application of biofeedback to wheelchair propulsion. These nonintuitive findings support the theory that force direction on the rim is already "optimized" given the mechanical constraints of the musculoskeletal system and its interaction with the wheelchair propulsion system.