Mechanical energy and power flow of the upper extremity in manual wheelchair propulsion

Objective. To investigate the characteristics of mechanical energy and power flow of the upper limb during wheelchair propulsion. Design. Mechanical energy and power flow of segments were calculated. Background. Very few studies have taken into account the mechanical energy and power flow of the musculoskeletal system during wheelchair propulsion. Mechanical energy and power flow have proven to be useful tools for investigating locomotion disorders during human gait. Methods. Twelve healthy male adults (mean age, 23.5 years) were recruited for this study. Three-dimensional kinematic and kinetic data of the upper extremity were collected during wheelchair propulsion using a Hi-Res Expert Vision system and an instrumented wheel, respectively. Results. During the initiation of the propulsion phase, joint power is generated in the upper arm or is transferred from the trunk downward to the forearm and hand to propel the wheel forward. During terminal propulsion, joint power is transferred upward to the trunk from the forearm and upper arm. The rate of change of mechanical energy and power flow for the forearm and hand have similar patterns, but the upper arm values differ. Conclusions. Joint power plays an important role in energy transfer as well as the energy generated and absorbed by muscles spanning the joints during wheelchair propulsion.