Graduation Year


Document Type




Degree Granting Department

Biomedical Engineering

Major Professor

William E. Lee, Ph.D.


Motion analysis, Paraplegia, Force transducers, EMG, Wheelchair transfer


Persons with paraplegia who use a manual wheelchair for mobility are at high risk for overuse injuries in the upper extremities. Years of shoulder overuse performing transfers, wheelchair propulsion, dressing, bathing, and household chores, (activities of daily living or ADL) leads to an increased incidence of cumulative trauma to the shoulders. Few studies have addressed the stressful task of wheelchair transfers among SCI individuals. The goal of this pilot study is to develop valid and reliable measurement technologies to quantify shoulder musculoskeletal stressors during wheelchair transfers and pressure relief tasks among individuals with SCI. Using a standard wheelchair, 10 participants were asked to perform 3 typical pairs of independent transfer tasks: wheelchair to/from bed, wheelchair to/from commode, and wheelchair to/from vehicle. Also, two pressure relief tasks (P/R) were performed sitting in a wheelchair, one using the armrest and one using the wheels.

By observation, the transfers in descending order from the most demanding to the least demanding were as follows: vehicle, commode, and bed. During a P/R using the wheels there is a 40% greater max shoulder force and a 47% greater mean shoulder force than when using the armrest. The max shoulder force of over 1000 N is generated at the initial push off, during a P/R using the wheels, then the force drops 45% to an average of 558 N. The max shoulder force of 722 N at the initial push off, during a P/R using the Armrest, drops 48% and then averages 378 N. During a P/R using the wheels there is a 104% greater max shoulder torque and a 17% greater mean shoulder torque than when using the armrest. As in the initial large amount of shoulder force there is also a large amount of shoulder torque that drops 77% during a P/R using the wheels. The shoulder torque decreases 62% during a P/R using the armrest.

Because of the greater distance the body's Center of Mass (COM) travels during the P/R using the armrest, 24% more work is done.