Movement and muscle activity pattern in wheelchair ambulation by persons with para-and tetraplegia.

The patterns of movement and muscle activation in wheelchair ambulation have been studied in two groups: subjects with paraplegia (n = 4) and tetraplegia (n = 3). All subjects were physically active and experienced wheelchair users. The tests were done in the subjects' own wheelchairs and under free-wheeling conditions. The tasks studied were: self-chosen normal velocity, maximal velocity and maximally accelerated start. Muscle activation was registered by surface electromyography performed on several arm and shoulder muscles. The movement pattern was studied by goniometry of the shoulder and elbow joints, as well as by observing video recordings. Speed and arm cycle frequency were also recorded. The movement pattern was divided into three phases: pull, push and recovery. Relatively concordant muscle activation patterns were noted within the groups, whereas differences were noted between the groups with regard to muscle activation, length of the pull and push phases and the velocity-dependent adaptation. The subjects with tetraplegia were more dependent on the pull phase. The self-chosen normal and maximal speeds of the subjects with tetraplegia were approximately half those of the subjects with paraplegia. Three different types of recovery movements were noted as well as a velocity-dependent adaptation. Major trunk movements during the rim phase were only noted at the maximally accelerated start. In conclusion, the results point to both similarities and differences in the movement pattern and muscle activation in individuals with para- and tetraplegia under different ambulation conditions. The differences are of such a magnitude that they are important enough to consider when teaching wheelchair techniques and developing rehabilitation programmes for different groups of patients with spinal cord injuries.