Abstract
Due to long-term physical inactivity when confined to a wheelchair, people with motor paralysis in their lower legs are always at risk of developing secondary diseases in the paralysis area; for example, muscle atrophy, loss of bone mineral density, and hypo-circulation. These diseases occur easily, but are difficult to cure. Daily stretching exercises are generally considered to be the most effective measure for prevention. However, often is the case that patients don't exercise due to a lack of willpower. We have developed an everyday rehabilitation device for individuals with motor disorders. It is comprised of a pair of linear actuators that mount under the seat of a wheelchair and are connected to each footrest, and works to prevent secondary disease by passively stretching the ankle joints. By installing the device on the wheelchair, patients do not have to transfer to another machine, which encourages them to use the device more frequently. The device has two different exercise modes: a rhythmical planter/dorsiflexion movement and a stretch mode. In the former mode, the neutral position was set at 105 deg. The range of the rotation angle was between +/-6 and +/-12 deg. The flapping frequency was set at 0.7 Hz based on a normal gait. In this study, we investigated the physiological effect of the former mode in the motion range of +/-12 deg. Twelve persons with spinal cord injuries participated in the experiment, and the EMG and blood flow in the paralyzed muscles were recorded during 10 min of passive ankle motion. As a result, we found that passive ankle motion can induce rhythmical muscular activity and enhance the blood flow in the calf muscles. These results suggest that this device might be effective for the prevention of secondary diseases, or the facilitation of neuromuscular function and peripheral circulation in paralyzed lower limbs.
