The Changes of Electromyographic Activity of Upper Extremity and Physiologic Cost Index According to Forward and Reverse Wheelchair Propulsion Methods

ABSTRACT

OBJECTIVE: To compare physiological cost index of the two manual wheel chair propulsion methods: pushing the handrim forward and reversely, and to find out whether the reverse propulsion method will help prevention of the carpal tunnel syndrome in manual wheelchair users. METHOD: The subjects were thirty healthy men in their twenties. All of them performed two manual wheelchair propulsion methods for two days, foreward propulsion on the first day and reverse propulsion the next day. Duration of the wheelchair propulsion was ten minutes. Electromyography (EMG) of wrist extensor groups, biceps brachii, pectoralis major, trapezius, and triceps brachii, and heart rates were recorded. The EMG activity of each individual was transformed to root mean square (RMS), EMG activity appearance time (%), and EMG activity continuance time (%). RESULTS: EMG activity of the wrist extensors in reverse propulsion of the wheelchair was less active compared to forward propulsion. In reverse propulsion method, energy efficiency was not significantly increased, but RMS of wrist extensor groups was significantly reduced. Contractions of trapezius and biceps brachii muscles appeared in earlier phase of propulsion. CONCLUSION: We concluded that reverse propulsion of the wheelchair will be more effective method of wheelchair propulsion compared to forward propulsion in preventing carpal tunnel syndrome in long-term wheelchair users. The reverse propulsion method in this study uses wrist extensor less, which can reduce the wrist extension movement during wheelchair propulsion. It can possibly contribute on the prevention of carpal tunnel syndrome in long-term wheelchair users.