Reduction of muscle fatigue in man by cyclical stimulation.

In order to develop a control system for electrical stimulation of paralysed muscle and improve muscle resistance to fatigue, it is useful to investigate the possibilities of simulating the control systems of the normal body. One way is the periodic shifting of stimulation from one muscle to another. This technique is called sequential stimulation and allows sufficient rest time for each muscle to reduce fatigue and consequently prolong muscle strength. It can also be seen to improve the muscle recovery time. In the following study, the muscles rectus femoris, vastus lateralis and vastus medialis were used to keep the knee locked and extended during stimulation. Several experiments were carried out using a three-channel computer controlled stimulator. The results for three-phase sequential stimulation (33% duty cycle per muscle) were most effective and significantly improved the muscle fatigue characteristics.