Effects of pulse duration on muscle fatigue during electrical stimulation inducing moderate-level contraction.

INTRODUCTION Neuromuscular electrical stimulation (NMES) is used to prevent muscle atrophy. However, the effect of pulse duration modulation for reducing muscle fatigue and pain is unknown. METHODS Two 2-minute stimulation protocols were applied to the knee extensors of 10 healthy individuals. In 1 session, a long pulse duration (1,000 μs) and a low current amplitude (LL), set to evoke 25% maximal voluntary contraction at 30 Hz, were applied. The other session was identical except that a short pulse duration (200 μs) and a high current amplitude (SH) were used. RESULTS Muscle fatigue was lower for LL than for SH (P < 0.01). Force recovery rate was higher for LL than for SH (P < 0.05). Pain scores were also lower for LL than for SH (P < 0.05). DISCUSSION The use of 1-ms pulse durations reduces fatigue and pain during NMES for moderate-level contractions compared with 200-μs durations. Muscle Nerve 57: 642-649, 2018.