Comparing Nerve Versus Muscle Wide-Pulse High-Frequency Electrical Stimulation for Maximal and Submaximal Efforts

The effectiveness of neuromuscular electrical stimulation hinges on the evoked torque level, which can be attained through either conventional (CONV) or wide-pulse high frequency (WPHF). However, the best electrode placement is still unclear. This study adopted a crossover design to compare the effects of WPHF applied to the tibial nerve trunk (N-WPHF) or muscle (M-WPHF) with CONV in healthy participants.

A total of 30 participants (age: 22.4 [4.5]) were involved in 4 sessions. During each session, participants performed: 2 maximal voluntary contractions, 2 contractions at maximal evoked torque, and 2 contractions at submaximal evoked torque at 20% maximal voluntary contraction. Neuromuscular electrical stimulation intensity-evoked torque, efficiency, and discomfort were measured in maximal and submaximal conditions. Statistical analyses were conducted using a 1-way mixed-model analysis of variance with repeated measures.

N-WPHF and M-WPHF showed higher evoked torque than CONV (P = .002 and P = .036) and greater efficiency than CONV for maximal evoked torque (P = .006 and P = .002). N-WPHF induced higher efficiency than M-WPHF and CONV for submaximal evoked torque (P = .004). Higher discomfort was observed for both N-WPHF and M-WPHF for submaximal evoked torque compared with CONV (P = .003 and P < .001).

Our results suggest that WPHF applied at either the nerve or muscle could be the best choice for the maximal condition, whereas nerve application is preferred for the submaximal condition.