Effects of Stimulation Pattern and Frequency on the Ability of the Human Quadriceps Femoris to Produce Repetitive Dynamic Contractions

Abstract

This study tested the ability of sixteen different electrical stimulation trains to produce repetitive lower leg movements through a fifty-degree target excursion. Five constant-frequency trains (CFTs), five variable-frequency trains (VFTs), five doublet frequency trains (DFTs) and a high-frequency (lOOHz) burst were tested. The results indicated that the DFT was the most successful train type, and that the high-frequency burst was the most successful train overall. The repetitive doublet activation offered by DFTs may have stimulated force augmentation mechanisms many times within a train, therefore improving performance in fatigued muscle. In addition, the success of the high-frequency burst may have been due to activation of the same mechanisms responsible for force augmentation as those triggered by doublets.