Doublet stimulation to reduce fatigue in electrically stimulated muscle during controlled leg lifts

Stimulation trains using doublets, two closely spaced stimulation pulses, are thought to reduce the rapid fatigue seen in electrically stimulated muscle. The purpose of this study was to determine if doublet trains could elicit more leg lifts than conventional singlet trains when using surface stimulation of human quadriceps muscle. Eighteen subjects had singlet and doublet stimulation trains applied to their quadriceps to produce closed-loop, leg lift trajectory cycles. Trials ran until the muscle fatigued. Data was collected from 23 legs. The mean±standard deviation of the number of cycles resulting from singlets was 160±105 while the number for doublets was 127±114. A paired t-test showed this difference to be significant. It is thought that the conflicting reports of doublet performance seen in the literature is due to the different protocols used by each study.