Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles

Abstract

This study compared knee extensors’ neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no difference was obtained between the two stimulation patterns for MVC and evoked torque decreases. Measurements conducted in the subgroup depicted a significant reduction of Pd, P20 and P80. Statistical analyses also revealed bigger P20 immediate reductions after CFT than after DFT. We concluded that DFT could be a useful stimulation pattern to produce and maintain greater force with quite similar fatigue than CFT.

Power output and fatigue properties using spatially distributed sequential stimulation in a dynamic knee extension task

“…lengthening or shortening the interval) or by a simple frequency reduction showed on the one hand increased fatigue resistance, but on the other hand there was decreased overall output power, which in the end is a critical factor for the applicability of such approaches (Binder-Macleod and Guerin 1990 ; Chou and Binder-Macleod 2007 ; Gorgey et al 2009 ; Graupe et al 2000 ; Kesar et al 2008 ; Thrasher et al 2005 ). By imitating physiological activation through more sophisticated initial stimulation bursts or by increasing both frequency and intensity, statistically significant increases in performance have been observed in isometric measurements (Chou et al 2008 ; Cometti et al 2016 ). However, both strategies have yet to be evaluated in functional tasks.…”

Current Change Rate Influences Sensorimotor Cortical Excitability During Neuromuscular Electrical Stimulation

“…Previous studies aiming to optimize NMES treatments have focused primarily on location, intensity, duration, or pulse patterns (Lagerquist and Collins, 2010; Muthalib et al, 2015; Cometti et al, 2016). To our knowledge, no previous reports have discussed the influence of the rising rate of stimulus current during NMES.…”

Event-Related Beta EEG Changes Induced by Various Neuromuscular Electrical Stimulation: A Pilot Study

“…The optimal selection of stimulation configuration for better clinical outcomes has been an open question for a long period. In clinical practice, the widely used NMES configuration is constant-frequency trains (CFT) of a single pulse with a fixed inter-pulse interval (IPI) [12], and more often with a narrow (about 250µs) pulse width as compared to a wide (~500µs) one. Therefore, previous NMES-induced cortical activity studies have also focused on NMES with CFT.…”

“…NMES with VFT usually have a stimulation set of two to multiple pulses with short IPI (250~500 µs) and then a long IPI (20~50ms) between different sets. When comparing VFT-NMES with a different number (N) of pulses within a stimulation set (called N-lets), a few studies reported doublet-frequency train (DFT, N=2) as one of the most successful configurations in force improvement in healthy subjects [12,15]. To explain the underlying mechanisms, previous studies mostly focused on the response in muscle contractions.…”