Neuromuscular adaptations to wide-pulse high-frequency neuromuscular electrical stimulation training
No studies have evaluated the potential benefits of wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) despite it being an interesting alternative to conventional NMES. Hence, this study evaluated neuromuscular adaptations induced by 3 weeks of WPHF NMES.
Ten young healthy individuals (training group) completed nine sessions of WPHF NMES training spread over 3 weeks, whereas seven individuals (control group) only performed the first and last sessions. Plantar flexor neuromuscular function (maximal voluntary contraction (MVC) force, voluntary activation level, H reflex, V wave, contractile properties) was evaluated before the first and last training sessions. Each training session consisted of ten 20-s WPHF NMES contractions (pulse duration: 1 ms, stimulation frequency: 100 Hz) interspaced by 40 s of recovery and delivered at an intensity set to initially evoke ~ 5% of MVC force. The averaged mean evoked forces produced during the ten WPHF NMES-evoked contractions of a given session as well as the sum of the ten contractions force time integral (total FTI) were computed.
Total FTI (+ 118 ± 98%) and averaged mean evoked forces (+ 96 ± 91%) increased following the 3-week intervention (p < 0.05); no changes were observed in the control group. The intervention did not induce any change (p > 0.05) in parameters used to characterize plantar flexor neuromuscular function.
Three weeks of WPHF NMES increased electrically evoked forces but induced no other changes in plantar flexor neuromuscular properties. Before introducing WPHF NMES clinically, optimal training program characteristics (such as frequency, duration and intensity) remain to be identified.
KeywordsExtra-force H reflex V wave Maximal voluntary contraction Maximal voluntary activation level Contractile properties
Physical activity auto-questionnaire
Maximal electromyography activity recorded during a maximal voluntary contraction
Force time integral
Maximal H-reflex amplitude
Stimulation intensity required to evoke the maximal soleus H-reflex amplitude
Stimulation intensity required to evoke maximal M-wave amplitude
Stimulation intensity necessary to evoke a force corresponding to 5% of MVC force
Maximal M-wave amplitude
Superimposed M-wave peak-to-peak amplitude
Maximal voluntary contraction
Neuromuscular electrical stimulation
Supramaximal 10-Hz paired stimulation
Supramaximal 100-Hz paired stimulation
Maximal root mean square
Ratio between V-wave and superimposed M-wave peak-to-peak amplitudes
Voluntary activation level
Wide-pulse high frequency
We thank all the participants who took part in the experiments and Dr. Julien Gondin for his helpful comments on the manuscript.
DN and NP conceived and designed the experiment. DN, MG, SM, DA and NP conducted experiments. DN, MG, SM and DA took part in data analysis. All authors were involved in data interpretation. DN wrote the manuscript. All authors read and approved the manuscript.
The present work was supported by internal institutional funds.
Compliance with ethical standards
Conflict of interest
The authors declare no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
- Gregory CM, Bickel CS (2005) Recruitment patterns in human skeletal muscle during electrical stimulation. Phys Ther 85(4):358–364Google Scholar