Factors associated with electrical stimulation-induced performance fatigability are dependent upon stimulation...

Area of Science:

• Physiology
• Rehabilitation Medicine
• Neuromuscular Electrical Stimulation

Background:

• Neuromuscular electrical stimulation (NMES) is commonly used to minimize muscle loss during disuse.
• Peripheral nerve stimulation (PNS) provides a more global contractile stimulus but receives less attention.
• Understanding the differences between NMES and PNS is crucial for optimizing rehabilitation strategies.

Purpose of the Study:

• To compare the effects of NMES and PNS on performance fatigability and voluntary force capacity.
• To investigate the differences in muscle fiber recruitment and myoelectrical activity between NMES and PNS.
• To determine the potential of PNS as a superior alternative to NMES in clinical rehabilitation.

Main Methods:

• Two fatigue protocols were assessed: quadriceps NMES and femoral nerve PNS.
• Maximal voluntary contractions (MVCs) were performed before and after each protocol to measure force loss.
• Knee-extensor force and M-wave features (e.g., duration, amplitude, area) were measured to quantify contractile function and myoelectrical activity.

Main Results:

• Both NMES and PNS induced significant reductions in voluntary and stimulated force.
• Myoelectrical indicators of muscle recruitment and nerve conduction time remained unchanged during both protocols.
• Progressive increases in M-wave duration and delayed muscle relaxation were observed during NMES only, indicating superficial fiber fatigue, which was not seen with PNS.

Conclusions:

• PNS appears to recruit a wider pool of muscle fibers and motor units compared to NMES.
• NMES-induced changes suggest fatigability and activation of superficial fibers, unlike PNS.
• PNS presents a potentially more favorable alternative to NMES for rehabilitation interventions, particularly in scenarios like immobilization or critical illness.