Spatially distributed sequential stimulation reduces muscle fatigue during neuromuscular electrical stimulation

Area of Science:

• Neuromuscular Electrical Stimulation (NMES)
• Muscle Physiology
• Rehabilitation Engineering

Background:

• Neuromuscular electrical stimulation (NMES) is limited by rapid muscle fatigue, leading to force decay.
• Previous research indicated Spatially Distributed Sequential Stimulation (SDSS) reduces fatigue in plantar flexors for individuals with spinal cord injury (SCI).

Purpose of the Study:

• To investigate the fatigue-reducing efficacy of SDSS across major lower limb muscle groups.
• To compare SDSS with conventional Single Active Electrode Stimulation (SES) in both able-bodied individuals and those with SCI.

Main Methods:

• SDSS utilized four sequentially activated electrodes with a 90° phase shift.
• SES employed a single active electrode.
• Both stimulation modes delivered a 40 Hz resultant frequency to the muscle.
• Fatiguing stimulation protocols were applied to major leg muscles in both able-bodied and SCI participants.

Main Results:

• SDSS demonstrated significantly higher fatigue indices compared to SES across major leg muscles.
• This effect was observed in both able-bodied individuals and individuals with SCI.
• The findings confirm and extend previous reports on SDSS's fatigue-reducing capabilities.

Conclusions:

• SDSS effectively reduces muscle fatigue in lower limb muscles for both able-bodied and SCI populations.
• This advanced NMES technique shows promise for improving functional movements in clinical settings.
• SDSS offers a superior alternative to conventional SES for mitigating NMES-induced muscle fatigue.