Knee extensor torque and perceived discomfort during symmetrical biphasic electromyostimulation.

Area of Science:

• Sports Medicine
• Biomechanics
• Rehabilitation Engineering

Background:

• Electrical muscle stimulation (EMS) is widely used for muscle strengthening and rehabilitation.
• Optimizing electrode placement is crucial for maximizing the efficacy of EMS.
• Understanding the impact of different electrode configurations on muscle force production is essential.

Purpose of the Study:

• To investigate the effects of two distinct electrode arrangements (parallel vs. crossed) on muscle force generation during simultaneous two-channel EMS.
• To compare the efficacy of parallel and crossed electrode placements in terms of voluntary peak torque (VPT) and perceived discomfort (PD).

Main Methods:

• Ten men and ten women university students participated in the study.
• Electrodes were placed on the quadriceps muscle group in proximal and distal positions, medially and laterally.
• Isokinetic voluntary peak torque (VPT) was measured at 60°/s.
• A symmetrical biphasic square wave current was applied using parallel (P) and crossed (X) electrode arrangements at maximal tolerance.

Main Results:

• No significant differences in percent VPT or perceived discomfort were found between male and female participants.
• The crossed (X) electrode arrangement resulted in a significantly greater percent VPT (57.2%) compared to the parallel (P) arrangement (46.5%).
• Electrode arrangement did not significantly affect peak perceived discomfort.

Conclusions:

• A two-channel EMS application utilizing a crossed electrode arrangement enhances knee extensor force production.
• The crossed electrode configuration offers a more effective method for increasing muscle force compared to the parallel arrangement.
• This EMS approach can achieve greater muscle activation without a corresponding increase in user discomfort.