Muscle force production with low and medium frequency burst modulated biphasic pulsed currents

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Neuromuscular Physiology

Background:

• Russian current (medium frequency burst modulated alternating current) is common for NMES but doesn't reach maximal voluntary forces.
• Low frequency BMAC and medium frequency BMBPC show improved force production over Russian current.
• The comparative efficacy of low versus medium frequency BMBPC for force generation is unknown.

Purpose of the Study:

• To compare elicited forces using BMBPC with low and medium kilohertz carrier frequencies.
• To assess perceived discomfort associated with different BMBPC frequencies.
• To determine if low frequency BMBPC yields greater force than medium frequency BMBPC.

Main Methods:

• A cross-over design study involving 23 subjects.
• Comparison of percent maximal voluntary isometric knee extensor forces (%MVIF) elicited by low and medium kilohertz BMBPC.
• Paired samples t-tests were used for data comparison, with perceived discomfort also assessed.

Main Results:

• Low frequency BMBPC elicited 98.4% of MVIF, significantly greater than the 40.4% elicited by medium frequency BMBPC (p < 0.001).
• A "huge effect" was observed (Cohen's d = 2.146).
• Perceived discomfort was significantly higher for low frequency (5.7/10) versus medium frequency (3.6/10) BMBPC (p < 0.001).

Conclusions:

• BMBPC utilizing a low frequency carrier current effectively elicits forces that approximate maximal volitional force.
• These findings provide novel evidence with significant clinical implications for optimizing NMES.
• Low frequency BMBPC represents a promising modality for enhancing muscle force production in clinical settings.