Training effects of sub-maximal electrostimulation in a human muscle

Area of Science:

• Neuromuscular Physiology
• Exercise Physiology
• Muscle Adaptation

Background:

• Sub-maximal training methods aim to improve muscle contractile properties.
• Electrostimulation and voluntary contractions are distinct training modalities.
• Understanding their comparative efficacy is crucial for optimizing training protocols.

Purpose of the Study:

• To compare the effects of electrostimulation (ES) and voluntary contraction (VC) training on adductor pollicis muscle contractile properties.
• To investigate changes in muscle force, tetanus kinetics, and fatigue resistance.
• To elucidate the underlying mechanisms of muscle adaptation to different training types.

Main Methods:

• 6-week sub-maximal training program involving daily ES (100 Hz) or VC.
• Training consisted of ten series of twenty 1-s contractions (60-65% maximum) with 1-s intervals.
• Muscle force, tetanus development/relaxation rates (dP0/dt), and surface action potential area were measured.

Main Results:

• VC training induced significantly greater increases in muscle force than ES.
• VC training accelerated tetanus time course and improved fatigue resistance; ES did not.
• Neither training method altered surface action potential total area.
• ES increased muscle force via peripheral changes, not altered neural command.

Conclusions:

• Voluntary contraction training is more effective than electrostimulation for enhancing muscle force and fatigue resistance.
• Electrostimulation may be complementary to voluntary training due to differential motor unit recruitment.
• Training adaptations differ between ES and VC, suggesting distinct physiological mechanisms.