Motor-unit coherence and its relation with synchrony are influenced by training

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Motor-unit synchronization and coherence reflect neural control of muscle force.
• Previous studies indicate training status influences motor-unit synchronization.

Purpose of the Study:

• To quantify and compare motor-unit coherence in the first dorsal interosseous muscles of untrained, skill-trained, and strength-trained individuals.
• To investigate the relationship between motor-unit coherence, synchronization, and training status.

Main Methods:

• Analysis of 394 motor-unit pairs from 13 subjects using data from a prior study.
• Quantification of motor-unit coherence strength across different frequency bands (e.g., 21-24 Hz, 3-9 Hz).
• Statistical analysis to determine associations between coherence, synchronization, and training groups.

Main Results:

• Motor-unit coherence was greater in the left versus right hand of untrained subjects (21-24 Hz).
• Skill-trained subjects showed lower coherence in both hands (21-27 Hz).
• Strength-trained subjects exhibited the highest motor-unit coherence in both hands (3-9 and 21-27 Hz).
• A strong association was found between motor-unit synchronization and coherence (r2 = 0.77), particularly in strength-trained individuals (r2 = 0.90).

Conclusions:

• Hand-specific differences in motor-unit coherence exist in untrained individuals.
• Strength training significantly enhances motor-unit coherence, suggesting neural adaptations.
• The findings suggest that altered coherence with training may involve cortical inhibition and common inputs to motor neurons.