Isokinetic elbow flexion and coactivation following eccentric training

Area of Science:

• Biomechanics
• Exercise Physiology
• Neuromuscular Adaptations

Background:

• Understanding the effects of eccentric training on muscle performance is crucial for optimizing athletic training protocols.
• Isokinetic dynamometry allows for precise measurement of torque and muscle activation across various angular velocities.

Purpose of the Study:

• To investigate the impact of a 7-week eccentric training program on torque production and muscle coactivation during elbow flexion.
• To determine the neural and muscular adaptations underlying changes in isokinetic performance.

Main Methods:

• Seventeen subjects were divided into an eccentric training group (EG) and a control group (CG).
• Maximal isokinetic elbow flexions and isometric actions were assessed at multiple angular velocities before and after the training period.
• Electromyography (EMG) of biceps brachii (BB) and triceps brachii (TB) was recorded to quantify muscle activation (RMS values).

Main Results:

• The EG demonstrated significant torque increases across all tested angular velocities, with the largest gains observed at high eccentric velocities (-120°/s).
• Increased RMS activity of the biceps brachii was noted under eccentric conditions and at high concentric velocities in the EG.
• No significant changes in triceps brachii activity were observed, indicating no alteration in coactivation levels due to training.

Conclusions:

• Eccentric training enhances torque production in elbow flexion, especially under eccentric and high-velocity concentric conditions.
• Observed performance improvements are primarily attributed to neural adaptations rather than changes in antagonist muscle coactivation.
• The findings support the efficacy of targeted eccentric training for improving specific aspects of muscular strength and performance.