The effects of imagery training on fast isometric knee extensor torque development

Area of Science:

• Neuromuscular Physiology
• Sports Science
• Motor Control

Background:

• The onset of neuromuscular activation is crucial for rapid force production.
• Imagery training is proposed as a method to enhance motor performance, but its effects on neuromuscular activation speed are unclear.

Purpose of the Study:

• To investigate the effects of physical training and imagery training on the fast onset of neuromuscular activation and knee extensor isometric torque development.
• To compare the efficacy of physical training, imagery training, and placebo training.

Main Methods:

• Forty healthy young adults were divided into physical training, imagery training, placebo training, and control groups.
• Training interventions consisted of three 15-minute sessions per week for 4 weeks.
• Knee extensor isometric torque and electromyography (EMG) were measured at 90° and 120° knee angles.

Main Results:

• Maximal torque increased similarly across all training groups at 90° knee angle.
• The torque-time integral over the first 40 ms (TTI40) significantly increased only after physical training, specifically at 90°.
• Physical training led to a significant increase in EMG at torque onset (EMG40), which correlated with TTI40 improvements.

Conclusions:

• Only physical training demonstrated a significant, knee-angle-specific improvement in contractile impulse onset compared to placebo and control groups.
• Physical training enhanced the fast onset of neuromuscular activation, leading to improved rapid torque development.
• Imagery training did not show significant benefits over placebo for these specific neuromuscular parameters.