Effect of damaging exercise on electromechanical delay

International audience; Introduction: In this study we aimed to quantify the effect of exercise-induced muscle damage on both the electrochemicaland mechanical components of electromechanical delay using very-high-frame-rate ultrasound. Methods: Fifteen participants underwent electrically evoked contractions of the medial gastrocnemius muscle with an ultrasound transducer on the muscle belly and on the myotendinous junction, before, 1 hour, and 48 hours after eccentric exercise of the plantar flexor muscles. Results: Maximal isometric plantar flexor torque was significantly lower at 1 hour (–41.1614.9%; P50.0001) and 48 hours –11.9614.9%; P50.038) post-exercise compared with pre-exercise. However, the delay between electrical stimulation and the onset of muscle activation, the delay between electrical stimulation and myotendinous junction motion, and the electromechanical delay were not altered significantly by eccentric exercise (P50.063). Conclusions: These findings suggest that moderate muscle damage does not affect the time for the electrochemical or mechanical components of electromechanical delay.