Eccentric exercise inhibits the H reflex in the middle part of the trapezius muscle

The objectives of this study were to (1) investigate the modulation of the H reflex immediately after and 24 h after eccentric exercise in the presence of delayed-onset muscle soreness (DOMS) and (2) test the reproducibility of the H reflex in trapezius across days. H reflexes were recorded from the dominant middle trapezius muscle by electrical stimulation of the C3/4 cervical nerve in ten healthy subjects. DOMS was induced by eccentric exercise of the dominant shoulder. H reflexes were obtained in four sessions: “24 h before”, “Pre”, “Post”, and “24 h after” eccentric exercise. Ratios of maximal H reflex and M wave responses ( H max / M max ) were compared between sessions. In addition, a between session comparison was done for the ratios of H reflex amplitudes ( H i_75 / M max , and H i_50 / M max ) obtained from the stimulus intensity needed to obtain 75 and 50 % of H max at “24 h before”. No ratio changes were found when comparing “24 h before” and “Pre” recordings. A decrease in H i_50 / M max was found at “Post” ( P