Effect of isokinetic vs free weight on the magnitude of eccentric exercise-induced muscle damage of elbow flexors in well-trained men

Abstract

Purpose The effect of eccentric exercise-induce muscle damage (EIMD) on elbow flexors is commonly analyzed after exercises performed at isokinetic dynamometers. However, it is possible that the magnitude of eccentric EIMD be different between exercises performed at free weights. Herein we compared the effect of eccentric exercise performed either with free weight (FW) or isokinetic dynamometer (ID) on the magnitude of elbow flexors EIMD in well-trained men. Methods Seventeen men were randomly assigned to FW (n = 8) and ID (n = 9) groups and were asked to perform four sets of 10 maximal eccentric contractions. Peak maximal voluntary isometric contraction (MVIC), delayed onset muscle soreness (DOMS), muscle thickness and echo intensity of elbow flexors were measured immediately before (baseline) and during each of the following four days after the intervention. Results For both ID and FW groups, the MVIC decreased immediately post (37%), 24 (26%), 48 (25%), 72 (20%) and 96 h (18%) after (P < 0.001). When compared to baseline, the DOMS increased across days (~ 4 cm; P < 0.001). The muscle thickness increased immediately after exercise for both protocols (~ 12%; P < 0.001), while no differences across days were observed for echo intensity (P > 0.285). No differences between groups were observed for the indirect markers. Conclusions Eccentric exercise of the elbow flexors performed with different resistance modalities induces EIMD with similar magnitude and duration in well-trained men. The free weight eccentric exercise can be used by trained subjects or trainers with comparable effects to isokinetic dynamometer machine.