Effects of Eccentric Exercise of the Extensors on Eccentric Exercise-Induced Muscle Damage of the Flexors in Limbs

Introduction We tested the hypothesis that muscle damage protection effect would be induced by its antagonist muscle eccentric exercise. Methods Sedentary young (20-28 yr) men were randomly assigned into six groups; three groups each for arm or leg exercise group (n = 12/group). One group performed two bouts of 30 maximal eccentric contractions (30MaxEC) of the elbow flexors (EF) or 60 maximal eccentric contractions (60MaxEC) of the knee flexors (KF) using a different arm (contra-EF-EF) or leg (contra-KF-KF) between bouts. The other two groups performed 30MaxEC of the elbow extensors (EE) or 60MaxEC of the knee extensors (KE) first followed by the 30MaxEC of EF or 60MaxEC of KF using the ipsilateral (ipsi-EE-EF, ipsi-KE-KF) or contralateral limb (contra-EE-EF, contra-KE-KF). The two exercise bouts were separated by 2 wk for all groups. Changes in muscle damage markers before to 5 d after exercise were compared among the groups by mixed-design two-way ANOVA. Results Changes in the markers after the second bout of the ipsi-EE-EF, contra-EE-EF, ipsi-KE-KF, and contra-KE-KF groups were smaller (P < 0.05) than those after the first bout of the contra-EF-EF and contra-KF-KF groups, respectively. The changes after the second bout were smaller (P < 0.05) for the ipsi-EE-EF than contra-EE-EF, and ipsi-KE-KF than contra-KE-KF group; however, those in the contra-EE-EF and contra-KE-KF groups were larger (P < 0.05) than those after the second bout of the contra-EF-EF and contra-KF-KF groups. Conclusions These results showed that the magnitude of muscle damage of EF or KF was reduced by the initial bout of EE or KE eccentric exercise performed by both ipsilateral and contralateral limbs, suggesting that muscle damage protective effect is conferred by the antagonist muscle in the same and opposite limbs.