A light load eccentric exercise confers protection against a subsequent bout of more demanding eccentric exercise

This study investigated the hypothesis that a light eccentric exercise (ECC) that does not induce a loss of muscle function and delayed onset muscle soreness would confer a protective effect against a more strenuous ECC. Eighteen young men were randomly placed into two groups: 10-40% (n = 9) and 40% (n = 9). Subjects in the 10-40% group performed ECC of the elbow flexors (six sets of five reps) using a dumbbell set at 10% of maximal isometric strength (MVC) at an elbow joint angle of 90 degrees, followed 2 days later by ECC using a dumbbell weight of 40% MVC. Subjects in the 40% group performed the 40% ECC only. Changes in MVC, range of motion (ROM), upper arm circumference (CIR), plasma creatine kinase (CK) activity and muscle soreness before, immediately after, 1-5 and 7 days following the 40% ECC were compared between groups by a two-way repeated measures ANOVA. No significant changes in any of the criterion measures were found immediately and 1-2 days after the 10% ECC. Following the 40% ECC, the 10-40% group showed significantly (P < 0.05) smaller decreases in MVC and ROM, and smaller increases in muscle soreness compared with the 40% group, but no significant differences between groups were evident for CIR and plasma CK activity. These results suggest that the 10% ECC induced some protection against a subsequent bout of 40% ECC performed 2 days later. It appears that the light eccentric exercise preconditioned the muscles for exposure to the subsequent damaging eccentric exercise bout. (C) 2007 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.