Purpose: The aim of this study was to compare the response of the muscle damage on knee extensors by using one bout of maximal fast (FV) or slow velocity (SV) eccentric exercise. Methods: Twelve healthy untrained male students were recruited in the study. By the counter-balance method, each subject with right and left legs of FV or SV eccentric exercise (rest interval between one bout of FV or SV eccentric exercise at least two weeks) performed one bout of 120°/s maximal voluntary isokinetic eccentric contractions (MAX; SV: at angular velocity of 30°/s for 6 sets 5 repetitions; FV: at angular velocity of 210°/s for 6 sets 35 repetitions; and range of knee joint angle was set at 5° to 125°, both) in order to compare the induced muscle damage in SV and FV. Muscle soreness (SOR), leg circumference (CIR), rang of motion of knee (ROM) , maximal isometric voluntary contraction strength (MVC), plasma creatine kinase activity (CK) were measured before, immediately after, 1, 2, 3, 4 and 5 days after MAX. All data were analyzed by a two-way repeated measures ANOVA. Results: After MAX, all the variables (SOR↑, CIR↑, ROM↓, MVC↓, CK↑) of FV were more significant than SV (p＜.05). Conclusion: These results suggest that, when FV and SV have the same time under tension FV would cause more muscle damage than SV after MAX in untrained subject.
