The effect of contraction type on muscle strength, work and fatigue in maximal isokinetic exercise

This study investigated knee extensor muscle strength, work and fatigue level under maximal isokinetic concentric and eccentric exercise. Seventeen male athletes were randomized into two groups and performed 10 sets of 10 maximal isokinetic concentric (N =8) or eccentric(N =9) contractions. Knee extensor peak torque and mean torque values per set were 54–121% and 53–133% higher in eccentric compared to concentric exercise, respectively, whereas the percent fall of performance in these variables was more accentuated in concentric exercise. Total work was significantly higher in eccentric exercise (19475 J) than concentric exercise (15758 J), while fatigue index was greater in concentric(36%) than eccentric (18%) exercise. In conclusion, maximal isokinetic eccentric exercise promotes larger overload to knee extensor muscles than its concentric counterpart due to higher torque produced by the muscle group and also thanks to minor muscle fatigue effects.