Blazevich, A. J., Cannavan, D., Coleman, D. R., Wytch, P., & Home, S. (2006). Neuromuscular and isometric force-velocity adaptations to concentric and eccentric strength training. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1794.

This study examined the mechanisms involved with a velocity-specific strength increase after slow-speed concentric or eccentric knee extensor training. Ss (M = 10; F = 11) with no history of resistance training performed 10 weeks of three times per week of either eccentric or concentric, isokinetic knee extensor training through 90 at 30/s. Before and after training, concentric and eccentric dynamic knee extensor moments were measured at 30/s and 180/s. Isometric knee extensor moments were measured in trials with a maximum rate of force development (fast) and in a ramped contraction reaching peak moment after five seconds (slow). EMG recordings were obtained from the superficial quadriceps femoris and biceps femoris muscles to infer antagonist torque during isometric contractions and knee extension torque.

Isometric knee extensor moments were greatest in fast trials, due to a greater quadriceps femoris muscle force (16.4%) with no difference in biceps femoris torque. After training, isometric force increased in both fast (9.5%) and slow (15.1%) trials in both groups, with the greater increase in slow force mirroring the dynamic force. Decreases in quadriceps femoris torque accounted for some of the increase in isometric moment in fast and slow trials.

Implication. Increased isometric knee extensor moments were greater in trials performed with a slow rate of force development than in fast trials. This is further verification on one aspect of the specificity of resistance training. Slow strength training does not improve fast movements of the same exercise. Consequently, it is invalid to assert that slow resistance training designed to improve strength will improve high-speed functional activities such as baseball pitching.

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