The Effects of Concentric Resistance Training on Eccentric Peak Torque and Muscle Cross-sectional Area.

This study was designed to investigate the effects of concentric resistance training on isokinetic concentric and eccentric peak torque and muscle cross-sectional area. Using a time-series design, 14 males with previous strength training experience were assigned to six weeks of control activity, followed by 12 weeks of high-resistance training of the knee extensors and flexors on variable resistance hydraulic equipment that allowed concentric contractions only. Angular velocities of movement about the knee and hip during training were maintained at approximately 1.05 rad.s-1. Peak concentric and eccentric torques of the knee extensors and flexors at 1.05 rad.s-1 were assessed three times before training and during the training program at six and 12 weeks. No significant changes in peak torque were observed over the control period. After six weeks of training, peak torque in all four tests were increased (p < .05) over pretraining values. After 12 weeks of training, torques were further increased (p < .05) over the values at the six-week point. Cross-sectional area (CSA) of the quadriceps femoris muscle and the hamstring muscle groups was measured by computerized tomography (CT) scanning techniques before training and during the program at six and 12 weeks. CSA was significantly (p < .05) increased for the quadriceps femoris muscle but not the hamstrings group after six weeks of training. After 12 weeks of training, the CSA of both muscle groups increased (p < .05) over the six-week measurement. The results of this study suggest that strength training effects are not completely specific to the contraction type utilized in training. J Orthop Sports Phys Ther 1991;13(3):132-137.