Resumen de Relationships Between Muscle Power Output Using the Stretch-Shortening Cycle and Eccentric Maximum Strength
Kazuyoshi Miyaguchi, Shinichi Demura
Miyaguchi, K and Demura, S. Relationships between muscle power output using the stretch-shortening cycle and eccentric maximum strength. J Strength Cond Res 22(6): 1735-1741, 2008-This study aimed to examine the relationships between muscle power output using the stretch-shortening cycle (SSC) and eccentric maximum strength under elbow flexion. Eighteen young adult males pulled up a constant light load (2 kg) by ballistic elbow flexion under the following two preliminary conditions: 1) the static relaxed muscle state (SR condition), and 2) using the SSC with countermovement (SSC condition).
Muscle power was determined from the product of the pulling velocity and the load mass by a power measurement instrument that adopted the weight-loading method. We assumed the pulling velocity to be the subject's muscle power parameters as a matter of convenience, because we used a constant load. The following two parameters were selected in reference to a previous study: 1) peak velocity (m[middle dot]s-1) (peak power) and 2) 0.1-second velocity during concentric contraction (m[middle dot]s-1) (initial power). Eccentric maximum strength by elbow flexion was measured by a handheld dynamometer.
Initial power produced in the SSC condition was significantly larger than that in the SR condition. Eccentric maximum strength showed a significant and high correlation (r = 0.70) with peak power in the SSC condition but not in the SR condition. Eccentric maximum strength showed insignificant correlations with initial power in both conditions. In conclusion, it was suggested that eccentric maximum strength is associated with peak power in the SSC condition, but the contribution of the eccentric maximum strength to the SSC potentiation (initial power) may be low
