Effect of resistance exercise with slow movement, and elucidation of the mechanism

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This study examined the effects of different exercise duration of concentric and eccentric actions during resistance exercise with slow movement on hormonal responses. Nine adult men performed following four trials on separate days.・Low-intensity resistance exercise with slow movement (5s for lifting action, 1 s for lowering action; 5-1 trial)・Low-intensity resistance exercise with slow movement (Is for lifting action, 5 s for lowering action, 1-5 trial)・Low-intensity resistance exercise with slow movement (3s for lifting action, 3 s for lowering action, 3-3 trial)High-intensity resistance exercise with normal movement (Is for lifting action, Is for lowering action, 1-1 trial)Resistance exercise consisted of 4 sets of bilateral knee extension. Blood samples were collected to determine blood hormone concentrations. Oxygen uptake and heart rate were also measured during each set of exercise and rest periods between sets.The results showed that total work volume throughout four sets of exercise was significantly greater in the 1-1 trial than other three trials. Among the trials using slow lifting, 1-5 trial showed a highest work volume, with significant difference between 1-5 and 5-1 trials. Blood lactate concentration after exercise showed significantly greater values in the 1-1 and 5-1 trials than in the 1-5 trial No significant difference was observed in the exercise-induced increases in hormone concentrations among the trials, but 1-5 trial showed smaller responses of noradrenalin and free testosterone. In addition, 1-1 and 5-1 trials showed greater values of oxygen uptake and heart rate. The exercise-induced strength loss showed no significant difference among the trials.These results indicate that slow-lifting exercise with longer duration of concentric phase augments exercise-induced metabolic stress. Alternatively, the exercise with longer duration of eccentric phase shows smaller secretions of noradrenalin and free testosterone, and respiratory responses.