Abstract

Rate of torque development (RTD) is considered important for improving the performance in sports requiring explosive strength. Although RTD was reported to be increased after explosive-type strength training (Tillin et al. Exp Physiol 2012;97:630–41.), the effect of subsequent detraining on the increased RTD remains unclear. Therefore, this study aimed to investigate the effect of explosive-type strength training and subsequent short-term detraining on RTD during isometric knee extension. Ten male subjects participated in this study. They underwent explosive-type strength training for 6 weeks (3 days per week) and detraining for 3 weeks. The training consisted of four sets of 10 repetitions of explosive contractions of less than 1 s. At the pre- and post-training phases (PRE and POST, respectively) and after the detraining phase (DE), we measured the quadriceps femoris muscle thickness using ultrasonography. In addition, we measured the maximum voluntary torque (MVT) during maximum voluntary isometric knee extension of 3–5 s and RTD during explosive isometric knee extension of less than 1 s. In PRE, POST and DE, quadriceps femoris muscle thickness did not change. In POST, MVT and RTD increased compared with those in PRE (p<0.05). In DE, no change was observed in MVT compared with that in POST. However, in DE, RTD decreased compared with that in POST (p<0.05). In addition, no difference was observed between PRE and DE. These findings suggest that RTD increased after the 6-week explosive-type strength training but returned to the pre-training level after the 3-week short-term detraining. It is necessary to take into account the time point at which we evaluate the effect of training after explosive-type strength training.