THE EFFECTS OF DETRAINING ON POWER ATHLETES

We investigated the effects of 14 d of resistive exercise detraining o n 12 power athletes. In comparing performances pre- to post-detraining , there were no significant (P > 0.05) changes in free weight bench pr ess (-1.7%), parallel squat (-0.9%), isometric (-7 %) and isokinetic c oncentric knee extension force (-2.3%), and vertical jumping (1.2%). I n contrast, isokinetic eccentric knee extension force decreased in eve ry subject (-12%, P < 0.05). Post-detraining, the changes in surface E MG activity of the vastus lateralis during isometric, and isokinetic e ccentric and concentric knee extension were -8.4%, -10.1%, and -12.7 % , respectively (all P > 0.05). No significant changes occurred in knee flexion forces or EMGs (P > 0.05). Percentages of muscle fiber types and the Type I fiber area remained unchanged, but Type II fiber area d ecreased significantly by -6.4% (P < 0.05). Levels of plasma growth ho rmone (58.3%), testosterone (19.2%), and the testosterone to cortisol ratio (67.6%) increased, whereas plasma cortisol (-21.5%) and creatine kinase enzyme levels (-82.3%) decreased (all P < 0.05). Short-term re sistive exercise detraining may thus specifically affect eccentric str ength or the size of the Type II muscle fibers, leaving other aspects of neuromuscular performance uninfluenced. Changes in the hormonal mil ieu during detraining may be conducive to an enhanced anabolic process , but such changes may not materialize at the tissue level in the abse nce of the overload training stimulus.