Further Potentiation of Dynamic Muscle Strength after Resistance Training

Purpose: One bout of 5-6 s of maximal voluntary isometric contraction (MVC) is known to enhance subsequent dynamic joint performance such as dynamic joint torque and power with maximal voluntary effort. On the other hand, such a muscle contraction can also induce muscle fatigue. It is then possible that individual differences in fatigue resistance is a factor that affects the balance between potentiation and fatigue. Here, we examined the effect of chronic heavy-resistance training on the extent and time course of the potentiation of maximal voluntary dynamic torque. Methods: Before and after a 12-wk intervention, maximal voluntary concentric knee extension torque at 210 degrees.s(-1) was measured in the following sequence: before and immediately after a 5-s MVC of knee extension and 1, 3, and 5 min thereafter. The training group performed heavy-resistance training exercise of knee extension consisting of five sets of eight repetitions with 80% of one-repetition maximum, three sessions a week during the intervention period. Results: Before the resistance training intervention, maximal voluntary concentric torque was significantly enhanced only at 1 and 3 min post-MVC. After the 12-wk resistance training, the maximal voluntary concentric torque was potentiated also immediately after the conditioning MVC and was further increased at 1-min point. Conclusion: These findings indicate that the contraction-induced potentiation of maximal voluntary dynamic torque is pronounced in strength-trained individuals.