Central Regulation and Neuromuscular Fatigue during Exercise of Different Durations.

Purpose: The aim of this study was to determine if exercise time trials (TT) of different durations would cause different levels of peripheral and central fatigue during exercise.

Methods: Twelve trained subjects (11 men, one woman) performed TT lasting 3, 10, and 40 min with repetitive self-paced concentric right knee extension at 60°·s on an isokinetic dynamometer. Neuromuscular function was assessed before, during, and immediately after the TT using voluntary and electrically evoked forces.

Potentiation increases peak twitch torque by enhancing rates of torque development and relaxation.

The aim of this study was to measure the extent to which potentiation changes in response to an isometric maximal voluntary contraction. Eleven physically active subjects participated in two separate studies. Single stimulus of electrical stimulation of the femoral nerve was used to measure torque at rest in unpotentiated quadriceps muscles (study 1 and 2), and potentiated quadriceps muscles torque in a 10 min period after a 5 s isometric maximal voluntary contraction of the quadriceps muscles (study 1).