[Effects of an eccentric exercise session short-term recovery of muscle contractility]

Short term effects of 5 sets of 10 maximal eccentric contractions of the elbow flexors, performed using an isokinetic ergometer, were studied. Maximal eccentric, isometric, concentric torque, myoelectrical activity of biceps and triceps brachii, voluntary activation, M-wave amplitude, as well as twitch and maximal contraction and relaxation velocities were measured before (Control), 2 minutes after (Post), 24 hours (Post24 h) and 48 hours (Post48 h) after the exercise session. Torque significantly decreased over the recovery period, whatever the contraction type, excepted concentric torque assessed at 240 degrees.s-1 which recovered its Control value at Post48 h. Activation level significantly decreased at Post (p < 0.05) and returned to its Control value at Post24 h. Twitch, as well as maximal contraction and relaxation velocities had significantly declined among the experimental procedure (p < 0.01). M-wave amplitude was not modified after the exercise. These results indicate that, over a 48 hour rest period, torque decrement following a maximal eccentric exercise session should mainly be due to a failure of the peripheral part of the neuromuscular system, and force recovery should closely be linked to the developed force value.