THE DELETERIOUS EFFECT OF TETANIC CONTRACTION ON RABBITS TRICEPS SURAE MUSCLE DURING CYCLIC LOADING

To elucidate the effect of nerve stimulation on the mechanical propert y of muscle-tendon unit, the triceps surae muscle of New Zealand White rabbit was tested with material testing machine. After anaesthesia, t he triceps surae muscle-tendon unit of rabbit was tested with cyclic l oading during nerve stimulation. The differences between initial and r esidual force disappeared in the presence of low amplitude and low fre quency nerve stimulation. Loading energy applied to the muscle-tendon unit did not change, but the unloading energy increased and energy los s decreased significantly. However, the residual force appeared again at the tetanic stimulation; the loading energy, unloading energy and e nergy loss all increased significantly. Relevance-intensive exercise t raining can result in muscle damage and muscle soreness, especially wh en the exercise involves eccentric contraction. However, the mechanism responsible for injury during eccentric contraction is still unknown. In the present study, we demonstrate that low amplitudes and frequenc ies of nerve-stimulation have a protective effect on the muscle-tendon unit. However, at the tetanic stimulation, the deleterious effect upo n the muscle-tendon unit appeared. This fact may contribute to a bette r understanding of the mechanism responsible for injury during eccentr ic contraction.