The protective effect of damaging eccentric exercise against repeated bouts of exercise in the mouse tibialis anterior muscle.

Using a damaging eccentric exercise regime of the mouse tibialis anterior (TA) muscle we have investigated the extent and time course of protection afforded by one bout of exercise against damage resulting from a second bout of activity. Maximal force and fibre morphology were preserved if the exercise was repeated within 21 days, but by 84 days muscles once again became susceptible to damage. Low-frequency force loss had a shorter time course of protection against repeated exercise, lasting less than 21 days. The results provide evidence for different mechanisms contributing to the development of muscle damage following eccentric exercise and provide a basis for characterizing the adaptive response of muscle to damaging exercise.