Muscle Damage Induced by Eccentric Exercise, Recovery and Adaptations

Exercises consisting of eccentric (lengthening) muscle contractions induce muscle damage represented by delayed onset muscle soreness and loss of muscle function lasting for multiple days, especially when they were performed in an unaccustomed condition. These symptoms are considered to be related to inflammation. The magnitude of muscle damage is reduced when the same eccentric exercises are repeated, or damaging eccentric exercises are preceded by low-intensity eccentric contractions or high-intensity isometric contractions at a long muscle length, known as the repeated bout effect and preconditioning effect, respectively. In sports, despite of the repeated bout effect and preconditioning effect, athletes experience muscle damage after a match or a competition. Thus, it is important for athletes and coaches to know how many days are required to recover from a previous match to be ready for the next match. This also requires some strategies to enhance recovery. In this chapter, characteristics of eccentric exercise-induced muscle damage are explained, strategies to minimize muscle damage and enhance recovery from muscle damage are presented, and the relationship between muscle damage and muscle adaptations such as muscle hypertrophy and strength gain are discussed in relation to inflammation.