Eccentric exercise-induced injuries to contractile and cytoskeletal musclefibre components

Exercise involving lengthening of an activated muscle can cause injury. Rec ent reports documented the mechanics of exercise-induced muscle injury as w ell as physiological and cellular events and manifestations of injury. Loss of the cytoskeletal protein desmin and loss of cellular integrity as evide nced by sarcolemmal damage occur early during heavy eccentric exercise. The se studies indicate that the earliest events in muscle injury are mechanica l in nature, while later events indicate that it may be more appropriate to conclude that intense exercise initiates a muscle remodeling process. We c onclude that muscle injury after eccentric exercise is differently severe i n muscles with different architecture, is fibre type-specific, primarily be cause of fibre strain in the acute phase, and is exacerbated by inflammatio n after the initial injury.