In eccentric muscle contraction, the muscle is lengthening while contracting. For example, in downhill walking, the thigh muscles are contracting eccentrically. It is well known that unaccustomed eccentric exercise causes pain and may lead to inflammation reactions on muscles few days after the exercise. The theme of the present chapter is molecular and cellular markers in skeletal muscle damage after voluntary exercise containing eccentric muscle contractions. The chapter contains three topics: In the first topic, the damaging process followed by regeneration is demonstrated with antibody stainings of connective tissue, plasma membrane, and cytoskeletal proteins. The second topic is infiltration of inflammatory cells in damaged skeletal muscle. Neutrophils are usually the first inflammatory cells mostly present in the injured tissues; however, neutrophils are not present in exercise-induced skeletal muscle damage. Finally, the relationship between skeletal muscle damage and systematic markers, serum creatine kinase and voluntary maximal force production, is described.
Part of the book: Muscle Cell and Tissue