Muscle damage induced by stretch-shortening cycle exercise.

Abstract

Strenuous stretch-shortening cycle exercise was used as a model to study the leakage of proteins from skeletal muscle. The analysis included serum levels of creatine kinase (S-CK), myoglobin (S-Mb), and carbonic anhydrase (S-CA III). Blood samples from power- (N=11) and endurance-trained (N=10) athletes were collected before, 0, and 2 h after the exercise, which consisted of a total of 400 jumps. The levels of all determined myocellular proteins increased immediately after the exercise (P < 0.05-0.001) among both subject groups. In the endurance group, the protein levels increased (P < 0.05-0.001) further during the following 2 h after the exercise, and the ratio of S-CA III and S-Mb decreased (P < 0.05) in a before-after comparison. This was not the case among the power group despite their greater mechanical work (P < 0.001) and higher ratio of eccentric and concentric EMG activity of the leg extensor muscles (P < 0.05). The differences of the determined protein levels between the subject groups might be due to obvious differences in the muscle fiber distribution, differences in recruitment order of motor units, and/or differences in training background.