Rapid adaptation to eccentric exercise-induced XXXX .

@entity1 @entity908 @entity925 @entity121
This study examined eccentric exercise-induced @entity121 and rapid adaptation. Twenty-two male subjects performed 70 eccentric actions with the knee extensors. Group A (n = 11) and group B (n = 11) repeated the same exercise 4 and 13 days after the initial bout, respectively. Criterion measures included @entity925 , muscle force generation (vertical jump height on a Kistler platform), and plasma levels of @entity908 kinase (CK), slow-twitch skeletal (cardiac beta-type) myosin heavy chains (MHC), and cardiac troponin I. Subjects were tested pre-exercise and up to day 4 following each bout. The initial exercise resulted in an increase in CK and MHC, a decrement in muscle force, and delayed onset @entity925 in all @entity1 . CK and MHC release correlated closely (rho = 0.73, p = 0.0001), both did not correlate with the decrement in muscle force generation after exercise. Because cardiac troponin I could not be detected in all samples, which excluded a protein release from the heart (cardiac beta-type MHC), this finding provides evidence for a injury of slow-twitch skeletal muscle fibers in response to eccentric contractions. Repetition of the initial eccentric exercise bout after 13 days (group B) did not cause @entity925 , a decrement in muscle reaction force with vertical jump or significant changes in plasma MHC and CK concentrations, whereas in case of repetition after 4 days (group A) only the significant increases in CK and MHC were abolished. The decrement in reaction force with vertical jump did not differ significantly from that after the initial exercise session, but perceived @entity925 was less pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)
