Partial protection against muscle damage by eccentric actions at short muscle lengths.
OBJECTIVE
This study investigated the hypothesis that maximal eccentric actions at a short muscle length would fail to confer a protective effect against muscle damage induced by maximal eccentric exercise at a long muscle length.


METHODS
Eleven males performed 24 maximal eccentric actions of the nondominant elbow flexors over a short extension range from an elbow joint angle of 0.87-1.74 rad (S-ECC) followed 4 wk later by eccentric actions at a long range of 2.27-3.14 rad (L-ECC). A second group of 11 males performed L-ECC on two occasions using the nondominant arm separated by 4 wk. Changes in maximal isometric strength, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase and aspartate aminotransferase activities, and B-mode ultrasound images were compared between bouts and between groups by two-way repeated measures ANOVA.


RESULTS
All measures changed significantly (P < 0.01) after the first bout; however, the effects were significantly (P < 0.01) smaller after S-ECC compared with L-ECC. The second bout resulted in significantly (P < 0.01) reduced changes in all measures compared with the first bout in the subjects who performed L-ECC on both occasions. The subjects who performed S-ECC in the first bout displayed significantly smaller changes after L-ECC than those seen after L-ECC alone, with the degree of attenuation being around 50-70%.


CONCLUSIONS
Contrary to the hypothesis, S-ECC provided partial but effective protection against L-ECC. This result suggests adaptations associated with the repeated bout effect were also produced after S-ECC, but the degree of adaptations was not as strong as that by L-ECC. Eccentric exercise at a short extension range can be used as a strategy to present severe muscle damage.
Nosaka
Kazunori
K
School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Western Australia, Australia. k.nosaka@ecu.edu.au
Newton
Mike
M
Sacco
Paul
P
Chapman
Dale
D
Lavender
Andrew
A
D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001132:Arm / Q000033:anatomy & histology; D001219:Aspartate Aminotransferases / Q000097:blood; D001265:Athletic Injuries / Q000517:prevention & control*; D003402:Creatine Kinase / Q000097:blood; D004551:Elbow Joint / Q000503:physiopathology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology; D010806:Physical Education and Training / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology
D001219:Aspartate Aminotransferases; D003402:Creatine Kinase