Concentric or eccentric training effect on eccentric exercise-induced muscle damage.
OBJECTIVE
The purpose of this study was to compare changes in muscle damage indicators following 24 maximal eccentric actions of the elbow flexors (Max-ECC) between the arms that had been previously trained either eccentrically or concentrically for 8 wk.


METHODS
Fifteen subjects performed three sets of 10 repetitions of eccentric training (ECC-T) with one arm and concentric training (CON-T) with the other arm once a week for 8 wk using a dumbbell representing 50% of maximal isometric force of the elbow flexors (MIF) determined at the elbow joint of 90 degrees (1.57 rad). The dumbbell was lowered from a flexed (50 degrees, 0.87 rad) to an extended elbow position (180 degrees, 3.14 rad) in 3 s for ECC-T, and lifted from the extended to the flexed position in 3 s for CON-T. Max-ECC was performed 4 wk after CON-T and 6 wk after ECC-T. Changes in MIF, range of motion (ROM), upper arm circumference (CIR), muscle soreness (SOR), and plasma creatine kinase (CK) activity were compared between the ECC-T and CON-T arms.


RESULTS
The first ECC-T session produced larger decreases in MIF and ROM, and larger increases in CIR and SOR compared with CON-T. CK increased significantly (P < 0.01) and peaked 4 d after the first training session, but did not increase in the following sessions. All measures changed significantly (P < 0.01) following Max-ECC; however, the changes were not significantly different between ECC-T and CON-T arms.


CONCLUSIONS
These results showed that ECC-T did not mitigate the magnitude of muscle damage more than CON-T, and CON-T did not exacerbate muscle damage.
Nosaka
Kazunori
K
Exercise and Sports Science, Graduate School of Integrated Science, Yokohama City University, Yokohama, Japan. nosaka@yokohama-cu.ac.jp
Newton
Mike
M
D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001132:Arm / Q000503:physiopathology; D001265:Athletic Injuries / Q000503:physiopathology; D003402:Creatine Kinase / Q000097:blood; D004550:Elbow / Q000503:physiopathology*; D015444:Exercise; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology; D010806:Physical Education and Training / Q000379:methods*; D016059:Range of Motion, Articular; D019415:Torque; D014891:Weight Lifting
D003402:Creatine Kinase