The consistency of inflammatory responses and muscle damage to high-force eccentric exercise
Andring, Jan Marie
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High-force eccentric exercise causes muscle damage and leads to inflammation resulting in increased levels of C-reactive protein (CRP) and interleukin-6 (IL-6). Indicators of muscle damage are creatine kinase (CK), decreased maximal isometric strength, muscle soreness (SOR) and swelling. This study investigated rank ordering of eccentric exercise of the non-dominant (ND) and dominant (D) elbow flexors. Rank ordering is determined by the magnitude and duration of the inflammatory response indicated by CRP, IL-6 and IL-10. Twelve subjects enrolled in the study, nine subjects performed high-force eccentric exercise on each arm, 3 weeks apart, consisting of 3x15 reps in the ND and D elbow flexors. Blood samples were taken at pre-exercise (0h), 4h, 8h, 12h, 24h and 120h post-exercise. Two subjects were eliminated from the data analysis because of elevated baseline IL-6 levels and insufficient strength losses. A Spearman rank order correlation was used to determine the consistency of the inflammatory response. A repeated measures ANOVA was used to detect significant changes over time and between arms as well as to determine an arm by time interaction. For CRP, no significant rank order correlation was detected and a RM ANOVA detected no significant differences. For IL-6, no significant rank order correlation was detected, but a trend (p = 0.071) was found. Also, a RM ANOVA detected a trend (p = 0.107) for IL-6 with a peak increase at 8h post-exercise. A significant rank order correlation was detected for CK (p < 0.05). A RM ANOVA detected a trend (p = 0.099) for a higher response in the ND arm. A significant rank order correlation was detected for maximal isometric strength (p < 0.05). A RM ANOVA detected significant strength decreases (p < 0.001) immediately post-exercise for both the ND and D arms. No significant rank order correlation was found for muscle soreness. A significant increase (p < 0.001) in soreness was detected at 24h post-exercise. For swelling, no significant rank order correlation was detected and no significant changes occurred. The consistency of the inflammatory response after high-force eccentric exercise in the ND and D elbow flexors is undetermined at this time.