Variability in Muscle Damage After Eccentric Exercise and the Repeated Bout Effect

Abstract

The first purpose of this study was to determine a possible explanation for the variability in the response to eccentric exercise by having participants repeat the same exercise 1 year apart. The second purpose was to examine whether initial injury in response to eccentric exercise was associated with the extent of the repeated bout effect (RBE). Male students performed 30 eccentric contractions (ECC) of the elbow flexors using a dumbbell set at 80% of the pre-exercise maximal isometric force (MIF). Participants were then classified into low (LR; n=6), medium (MR; n=6), high (HR; n=5), and higher (HrR; n=7) based on the increase in blood creatine kinase (CK) activity. A year later, participants repeated this exercise (ECC30). Four days after ECC30, participants performed 70 eccentric contractions (ECC70). Range of motion, MFI upper arm circumference, soreness, and blood CK activity were measured before and up to 9 days after each bout. The change in the criterion measures following ECC and ECC30 were similar for each group. There were no further changes in all parameters after ECC70 for MR, HR, and HrR, although there was a small increase in CK after ECC70 for LR. LR showed a smaller RBE after ECC70 compared with the other groups. It is concluded that participants who exercised 1 year apart showed remarkably similar responses between the bouts. The extent of the RBE following the second bout for the LR group is less for participants who demonstrate the least evidence of muscle damage after a first exercise bout.

Insights into the molecular etiology of exercise-induced inflammation: opportunities for optimizing performance

“…Now it is also well-understood that athletes may be low-, moderate-, and high-respondents to EIMD, a fact that also explains the substantial interindividual variability in the responses seen following various types of exercise protocols used to induce muscle micro-injury 73,108,155,163,168,173–175. This phenomenon may be attributed to a number of factors such as age,154,176,177 preconditioning,178–180 gender,80,166 genetics,181,182 physical conditioning level,57,183–185 and joint range of motion 186.…”

Muscle force loss and soreness subsequent to maximal eccentric contractions depend on the amount of fascicle strain in vivo

“…In this context, although it is well known that the muscle force impairment after eccentric exercise differs greatly between subjects, this variability remains poorly understood (Chen 2006). Thus, we can speculate that the variability in fascicle lengthening due to variable tendon contributions and AGR could be involved in the variability in EIMD magnitude.…”

Length of Rest Interval Between Resistance Exercise Sets: Performance and Inter-Individual Variability of Ck Activity

“…It has been shown that subtle force applications at long muscle lengths can alter a participant's high or low response to the exercise. 7 Because a force-angle curve was not determined during muscle actions in this study, it is possible that "responder" consistency was due to the manner in which participants performed the exercise, as well as the behavioral factors (i.e. the speed of muscle actions during RI30 and RI90 or whether the participants had participated in physical activity in the past) which may partially account for the consistent response in this study.…”

“…Conflicting results can be attributed to great interindividual variability on serum CK activity. 7 For example, Machado and Willardson 22 verify differences in serum CK activity following resistance exercise sessions with 1-or 3-min RI lengths when high responder (HR) subjects (i.e. subjects who had a great post-exercise serum CK activity peak) were separated from each group, while the analysis of groups without stratification (i.e.…”