Muscle damage and inflammation after eccentric exercise: can the repeated bout effect be removed?

Abstract

The current consensus in exercise physiology is that the repeated bout effect always appears after few eccentric exercise sessions. This is the first attempt to challenge this tenet, by exploiting specificity in muscle plasticity. More specifically, we examined whether the opposing adaptations in muscle induced after concentric and eccentric exercise can attenuate and/or remove the repeated bout effect. Seventeen young men were randomly assigned into one of the following groups: (1) the alternating eccentric‐concentric exercise group; and (2) the eccentric‐only exercise group. Both groups performed 8 weeks of resistance exercise using the knee extensors of both legs on an isokinetic dynamometer. The alternating eccentric‐concentric exercise group performed an alternating exercise protocol, switching between eccentric‐only and concentric‐only exercise every 4 weeks, while the eccentric‐only group performed eccentric exercise. Evaluation of muscle damage using physiological (isometric torque, delayed onset muscle soreness, and range of movement) and biochemical (creatine kinase) markers and inflammation (C‐reactive protein) was performed at weeks 1, 5, and 10. Baseline isometric peak torque was also evaluated at week 14 after another cycle (4 weeks) of alternating or eccentric‐only exercise training. In the alternating eccentric‐concentric exercise group, the concentric exercise training performed prior to eccentric exercise reduced dramatically the repeated bout effect by reversing muscle back to its unaccustomed state. On the contrary, the eccentric‐only exercise group exhibited a typical manifestation of the repeated bout effect. Interestingly, muscle strength was elevated similarly for both alternating and eccentric‐only exercise groups after 13 weeks of training. The alternating eccentric‐concentric exercise scheme, implemented in the present study, has for the first time successfully overcame the repeated bout effect. The similarity in muscle strength measurements following the two protocols is against the notion that inflammation plays an important role in exercise‐induced adaptations in muscle.

Effect of Branched-Chain Amino Acid Supplementation on Recovery Following Acute Eccentric Exercise

“…Similar results from two cross-over investigations examining BCAA supplementation on recovery of muscle function in untrained individuals reported favorable outcomes of muscle function assessments [ 39 , 40 ]. However, these findings may be influenced by the repeated bout phenomena and should be considered a limitation [ 41 , 42 ]. While MVIC testing is a popular, valid and reliable measure of muscle function and recovery [ 43 ], it is important to note that the isometric movement associated with MVIC testing is distinctly different from several types of athletic performance movements.…”

Two repetitive bouts of intense eccentric‐concentric jaw exercises reduce experimental muscle pain in healthy subjects

“…Interestingly, it has to be taken into account that the protocol adopted in the current study is, to our knowledge, the first one able to elicit eccentric contractions of the jaw‐closing muscles, but still in association with concentric contractions. Even though it has been proved in limb studies that also not‐eccentric‐only exercises can still play a protective role on muscle damage, a recent study showed that alternating cycles of eccentric‐only and concentric‐only contractions reduced dramatically the positive effects by reversing muscles back to their unaccustomed status . Therefore, it can be hypothesised that being able to perform eccentric‐only contractions of the masticatory muscles might produce greater protective effects against muscle damage.…”

“…Even though it has been proved in limb studies that also not-eccentric-only exercises can still play a protective role on muscle damage, 15 a recent study showed that alternating cycles of eccentric-only and concentric-only contractions reduced dramatically the positive effects by reversing muscles back to their unaccustomed status. 30 Therefore, it can be hypothesised that being able to perform eccentric-only contractions of the masticatory muscles might produce greater protective effects against muscle damage. However, due to the muscle anatomy and physiology of the craniofacial complex, eccentric-only contractions are unlikely to be developed in human jaw muscles.…”

Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications

“…Previous investigators have shown that prior muscle action history influences subsequent physiological responses to eccentric loading (McHugh et al, 1999 ; Nosaka et al, 2001 ; Margaritelis et al, 2015 ). Adaptations involving the skeletal muscle ultrastructure and the ability to withstand oxidative stress may occur in response to submaximal eccentric loading (Lima and Denadai, 2015 ; Deyhle et al, 2016 ).…”