Effects of prior concentric training on eccentric exercise induced muscle damage

Abstract

Background: Exercise induced muscle damage (EIMD) from strenuous unaccustomed eccentric exercise is well documented. So too is the observation that a prior bout of eccentric exercise reduces the severity of symptoms of EIMD. This has been attributed to an increase in sarcomeres in series. Recent studies have suggested that prior concentric training increases the susceptibility of muscle to EIMD following eccentric exercise. This has been attributed to a reduction of sarcomeres in series, which decreases muscle compliance and changes the length-tension relation of muscle contraction. Objective: To assess the effects of prior concentric training on the severity of EIMD. Methods: Four men and four women (mean (SD) age 21.1 (0.8) years) followed a four week concentric training programme. The elbow flexor musculature of the non-dominant arm was trained at 60% of one repetition maximum dynamic concentric strength performance, three times a week, increasing to 70% by week 3. After three days of rest, participants performed 50 maximal isokinetic eccentric contractions on both arms. All participants gave written informed consent before taking part in this study, which was approved by the school ethics committee. Strength, relaxed arm angle (RAA), arm circumference, and soreness on active extension and flexion were recorded immediately before eccentric exercise, one hour after, and at 24 hour intervals for three days. Data were analysed with fully repeated measures analyses of variance. Results: Strength retention was significantly (p<0.01) greater in the control arm than the trained arm (84.0 (13.7)%, 90.4 (14.7)%, 95.2 (10.5)%, 103.5 (7.6)% v 75.5 (11.3)%, 77.6 (15.3)%, 80.1 (13.9)%, 80.9 (12.5)%) at one, 24, 48, and 72 hours respectively. Similarly, soreness was greater in the trained arm (0.7 (0.6), 3.1 (1.4), 3.0 (1.5), 1.9 (2.3)) than in the untrained arm (0 (0.2), 1.6 (1.3), 1.4 (0.6), 0.6 (0.4)) at one, 24, 48, and 72 hours respectively (p<0.05). Concentric training induced a significant reduction in RAA (165.2 (6.7)°v 157.3 (4.9)°) before the eccentric exercise bout (p<0.01). This was further reduced and remained lower in the trained arm at all time points after the eccentric exercise (p<0.01). The arm circumference of the concentrically trained arm was significantly greater than baseline (p<0.05) at 72 hours (30.3 (2.9) v 29.8 (3.3) cm). Conclusions: These findings extend the understanding of the effects of prior concentric training in increasing the severity of EIMD to an upper limb exercise model. The inclusion of concentric conditioning in rehabilitation programmes tends to exacerbate the severity of EIMD in subsequent unaccustomed exercise. However, where concentric conditioning is indicated clinically, the net effect of conditioning outcome and EIMD may still confer enhanced strength performance and capability to dynamically stabilise a joint system.

Aspectos atuais sobre estresse oxidativo, exercícios físicos e suplementação

“…The consumption of adenosine triphosphate (ATP), the alteration in the calcium homeostasis and the ORS production have been shown in the injury and muscular necrosis etiology (1)(2)(3)(4)(5) (figure 1).…”

“…Post-injury pain induced by exercise frequently has its peak between 24 to 48 post-exercise hours. Muscular injury induced by performance of an eccentric exercises bout may be derived from connective tissues rupture ligated to adjacent myofibrils from the muscular cell itself, from the basal laminate adjacent to the plasmatic membrane, the plasmatic membrane of the muscular cell, the sarcomere, the plasmatic reticule, or even of a combination of these components (1)(2)(3)(4) . Muscular fibers injuries are usually evaluated by the determination of the reflux of cytosolic enzymes specific for blood circulation, combined with histological techniques or ultrastructural evaluation through electronic microscopy in order to evaluate the local effects.…”

Efeito citotóxico provocado por ciclofosfamida na massa corporal e no tecido muscular estriado esquelético de ratos treinados.

“…Assim como observado por CAMARGO-FILHO et al (2006), durante o treinamento, os animais realizaram força excêntrica ao fundo do tanque, com o objetivo de impulsionar o corpo para cima. A lesão muscular provocada através da realização do exercício excêntrico pode ocorrer devido a ruptura de tecidos conectivos ligados as miofibrilas adjacentes, que podem ser da própria célula muscular, da lâmina basal adjacente à membrana plasmática, da membrana plasmática da própria célula muscular, do sarcômero, do retículo sarcoplasmático ou da combinação de todos esses componentes (GLEESON et al, 2003;INGALLS et al, 2004;PROSKE;MORGAN, 2001). Após a realização de exercícios, principalmente excêntricos, ocorrem alterações de células inflamatórias circulantes, consequência de citocinas produzidas pelos tecidos musculares.…”

Clinical Practice Patterns and Beliefs in the Management of Hamstrings Strain Injuries

“…49 Whereas eccentric training has been shown to cause protective adaptations by allowing increased strength at longer muscle lengths through an increase in the number of sarcomeres in series, [50][51][52][53] concentric strengthening results in a decrease in sarcomeres in series. 49,54 Concentric training causes peak torque to occur at a greater angle of knee flexion (shorter muscle length) during the gait cycle by altering the length-tension relationship of the hamstrings, and this shift in peak torque production to shorter muscle lengths is a risk factor for HSI. 55 We observed much lower use rates of isokinetic strengthening, and although this exercise may not be a practical clinical rehabilitation method, its utility for HSI rehabilitation should be considered.…”