Damaging Eccentric Exercise Research Articles

Effects of eccentric treadmill exercise on inflammatory gene expression in human skeletal muscle

The present study examined the skeletal muscle expression of several genes related to the inflammatory process before and after a bout of downhill running. Twenty-nine males between the ages of 18 and 35 years performed a 45-min downhill (-17.5%) treadmill protocol at 60% of maximal oxygen consumption. Venous bloods samples and muscle biopsy samples from the vastus lateralis were donated prior to and at 3-h and 24-h postexercise, along with ratings of perceived muscle soreness. Serum creatine kinase (CK) was determined, as was skeletal muscle gene expression of interleukin (IL)-6, IL-8, IL-12 (p35), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, cyclooxygenase 2 (COX2), and nuclear factor kappa B (NFkB) (p105/p50). Gene expression was analyzed using RT-PCR and compared with a standard housekeeping gene (beta-actin). Data were analyzed for statistical differences using multivariate analysis of variance with univariate follow-up. In addition, Pearson correlations were conducted to determine if any significant relationship exists between any of these transcripts and both CK and muscle soreness. Significant (p < 0.05) up-regulations in IL-6, IL-8, and COX2 mRNA expression were observed compared with baseline, whereas no significant changes for IL-12, IL-1beta, TNF-alpha, or NFkB were noted. Significant increases in IL-6 mRNA were observed at 3 h (p < 0.001) and 24 h (p = 0.043), whereas significant increases in IL-8 (p = 0.001) and COX2 (p = 0.046) mRNA were observed at 3-h postexercise. In addition, muscle soreness was significantly correlated with IL-8 at 24 h (r = -0.370; p = 0.048), whereas CK was significantly related to NFkB at baseline (r = -0.460; p = 0.012). These data indicate that increases in the mRNA expression of IL-6, IL-8, and COX2 occur in the vastus lateralis as a result of damaging eccentric exercise in young, recreationally trained males. Further, it appears that IL-8 transcription may play some role in inhibiting postexercise muscle soreness, possibly through regulation of angiogenesis.

Neuromuscular And Perceptual Aspects Of Eccentric Muscle Damage And Recovery

Strength loss following damaging eccentric exercise (Edam) has been widely studied but changes in functional (power) and perceptual (perceived exertion and mood states) responses have received less attention. PURPOSE: The purposes of this investigation were to: 1) quantify neuromuscular function during Edam, 2) evaluate changes in maximal power (Pmax), muscle soreness (SOR), rating of perceived exertion (RPE), and mood states, and 3) test the hypothesis that the joints that absorb the greatest eccentric work would exhibit the greatest reductions in power during recovery. METHODS: Twenty-two trained cyclists (age: 31±7yrs) performed eccentric cycling (-70±4kJ) with their right leg (damage) and concentric cycling (69±3 kJ) with their left leg (control). Single-leg Pmax was assessed with inertial-load cycling and biomechanical joint powers at the ankle, knee, and hip were determined using inverse dynamic techniques. SOR associated with a squat movement was measured using a visual analog scale. RPE during a standardized submaximal cycling task was assessed with a Borg scale, and mood states were quantified using a profile of mood states questionnaire (POMS). Measures were evaluated at six time points (baseline, 0, 24, 48, 72, 96hr post Edam). Differences in dependent variables were assessed using repeated measures ANOVA procedures. RESULTS: The knee absorbed more work (63%) during Edam than the ankle, hip, and upper body (7%, 23%, and 6%, respectively). Compared to baseline, Pmax decreased (0-72hr), SOR increased (0-96hr), and RPE increased (0-72hr) in the damaged leg. Total mood disturbance increased only at the 0 hr time point. No alterations were observed in relative joint powers during sprint cycling. CONCLUSION: Multi-joint eccentric exercise produced greater alterations in neuromuscular and perceptual responses compared to equally matched concentric exercise. RPE provided more functional indications of recovery compared to SOR as participants were able to perform challenging submaximal exercise despite being sore for several days. The lack of alterations in relative joint powers did not support our hypothesis, suggesting that individual variability in joint power production/absorption strategies may have been a factor. Supported by the Gatorade Sports Science Institute.

Plasma Matrix Metalloproteinase-9 Activity As A Marker Of Exercise-induced Muscle Injury In Humans

PURPOSE: The role of matrix metalloproteinases (MMPs) in skeletal muscle remodeling has received increasing scientific attention regarding its role in skeletal muscle damage and repair. The purpose of this study was to determine if eccentric exercise-induced changes in plasma MMP-9 activity were correlated with indices of muscle damage post-exercise in humans. METHODS: Fifteen males unaccustomed to eccentric exercise participated in a protocol involving eccentric exercise (120% concentric maximum) of the non-dominant upper arm. The dependent measures included force/angle curves, range of motion (ROM), arm circumference, soreness perception, plasma MMP-9, & creatine kinase (CK) levels. Dependent measures were re-assessed Immediately Post (IP), 1-, 2-, 4-, and 7-days post task. Functional and biochemical variables were correlated in time and magnitude of response with Spearman's rho correlational analyses. RESULTS: Plasma MMP-9 activity increased up to an average of 137% of pre-levels during follow-up time points; however, the timing and magnitude of the increase varied across subjects. There were significant increases in soreness perception (45.27/100 mm 2-days post), optimal angle of force production (+10.5 degrees IP), biceps belly and elbow joint circumference (+8.27 mm 4-days post and +10.76 mm 7-days post, respectively), and CK activity (12.3 fold increase 4-days post), and significant decreases in ROM (-18.57 degrees IP), and force production (53.9% IP, 57.7% 1-day post) during the week following the exercise task. Immediately post eccentric exercise, changes in MMP-9 activity were temporally correlated with a change in the optimal angle of force production (r=0.580). At the timepoint of peak perceived soreness (2-days post), MMP-9 activity was significantly correlated with both CK activity (r=0.636) and an increase in elbow joint circumference (r=0.554). CONCLUSIONS: These data demonstrate that plasma MMP-9 activity is increased following a damaging eccentric exercise task in humans and that the change in MMP-9 activity is correlated with indices of muscle damage. Supported by NIH Grant KO1 AR050505-01.

Effects of concentric and repeated eccentric exercise on muscle damage and calpain–calpastatin gene expression in human skeletal muscle

The purpose of this study was to compare the responsiveness of changes in Ca(2+)-content and calpain-calpastatin gene expression to concentric and eccentric single-bout and repeated exercise. An exercise group (n = 14) performed two bouts of bench-stepping exercise with 8 weeks between exercise bouts, and was compared to a control-group (n = 6). Muscle strength and soreness and plasma creatine kinase and myoglobin were measured before and during 7 days following exercise bouts. Muscle biopsies were collected from m. vastus lateralis of both legs prior to and at 3, 24 h and 7 days after exercise and quantified for muscle Ca(2+)-content and mRNA levels for calpain isoforms and calpastatin. Exercise reduced muscle strength and increased muscle soreness predominantly in the eccentric leg (P < 0.05). These responses as well as plasma levels of creatine kinase and myoglobin were all attenuated after the repeated eccentric exercise bout (P < 0.05). Total muscle Ca(2+)-content did not differ between interventions. mRNA levels for calpain 2 and calpastatin were upregulated exclusively by eccentric exercise 24 h post-exercise (P < 0.05), with no alteration in expression between bouts. Calpain 1 and calpain 3 mRNA did not change at any specific time point post-exercise for either intervention. Our mRNA results suggest a regulation on the calpain-calpastatin expression response to muscle damaging eccentric exercise, but not concentric exercise. Although a repeated bout effect was demonstrated in terms of muscle function, no immediate support was provided to suggest that regulation of expression of specific system components is involved in the repeated bout adaptation.

A light load eccentric exercise confers protection against a subsequent bout of more demanding eccentric exercise

This study investigated the hypothesis that a light eccentric exercise (ECC) that does not induce a loss of muscle function and delayed onset muscle soreness would confer a protective effect against a more strenuous ECC. Eighteen young men were randomly placed into two groups: 10-40% (n=9) and 40% (n=9). Subjects in the 10-40% group performed ECC of the elbow flexors (six sets of five reps) using a dumbbell set at 10% of maximal isometric strength (MVC) at an elbow joint angle of 90 degrees , followed 2 days later by ECC using a dumbbell weight of 40% MVC. Subjects in the 40% group performed the 40% ECC only. Changes in MVC, range of motion (ROM), upper arm circumference (CIR), plasma creatine kinase (CK) activity and muscle soreness before, immediately after, 1-5 and 7 days following the 40% ECC were compared between groups by a two-way repeated measures ANOVA. No significant changes in any of the criterion measures were found immediately and 1-2 days after the 10% ECC. Following the 40% ECC, the 10-40% group showed significantly (P<0.05) smaller decreases in MVC and ROM, and smaller increases in muscle soreness compared with the 40% group, but no significant differences between groups were evident for CIR and plasma CK activity. These results suggest that the 10% ECC induced some protection against a subsequent bout of 40% ECC performed 2 days later. It appears that the light eccentric exercise preconditioned the muscles for exposure to the subsequent damaging eccentric exercise bout.

Functional and perceptual responses following damaging eccentric exercise

Functional and perceptual responses following damaging eccentric exercise

Changes in Passive Muscle Stiffness Following Eccentric Exercise

0138 PURPOSE: Limited published data exist quantifying the changes in passive muscle stiffness following damaging eccentric exercise. The purpose of this study was to quantify the changes in passive stiffness of the knee extensors following a bout of eccentric exercise. METHODS: Nine subjects (4 women, 5 men; age 35±5 yr) performed 120 isokinetic eccentric knee extension contractions (60°/s) at 90% of maximum isometric strength. Isometric strength, passive stiffness and quadriceps pain were recorded prior to eccentric exercise, immediately post-exercise, and on the three subsequent days. Isometric strength was measured at 70° knee flexion. Passive stiffness was defined as the increase in torque during passive knee flexion from 70° to 110° at 5°/s. Surface EMG recordings were used to verify muscle relaxation during stretch. Quadriceps pain was measured on a scale of 0–10 (0 = no discomfort, 10 = walking with a limp). Data were analyzed using repeated measures analysis of variance. RESULTS: There was significant strength loss (P<0.05) and pain (P<0.01) following the eccentric exercise, peaking two days post-exercise (strength loss 25%, pain 4.1/10). There was no significant change in passive stiffness (P = 0.25): stiffness was 110% of baseline immediately post-exercise and 97%, 103% and 99% of baseline on the subsequent three days. CONCLUSION: Previous studies (Whitehead et al 2001; Howell et al 1993) have demonstrated dramatic increases in passive muscle stiffness in the plantarflexors (140% of baseline) and elbow flexors (200% of baseline) following damaging bouts of eccentric exercise. By contrast, in the present study, stiffness in the knee extensors was not increased, despite marked strength loss and pain. Stiffness changes following eccentric exercise appear to be independent of other symptoms of damage and may be more dependent on the size of the exercising muscle group.

Effect of cryotherapy on muscle soreness and strength following eccentric exercise.

The purpose of this study was to determine whether a post-exercise cryotherapy protocol could facilitate recovery of elbow flexor strength and reduce the severity of delayed onset muscle soreness following eccentric exercise. Eight resistance-trained males (23 +/- 3 yr) performed 64 eccentric elbow flexions with each arm. One arm was subjected to five, 20 minute immersions in a 5 +/- 1 degree C ice-water bath interspersed by 60 minute rest periods. The non-immersed arm served as the control. A main effect for time was observed for all dependent variables (p < 0.05). Isometric torque (mean SE) decreased from a pre-exercise value of 87.9 +/- 4.5 Nm to 65.2 +/- 4.5 Nm immediately post-exercise. Isokinetic torque at 60 and 300 degrees x s(-1) decreased from 71.0 +/- 3.5 NM and 48.4 +/- 2.8 Nm to 55.8 +/- 3.3 Nm and 39.8 +/- 3.1 Nm, respectively. All torque measures returned to pre-test levels by 72 h. Muscle soreness peaked 48 h post-exercise and was evident until 120 h. Limb volume increased by 200 +/- 18 ml immediately post-exercise (p < 0.05) but was not significantly elevated thereafter. No significant difference between the immersed and control arms were observed for any variable. The result suggest that the use of cryotherapy immediately following damaging eccentric exercise may not provide the same therapeutic benefits commonly attributed to cryotherapy following traumatic muscle injury.

The protective effect of damaging eccentric exercise against repeated bouts of exercise in the mouse tibialis anterior muscle.

Using a damaging eccentric exercise regime of the mouse tibialis anterior (TA) muscle we have investigated the extent and time course of protection afforded by one bout of exercise against damage resulting from a second bout of activity. Maximal force and fibre morphology were preserved if the exercise was repeated within 21 days, but by 84 days muscles once again became susceptible to damage. Low-frequency force loss had a shorter time course of protection against repeated exercise, lasting less than 21 days. The results provide evidence for different mechanisms contributing to the development of muscle damage following eccentric exercise and provide a basis for characterizing the adaptive response of muscle to damaging exercise.

Acute phase response in exercise. II. Associations between vitamin E, cytokines, and muscle proteolysis

Cytokines such as interleukin 1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin 6 (IL-6) mediate a variety of host responses to trauma and infection, including skeletal muscle proteolysis. This investigation assesses the influence of damaging eccentric exercise on in vitro production and plasma concentrations of cytokines and their relationship to muscle protein breakdown. In a double-blind placebo-controlled protocol, 21 male subjects took vitamin E supplements (800 IU/day) for 48 days, then ran downhill on an inclined treadmill. Twenty-four hours after this single session of eccentric exercise, endotoxin-induced secretion of IL-1 beta was augmented 154% (P less than 0.01) in cells obtained from the placebo subjects, but no significant exercise-related changes were observed in cells from the vitamin E-supplemented subjects. TNF-alpha secretion was also significantly increased 24 h after exercise, but the response was not inhibited by vitamin E. In contrast, IL-6 secretion did not change after exercise, but dietary vitamin E supplementation significantly reduced IL-6 secretion throughout the 12-day period of observation (P = 0.023). Urinary 3-methylhistidine excretion correlated with mononuclear cell secretion of both IL-1 beta (P less than 0.05) and prostaglandin E2 (P less than 0.05), supporting the concept that these mononuclear cell products contribute to the regulation of muscle proteolysis.

Availability of substrates and capacity for prolonged heavy exercise in man.

Availability of substrates and capacity for prolonged heavy exercise in man.