Effects Of Eccentric Exercise Research Articles

The effects of eccentric exercise-induced muscle damage on running kinematics at different speeds

This study investigated the effects of knee localised muscle damage on running kinematics at varying speeds. Nineteen young women (23.2 ± 2.8 years; 164 ± 8 cm; 53.6 ± 5.4 kg), performed a maximal eccentric muscle damage protocol (5 × 15) of the knee extensors and flexors of both legs at 60 rad · s-1. Lower body kinematics was assessed during level running on a treadmill at three speeds pre- and 48 h after. Evaluated muscle damage indices included isometric torque, muscle soreness and serum creatine kinase activity. The results revealed that all indices changed significantly after exercise, indicating muscle injury. Step length decreased and stride frequency significantly increased 48 h post-exercise only at the fastest running speed (3 m · s-1). Support time and knee flexion at toe-off increased only at the preferred transition speed and 2.5 m · s-1. Knee flexion at foot contact, pelvic tilt and obliquity significantly increased, whereas hip extension during stance-phase, knee flexion during swing-phase, as well as knee and ankle joints range of motion significantly decreased 48 h post-exercise at all speeds. In conclusion, the effects of eccentric exercise of both knee extensors and flexors on particular tempo-spatial parameters and knee kinematics of running are speed-dependent. However, several pelvic and lower joint kinematics present similar behaviour at the three running speeds examined. These findings provide new insights into how running kinematics at different speeds are adapted to compensate for the impaired function of the knee musculature following muscle damage.

Human alpha-actinin-3 genotype association with exercise-induced muscle damage and the repeated-bout effect

Alpha-actinin-3 (ACTN3) is an integral part of the Z line of the sarcomere. The ACTN3 R577X (rs1815739) polymorphism determines the presence or absence of functional ACTN3, which may influence the extent of exercise-induced muscle damage. This study aimed to compare the impact of, and recovery from, muscle-damaging eccentric exercise on subjects with or without functional ACTN3. Seventeen young men (20-33 years old), homozygous for the R (n = 9) or X (n = 8) alleles, performed two bouts of stretch-shortening exercise (50 drop jumps) two weeks apart. Muscle soreness, plasma creatine kinase (CK) activity, jump height, maximal voluntary isometric torque (MVC), peak concentric isokinetic torque (IT), and electrically stimulated knee extension torques at 20 and 100 Hz were measured at baseline and at a number of time points up to 14 days after each bout. There were no significant baseline differences between the groups. However, significant time point × genotype interactions were observed for MVC (p = 0.021) and IT (p = 0.011) for the immediate effect of eccentric exercise in bout 1. The RR group showed greater voluntary force decrements (RR vs. XX: MVC, -33.3% vs. -24.5%; IT, -35.9% vs. -23.2%) and slower recovery. A repeated-bout effect was clearly observed, but there were no differences by genotype group. The ACTN3 genotype modulates the response of muscle function to plyometric jumping exercise, although the differences are modest. The ACTN3 genotype does not influence the clearly observed repeated-bout effect; however, XX homozygotes recover baseline voluntary torque values faster and thus may be able to undertake more frequent training sessions.

Erratum to: Effects of eccentric exercise on systemic concentrations of pro- and anti-inflammatory cytokines and prostaglandin (E2): comparison between young and postmenopausal women

Erratum to: Effects of eccentric exercise on systemic concentrations of pro- and anti-inflammatory cytokines and prostaglandin (E2): comparison between young and postmenopausal women

Effects of eccentric exercise on toll-like receptor 4 signaling pathway in peripheral blood mononuclear cells

This study aimed to investigate the response of the toll-like receptor 4 (TLR4) signaling pathway to an acute bout of eccentric exercise, and to assess whether eccentric training attenuated the effects induced by acute eccentric exercise. Twenty men (22.4 ± 0.5 yr) were divided into a control group (CG, n = 8) and a training group (TG, n = 12). Both groups performed two acute eccentric bouts on a squat machine in a 9-wk interval. During this time, TG followed a 6-wk eccentric training program (3 session/wk; 3-5 sets of 10 repetitions with loads ranging between the 40 and 50% of maximal isometric voluntary contraction). CD14, TLR4, and TNF-α mRNA levels, and CD14, TLR4, myeloid differentiation factor 88, tumor necrosis factor receptor-associated factor 6, TIR-domain-containing adapter-inducing interferon-β, phospho-IκB kinases, phospho-IκB, phospho-ERK-1/2, and TNF-α protein concentration were measured in peripheral blood mononuclear cells, before, immediately, and 2 h after each eccentric bout. The first acute eccentric bout triggered a proinflammatory response mediated by an upregulation of all of the factors measured within the TLR4 signaling pathway. Following the training period and after the second acute bout, CG showed a similar proinflammatory response than that seen after the first bout. However, the eccentric training intervention decreased significantly the protein concentration of all factors analyzed in TG compared with results obtained after the first bout. These results suggest that the TLR4-signaling pathway plays a critical role in the proinflammatory response seen after acute eccentric exercise. This response was attenuated after an eccentric training program through myeloid differentiation factor 88-dependent and -independent pathways.

Effects of eccentric exercise on systemic concentrations of pro- and anti-inflammatory cytokines and prostaglandin (E2): comparison between young and postmenopausal women

The present study aimed to analyze the magnitude of muscle damage and inflammatory responses induced by eccentric exercise in young (YW) and postmenopausal women (PMW). Seventeen healthy women (nine YW, 23.89 ± 2.03 years; and eight PMW, 51.13 ± 5.08 years) performed five sets of six maximal eccentric actions of the elbow flexors. Changes in isometric strength, range of motion, muscle soreness, and upper-arm circumference were evaluated pre, post, 24, 48, and 72 h following eccentric exercise. Changes in creatine kinase activity, interleukin 6 (IL-6), interleukin 10 (IL-10), tumor necrosis factor-α (TNF-α), and prostaglandin E(2) (PGE(2)) were measured pre, 24, 48, and 72 h following eccentric exercise. For intra and inter-group analysis, a two-way repeated measures ANOVA was applied followed by a Tukey's post hoc test. Pearson's correlation was used to analyze the correlations between variables. It was observed no differences between groups for the markers of muscle damage, although significant modifications (p < 0.05) occurred within groups throughout time for all variables. Post menopausal women showed significantly higher values for TNF-α (p < 0.05). Also, IL-6 presented superior pre value for PMW. For YW, IL-6 and IL-10 values increased 72 h post-eccentric exercise compared to pre. Further, IL-10 was higher for YW than PMW 72 h post-eccentric exercise. Significant correlations (p < 0.05) were found between age and soreness, and between age and PGE(2). In conclusion, YW do not have attenuated muscle damage compared to PMW who do not make use of hormonal replacement therapy. In addition, YW have a greater anti-inflammatory response after eccentric exercise compared to PMW.

Forearm muscle blood flow following eccentric exercise

Exercise-induced muscle injury is associated with performing exercise that involves eccentric contractions. Although the effects of eccentric exercise on muscle injury are well known, previous studies investigating muscle blood flow following eccentric exercise have revealed conflicting results. The purpose of this study was to examine forearm muscle blood flow (FBF) during submaximal handgrip exercise following eccentric exercise of the elbow flexors. Seven healthy male subjects (27.9 ± 3.7 yrs; ± SD) performed two bouts (5 min) of dynamic handgrip exercise at 10% of maximal handgrip strength before and 48 hrs following damaging exercise (2 × 25 maximal eccentric contractions). Mean blood velocities (MBV) were measured continuously in the brachial artery using Doppler ultrasound. FBF was calculated using arterial diameters obtained at rest (Pre; 4.06 ± 0.34 mm: Post; 4.21 ± 0.30 mm, p>0.05). Despite a significant decrease (p<0.05) in maximal biceps brachii isometric strength from pre- (16.9 ± 3.6 kg) to post-injury (12.9 ± 4.6 kg), there was no difference in FBF at rest (Pre; 15.7 ± 4.1 ml/min: Post; 18.4 ± 5.4 ml/min) or at end exercise (Pre; 144.9 ± 34.7 ml/min: Post; 158.3 ± 28.4 ml/min) between conditions. It is concluded that muscle injury does not alter FBF during submaximal handgrip exercise suggesting that mediators involved in muscle injury and repair do not contribute to the regulation of muscle blood flow.

The acute response of tendon to loading: implications for rehabilitation

Achilles tendinopathy is a common disorder involving physically active and sedentary individuals alike. Although the processes underlying its development are poorly understood, tendinopathy is widely regarded as an ‘overuse’ injury in which the tendon fails to adapt to prevalent loading conditions. Paradoxically, there is emerging evidence that heavy eccentric loading of the Achilles tendon may be an effective conservative approach for treatment of tendinopathy, with success rates of 60–80% reported. Interestingly, loading exercises involving other forms of muscle action, such as concentric activation, have been shown to be less effective treatment options. However, little is known about the acute response of tendon to exercise at present, and there are few plausible explanatory mechanisms for the observed beneficial effects of eccentric exercise, as opposed to other forms of strain stimuli. This paper presents the findings from a series of experiments undertaken to evaluate the effect of various strain stimuli on the time-dependent response of human Achilles tendon in vivo. It was shown for the first time, that heavy resistive ankle plantarflexion/ dorsiflexion exercises induced an immediate and significant decrease in Achilles tendon thickness (~15%). While thickness returned to pre-exercise levels within 24 hours, the recovery was exponential, with primary recovery occurring in less than 6 hours post-exercise. We proposed that such a diametral strain response with tensile loading reflects collagen realignment, Poison’s effects and radial extrusion of water from the tendon core. With unloading, the recovery of tendon dimensions likely reflects the re-diffusion of water via osmotic and/or inflammatory driven processes. Interestingly, prolonged walking was found to induce a similar diametral strain response. In subsequent studies, we demonstrated that eccentric exercise resulted in a greater reduction (-21%) in Achilles tendon thickness than isolated concentric exercise alone (-5%), despite a similar loading impulse. These novel findings, coupled with observations of a reduced diametral strain response with tendon pathology, highlight the importance of fluid movement to tendon function, nutrition and health. They also provide new insights into potential mechanisms underlying Achilles tendinopathy that impact rehabilitation strategies.

Possession Of Slc30a8 TT Genotype Mitigates The Effects Of Eccentric Exercise In Men

Possession Of Slc30a8 TT Genotype Mitigates The Effects Of Eccentric Exercise In Men

A Muscle's Functional Role Influences the Effect of Eccentric Exercise on Arm Movement Kinematics

A Muscle's Functional Role Influences the Effect of Eccentric Exercise on Arm Movement Kinematics

Biomechanical characteristics of the eccentric Achilles tendon exercise

Background Eccentric exercise has been shown to provide good short-term clinical results in the treatment of painful mid-portion chronic Achilles tendinopathies. However, the mechanisms behind the positive effects of eccentric rehabilitation regimes are not known, and research into the biomechanics of the exercise may improve our understanding. Methods Sixteen healthy subjects performed one-legged full weight bearing ankle plantar and dorsiflexion exercises during which three-dimensional ground reaction forces (GRF), ankle joint kinematics and surface electromyography (EMG) of the lower leg muscles were recorded. Joint kinematics, GRF frequency contents, average EMG amplitudes, and Achilles tendon loads were calculated. Findings The eccentric movement phase was characterized by a higher GRF frequency content in the 8–12 Hz range, and reduced EMG activity in the lower leg muscles. No differences in Achilles tendon loads were found. Interpretation This descriptive study demonstrates differences in the movement biomechanics between the eccentric and concentric phases of one-legged full weight bearing ankle dorsal and plantar flexion exercises. In particular, the findings imply that although the tendon loads are similar, the tendon is vibrated at higher frequencies during the eccentric phase than during the concentric phases. This study provides data that may explain the mechanisms behind the effectiveness of eccentric exercises used in the treatment of Achilles tendinopathies.

Eccentric Exercise Alters The Kinematic Structure Of Pointing Movements

It is known that the performance of eccentric muscle contractions often leads to delayed muscle soreness accompanied by declines in strength and isometric force steadiness. However, the effect of eccentric exercise on the performance of a dynamic motor task is not clear. PURPOSE: To examine the effects of a bout of eccentric exercise on kinematic measures related to accuracy (i.e. submovements) during spatially-constrained pointing movements. METHODS: 17 untrained subjects (10 M, 7 F; 26 ± 3 yrs.) performed 20 rapid discrete elbow-extension pointing movements with their right arm before, immediately after (fatigue and muscle damage), and 24-hours after (muscle damage only) fatiguing eccentric exercise on a isokinetic dynamometer. Endpoint (fingertip) movement kinematics were obtained for each pointing trial and examined for secondary submovements indentified by zero crossings in the tangential velocity and acceleration profiles. RESULTS: MVC force declined by 44% immediately after eccentric exercise and remained depressed (22%) 24-hrs after the exercise indicating the existence of muscle damage. Movement times were slower and peak velocity decreased immediately after, and only partially recovered 24-hrs after the exercise compared with before (222 ± 40, 248 ± 37 and 238 ± 42ms, P<0.05; 3.4 ± 0.6, 3.1 ± 0.6 and 3.3± 0.7m/s, P<0.01). Only 8% of the trials exhibited submovements before the eccentric exercise, however that number grew to 87% of trials immediately afterward and 29% of trials 24 hrs after. In those trials requiring submovements, subjects traveled 85 ± 8, 64 ± 6 and 72 ± 11% (P<0.001) of the total movement time before using a secondary submovement. CONCLUSIONS: These results demonstrate that kinematic measures associated with movement accuracy are altered from eccentric exercise and only partially restored after 24 hrs.

Effect of eccentric exercise on insulin resistance and skeletal muscle GLUT-4 protein expression of type Ⅱ diabetes rats

Effect of eccentric exercise on insulin resistance and skeletal muscle GLUT-4 protein expression of type Ⅱ diabetes rats

The effect of eccentric exercise on lower limbs muscle activity, muscle fatigue, and blood creatine kinase activity

The effect of eccentric exercise on lower limbs muscle activity, muscle fatigue, and blood creatine kinase activity

Effect of eccentric exercise on the healing process of injured patellar tendon in rats

BackgroundEarlier studies have reported positive results from eccentric training in patients with tendon disorders. The reasons for the beneficial clinical effects of eccentric training are not known. Vascularization followed by regression of the vasculature enhances the healing response of injured tendons. Eccentric exercise induces a more beneficial healing response than concentric exercise. MethodsSixty rats with patellar tendon injuries were divided into three groups: nonexercise controls (group N; n = 20); concentric exercise group (group C; n = 20); eccentric exercise group (group E; n = 20). Each rat was taught to run uphill or downhill for 14 days. Patellar tendons were removed 1, 4, 7, 10, and 14 days following injury. Vascular endothelial growth factor (VEGF), angiopoietin-1, and angiopoietin-2 were measured by reverse transcription polymerase chain reaction. ResultsIn group C, VEGF mRNA was increased 1 and 4 days following injury but was decreased on days 7, 10, and 14. In group E, VEGF mRNA was elevated only on day 1. In group N, VEGF mRNA remained at a low level throughout all 14 days. The angiopoietin-2/angiopoietin-1 ratio was higher for group C than for group E. ConclusionsIn the presence of VEGF, angiopoietin-1 promotes vessel stability, whereas angiopoietin-2 has the opposite effect. Eccentric exercise contributes to stabilized angiogenesis during the early phase of tendon injury. Conversely, concentric exercise, which induces destabilized angiogenesis, leads to a delayed healing response. Initiation of eccentric exercise immediately after tendon injury may help improve healing by reducing vascularity.

Effects of Eccentric Exercise on NF-κB Activation in Blood Mononuclear Cells

Effects of Eccentric Exercise on NF-κB Activation in Blood Mononuclear Cells

Effects of Eccentric Exercise on Passive Mechanical Properties of Human Gastrocnemius in vivo

In this study, we used a newly developed method for measuring passive length-tension relations of a single human muscle in vivo to quantify changes in the mechanical properties of the human gastrocnemius after eccentric exercise. Twelve subjects performed eccentric exercise on the right leg for 1 h by walking backward downhill on a treadmill. Passive ankle torque was measured as the ankle was rotated within its available range, with the knee in eight different angles. Subjects were studied before exercise, 1 h after exercise, and 24 h later, with further measurements at 48 h and at 1 wk in a subset of six subjects. Subjects also rated the level of perceived muscle soreness on a 10-point scale during walking on flat ground. We examined passive tension in the gastrocnemius at a standard length before and at various times after exercise. Muscle tension increased significantly at this length 1 h after exercise (34.7 +/- 7.3%; mean +/-SEM), peaked at 24 h (88.4 +/- 12.6%), declined at 48 h (45.5 +/- 4.4%), and returned to the control level at 1 wk. Stiffness of the gastrocnemius in the sitting and standing postures (i.e., at short and long lengths) was derived from passive length-tension relations. Stiffness increased after exercise, and the relative changes in muscle stiffness were similar in both positions. There was no apparent correlation between stiffness and subjective reports of muscle soreness during walking. This study provides the first specific measurements of the increase in stiffness of the human gastrocnemius in vivo after a single bout of eccentric exercise. The increase peaks at 24 h and is nearly fully resolved within 1 wk.

The Immediate Effects of Eccentric Exercise on Isokinetic Concentric Torque Production, Median Angle and Hamstring Extensibility

The Immediate Effects of Eccentric Exercise on Isokinetic Concentric Torque Production, Median Angle and Hamstring Extensibility

(698): Effects of eccentric exercise on pain and pain sensitivity in patients with fibromyalgia and normal controls: Evidence of functional anti-hyperalgesic mechanisms

(698): Effects of eccentric exercise on pain and pain sensitivity in patients with fibromyalgia and normal controls: Evidence of functional anti-hyperalgesic mechanisms

Effects of Eccentric Exercise on Joint Stiffness and Muscle Connectin (Titin) Isoform in the Rat Hindlimb

We investigated the effects of repeated eccentric exercise for rat medial gastrocnemius muscle on ankle joint stiffness and muscle connectin (titin) isoform composition (longer form, alpha-connectin; shorter form, beta-connectin). Male Wistar rats were trained on a custom-made, isokinetic dynamometer (eccentric-exercise group, n = 6; sham-operated group, n = 6). The exercise session consisted of 20 eccentric contractions elicited by submaximal electric stimulations under anesthesia. The contracting muscle was forcibly lengthened by an isokinetic dorsi-flexion of the ankle joint (velocity, 30 degrees/s; range of motion, 45 degrees). Rats in the eccentric-exercise group were trained every two days for 20 days (10 sessions in total). The static passive resistive torque (PRT) of 45 degrees at the ankle joint was used as a measure of the joint stiffness, and was determined before and after the experimental period. After 10 sessions of eccentric exercise, the wet weight of medial gastrocnemius muscle significantly increased (P < 0.05), whereas the static PRT significantly decreased (P < 0.05) in the eccentric-exercise group, when compared to the sham-operated group. Myosin-ATPase staining showed a decrease in the number of type IIb/IId fibers (P < 0.001) and an increase in the number of type IIa fibers (P < 0.05). However, no significant difference was seen in the connectin (titin) isoform composition between the eccentric-exercise group and the sham-operated group, suggesting that the reduction in PRT was not due to change in resting mechanical properties of muscle fibers.

Altering the Length-Tension Relationship with Eccentric Exercise

The effects of eccentric exercise on muscle injury prevention and athletic performance are emerging areas of interest to researchers. Of particular interest are the adaptations that occur after a single bout, or multiple bouts of eccentric exercise. It has been established that after certain types of eccentric exercise, the optimum length of tension development in muscle can be shifted to longer muscle lengths. Altering the length-tension relationship can have a profound influence on human movements. It is thought that the length-tension relationship is influenced by the structural makeup of muscle. However, the mechanism responsible for the shift in optimum length is not readily agreed upon. Despite the conflict, several studies have reported a shift in optimum length after eccentric exercise. Unfortunately, very few of these studies have been randomised, controlled training studies, and the duration of the shift has not yet been established. Nonetheless, this adaptation may result in greater structural stability at longer muscle lengths and consequently may have interesting implications for injury prevention and athletic performance. Both contentions remain relatively unexplored and provide the focus of this review.