Low-intensity Eccentric Exercise Research Articles

Repeated bout effect and muscle damage at variable eccentric exercise intensities in active young men: a longitudinal repeated measures investigation

Abstract Exercise-induced muscle damage (EIMD) and repeated bout effect (RBE) are widely researched across various populations and at various intensities. Despite the existence of vast literature, there is lack of comparison of low versus submaximal versus maximal intensity required for preconditioning. The aim of the study was to compare the muscle damage and RBE at various intensities of eccentric exercise in active young men. Thirty-six healthy, physically active men were recruited and randomly assigned to three different groups low-high (L-H, n = 12), submaximal-high (M-H, n = 12) and maximal-high (H-H, n = 12). All participants performed 2 exercise bouts separated by 14 days. L-H, M-H and H-H groups performed low (10% of 1RM), moderate (50% of 1RM) and high (90% of 1RM) intensity eccentric exercise for knee extensors, respectively, in the 1st bout followed by high (100% of 1RM) intensity in the second bout. Muscle soreness (SOR), thigh circumference (CIR), maximal voluntary isometric contraction (MVIC), range of motion (ROM) and blood lactate (Bl Lac) were measured before, immediately, at 24 h, at 48 h and at 72 h after exercise. A significant effect of time appeared for MVIC (), CIR (), ROM () and Bl Lac (). The bout × time interaction, as well as bout × time × group interaction was also found significant indicating changes in muscle strength and ROM. Circumference changed significantly with a significant bout × group interaction effect . SOR () was significant between the bouts. Therefore, exhibiting attenuation of muscle damage markers after the second bout. Findings of the present study showed that muscle damage was evident at all three intensities. Moreover, it was greater after moderate and high intensity as compared to low intensity eccentric exercise. RBE was elicited after three intensities indicating their role in preconditioning the muscles of active men.

Protective effect by low-intensity downhill running training against muscle damage and oxidative stress after high-intensity downhill running in rats.

This study examined the effects of low-intensity eccentric exercise training performed before high-intensity eccentric exercise on muscle damage markers, oxidative stress and antioxidant defense. Twenty-two rats were divided into 3 groups; control (CON; n = 6), high-intensity eccentric exercise (HE; n = 8) and low-intensity eccentric exercise training plus high-intensity eccentric exercise (LET + HE; n = 8). Rats in the HE group performed HE at once. Rats in the LET + HE group performed LET and then HE protocol was applied. Blood and vastus intermedius muscle samples were taken 24 hours after the last exercise session for analyses of muscle damage, oxidative stress, and antioxidant defense markers. Muscle damage markers were higher in the HE group than the CON (137%-488%) and the LET + HE groups (82%-110%) (P < 0.05). Oxidative stress marker was higher in the HE group than the CON (65%) and the LET + HE (50%) groups (P < 0.05). Antioxidant defense markers were higher in the LTE + HE group than the HE group (39%-51%) (P < 0.05). In conclusion, low-intensity eccentric exercise training performed before high-intensity eccentric exercise conferred a protective effect against muscle damage by reducing oxidative stress and increasing antioxidant defense.

Striking muscle adaptations induced by volume-dependent repeated bouts of low-intensity eccentric exercise of the elbow flexors.

We investigated the effects of repeating 30 low-intensity eccentric contractions with a dumbbell corresponding to 10% maximal isometric strength (10%EC) on muscle strength and hypertrophy, and muscle damage after 30 maximal eccentric contractions (MaxEC) of the elbow flexors. Young men were placed into 1 of 3 experimental groups that performed 10%EC either once, twice a week for 4 (8 bouts) or 8 weeks (16 bouts) before MaxEC, or a control group that performed 2 bouts of MaxEC separated by 2 weeks (n = 13/group). Repeating 16 bouts of 10%EC increased (P < 0.05) maximal voluntary contraction strength (30 ± 21%) and muscle thickness (4.2 ± 2.3%) greater than 8 bouts (16 ± 4%, 1.9 ± 1.3%). Changes in the muscle damage markers after MaxEC were smaller (P < 0.05) for the experimental groups than the control group, and the magnitude of muscle damage protection was greater (P < 0.05) after 16 bouts (65 ± 30%) than 8 bouts (55 ± 33%), followed by 1 bout (34 ± 27%). The protection by 16 bouts was similar (P = 0.81) to that shown by the second MaxEC of the control group. These results showed that 10%EC produced potent muscle adaptation effects accumulatively and conferred muscle damage protection, but 1 bout of 10%EC was still effective for conferring approximately 20% of the protection of that by 16 bouts. Novelty: Repeating low-intensity eccentric exercise induces large increases in muscle strength and hypertrophy. Low-intensity eccentric exercise protects muscle damage induced by maximal eccentric contractions, and the protection is reinforced by repeating it. These are especially beneficial for individuals who are frail and cannot tolerate high-intensity resistance training.

The Effect of Eccentric Resistance Training with and Without Blood Flow Restriction on Serum IL6 and MMP9 Levels in Young Active Men

Background: It has been assumed that during and after BFR exercises, many blood factors are activated and angiogenesis response is stimulated in the arteries. Objectives: Therefore, the current study aimed to determine the effect of two eccentric resistance training methods with and without blood flow restriction on serum IL6 and MMP9 levels in active young men. Methods: In this quasi-experimental study, 16 healthy men with a mean age of 27.8 ± 2.85 (years), the weight of 79.4 ± 12.4 (kg), and a body mass index of 25.5 ± 3.7 (kg/m2) were randomly assigned to either low-intensity eccentric group with BFR or the high-intensity eccentric without BFR. The high-intensity (70% - 80% maximum voluntary contraction MVC) eccentric exercise without BFR included 3 - 5 cycles of eccentric contraction of the quadriceps muscles, up to exhaustion, whereas low-intensity eccentric exercise executed similar exercise modality at intensity of 20% - 30% MVC with blood flow restriction up to exhaustion. Blood samples were taken from antecubital both before and after the exercise to measure serum IL6 and MMP9 values using the ELISA method. Data were analyzed using paired t-test and analysis of variance with repeated measure test in SPSS version 22. A P value of &lt; 0.05 was defined as statistically significant. Results: High-intensity resistance per se and low-intensity resistance exercise with BFR similarly resulted in a non-significant reduction of IL-6 and elevated levels of MMP-9 serum levels in active young men. Conclusions: Overall, the results indicated that a low-intensity resistance exercise session with restricted blood flow and a high-intensity resistance exercise without blood flow restriction equally did not affect IL6 and MMP9 serum of active young men. Further studies are needed to clarify the exact exercise modality that sufficiently stimulates angiogenesis.

Effect Of Low Intensity Eccentric Exercise Training On Maximal Eccentric Exercise İnduced Muscle Damage

PURPOSE: The aim of this study was to investigate the effects of low-intensity eccentric exercise performed before maximal eccentric exercise which causes muscle damage and oxidative stress on muscle injury markers and oxidative stress. METHODS: The study was carried out with 22 male Wistar albino rats obtained from Experimental Animal Research and Application Center of Selcuk University. Rats were randomly divided into 3 groups. Rats in the control group (K, n: 6) were not given any exercise protocol. The maximal eccentric exercise protocol was applied to the rats in the maximal eccentric exercise group (M, n: 8) only one at rate of 20 m / min, at -150 inclination for 90 min. Low intensity eccentric exercise protocol, which does not cause muscle damage was applied to the rats in the low intensity eccentric exercise + maximal eccentric exercise group (DY+M, n: 8) at 10 m / min, at -150 inclination, 30 min / day for one week and maximal eccentric exercise protocol was applied 24 hours after this exercise. Blood and muscle tissue samples were taken 24 hours after the last exercise session and creatine kinase (CK), lactate dehydrogenase (LDH) and superoxide dismutase (SOD1) activities and myoglobin (Mg), malondialdehyde (MDA) and glutathione (GSH) levels were measured. RESULTS: Serum Mg level was higher in the M group compared to the DY+M and the K groups. Serum CK and LDH activities were higher in the DY+M and the M groups compared to the K group. MDA level was higher in M group compared to K and DY+M groups in vastus intermedius muscle, in M group compared to the K group in gastrocnemius muscle and in the DY+M and the M groups compared to the K group in plasma. GSH level in the vastus intermedius muscle and plasma was higher in the DY+M group compared to the M group. GSH level in gastrocnemius muscle was not different between groups. SOD1 activity was higher in the DY+M group compared to the K group in the vastus intermedius muscle, in the DY+M group compared to the K and the M groups in the gastrocnemius muscle. SOD1 activity in plasma was not different between groups. CONCLUSIONS: Low intensity eccentric exercise training applied before the maximal eccentric exercise has a partial protective effect against muscle damage, especially in the vastus intermedius muscle prevents the formation of oxidative stress and strengthens the antioxidant defense.

ACUTE EFFECT OF LOW-INTENSITY ECCENTRIC EXERCISE ON ANGLE OF PEAK TORQUE IN SUBJECTS WITH DECREASED HAMSTRING FLEXIBILITY

Decreased hamstring flexibility and the angle of peak torque (APT) occurring at a shorter muscle length are considered risk factors for hamstring strain injury. Subjects with decreased hamstring flexibility have an APT that occurs at a shorter muscle length; hence, the susceptibility to hamstring strain injury could be associated with the APT occurring at a shorter muscle length. Low-intensity eccentric exercise (ECC-Ex) may reduce hamstring strain injury risk in the subjects with decreased hamstring flexibility by allowing the APT to occur a longer muscle length. However, the acute effect of low-intensity ECC-Ex on the subjects with decreased hamstring flexibility has not been established. The purpose of this study was to investigate the acute effect of low-intensity ECC-Ex on the peak torque, APT, and hip flexion angle in the subjects with decreased hamstring flexibility. The authors hypothesized that low-intensity ECC-Ex would shift the APT, allowing it to occur at a longer muscle length with a minimum decrease of peak torque and hip flexion angle in the subjects with decreased hamstring flexibility. Case-control study. Twelve male college students were categorized into normal group [n = 6 (12 legs)] and decreased hamstring flexibility group [n = 6 (12 legs)] based on the median value of the baseline hip flexion angle (i.e., 80.8 °) measured by passive straight leg raise test. Peak torque and APT during maximal voluntary eccentric knee flexion (via isokinetic dynamometer) and hip flexion angle were evaluated before and after the low-intensity ECC-Ex in both groups. Low-intensity ECC-Ex shifted the APT, causing it to occur at a longer muscle length in the decreased hamstring flexibility group. Low-intensity ECC-Ex increased the hip flexion angle and did not change the peak torque in both groups. The results of the present study demonstrated that low-intensity ECC-Ex shifts the APT to occur at a longer muscle length and increases the hip flexion angle without a decrease in peak torque in the subjects with the decreased hamstring flexibility. 3b.

The Effect Of Low Intensity Eccentric Exercise On Torque angle Relationship, Muscle Strength And Flexibility

The Effect Of Low Intensity Eccentric Exercise On Torque angle Relationship, Muscle Strength And Flexibility

The effect of eccentric exercise with blood flow restriction on neuromuscular activation, microvascular oxygenation, and the repeated bout effect.

To examine the effect of low-intensity eccentric contractions with and without blood flow restriction (BFR) on microvascular oxygenation, neuromuscular activation, and the repeated bout effect (RBE). Participants were randomly assigned to either low-intensity (LI), low-intensity with BFR (LI-BFR), or a control (CON) group. Participants in LI and LI-BFR performed a preconditioning bout of low-intensity eccentric exercise prior to about of maximal eccentric exercise. Participants reported 24, 48, 72, and 96h later to assess muscle damage and function. Surface electromyography (sEMG) and near-infrared spectroscopy (NIRS) were used to measure neuromuscular activation and microvascular deoxygenation (deoxy-[Hb + Mb]) and [total hemoglobin] ([THC]) during the preconditioning bout, respectively. During set-2, LI-BFR resulted in greater activation of the VM-RMS (47.7 ± 11.5% MVIC) compared to LI (67.0 ± 20.0% MVIC), as well as during set-3 (p < 0.05). LI-BFR resulted in a greater change in deoxy-[Hb + Mb] compared to LI during set-2 (LI-BFR 13.1 ± 5.2µM, LI 6.7 ± 7.9µM), set-3 (LI-BFR 14.6 ± 6µM, LI 6.9 ± 7.4µM), and set-4 (p < 0.05). [THC] was higher during LI-BFR compared to LI (p < 0.05). All groups showed a decrease in MVIC torque immediately after maximal exercise (LI 74.2 ± 14.1%, LI-BFR 75 ± 5.1%, CON 53 ± 18.6%). At 24, 48, 72, and 96h post maximal eccentric exercise, LI and LI-BFR force deficit was not different from baseline. This study suggests that the neuromuscular and deoxygenation (i.e., metabolic stress) responses were considerably different between LI and LI-BFR groups; however, these differences did not lead to improvements in the RBE inferred by performing LI and LI-BFR.

저강도 원심성 운동과 동적 스트레칭이 지연성 근육통에 미치는 효과 비교

We investigated to compare the effects of a low intensity eccentric exercise and dynamic stretching on symptoms of delayed onset muscle soreness (DOMS). The eighteen women who had not participated in a regular exercise programme for the lower extremities in the previous five months were randomly assigned to one of three experimental groups: control group, a low intensity eccentric exercise group and dynamic stretching group. We measured the joint range of motion (ROM), maximal voluntary isometric exercise (MVIC), muscle soreness rating scale and ultrasound image measurement before eccentric exercise inducing DOMS, and 24, 48, and 72 hours after an eccentric exercise inducing DOMS. The exercise programme in a low intensity eccentric exercise group and dynamic stretching group were respectively performed 3 times a week for 4 weeks before eccentric exercise inducing DOMS. There was significantly different between the groups in muscle soreness rating scale and MVIC (p<.05). However, there was not significantly different between groups in ultrasound image measurement and ROM (p<.05). These results suggest that a low intensity eccentric exercise group and dynamic stretching group effectively reduced muscle soreness rating scale out of the symptoms of DOMS. A low intensity eccentric exercise group may be an effective improvement than dynamic stretching group in muscle soreness rating scale.

Muscle damage protection by low-intensity eccentric contractions remains for 2 weeks but not 3 weeks

This study investigated the hypothesis that the protective effect conferred by a low-intensity eccentric exercise against maximal eccentric exercise would not last more than a week. Untrained men (21.3 ± 1.6 years) were allocated into either a control or one of four repeated bout groups (n = 13 per group). The repeated bout groups performed 30 low-intensity eccentric contractions (ECC) of the elbow flexors with a dumbbell set at 10% of maximal isometric strength (10%-ECC) either 2 days, 7 days (1 week), 14 days (2 weeks) or 21 days (3 weeks) before 30 maximal eccentric contractions (Max-ECC). The control group performed Max-ECC only. Changes in maximal voluntary contraction strength, optimum angle, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase activity and myoglobin concentration, and ultrasound echo-intensity following 10%-ECC were analysed by a one-way repeated measures ANOVA. Changes in the variables following Max-ECC were compared among the groups by a two-way repeated measures ANOVA. The 10%-ECC did not change any variables, showing no indication of muscle damage. The changes in all variables following Max-ECC were smaller (P < 0.05) for 2-day, 1- and 2-week groups than control group, without significant differences between 2-day and 1-week groups. The 2-week group showed greater (P < 0.05) changes in all variables compared with 2-day and 1-week groups. Changes in the variables were similar between 3-week and control groups, except for muscle soreness showing smaller (P < 0.05) changes for 3-week group. These results suggest that non-damaging eccentric exercise confers a protective effect against Max-Ecc, but the effect is attenuated between 1 and 2 weeks.

Potent Protective Effect Conferred by Four Bouts of Low-Intensity Eccentric Exercise

It is known that submaximal eccentric exercise does not confer as strong a protective effect as maximal eccentric exercise. This study tested the hypothesis that four bouts of submaximal eccentric exercise would confer a similar protective effect to one bout maximal eccentric exercise. Thirty untrained men were placed into 4 x 40% (40%) or control (CON) groups (n = 15 per group) by matching preexercise maximal voluntary isometric contraction strength (MVC). The 40% group performed 30 eccentric contractions with a load of 40% MVC (40% ECC) every 2 wk for four times followed 2 wk later by 30 maximal eccentric exercise (100% ECC) of the elbow flexors of the nondominant arm. The CON group performed two bouts of the 100% ECC separated by 2 wk. MVC at six angles, optimum angle (OA), concentric isokinetic strength (30 degrees x s(-1) and 300 degrees x s(-1)), range of motion, upper arm circumference, plasma creatine kinase activity and myoglobin concentration, muscle soreness, and echo intensity of B-mode ultrasound images were taken before to 5 d after each exercise. No significant differences in the changes in any measures were evident between the 100% ECC of the 40% group and the second 100% ECC of the CON group. Changes in all measures except for OA and upper arm circumference after the second to the fourth 40% ECC bouts were significantly smaller than those after the first 40% ECC bout. The changes in the measures after any of the 40% ECC bouts were significantly (P < 0.05) smaller than those after the first 100% ECC bout of the CON group. These results suggest that repeating submaximal eccentric exercise confers the same magnitude of protective effect as one bout of maximal eccentric exercise against the subsequent maximal eccentric exercise.

Neuromuscular fatigue following high versus low-intensity eccentric exercise of biceps brachii muscle

Purpose This study investigated neuromuscular fatigue following high versus low-intensity eccentric exercise corresponding to the same amount of work. Methods Ten volunteers performed two eccentric exercises of the elbow flexors: a high-intensity versus a low-intensity exercise. Maximal voluntary contraction torque and surface electromyography of the biceps brachii muscle were recorded before, immediately and 48 h after exercises. Maximal voluntary activation level, neural ( M-wave) and contractile (muscular twitch) properties of the biceps brachii muscle were analysed using electrical stimulation techniques. Results Maximal voluntary contraction torque was significantly ( P < 0.01) reduced immediately and 48 h after exercise but the reduction was not different between the two conditions. Electromyography associated with maximal voluntary contraction significantly decreased ( P < 0.05) immediately and 48 h after exercise for both conditions while maximal voluntary activation level was only significantly reduced immediately after the high-intensity exercise. Peak twitch alterations were observed immediately and 48 h after exercise for both conditions while M-wave did not change. Conclusion High and low-intensity eccentric exercises with the same amount of work induced the same reduction in maximal strength capacities of the biceps brachii muscles. The magnitude of peripheral and central fatigue was very similar in both conditions.

EQUAL VOLUMES OF HIGH AND LOW INTENSITY OF ECCENTRIC EXERCISE IN RELATION TO MUSCLE DAMAGE AND PERFORMANCE

We examined differences in muscle damage and muscle performance perturbations in relation to the same volumes of high (HI) and low intensity (LI) of eccentric exercise. Untrained young healthy men (n = 12) underwent 2 isokinetic quadriceps eccentric exercise sessions, 1 on each randomly selected leg, separated by a 2-week interval. In the first session subjects performed HI exercise (i.e., 12 sets of 10 maximal voluntary efforts). In the second session, volunteers were subjected to continuous exercise of LI (50% of peak torque) until the total work done was approximately equal to that generated during HI. Muscle damage (serum creatine kinase concentration [CK], delayed onset of muscle soreness, and range of motion) and muscle performance (eccentric [EPT] and isometric peak torque [IPT]) indicators were assessed pre-exercise and 24, 48, 72, and 96 hours postexercise. Compared to baseline data, changes in muscle damage indicators were significantly different (p < 0.05) at almost all post-exercise time points in both conditions. However, apart from the significant elevation of CK at 24 hours after HI (p < 0.05), no other significant differences were observed between the 2 exercise conditions (p > 0.05). The main finding in relation to muscle performance was that decrements following HI exercise were significantly greater (p < 0.05) compared to LI. Compared with baseline data, the EPT values following HI and LI exercise were as follows: 24 hours, 72.1% vs. 92%; 48 hours, 81.9% vs. 94.8%; 72 hours, 77.7% vs. 100.6%; 96 hours, 86.8% vs. 107.9%. The corresponding data for IPT were as follows: 24 hours, 86.4% vs. 102.8%; 48 hours, 84.2% vs. 107%; 72 hours, 84.8% vs. 109.2%; 96 hours, 86.8% vs. 114.4%. These results indicate that matching volumes of HI and LI eccentric exercise have similar effects on muscle damage, but HI has a more prominent effect on muscle performance.

Equal Volumes of High and Low Intensity of Eccentric Exercise in Relation to Muscle Damage and Performance

We examined differences in muscle damage and muscle performance perturbations in relation to the same volumes of high (HI) and low intensity (LI) of eccentric exercise. Untrained young healthy men (n = 12) underwent 2 isokinetic quadriceps eccentric exercise sessions, 1 on each randomly selected leg, separated by a 2-week interval. In the first session subjects performed HI exercise (i.e., 12 sets of 10 maximal voluntary efforts). In the second session, volunteers were subjected to continuous exercise of LI (50% of peak torque) until the total work done was approximately equal to that generated during HI. Muscle damage (serum creatine kinase concentration [CK], delayed onset of muscle soreness, and range of motion) and muscle performance (eccentric [EPT] and isometric peak torque [IPT]) indicators were assessed pre-exercise and 24, 48, 72, and 96 hours postexercise. Compared to baseline data, changes in muscle damage indicators were significantly different (p < 0.05) at almost all postexercise time points in both conditions. However, apart from the significant elevation of CK at 24 hours after HI (p < 0.05), no other significant differences were observed between the 2 exercise conditions (p > 0.05). The main finding in relation to muscle performance was that decrements following HI exercise were significantly greater (p < 0.05) compared to LI. Compared with baseline data, the EPT values following HI and LI exercise were as follows: 24 hours, 72.1% vs. 92%; 48 hours, 81.9% vs. 94.8%; 72 hours, 77.7% vs. 100.6%; 96 hours, 86.8% vs. 107.9%. The corresponding data for IPT were as follows: 24 hours, 86.4% vs. 102.8%; 48 hours, 84.2% vs. 107%; 72 hours, 84.8% vs. 109.2%; 96 hours, 86.8% vs. 114.4%. These results indicate that matching volumes of HI and LI eccentric exercise have similar effects on muscle damage, but HI has a more prominent effect on muscle performance.