High-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.

The Effect of Combining Blood Flow Restriction with the Nordic Hamstring Exercise on Hamstring Strength: Randomized Controlled Trial.

(1) Background: It is a matter of curiosity what effect the blood flow restriction (BFR) method, which is usually combined with low-intensity resistance exercises, will have when used with high-intensity eccentric exercises. (2) Methods: The present study examined the effects of combining BFR with nordic hamstring exercises (NHEs) on hamstring muscle strength, bilateral deficit (BLD), and training volume. Thirty young female volleyball players, who trained three times a week, participated voluntarily in the study. These players were stratified into three groups, each comprising ten individuals: a control group (CG), an NHE group, and an NHE + BFR group. Hamstring muscle strength and BLD values were determined using an H-BORD device, while training volume was measured in terms of sets and repetitions. (3) Results: Statistical analysis revealed that there were no statistically significant differences in non-dominant and dominant leg peak torque parameters in the exercise groups (F = 2.65; p = 0.097; ηp2 = 0.17; F = 1.15; p = 0.0334; ηp2 = 0.084), while the total training volume was lower in the NHE + BFR group. (4) Conclusions: As a result, it was seen that adding the BFR method to NHE did not provide additional gains. However, due to the low training volume of BFR + NHE, it may be recommended to apply BFR together with NHE to athlete groups.

Effects of branched-chain amino acid supplementation on skeletal muscle proteolytic pathways after exercise-induced muscle injury in rats

To explore the role of branched-chain amino acid(BCAA) supplementation on muscle damage and the regulation of Krüppel-like factor 15(KLF15) and nuclear factor kappa B(NF-κB) mediated proteolytic pathways after an acute eccentric exercise. Male SD rats were divided into placebo group(PLA) and BCAA group(BCAA) randomly, 32 rats per group. Both group were then placed into subgroups: placebo and pre-exercise group(PC), placebo and immediately after exercise group(PE), placebo and 6 h after exercise group(PE6), placebo and 12 h after exercise group(PE12), BCAA and pre-exercise group(BC), BCAA and immediately after exercise group(BE), BCAA and 6 h after exercise group(BE6), BCAA and 12 h after exercise group(BE12), 8 rats per group. Rats in BCAA groups were supplied with BCAA(1 g/(kg·d·BW), 3 days) before the exercise day and placebo groups with equal volume of distilled water. The exercised groups performed a 2 h eccentric exercise on treadmill(16 m/min, -16° slope). Blood and gastrocnemius were collected according to the time points. RT-qPCR was used to measure the mRNA expression of KLF15, NF-κB, FoxO1, Atrogin-1 and MuRF1 in gastrocnemius. (1) No damage was found in myocytes of BC and PC group. The process of morphological damage in BCAA group was relatively faster. (2) The mRNA expression levels of KLF15, FoXO1, Atrogin-1 and MuRF1 in PE were higher than those in PC(P<0.05, P<0.01), NF-κB and Atrogin-1 in PE12 were higher than those in PC(P<0.05). The mRNA expression levels of FoXO1 in BE were higher than those in BC(P<0.05). Compared with PE, the mRNA expression levels of KLF15, Atrogin-1 and MuRF1 in BE were lower(P<0.05, P<0.01), NF-κB and Atrogin-1 in BE12 were lower than those in PE12(P<0.05). The level of serum 3-MH in PE12 group was higher than that in PC group(P<0.05). The proteolysis of skeletal muscle after high-intensity eccentric exercise is mediated by two different pathways: KLF15 and NF-κB, whose activation is time-dependent. BCAA may reduce skeletal muscle proteolysis by lowering the level of gene transcription in the KLF15 and NF-κB related protein degradation pathway, which occurs immediately after exercise.

The Combined Effect of Taurine and Omega-3 Supplementation on Delayed Onset Muscle Soreness in High-Intensity Eccentric Exercise

Background: Eccentric exercise makes more tensions in active muscle fibers, resulting in muscle damage and delayed pain. Therefore, Delayed-Onset Muscle Soreness (DOMS) is a common result of severe eccentric contractions. This study aimed to clarify the combined effect of taurine and omega-3 supplementation on DOMS and muscle damage after high-intensity eccentric exercise in young untrained men.
 Methods: Forty-eight young untrained males were assigned to four groups (taurine+omega-3 [combined], taurine, omega-3, and one placebo group) and given 1,500 mg taurine and 1,500 mg omega-3 or 1,500 mg taurine or 1,500 mg omega-3 or placebo twice a day respectively. Each group received its supplements for twenty-eight days. DOMS and muscle damage in the lower body developed using a leg press with a weight equivalent to 70% of 1RM (One-Repetition Maximum). Lactate dehydrogenase (LDH), Creatine kinase (CK) and perceived muscle soreness measures were repeated before, immediately, 24, 48, and 72 hr after eccentric activity. p<0.05 was considered to be statistically significant.
 Results: In the combined group, there was no increase in CK and LDH in immediate time and 72 hr after the exercise, respectively, compared to the period before the workout. At 24 and 48 hr after the training, there was a significant decrease in muscle pain perception in all groups compared to placebo (p<0.05).
 Coclusion: A combination of 1500 mg taurine and 1500 mg omega-3, two times a day, for four weeks can reduce the levels of CK and LDH enzymes as some indicators of muscle damage. It also attenuates exercise-induced DOMS and muscle damage.

PTEN Inhibitor Treatment Lowers Muscle Plasma Membrane Damage and Enhances Muscle ECM Homeostasis after High-Intensity Eccentric Exercise in Mice.

Exercise-induced muscle damage (EIMD) is a common occurrence in athletes and can lead to delayed onset muscle soreness, reduced athletic performance, and an increased risk of secondary injury. EIMD is a complex process involving oxidative stress, inflammation, and various cellular signaling pathways. Timely and effective repair of the extracellular matrix (ECM) and plasma membrane (PM) damage is critical for recovery from EIMD. Recent studies have shown that the targeted inhibition of phosphatase and tension homolog (PTEN) in skeletal muscles can enhance the ECM environment and reduce membrane damage in Duchenne muscular dystrophy (DMD) mice. However, the effects of PTEN inhibition on EIMD are unknown. Therefore, the present study aimed to investigate the potential therapeutic effects of VO-OHpic (VO), a PTEN inhibitor, on EIMD symptoms and underlying mechanisms. Our findings indicate that VO treatment effectively enhances skeletal muscle function and reduces strength loss during EIMD by upregulating membrane repair signals related to MG53 and ECM repair signals related to the tissue inhibitor of metalloproteinases (TIMPs) and matrix metalloproteinase (MMPs). These results highlight the potential of pharmacological PTEN inhibition as a promising therapeutic approach for EIMD.

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.

Preliminary Investigations Into the Effect of Exercise-Induced Muscle Damage on Systemic Extracellular Vesicle Release in Trained Younger and Older Men.

Background: Exercise-induced muscle damage (EIMD) results in transient muscle inflammation, strength loss, and muscle soreness and may cause subsequent exercise avoidance. Research has recently proven that skeletal muscle can also release extracellular vesicles (EVs) into the circulation following a bout of exercise. However, EV’s potential role, including as a biomarker, in the response to eccentric resistance exercise stimulus remains unclear.Methods: Twelve (younger, n=7, 27.0±1.5years and older, n=5, 63.0±1.0years) healthy, physically active males, undertaking moderate, regular physical activity (3–5 times per week) performed a unilateral high intensity eccentric exercise protocol. Venous plasma was collected for assessment of EVs and creatine kinase (CK) prior to EIMD, immediately after EIMD, and 1–72h post-EIMD, and maximal voluntary isometric contraction (MVIC) and delayed onset muscle soreness (DOMS) were assessed at all time points, except 1 and 2h post-EIMD.Results: A significant effect of both time (p=0.005) and group (p<0.001) was noted for MVIC, with younger participants’ MVIC being higher throughout. Whilst a significant increase was observed in DOMS in the younger group (p=0.014) and in the older group (p=0.034) following EIMD, no significant differences were observed between groups. CK was not different between age groups but was altered following the EIMD (main effect of time p=0.026), with increased CK seen immediately post-, at 1 and 2h post-EIMD. EV count tended to be lower in older participants at rest, relative to younger participants (p=0.056), whilst EV modal size did not differ between younger and older participants pre-EIMD. EIMD did not substantially alter EV modal size or EV count in younger or older participants; however, the alteration in EV concentration (ΔCount) and EV modal size (ΔMode) between post-EIMD and pre-EIMD negatively associated with CK activity. No significant associations were noted between MVIC or DOMS and either ΔCount or ΔMode of EVs at any time point.Conclusion: These findings suggest that profile of EV release, immediately following exercise, may predict later CK release and play a role in the EIMD response. Exercise-induced EV release profiles may therefore serve as an indicator for subsequent muscle damage.

Bcaa Alleviates Rats Skeletal Muscle Protein Degradation After Eccentric Exercise By Reducing KLF15 Expression

PURPOSE: Exercise-induced muscle damage after high-intensity eccentric exercise can lead to degradation of skeletal muscle protein, thereby affecting the training effect. The purpose of this study is to explore the effect of branched-chain amino acid (BCAA) supplementation on muscle damage caused by one-time eccentric exercise, and the regulation of KLF15-mediated proteolytic pathways in the process. METHODS: 64 male SD rats were randomly divided into eight groups: placebo + control group (PC, n = 8), placebo + immediately after exercise group (PE, n = 8), placebo +6 h after exercise group (PE6, n = 8), placebo +12 h after exercise group (PE12, n = 8), BCAA + control group (BC, n = 8), BCAA + immediately after exercise group (BE, n = 8), BCAA +6 h after exercise group (BE6, n = 8), BCAA +12 h after exercise group (BE12, n = 8). Rats in BCAA groups were supplied BCAA (1 g/kg/day) 3 times before exercise. The placebo groups were supplied the same volume of distilled water. Rats in exercise groups underwent a bout of 2 h eccentric exercise on treadmill (-16° slope, a speed of 16 m/min). Blood and gastrocnemius were collected immediately after exercise in PE and BE, 6 h after exercise in PE6 and BE6, and 12 h after exercise in PE12 and BE12. The expression of 3-MH in blood was detected by ELISA. RT-qPCR was used to measure the mRNA expression of KLF15, Atrogin-1, MuRF-1 and MHC-II in gastrocnemius. RESULTS: The mRNA expression of MHC-II (P < 0.05), KLF15 (P < 0.05), Atrogin-1 (P < 0.05), MuRF-1 (P < 0.01) in PE were higher than those in PC, MHC-II (P < 0.05) in PE6 and Atrogin-1 (P < 0.05) in PE12 were higher than in PC. MHC-II (P < 0.05) was higher in BE6 than in BE. Compared with PE, the mRNA expression of KLF15 (P < 0.01), Atrogin-1(P < 0.05), MuRF-1 (P < 0.01) in BE were significantly lower, Atrogin-1 (P < 0.05) in BE12 was lower than that in PE12. 3-MH (P < 0.05) content was higher in PE12 than in PC, 3-MH (P < 0.01) content was lower in BE and BE6 than in BC, 3-MH (P < 0.01) content was higher in BC than in PC. CONCLUSIONS: BCAA may reduce skeletal muscle proteolysis by lowering the level of gene transcription in the KLF15-related protein degradation pathway, which occurs immediately after exercise.

The effectiveness of natural supplements on prevention and treatment of delayed onset muscle soreness and markers of muscle damage: a review of literature

Objective. Unaccustomed or high-intensity eccentric exercise often leads to delayed onset muscle soreness (DOMS) that presents as pain, soreness, or swelling. Nonsteroidal anti-inflammatory medications (NSAIDs) are often used to treat DOMS. Due to the potential adverse effects of NSAIDs, commerically available supplements have been suggested as a potential alternative treatment of DOMS. The purpose of this review is to examine the effects of commerically available supplements on DOMS and markers of muscle damage and inflammation. Method. Existing publications were examined and summarized regarding the effects of supplements such as curcumin, green tea extract, ginseng, ginger, branch chain amino acids, anatabine, pomegranate juice, and protease on DOMS and markers of both muscle damage and inflammation following eccentric exercise. Results. Consuming branched chain amino acids (BCAA), pomegranate, and curcumin appear to have the greatest effect in preventing and treating DOMS. Anatabine and ginseng do not appear to decrease markers of muscle damage, inflammation, or DOMS. Conclusion. Consuming supplements before or after exercise with anti-inflammatory and analgesia properties may be just as effective as NSAIDs in treating and preventing DOMS. Further studies should be conducted to determine the long-term effects of commerically available supplements and the safest dosage that can be consumed for maximal benefits.

The torque-frequency relationship is impaired similarly following two bouts of eccentric exercise: No evidence of a protective repeated bout effect

High-intensity eccentric exercise can lead to muscle damage and weakness. The ‘repeated bout effect’ (RBE) can attenuate these impairments when performing a subsequent bout. The influence of eccentric exercise-induced muscle damage on low-frequency force production is well-characterized; however, it is unclear how eccentric exercise and the RBE affect torque production across a range of stimulation frequencies (i.e., the torque-frequency relationship). We investigated the influence of an initial (Bout 1) and repeated bout (Bout 2) of eccentric exercise on the elbow flexor torque-frequency relationship. Eleven males completed two bouts of high-intensity eccentric elbow flexions, 4 weeks apart. Torque-frequency relationships were constructed at baseline and 0.5, 24, 48, 72, 96, and 168 h following both bouts via percutaneous stimulation at 1, 6, 10, 20, 30, 40, 50, and 100 Hz. Serum creatine kinase activity, self-reported muscle soreness, and isometric maximum voluntary contraction torque indirectly inferred the presence of muscle damage following Bout 1, and attenuation of muscle damage following Bout 2. Torque amplitude at all stimulation frequencies was impaired 30 min following eccentric exercise, however, torque at lower (1–10 Hz) and higher frequencies (40–100 Hz) recovered within 24 h while torque across the middle frequency range (20–30 Hz) recovered by 48 h. No between-bout differences were detected in absolute or normalized torque at any stimulation frequency, indicating no protective RBE on the elbow flexor torque-frequency relationship.

Effect of Arm Eccentric Exercise on Muscle Damage of the Knee Flexors After High-Intensity Eccentric Exercise

Repeated bout effect (RBE) describes a phenomenon that an initial unaccustomed eccentric exercise (ECC) bout can confer a protective effect against muscle damage from the subsequent same exercise. This protection has been observed in the same muscle, as well as the contralateral homologous (CL-RBE) muscle. But it is unknown whether the RBE is evident for non-local unrelated heterogonous muscles. The purpose of this study was to examine whether an initial elbow flexion (EF) muscle-damaging ECC could confer RBE against muscle damage from the subsequent ECC performed in the remote lower limb knee flexor (KF) muscle group. Twenty-seven young individuals were randomly assigned into the experimental (EXP: n = 15) and the control (CON: n = 12) groups. All participants performed a baseline unilateral KF ECC (six sets of 10 repetitions) on a randomly chosen leg. After a washout period (4 weeks), the EXP group performed 60 high-intensity unilateral EF ECC on a randomly chosen arm, followed by the same intensity exercise using the contralateral KF muscle group 2 weeks later. The CON group performed the same contralateral KF ECC, but with no prior EF ECC bout. Changes in the KF muscle damage indirect markers (muscle soreness, range of motion, and maximal isometric strength) after the ECC were compared between the baseline and second bouts for both groups with mixed factorial three-way (group × bout × time) ANOVA. Additionally, index of protection for each damage marker was calculated at 1 and 2 days after the ECC and compared between groups with independent t-tests. For both groups, the magnitude of the changes in the damage markers between the baseline and the second ECC bouts were not significantly different (all values of p > 0.05). As for the index of protection, relative to the CON, the EXP showed an exacerbating damaging effect on the KF isometric strength following the second ECC bout, particularly at the 1-day post-exercise time point (index of protection: EXP vs. CON mean ± SD = −29.36 ± 29.21 vs. 55.28 ± 23.83%, p = 0.040). Therefore, our results do not support the existence of non-local RBE.

Urinary N-terminal fragment of titin: A surrogate marker of serum creatine kinase activity after exercise-induced severe muscle damage

ABSTRACT We aimed to evaluate whether changes in the noninvasively assessed urinary N-terminal fragment of titin (U-titin) concentration may be associated with those of serum creatine kinase (CK) activity, transverse relaxation time (T2), maximal voluntary contraction (MVC) torque, range of motion (ROM), and muscle soreness, following high-intensity eccentric exercise. Twenty-eight healthy young men performed 30 maximal isokinetic (120°/s) eccentric elbow flexor contractions using an isokinetic dynamometer. U-titin concentration, serum CK activity, T2, MVC torque, ROM, and muscle soreness were measured before and after a maximum of 4 days. Both U-titin concentration and serum CK activity increased post-exercise in a similar manner, though the former elevated slightly earlier (p < 0.05). The peak values of log U-titin concentration following eccentric exercise were strongly correlated with those of log serum CK activity (r = 0.90, p < 0.05) and T2 (r = 0.84, p < 0.05). There were moderate correlations between peak values of U-titin concentration and those of MVC torque (r = 0.69, p < 0.05) and ROM decline rate (r = 0.45, p < 0.05). These results suggest that in healthy young men, the non-invasive marker, U-titin, may be used as a serum CK surrogate following exercise-induced severe muscle damage.

Eccentric exercise per se does not affect muscle damage biomarkers: early and late phase adaptations.

Acute high-intensity unaccustomed eccentric exercise performed by naive subjects is accompanied by disturbances in muscle damage biomarkers. The aim of the study was to investigate whether a causal relationship indeed exists between eccentric exercise and muscle damage. Twenty-four men randomly assigned into a concentric only or an eccentric-only training group and performed 10weeks of isokinetic resistance exercise (one session/week of 75 maximal knee extensors actions). Physiological markers of muscle function and damage (i.e., range of motion, delayed onset muscle soreness, isometric, concentric and eccentric peak torque) were assessed prior to and 1-3 and 5days post each session. Biochemical markers of muscle damage (creatine kinase) and inflammation (C-reactive protein) were measured prior and 2days post each session. After the first bout, eccentric exercise induced greater muscle damage compared to concentric exercise; however, during the nine following sessions, this effect progressively diminished, while after the 10th week of training, no alterations in muscle damage biomarkers were observed after either exercise protocol. Additionally, strength gains at the end of the training period were comparable between the two groups and were mode-specific. (1) eccentric exercise per se does not affect muscle damage biomarkers; (2) muscle damage occurs as a result of muscle unaccustomedness to this action type; (3) exercise-induced muscle damage is not a prerequisite for increased muscle strength. Collectively, we believe that muscle unaccustomedness to high-intensity eccentric exercise, and not eccentric exercise per se, is the trigger for muscle damage as indicated by muscle damage biomarkers.

Efek Suplementasi Omega 3 dan Latihan Fisik Terhadap Respon Inflamasi

The aims of this article is to find out how the effects of omega 3 supplementation and physical exercise on the inflammatory response. The method applied is literature review. The results showed that omega 3 supplementation and regular exercise can reduce the inflammatory response that is not controlled. Inflammation is a protective response caused by injury or tissue damage. After physical activity the body will experienced an increase in inflammatory markers, namely C-Reactive Protein (CRP), Interleukin 1 (IL-1), Interleukin 6 (IL-6), Interleukin 10 (IL-10) and Tumor Necrosis Factor-a (TNF-a). Physical exercise, especially high-intensity eccentric exercises, will cause damage to muscle fibers and delayed muscle pain (DOMS) which results in disruption to muscle strength. Muscle pain is caused by an inflammatory process due to increased levels (TNF-a) in response to muscle damage. Inflammatory response that is not controlled can be controlled by giving omega 3 supplementation. It can be concluded that omega 3 supplementation and regular exercise are proven to reduce the inflammatory response that is not controlled, soto reduce the intensity of pain which support the performance in carrying out the exercise program.

The Effects of Supersaturated Hydrogen-Rich Water Bathing on Biomarkers of Muscular Damage and Soreness Perception in Young Men Subjected to High-Intensity Eccentric Exercise.

High-intensity eccentric exercise can cause a delayed onset of muscle soreness (DOMS), a short-term condition characterized by muscle damage and tenderness that might hold up recovery and jeopardize exercise routine. Previous studies indicated that hydrogen-rich water (HRW) might be a helpful topical intervention to boost recovery in musculoskeletal medicine, yet no data are available concerning the effectiveness and safety of whole-body bathing with supersaturated HRW after DOMS-inducing exercise. This study evaluates the effects of a single-session bathing with HRW on biochemical markers of muscular damage in healthy young men. The six volunteers who were exposed to DOMS-inducing eccentric exercise were assigned to either supersaturated HRW or control whole-body bathing in a double-blind crossover design. Immediately after an exercise session, the participants were immersed up to the neck into a 200 L bathtub with supersaturated HRW (8 mg of H2 per L) or control water (no hydrogen) for 30 min. Blood biomarkers of inflammation and muscular damage and Visual Analogue Scale (VAS) scores for muscle soreness were assessed at baseline (before exercise) and at 24-hour follow-up. Two-way ANOVA revealed a significant difference between two groups in serum creatine kinase (CK) response over the period of intervention (P=0.04). A single-session bathing in HRW prevented a rise in circulating biomarkers of muscular damage induced by exercise at 24-hour follow-up, retaining the levels of all biomarkers similar to the baseline values (P > 0.05). On the other hand, serum CK, aldolase, and aspartate transaminase were significantly elevated at 24-hour follow-up as compared to the baseline levels after the control bath (342 ± 309 U/L vs. 465 ± 295 U/L; P > 0.05). HRW bath also induced a significant drop in VAS scores for muscle soreness in comparison with control water, both immediately after an intervention (32.7 ± 8.6% vs. 20.0 ± 12.8%; P=0.02) and at 24-hour follow-up (31.6 ± 24.3% vs. 22.4 ± 27.5%; P=0.03), respectively. No participants reported any major side effects during the trial. This pilot study suggests that the whole-body bathing in supersaturated HRW is a safe procedure that attenuates muscular damage and can ease sore muscles after high-intensity eccentric exercise.

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.

Effects of Pre-exercise Acute Vibration Training on Symptoms of Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis.

Tan, J, Shi, X, Witchalls, J, Waddington, G, Lun Fu, AC, Wu, S, Tirosh, O, Wu, X, and Han, J. Effects of pre-exercise acute vibration training on symptoms of exercise-induced muscle damage: a systematic review and meta-analysis. J Strength Cond Res 36(8): 2339-2348, 2022-Exercise-induced muscle damage (EIMD) normally occurs after unaccustomed high-intensity eccentric exercises. Symptoms of EIMD include delayed-onset muscle soreness (DOMS), tenderness, stiffness, swelling, reduced strength, and increased creatine kinase (CK) levels in the blood. Vibration training (VT) may be useful as a pre-exercise intervention in attenuating EIMD on the basis of tonic vibration reflex (TVR) through a more efficient distribution of contractile stress over muscle fibers. The objective of this meta-analysis is to examine the effects of acute VT on symptoms of EIMD when performed as the pre-exercise intervention. Randomized controlled trials (RCTs) published in the 8 databases of Cochrane Library, PubMed, Embase, Web of Science, EBSCO, China National Knowledge Infrastructure, Airiti Library and WanFang Data from 1966 (the earliest available time) to January 2019 were searched. A total of 2,324 records were identified and 448 articles were screened with the title and abstract. Two investigators identified eligible studies, extracted data, and assessed the risk of bias independently. Review Manager 5.3 designed by Cochrane was used for the current meta-analysis. Six RCTs involving 180 subjects were included in the analysis. A low-to-moderate methodological quality of the included studies was revealed using the physiotherapy evidence database scale. The results showed that acute VT was superior to the control group for the reduction of DOMS on pain visual analogue scale at 24, 48 hours and pressure pain threshold at 24 hours. In addition, superior effects of acute VT were also found on the indirect markers of muscle damage including CK at 24, 72 hours, and lactate dehydrogenase at 24 hours. The current meta-analysis has collated the evidence to demonstrate that receiving acute VT before unaccustomed high-intensity eccentric exercises may be effective in attenuating markers of muscle damage and the development of DOMS when compared with a control group. The possible mechanisms of this effect could be attributed to an improved synchronization of muscle fiber caused by TVR, which could result in even distribution of exterior loads and eventually attenuate disruptions of muscle fibers. In addition, increased blood flow may also be helpful to prevent accumulation of metabolic substances and attenuate subsequent symptoms of EIMD. Vibration training may be used as a pre-exercise intervention to alleviate symptoms of EIMD caused by unaccustomed high-intensity eccentric exercise. Because of the limited quantity and quality of included studies, more high-quality studies are required to ascertain the effect of VT on symptoms of EIMD.

Effect of Body Fat Percentage on Muscle Damage Induced by High-Intensity Eccentric Exercise.

This study aimed to investigate the impact of percent body fat (%BF) on muscle damage after high-intensity eccentric exercise. Thirty healthy male undergraduates (mean age: 22.0 ± 2 years, height: 176.9 ± 5 cm, weight: 75.8 ± 11.6 kg) participated in this study, and they were classified according to their %BF into a high %fat group (HFG, ≥20%, n = 15) and a low %fat group (LFG, ≤15%, n = 15). For eccentric exercise, two sets of 25 reps were performed on a modified preacher curl machine using the elbow flexor muscle. Maximal isometric strength, muscle soreness (passive and active), creatine kinase (CK), and myoglobin (Mb) were measured as indices of muscle damage. The data were analyzed with repeated measures ANOVA. The results show that there is a significant group–time interaction for both CK and Mb after eccentric exercise (p = 0.007, p = 0.015, respectively), with a greater increase in the HFG than in the LFG. However, there was no significant group–time interaction for maximal isometric strength and muscle soreness (passive and active) (p > 0.05). These results suggest that %BF is a factor that alters the muscle damage indices CK and Mb, which indicate membrane disruption, after eccentric exercise.

Comparison of Acute Level of CK After Five Weeks Eccentric vs Concentric High Intensity Strength Exercise in Healthy Subject

Background: Musculoskeletal injuries both in sport and recreational activities, at each age level, can lead to immobilization. Injury and immobilization can lead to muscle strength decrease and deconditioning. These conditions can be addressed by provision of strength training therapy especially for people with low exercise tolerance such as the elderly and patients with chronic disease. Existing studies stated eccentric exercise can increase muscle strength with less energy expenditure compared to concentric exercise. However eccentric exercise can lead to muscle damage indicated with an acute CK level increase, and eccentric exercise has not been carried out regularly for post muscle injuries and deconditioned patients. The American College of Sport Medicine (ACSM) stated strength increase and muscle hypertrophy require high intensity load strengthening exercise with a minimum load of 70% 1 Maximum Repetition. The recommended load was given to the subjects in this research. Our pleriminary study intervention was well tolerated by healthy subjects.Aim: Comparing acute CK level alteration in high intensity eccentric and concentric muscle strengthening exercise on untrained healthy subjects.Methods: Randomized pre test and post test group design. Subjects of the study (n = 16) were untrained healthy males. CK level was evaluated by laboratory test.Results: Our study showed decline of acute CK level in both groups with p value 0.65 and 0.76, respectively. No significant differences found on both groups.Conclusion: The increase of acute CK level after five weeks of eccentric strengthening exercise is not higher than that in concentric strengthening exercise.

Comparison of Acute Level of CK After Five Weeks Eccentric vs Concentric High Intensity Strength Exercise in Healthy Subject

Background: Musculoskeletal injuries both in sport and recreational activities, at each age level, can lead to immobilization. Injury and immobilization can lead to muscle strength decrease and deconditioning. These conditions can be addressed by provision of strength training therapy especially for people with low exercise tolerance such as the elderly and patients with chronic disease. Existing studies stated eccentric exercise can increase muscle strength with less energy expenditure compared to concentric exercise. However eccentric exercise can lead to muscle damage indicated with an acute CK level increase, and eccentric exercise has not been carried out regularly for post muscle injuries and deconditioned patients. The American College of Sport Medicine (ACSM) stated strength increase and muscle hypertrophy require high intensity load strengthening exercise with a minimum load of 70% 1 Maximum Repetition. The recommended load was given to the subjects in this research. Our pleriminary study intervention was well tolerated by healthy subjects.Aim: Comparing acute CK level alteration in high intensity eccentric and concentric muscle strengthening exercise on untrained healthy subjects.Methods: Randomized pre test and post test group design. Subjects of the study (n = 16) were untrained healthy males. CK level was evaluated by laboratory test.Results: Our study showed decline of acute CK level in both groups with p value 0.65 and 0.76, respectively. No significant differences found on both groups.Conclusion: The increase of acute CK level after five weeks of eccentric strengthening exercise is not higher than that in concentric strengthening exercise.