Study on Mechanism of Dendrobium officinale Kimura et Migo in Preventing and Treating Exercise-induced Muscle Damage(EIMD)in Rats

[Objectives]This study was conducted to observe the mechanism of Dendrobium officinale Kimura et Migo on gastrocnemius muscle in rats with exercise-induced muscle damage(EIMD).[Methods]The micro-injury model of skeletal muscle was established by treadmill training.Forty two SD rats were randomly divided into a control group,1,12 and 24 h exercise groups,D.officinale 2 ml+1 h exercise group,D.officinale 2 ml+12 h exercise group,and D.officinale 2 ml+24 h exercise group,with 6 rats in each group.Various D.officinale groups were given the drug once in the morning and once in the evening at a dose of 2 ml/time,a week in advance.Except for the quiet group,the samples were collected from the 1,12 and 24 h exercise groups after anesthesia following 1,12 and 24 h of exercise for the last time,respectively,and the D.officinale 2 ml+1 h exercise group,D.officinale 2 ml+12 h exercise group and D.officinale 2 ml+24 h exercise group were also sampled after anesthesia following 1,12 and 24 h of exercise for the last time,respectively.The contents of ATP,CK-MM and CK in rat serum were determined by enzyme-linked immunosorbent assay(ELISA).The histopathological changes of gastrocnemius muscle were observed by HE staining.PCR and Western-blot detection were carried out to analyze the effects of D.officinale on IGF-1 mRNA and protein expression in gastrocnemius muscle.[Results]Compared with the quiet group,the ATP contents in the serum of rats in the 1,12 and 24 h exercise groups significantly decreased(P<0.01),while the CK and CK-MM contents significantly increased(P<0.01).The expression of IGF-1 mRNA and protein in the gastrocnemius muscle tissue significantly increased(P<0.01).Compared with the 1 h exercise group,the ATP content and IGF-1 protein expression in the gastrocnemius muscle tissue of the D.officinale liquid+1 h exercise group significantly increased(P<0.05),while the CK and CK-MM contents significantly decreased(P<0.01).Compared with the 12 h exercise group,the D.officinale liquid+12 h exercise group showed a significant increase in ATP content(P<0.01),significant increases in IGF-1 mRNA and protein expression in the gastrocnemius muscle tissue(P<0.01),and significant decreases in CK and CK-MM contents(P<0.01).Compared with the 24 h exercise group,the ATP content and IGF-1 mRNA and protein expression in the gastrocnemius muscle tissue of the D.officinale liquid+24 h exercise group significantly increased(P<0.01),while the CK and CK-MM contents significantly decreased(P<0.01).From the pathological tissue morphology of the gastrocnemius muscle in rats with EIMD treated with D.officinale,it could be concluded that the gastrocnemius muscle of each exercise group was significantly damaged,and the damage was significantly alleviated after administration of D.officinale liquid.[Conclusions]The effects and mechanism of D.officinale on prevention and treatment of EIMD in rats might be related to the promotion of IGF-1 mRNA and protein expression in injured tissues by reducing ATP energy consumption,CK-MM and CK activity.

Tribulus terrestris extracts alleviate muscle damage and promote anaerobic performance of trained male boxers and its mechanisms： Roles of androgen, IGF-1, and IGF binding protein-3

Purpose: To investigate the effects of Tribulus terrestris(TT) extracts on muscle mass, muscle damage, and anaerobic performances of trained male boxers and its mechanisms: roles of plasma androgen, insulin growth factor 1(IGF-1), and IGF-1 binding protein-3(IGFBP-3).Methods: Fifteen male boxers were divided into exercise group(E, n = 7) and exercise plus TT group(E + TT, n = 8). The 2 groups both undertook3-week high-intensity and 3-week high-volume trainings separated by a 4-week rest. TT extracts(1250 mg/day) were orally administered by boxers in E + TT group. TT extract compositions were detected by UHPLC–Q-TOF/MS. Before and at the end of the 2 trainings, muscle mass, anaerobic performance, and blood indicators were explored.Results: Compared with E group, decreases of plasma CK(1591.5 ± 909.6 U/L vs. 2719.9 ± 832.5 U/L) and IGFBP-3(3075.5 ± 1072.5 ng/m L vs. 3950.8 ± 479.3 ng/m L) as well as increases of mean power(MP, 459.4 ± 122.3 W vs. 434.6 ± 69.5 W) and MP/body weight(MP/BW, 7.5 ± 0.9 W/kg vs. 7.1 ± 1.1 W/kg) were detected in E + TT group after a high-intensity training. For high-volume training, reduction of IGFBP-3(2946.4 ± 974.1 ng/m L vs. 3632.7 ± 470.1 ng/m L) and increases of MP(508.7 ± 103.2 W vs. 477.8 ± 49.9 W) and MP/BW(8.2 ± 0.3 W/kg vs.7.5 ± 0.9 W/kg) were detected in E + TT group, compared with E group. Muscle mass, blood levels of testosterone, dihydrotestosterone(DHT),and IGF-1 were not signifiantly changed between the 2 groups.Conclusion: Taking 1250 mg capsules containing TT extracts did not change muscle mass and plasma levels of testosterone, DHT, and IGF-1 but significantly alleviated muscle damage and promoted anaerobic performance of trained male boxers, which may be related to the decrease of plasma IGFBP-3 rather than androgen in plasma.

Single dose of intra-muscular platelet rich plasma reverses the increase in plasma iron levels in exercise-induced muscle damage:A pilot study

Background:Platelet rich plasma(PRP) therapy is widely used in enhancing the recovery of skeletal muscle from injury.However,the impact of intramuscular delivery of PRP on hematologic and biochemical responses has not been fully elucidated in exercise-induced muscle damage.The purpose of this investigation the effects of intramuscular delivery of PRP on hematologic and biochemical responses and recovery strategy muscle damage induced by high intensity muscle exercise(exercise-induced muscle damage,EIMD).Methods:Moderately active male volunteers participated in this study and were assigned to a control group(control,n = 6) and PRP administration group(PRP,n = 6).The subjects performed exercise with a load of 80% one repetition maximum(1RM) maximal voluntary contraction of the elbow flexors until point of exhaustion of the non-dominant arm was reached.The arms were treated with saline or autologous PRP post-24 h EIMD.Venous blood samples were obtained in the morning to establish a baseline value and 1–4 days post-exercise and were analyzed for serum ferritin,iron,iron binding capacity(IBC),creatinine kinase(CK),lactate dehydrogenase(LDH),aspartate aminotransferase(AST),and alanine aminotransferase(ALT).Results:The baseline levels of plasma iron,ferritin,IBC,CK,LDH,AST,and ALT were similar in both the control and PRP groups.However,24-h following exercise a significant increase in these parameters was observed in both groups between 1 and 4 days during the recovery period.Interestingly,PRP administration decreased plasma iron levels compared to the control on the second day post-exercise.Plasma IBC increased in PRP group from Days 2 to 4 post-exercise compared to the control group whilst PRP administration had no effect on plasma ferritin,CK,AST,ALT,or LDH.Conclusion:Acute exhaustive exercise increased muscle damage markers,including plasma iron,IBC,and ferritin levels,indicating muscle damage induced by exercise.PRP administration improves inflammation by reversing the increase in the iron levels post-exercise without displaying any myotoxicity and may have a role to play in the recovery of exercise-induced muscle damage.

Effect of Chronic Supplementation of Branched Chain Amino Acids on Exercise-Induced Muscle Damage in Trained Athletes

PURPOSE： Branched Chain Amino Acids （BCAA） has been considered an important nutritional strategy to improve skeletal muscle protein turnover in many conditions especially following exercise induced muscle damage. Exercise induced muscle damage （EIMD）, a phenomenon impairs muscle function and hampers athletic performance. The effects of consumption of BCAA for a chronic period （4 weeks） on EIMD in trained athletic population have never been explored. Therefore, the aim of the present study was to examine the effects of chronic consumption （4 weeks） of BCAA on indices of muscle damage elicited via a bout of damaging exercise in trained athletes. METHODS： Twenty trained males （20 road cyclists） aged 18-28 years were randomly assigned to two groups （BCAA and Placebo） （n = 10）. The damaging exercise consisted of 100 consecutive drop-jumps. Biochemical markers including creatine kinase （CK）, high sensitivity c reactive protein （hs-cRP） and myeloperoxidase （MPO）, isometric knee muscle strength, muscle soreness, aerobic capacity （WO2max） and heart rate （HR） were measured. RESULTS： Differences were observed in pre-and post-supplementation periods among all the participants with mean height and weight values of 168.57 （4.5） cm and 61.74 （4.55） kg respectively as calculated by the anthropologist randomly allocated to the two groups in all tested parameters indicating the effectiveness of BCAA in attenuating muscle damage and enhancing muscle recovery with chronic consumption when compared to placebo, however in contrast to our expectations based on symptoms and our clinical judgment during the study statistically significant difference （P 〈 0.05） were noticed with biochemical indices only. CONCLUSION： Our findings suggest that chronic BCAA supplementation proved to be an effective meansof reducing muscle damage, enhancing muscle protein synthesis and recovery following EIMD as compared to placebo in well trained athletic population.

Effects of exercise-induced skeletal muscle damage and ultrastructure of muscle

Micro- injury （exercise-induced muscle damage, EIMD） will cause a temporary decline in muscle function, if not handled properly, it could cause more serious injury or overtraining, and even lead to the end of the athletes ＇ sports life. However, some studies have shown that an appropriate period of eccentric exercise training resulted in EIMD while promoted heart muscle fiber hypertrophy and corresponding muscle growth faster than exercise training, and there are the typical ＂ repetitive training effect＂ , ie after a period of the EIMD recovery, the muscle＇ s injury or delayed onset muscle soreness （DOMS） caused by the same movement is significantly reduced. So its deep study could help to guide the athlete to avoid or mitigate the negative effects which brought by EIMD, while could help to further clarify the process of the body to adapt to exercise training or mechanism.

ACIDIC FIBROBLAST GROWTH FACTOR REDUCES RAT SKELETAL MUSCLE DAMAGE CAUSED BY ISCHEMIA AND REPERFUSION

Acute interruption of arterial blood flow to the extremities is often associated with significant morbidity and mortality. Broad spectrum mitogenic and non mitogenic activities of FGFs inspired us to study its protecting effects on tissue injuries in ischemia reperfusion condition. We found that systemic administration of aFGF after reperfusion onset prevented severe skeletal muscle injuries. In rats treated with aKGF, the tissue edema was reduced significantly, the tissue viability was increased, and the muscle fibers contained more succinate dehydrogenase (SDH) and adenosine triphosphatasc (ATPase). The pathological results supported the concept of improved prevention with aFGF treatment. The possible tissue protection by aFGF may come from its ability to regulate the concentration of evtra- and intracellular calcium ion. Besides, it may moderate other Ca2+ dependent enzyme conversion processes. Also, it may take part in the vascular tone regulation under ischemia and reperfusion conditions. These results suggest further study of tissue ischemia prevention with FGF and its possible mechanisms in the future.

Effect of repeated eccentric exercise on muscle damage markers and motor unit control strategies in arm and hand muscle

To examine the contralateral repeated bout effect(CL-RBE)on muscle damage markers and motor unit(MU)control strategies,seventeen healthy adults performed two bouts of 60 eccentric contractions with elbow flexor(EF group;n=9)or index finger abductor(IA group;n=8)muscles,separated by 1 week.All participants randomly performed eccentric exercise on either the right or left arm or hand muscles,and muscle damage markers and submaximal trapezoid contraction tests were conducted pre,post,1-and 2-day post eccentric protocol.One week after the first bout,the same exercise protocol and measurements were performed on the contralateral muscles.Surface electromyographic(EMG)signals were collected from biceps brachii(BB)or first dorsal interosseous(FDI)during maximal and submaximal tests.The linear regression analyses were used to examine MU recruitment threshold versus mean firing rate and recruitment threshold versus derecruitment threshold relationships.EMG amplitude from BB(bout 1 vs.bout 2=65.71%±22.92%vs.43.05%±18.97%,p=0.015,d=1.077)and the y-intercept(group merged)from the MU recruitment threshold versus derecruitment threshold relationship(bout 1 vs.bout 2=7.10±14.20 vs.0.73±16.24,p=0.029,d=0.513)at 50%MVIC were significantly different between two bouts.However,other muscle damage markers did not show any CL-RBE in both muscle groups.Therefore,despite changes in muscle excitation and MU firing behavior,our results do not support the existence of CL-RBE on BB and FDI muscles.

Neuromuscular,biomechanical,and energetic adjustments following repeated bouts of downhill running

Purpose This study used downhill running as a model to investigate the repeated bout effect(RBE)on neuromuscular performance,running biomechanics,and metabolic cost of running.Methods Ten healthy recreational male runners performed two 30-min bouts of downhill running(DR1 and DR2)at a-20%slope and 2.8 m/s 3 weeks apart.Neuromuscular fatigue,level running biomechanics during slow and fast running,and running economy parameters were recorded immediately before and after the downhill bouts,and at 24 h,48 h,72 h,96 h,and 168 h thereafter(i.e.,follow-up days).Results An RBE was confirmed by attenuated muscle soreness and serum creatine kinase rise after DR2 compared to DR1.An RBE was also observed in maximum voluntary contraction(MVC)force loss and voluntary activation where DR2 resulted in attenuated MVC force loss and voluntary activation immediately after the run and during follow-up days.The downhill running protocol significantly influenced level running biomechanics;an RBE was observed in which center of mass excursion and,therefore,lower-extremity compliance were greater during follow-up days after DR1 compared to DR2.The observed changes in level running biomechanics did not influence the energy cost of running.Conclusion This study demonstrated evidence of adaptation in neural drive as well as biomechanical changes with the RBE after DR.The higher neural drive resulted in attenuated MVC force loss after the second bout.It can be concluded that the RBE after downhill running manifests as changes to global and central fatigue parameters and running biomechanics without substantially altering the energy cost of running.

Downhill running impairs peripheral but not central neuromuscular indices in elbow flexor muscles

The purpose of this study was to examine the effects of a 1-h downhill running exercise on the elbow flexor muscles’neuromuscular functions.Seventeen adults(Control[CON]:n=9;Experimental[EXP]:n=8)completed this study.The CON rested for 30 min while the EXP performed the downhill running.Before,10 min,24 h,and 48 h after the interventions,dependent variables(knee extensor muscle soreness,elbow flexion and knee extension isometric strength,elbow flexion resting twitch and voluntary activation[VA],and the biceps surface electromyography[EMG]amplitude)were measured.Knee extensor muscle soreness was significantly greater in the EXP than the CON group following the intervention throughout the entire 48 h.This was accompanied by the greater decline in the knee extension strength in the EXP than the CON(mean±SD:-6.9±3.4%vs.1.0±3.2%,p=0.044).The elbow flexion strength,VA,and EMG amplitude were not affected by the exercise.However,the decline of the elbow flexion resting twitch was greater in the EXP than the CON(±19.6±6.3%vs.8.7±5.9%,p=0.003).Therefore,the downhill running impaired the remote elbow flexor muscles at a peripheral level.

An examination of acute cross-over effects following unilateral low intensity concentric and eccentric exercise

We compared the effects of low intensity concentric(CON)and eccentric(ECC)exercise on the force and neural responses of the dominant(exercised)elbow flexors(EFs),and studied if these conditions could induce cross-over effects to the contralateral(non-exercised)EFs.Fifteen subjects(8 males)completed all conditions(CON and ECC:6 sets of low intensity exercise to failure;control:rest)in separate visits with a randomized order.Maximal isometric force and electromyography(EMG)of the dominant and contralateral EFs were assessed at pre,immediate-,24-,and 48-h-post.Two-factor(condition and time)linear mixed-model analyses were performed to examine the force and EMG responses.Immediately post CON,contralateral EFs force was significantly(p=0.026)higher(12.41%)than control,but no cross-over effects regarding the neural responses were observed.Immediately post ECC,dominant EFs force was significantly lower in ECC,compared to CON(p=0.003)and control(p<0.001).This force remained depressed at 24-and 48-h post ECC,when compared to CON(p<0.001)and control(p<0.001).Our data suggests that submaximal unilateral exercises are not likely to impair contralateral muscle strength performance.Instead,concentric exercises may acutely improve muscle strength for the contralateral limb.However,this effect is not explained by changes in muscle excitation.