BACKGROUND & AIMS: :Exercise-induced muscle damage (EIMD) is accompanied by inflammatory and immune responses. However, due to the repeated bout effect, there will probably be less EIMD. Hence, the purpose was to investigate inflammatory and immune responses over a three-day period of downhill running in active females. Eleven moderately trained healthy females performed three 60-minute bouts of downhill running in -13.5% grade, separated by 24 hours, at a speed eliciting 70-80% of their VO2peak on level grade. Delayed onset muscle soreness (DOMS), range of motion (ROM) and maximum knee isotonic strength (1RM) were measured pre- and two-hour post every bout. Blood variables, including CBC, serum lactate dehydrogenase (LDH), creatine kinase (CK), myoglobin (Mb), IL-10, IL-6 and Monocyte chemoattractant protein-1 (MCP-1) were measured at 1 hour before the first bout and two hours after every bout. Data was analysed by repeated measure ANOVA (P<0.05). Although CK, LDH, Mb, IL-10, IL-6, MCP-1, total leukocyte count, monocytes and neutrophils increased significantly following the first bout, CK, LDH, Mb, IL-10, monocytes and neutrophils were only significantly higher following the third bout compared to the baseline (all P<0.05). Moreover, IL-10 and IL-6 decreased following the second and third bouts compared to the first bout (P<0.05). In comparison with the baseline, lymphocytes decreased after the second bout, DOMS increased following the second and third bouts, 1RM decreased following the first and second bouts (all P<0.05). ROM showed no significant difference. The three-day period of downhill running did not exacerbate EIMD and inflammatory response was partly attenuated.

背景与目标： ：运动引起的肌肉损伤（EIMD）伴有炎症和免疫反应。但是，由于重复的回合效应，EIMD可能会减少。因此，目的是研究活跃女性在下坡跑步三天后的炎症反应和免疫反应。十一名接受过中等训练的健康女性在-13.5％的坡度上进行了三场60分钟的下坡跑，间隔24小时，其速度导致其VO2peak达到水平水平的70-80％。每次发作前和发作后两小时测量延迟发作的肌肉酸痛（DOMS），运动范围（ROM）和最大膝部等张强度（1RM）。在首次检查前1小时测量了包括CBC，血清乳酸脱氢酶（LDH），肌酸激酶（CK），肌红蛋白（Mb），IL-10，IL-6和单核细胞趋化蛋白1（MCP-1）在内的血液变量。回合和每次回合后两个小时。通过重复测量ANOVA分析数据（P <0.05）。尽管第一次发作后CK，LDH，Mb，IL-10，IL-6，MCP-1，总白细胞计数，单核细胞和中性粒细胞显着增加，但CK，LDH，Mb，IL-10，单核细胞和中性粒细胞仅显着升高与基线相比，在第三次回合之后（所有P <0.05）。此外，与第一次发作相比，第二次和第三次发作后IL-10和IL-6降低（P <0.05）。与基线相比，第二次发作后淋巴细胞减少，第二次和第三次发作后DOMS增加，第一次和第二次发作后1RM降低（所有P <0.05）。 ROM没有显着差异。三天的下坡跑步不会加剧EIMD，并且炎症反应会部分减弱。

BACKGROUND & AIMS: PURPOSE:To investigate the effect of warmup by application of the thermal agent Deep Heat (DH) on muscle mechanical properties using magnetic resonance elastography (MRE) at 3T before and after exercise-induced muscle damage (EIMD). MATERIALS AND METHODS:Twenty male participants performed an individualized protocol designed to induce EIMD in the quadriceps. DH was applied to the thigh in 50% of the participants before exercise. MRE, T2 -weighted MRI, maximal voluntary contraction (MVC), creatine kinase (CK) concentration, and muscle soreness were measured before and after the protocol to assess EIMD effects. Five participants were excluded: four having not experienced EIMD and one due to incidental findings. RESULTS:Total workload performed during the EIMD protocol was greater in the DH group than the control group (P < 0.03), despite no significant differences in baseline MVC (P = 0.23). Shear stiffness |G*| increased in the rectus femoris (RF) muscle in both groups (P < 0.03); however, DH was not a significant between-group factor (P =  0.15). MVC values returned to baseline faster in the DH group (5 days) than the control group (7 days). Participants who displayed hyperintensity on T2 -weighted images had a greater stiffness increase following damage than those without: RF; 0.61 kPa vs. 0.15 kPa, P < 0.006, vastus intermedius; 0.34 kPa vs. 0.03 kPa, P = 0.06. CONCLUSION:EIMD produces increased muscle stiffness as measured by MRE, with the change in |G*| significantly increased when T2 hyperintensity was present. DH did not affect CK concentration or soreness; however, DH participants produced greater workload during the EIMD protocol and exhibited accelerated MVC recovery. LEVEL OF EVIDENCE:1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1115-1127.

背景与目标： 目的：研究在运动诱发的肌肉损伤（EIMD）前后，在3T时使用磁共振弹性成像（MRE）来施加热剂深热（DH）对肌肉力学性能的热身作用。
材料与方法：二十名男性受试者进行了个性化设计，旨在诱发股四头肌EIMD。在运动前，将DH应用于50％的参与者的大腿上。在评估EIMD效果之前和之后，测量了MRE，T2加权MRI，最大自愿收缩（MVC），肌酸激酶（CK）浓度和肌肉酸痛。五名参与者被排除在外：四名未经历过EIMD，一名因偶然发现。
结果：尽管基线MVC无显着差异（P = 0.23），但DH组在EIMD方案期间执行的总工作量大于对照组（P <0.03）。剪切刚度| G * |两组的股直肌（RF）肌肉均增加（P <0.03）；然而，DH不是一个显着的组间因素（P = 0.15）。在DH组（5天）中，MVC值返回基线的速度比对照组（7天）更快。与没有以下情况的参与者相比，在T2加权图像上表现出高强度的参与者在受到损伤后的刚度增加更大。 0.61 kPa和0.15 kPa，P <0.006，中间臀大肌; 0.34 kPa对0.03 kPa，P = 0.06。
结论：通过| MRE测量，EIMD产生增加的肌肉僵硬度，| G * |的变化。存在T2高强度时，血红蛋白显着增加。 DH不影响CK浓度或酸痛；但是，DH参与者在EIMD协议期间产生了更大的工作量，并表现出加速的MVC恢复。
证据级别：1技术效力：第2阶段。雷森成像2017; 46：1115-1127。

BACKGROUND & AIMS: :This study examined whether avoiding or experiencing exercise-induced muscle damage (EIMD) influences strength gain after downhill walking training. Healthy young males performed treadmill downhill walking (gradient: -28%, velocity: 5 km · h(-1) and load: 10% of body mass) 1 session per week for four weeks using either a ramp-up protocol (n = 16), where exercise duration was gradually increased from 10 to 30, 50 and 70 min over four sessions, or a constant protocol (n = 14), where exercise duration was 40 min for all four sessions. Indirect markers of EIMD were measured throughout the training period. Maximal knee extension torque in eccentric (-1.05 rad·s(-1)), isometric and concentric (1.05 rad·s(-1)) conditions were measured at pre- and post-training. The ramp-up group showed no indications of EIMD throughout the training period (e.g., plasma creatine kinase (CK) activity: always <185 U · L(-1)) while EIMD was evident after the first session in the constant group (CK: peak 485 U · L(-1)). Both groups significantly increased maximal knee extension torque in all conditions with greater gains in eccentric (ramp-up: +19%, constant: +21%) than isometric (+16%, +15%) and concentric (+12%, +10%) strength without any significant group-difference. The current results suggest that EIMD can be avoided by the ramp-up protocol and is not a major determinant of training-induced strength gain.

背景与目标： ：这项研究检查了下坡步行训练后避免或经历运动引起的肌肉损伤（EIMD）是否会影响力量增长。健康的年轻男性在跑步机上进行下坡步行（坡度：-28％，速度：5 km·h（-1），负荷：体重的10％），每周一次，每次1次，为期四周，采用增加训练方案（n = 16），运动时间在四个疗程中从10分钟逐渐增加到30分钟，50和70分钟，或恒定协议（n = 14），其中四个疗程的运动持续时间均为40分钟。在整个训练期间，都对EIMD的间接指标进行了测量。在训练前和训练后，在偏心（-1.05 rad·s（-1）），等距和同心（1.05 rad·s（-1））条件下测量最大膝盖伸展扭矩。稳定组在整个训练期间均未显示EIMD的征兆（例如血浆肌酸激酶（CK）活性：始终<185 U·L（-1）），而在恒定组（CK）的第一次训练后，EIMD明显：峰值485 U·L（-1））。两组均在所有情况下显着增加最大膝关节伸展扭矩，偏心肌（斜率：19％，常数：21％）比等轴测力（16％，15％）和同心力（12％，10％）要大得多显着的群体差异。目前的结果表明，可以通过增加规程避免EIMD，它不是训练诱发的力量增加的主要决定因素。

BACKGROUND & AIMS: :Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVO2peak) corresponding to peak oxygen uptake (VO2peak). Only EXP performed a 30-min DR (- 15%) on a treadmill at 70% vVO2peak fourteen days before LR. Indirect EIMD markers and neuromuscular function were assessed before, immediately and 48 h after DR and LR. Knee extension isometric peak torque (IPT) decreased (- 36.3 ± 26%, p < 0.05) immediately following DR with full recovery reached 48 h post-DR. Muscle soreness developed (p < 0.05) immediately (37 ± 25 mm) and 48 h (45 ± 26 mm) post-DR. IPT and rate of torque development (RTD) at late phases (> 150 ms) from the onset of muscle contraction decreased significantly (- 10.7 ± 6.1% and from - 15.4 to - 18.7%, respectively) immediately after LR for the CON group and remained below baseline values (- 5.6 ± 8.5% and from - 13.8 to - 14.9%, respectively) 48 h post-LR. However, IPT and late RTD were not significantly affected by LR for the EXP group, showing a group x time interaction effect. We concluded that a single DR bout can be used to attenuate fatigue induced by a LR performed fourteen days after.

背景与目标： ：疲劳可以定义为运动引起的力量损失。在跑步过程中，疲劳可以通过重复的低强度偏心收缩引起的肌肉损伤（EIMD）来部分解释。先前的研究表明，下坡跑步（DR）会减弱随后的EIMD。因此，我们测试了30分钟的DR搏动是否会减轻随后60分钟的水平跑步（LR）引起的疲劳。二十七名男大学生被随机分配到实验组（EXP）或对照组（CON）。所有参与者均在跑步机上以对应于峰值摄氧量（VO2peak）的速度（vVO2peak）的70％进行LR。只有EXP在LR前14天以70％vVO2peak在跑步机上执行30分钟的DR（-performed15％）。在DR和LR之前，之后和48小时后评估间接EIMD标记和神经肌肉功能。 DR后立即伸膝等距峰值扭矩（IPT）降低（-36.3±26％，p <0.05），并在DR后48小时完全恢复。 DR后立即（37±25 mm）和48 h（45±26 mm）出现肌肉酸痛（p 150 ms）的IPT和扭矩发展速率（RTD）显着下降（分别从-10.7±6.1％和从-15.4降至-18.7％） LR后48小时仍低于基线值（分别为-5.6±8.5％和从-13.8至-14.9％）。但是，对于EXP组，IPT和晚期RTD不受LR的显着影响，显示了组x时间交互作用。我们得出的结论是，单次DR发作可用于减轻14天后进行的LR引起的疲劳。

BACKGROUND & AIMS: :Eccentric exercise is known to cause changes to the ultrastructure of skeletal muscle and, in turn, may alter the ability of the muscle to store and utilise intracellular substrates such as intramyocellular lipid (IMCL). The purpose of this study was to test the hypothesis that exercise-induced muscle damage (EIMD) results in IMCL accumulation. Six males (31 ± 6 years; mean ± SD, and 72.3 ± 9.7 kg body mass) performed 300 unilateral, maximal, isokinetic, eccentric contractions (Ecc) (30° s(-1)) of the quadriceps on an isokinetic dynamometer, followed immediately by an equal amount of work by the contralateral leg but with concentric action (Con). Phosphate compounds and IMCL content of the vastus lateralis of both legs were measured using (31)P and (1)H magnetic resonance spectroscopy. IMCL content was higher in Ecc than Con 24 h post but the reverse was evident 48 h post-exercise (P = 0.046). A significant time × trial interaction for resting [P(i)] (P = 0.045), showed increases in Ecc across time but no change in Con. A significant main effect of trial (P = 0.002) was apparent indicating the Ecc leg had marked metabolic dysfunction. The P(i)/PCr ratio showed a significant effect of trial (P = 0.001) with an increase evident in Ecc leg, primarily due to increases in [P(i)]. The present study highlights changes in IMCL content of skeletal muscle following EIMD.

背景与目标： 众所周知，离心运动会引起骨骼肌超微结构的变化，进而可能改变肌肉存储和利用细胞内底物（如肌细胞内脂质（IMCL））的能力。本研究的目的是检验运动诱发的肌肉损伤（EIMD）导致IMCL积累的假说。六名男性（31±6岁;平均±SD和72.3±9.7千克体重）在等速测力计上进行了300次四头肌的单侧，最大，等速，偏心收缩（Ecc）（30°s（-1）），随后立即由对侧腿进行同等的工作量，但采取同心作用（Con）。使用（31）P和（1）H磁共振波谱法测量双腿大外侧外侧的磷酸盐化合物和IMCL含量。 Ecc的IMCL含量高于Con 24小时后的Con，但运动后48 h则相反（P = 0.046）。休息[P（i）]（P = 0.045）的显着时间×交互作用表明，随着时间的推移Ecc增加，但Con不变。试验的主要主要作用很明显（P = 0.002），表明Ecc腿有明显的代谢功能障碍。 P（i）/ PCr比显示出显着的试验效果（P = 0.001），Ecc腿明显增加，这主要是由于[P（i）]的增加。本研究强调了EIMD后骨骼肌IMCL含量的变化。

BACKGROUND & AIMS: :To investigate the effects of allicin supplementation on exercise-induced muscle damage (EIMD), interleukin-6 (IL-6), and antioxidative capacity, a double-blinded, placebo-controlled study was conducted in well-trained athletes. Subjects were randomly assigned to an allicin supplementation group (AS group) and a control group, and received either allicin or placebo for 14 days before and 2 days after a downhill treadmill run. Plasma creatine kinase (CK), muscle-specific creatine kinase (CK-MM), lactate dehydrogenase (LDH), IL-6, superoxide dismutase (SOD), total antioxidative capacity (TAC), and perceived muscle soreness were measured pre and post exercise. AS group had significantly lower plasma levels of CK, CK-MM and IL-6, and reduced perceived muscle soreness after exercise, when compared with the control group. AS group also demonstrated a trend toward reducing plasma concentration of LDH after exercise (P = 0.08), although not statistically significant. Allicin supplementation induced a higher value of TAC at rest, and this higher value was maintained 48 h after exercise, however, there was no difference in SOD values after exercise between the two groups. The results suggested that allicin might be a potential agent to reduce EIMD. Further studies concerning anti-inflammatory and anti-oxidative effects of allicin on EIMD are needed.

背景与目标： ：为了研究补充大蒜素对运动诱发的肌肉损伤（EIMD），白介素6（IL-6）和抗氧化能力的影响，在训练有素的运动员中进行了双盲，安慰剂对照研究。将受试者随机分配至大蒜素补充组（AS组）和对照组，并在下坡跑步机跑步前14天和跑步后2天接受大蒜素或安慰剂治疗。前后分别测量血浆肌酸激酶（CK），肌肉特异性肌酸激酶（CK-MM），乳酸脱氢酶（LDH），IL-6，超氧化物歧化酶（SOD），总抗氧化能力（TAC）和感觉到的肌肉酸痛锻炼。与对照组相比，AS组的CK，CK-MM和IL-6血浆水平显着降低，并且运动后的肌肉酸痛感降低。 AS组还显示出运动后LDH血浆浓度降低的趋势（P = 0.08），尽管在统计学上没有统计学意义。补充大蒜素后，静息时的TAC值较高，运动后48小时仍保持较高值，但是两组运动后的SOD值无差异。结果表明，大蒜素可能是减少EIMD的潜在药物。需要进一步研究大蒜素对EIMD的抗炎和抗氧化作用。

BACKGROUND & AIMS: :AMP-activated protein kinase (AMPK) has been shown to regulate protein metabolism in skeletal muscle. We previously found that levels of Forkhead box proteins, FoxO1 and FoxO3a, and myostatin in rat gastrocnemius increased after exercise-induced muscle damage (EIMD). Eccentric muscle contractions (ECs), defined as elongation of muscle under tension, were used for inducing EIMD. The objective of this study was to clarify whether AMPK participates in activation and expression of FoxO proteins and myostatin in rat gastrocnemius muscle after EIMD. Wistar rats were randomly assigned into the following three groups; CON (n = 6), 180ECs group (ankle angular velocity, 180°/s; n = 6), and 30ECs group (ankle angular velocity, 30°/s; n = 6). 20 ECs were conducted with percutaneous electrical stimulation of gastrocnemius and simultaneous forced dorsiflexion of ankle joint (from 0° to 45°). To evaluate activation of AMPK, we measured the phosphorylated states of AMPK and acetyl CoA carboxylase. For evaluation of the direct relationships of AMPK and other proteins, we also examined contents of FoxOs and myostatin with stimulation of L6 myotube with AMPK agonist, 5 -aminoimidazole -4 -carboxamide -1-β-d-ribofuranoside (AICAR) (0.1, 0.5, 1, 1.5, and 2 mM). Western blotting was employed for protein analysis. Significant torque deficit was only observed in the 180ECs, suggesting EIMD. We also observed that phosphorylated AMPKα was induced in response to 180ECs (p < 0.01 vs. CON). Additionally, the level of phosphorylated acetyl CoA carboxylase was significantly higher in response to 180ECs and 30ECs. The phosphorylated states of FoxO1, FoxO3a, and myostatin expression were increased significantly in response to 180ECs. Furthermore, treatment of L6 myotubes with AICAR showed similar tendencies to that observed in in vivo gastrocnemius muscle treated with 180ECs. Therefore, we conclude that activation of AMPK plays a key role in increasing the level of FoxO1, FoxO3a, and myostatin in gastrocnemius after EIMD.

背景与目标： ：AMP激活的蛋白激酶（AMPK）已被证明可调节骨骼肌中的蛋白代谢。我们以前发现运动诱发的肌肉损伤（EIMD）后，大鼠腓肠肌中Forkhead box蛋白，FoxO1和FoxO3a和肌生长抑制素的水平增加。偏心肌收缩（ECs）定义为在张力下的肌肉伸长，用于诱发EIMD。这项研究的目的是阐明EIMD后AMPK是否参与大鼠腓肠肌中FoxO蛋白和肌肉生长抑制素的激活和表达。 Wistar大鼠随机分为以下三组： CON（n = 6），180ECs组（踝角速度，180°/ s; n = 6）和30ECs组（踝角速度，30°/ s; n = 6）。在经皮电刺激腓肠肌并同时强迫踝关节背屈（0°至45°）的情况下进行20个EC。为了评估AMPK的激活，我们测量了AMPK和乙酰辅酶A羧化酶的磷酸化状态。为了评估AMPK与其他蛋白质的直接关系，我们还检查了AMPK激动剂5-氨基咪唑-4-甲酰胺-1-β-d-核呋喃核苷（AICAR）刺激L6肌管后FoxOs和肌生长抑制素的含量0.5、1、1.5和2 mM）。 Western印迹用于蛋白质分析。仅在180EC中才观察到明显的扭矩不足，提示为EIMD。我们还观察到磷酸化的AMPKα是在响应180ECs时被诱导的（p <0.01 vs.CON）。另外，响应180EC和30EC，磷酸化的乙酰辅酶A羧化酶的水平明显更高。 FoxO1，FoxO3a和肌生长抑制素表达的磷酸化状态响应180ECs显着增加。此外，用AICAR治疗L6肌管的趋势与在用180ECs治疗的体外腓肠肌中观察到的趋势相似。因此，我们得出结论，EIMD后AMPK的激活在腓肠肌增加FoxO1，FoxO3a和肌生长抑制素的水平中起着关键作用。