Metabolic demand and muscle damage induced by eccentric cycling of knee extensor and flexor muscles

The aim of this study was to examine the metabolic demand and extent of muscle damage of eccentric cycling targeting knee flexor (FLEX) and knee extensor (EXT) muscles. Methods: Eight sedentary men (23.3?±?0.7?y) underwent two eccentric cycling sessions (EXT and FLEX) of 30?min each, at 60% of the maximum power output. Oxygen consumption (VO₂), heart rate (HR) and rated perceived exertion (RPE) were measured during cycling. Countermovement and squat jumps (CMJ and SJ), muscle flexibility, muscle soreness and pain pressure threshold (PPT) of knee extensor and flexor muscles were measured before, immediately after and 1–4 days after cycling. Results: FLEX showed greater VO₂ (+23%), HR (+14%) and RPE (+18%) than EXT. CMJ and SJ performance decreased similarly after cycling. Muscle soreness increased more after EXT than FLEX and PPT decreased in knee extensor muscles after EXT and decreased in knee flexor muscles after FLEX. Greater loss of muscle flexibility in knee flexor muscles after FLEX was observed. Conclusion: Eccentric cycling of knee flexor muscles is metabolically more demanding than that of knee extensors, however muscle damage induced is similar. Knee flexors experienced greater loss of muscle flexibility possibly due to increased muscle stiffness following eccentric contractions.     

预热应激对骨骼肌保护作用及机制研究

研究的主要目的是观察预热应激是否对大鼠骨骼肌离心运动损伤具有保护作用,并对预热应激的保护作用机制进行探讨。实验大鼠分为预热应激组和正常组。预热应激组大鼠恢复24h后,两组进行大强度离心运动,然后分别比较腓肠肌最大强直收缩力、血清肌酸激酶（CK）、乳酸脱氢酶（LDH）、丙二醛（MDA）的变化。结果发现,预热应激组大鼠离心运动后最大强直收缩力比正常组下降少且恢复快,CK在运动后即刻显著低于正常组,MDA显著低于正常组。     

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.     

Protection against muscle damage in competitive sports players: the effect of the immunomodulator AM3

Strenuous physical exercise of the limb muscles commonly results in damage, especially when that exercise is intense, prolonged and includes eccentric contractions. Many factors contribute to exercise-induced muscle injury and the mechanism is likely to differ with the type of exercise. Competitive sports players are highly susceptible to this type of injury. AM3 is an orally administered immunomodulator that reduces the synthesis of proinflammatory cytokines and normalizes defective cellular immune fractions. The ability of AM3 to prevent chronic muscle injury following strenuous exercise characterized by eccentric muscle contraction was evaluated in a double-blind and randomized pilot study. Fourteen professional male volleyball players from the First Division of the Spanish Volleyball League volunteered to take part. The participants were randomized to receive either placebo (n?=?7) or AM3 (n?=?7). The physical characteristics (mean±s) of the placebo group were as follows: age 25.7±2.1 years, body mass 87.2±4.1?kg, height 1.89±0.07?m, maximal oxygen uptake 65.3±4.2?ml?·?kg^?1?·?min^?1. Those of the AM3 group were as follows: age 26.1±1.9 years, body mass 85.8±6.1?kg, height 1.91±0.07?m, maximal oxygen uptake 64.6±4.5?ml?·?kg^?1?·?min^?1. All participants were evaluated for biochemical indices of muscle damage, including concentrations of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatine kinase (CK) and its MB fraction (CK-MB), myoglobin, lactate dehydrogenase, urea, creatinine and γ-glutamyltranspeptidase, both before and 30 days after treatment (over the peak of the competitive season). In the placebo group, competitive exercise (i.e. volleyball) was accompanied by significant increases in creatine kinase (494±51 to 560±53?IU?·?l^?1, P?<?0.05) and myoglobin (76.8±2.9 to 83.9±3.1?μg?·?l^?1, P?<?0.05); aspartate aminotransferase (30.8±3.0 to 31.1±2.9?IU?·?l^?1) and lactate dehydrogenase (380±31 to 376±29?IU?·?l^?1) were relatively unchanged after the 30 days maximum effort. AM3 not only inhibited these changes, it led to a decrease from baseline serum concentrations of creatine kinase (503±49 to 316±37?IU?·?l^?1, P?<?0.05) and myoglobin (80.1±3.2 to 44.1±2.6?IU?·?l^?1, P?<?0.05), as well as aspartate aminotransferase (31.1±3.3 to 26.1±2.7?IU?·?l^?1, P?<?0.05) and lactate dehydrogenase (368±34 to 310±3?IU?·?l^?1, P?<?0.05). The concentration of CK-MB was also significantly decreased from baseline with AM3 treatment (11.6±1.2 to 5.0±0.7?IU?·?l^?1, P?<?0.05), but not with placebo (11.4±1.1 to 10.8±1.4?IU?·?l^?1). In conclusion, the use of immunomodulators, such as AM3, by elite sportspersons during competition significantly reduces serum concentrations of proteins associated with muscle damage.     

蜂胶黄酮对小鼠缺血再灌注后心肌线粒体损伤的保护作用

目的:探讨蜂胶黄酮对小鼠力竭游泳后心肌线粒体缺血再灌注损伤的保护作用.方法:将70只小鼠随机分为安静组(A组)、力竭对照组(B组)和力竭给药组(C组).A、B组常规喂养,C组灌喂蜂胶黄酮液.B、C组进行4周递增负荷游泳训练,并于最后一次训练至力竭,测定其安静时、力竭后即刻、6小时和24小时心肌线粒体超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、总-抗氧化能力(T-AOC)、丙二醛(MDA)、Ca2、磷脂酶A2(PLA2)等指标.结果:缺血再灌注后B组小鼠心肌线粒体中抗氧化物质(SOD、GSH-Px、T-AOC)活性显著下降,MDA含量、PLA2活性显著升高,心肌钙离子明显超载,尤以力竭运动后6h最为显著;而补充蜂胶黄酮的C组与B组相比,抗氧化物质活性显著提高,自由基MDA含量、PLA2活性显著下降,钙离子明显减少.结论:蜂胶黄酮对缺血再灌注损伤的心肌线粒体有积极的保护作用.     

细胞骨架及运动性骨骼肌微损伤研究进展

综述了细胞骨架的结构和功能的研究进展,分析了骨骼肌细胞骨架在维持骨骼肌肌小节的正常结构和功能中的重要性。重点叙述了骨骼肌细胞骨架蛋白desmin、dystrophins、arcoglycant、itin和nebulin在运动中的变化,对细胞骨架蛋白在运动性骨骼肌微损伤中的作用进行了讨论。     

甲醛致运动大鼠骨骼肌氧化损伤及刺五加的作用研究

目的：探讨甲醛染毒对运动大鼠骨骼肌的毒性及刺五加的保护作用。方法：采用40只2月龄雄性WiStar大鼠,体重（180士10）g,随机分为对照组、模型组、刺五加组进行动式染毒,甲醛剂量分别为0．8mg／m3,2．4mg／m3。每天染毒30min,每周6次,连续4周,刺五加的灌胃剂量为104．17mg／kg,测定运动大鼠骨骼肌组织中的超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GsH-Px）、过氧化氢酶（CAT）的活性和丙二醛（MDA）的含量。结果：模型组与对照组相比,模型组大鼠骨骼肌组织中CAT、GSH-PX、SOD活性均明显低于对照组（P〈O．05）,MDA含量明显高于对照组（P〈O．05）。刺五加组与模型组相比,刺五加组大鼠骨骼肌组织中CAT、GSH-PX、SOD活性明显高于模型组（P〈O．05）,MDA含量显著低于模型组（P〈O．01）。结论：甲醛可以造成运动大鼠骨骼肌组织的氧化性损伤,而灌服刺五加可以有效缓解其毒性。     

高压氧、自由基与骨骼肌损伤的研究进展

运用文献资料法,通过查阅近年来国内外有关高压氧、自由基及骨骼肌损伤的相关文献,综述了三者各自的研究动态,并针对两两之间的相互关系进行详细阐述.主要结论:高压氧疗法在骨骼肌损伤治疗中有独特的良好作用,为避免其毒性作用的发生,必须掌握好治疗时的压力、浓度及时间;关于自由基与骨骼肌损伤之间的关系,目前尚存在争论,二者可能是同时发生、相互影响和相互促进的,其确切关系还有待于进一步研究.     

预热适应对运动大鼠骨骼肌的保护作用及对自由基代谢的影响

目的:观察为期16天的预热适应对大鼠一次性离心运动后骨骼肌损伤的保护作用及对自由基代谢的影响。方法:5周龄SPF级雄性SD大鼠80只,随机分为非预热适应组和预热适应组。并根据取材点不同将非预热适应组和预热适应组分别分为非预热适应安静对照组、单纯运动后即刻、24 h、48 h组、6 d组;预热适应安静对照组和预热适应运动后即刻、24 h、48h、6 d组。为期16天的预热适应结束后,室温恢复24 h,除非预热适应安静对照组和预热适应安静对照组外,运动组大鼠均进行一次性力竭离心运动。运动结束后,分别在运动后即刻、24h、48 h和6 d取腓肠肌,进行光镜观察和SOD、MDA含量测试。结果:1)光镜下观察到,预热适应大鼠运动后骨骼肌损伤较单纯运动大鼠相应的时间点明显减轻。2)预热适应大鼠运动后SOD活性较单纯运动大鼠同一时间点的值均高,其中预热适应运动后24 h显著高于单纯运动后24 h(P<0.01);而MDA含量较单纯运动大鼠同一时间点的值均低,其中预热适应运动后24 h、48 h与单纯运动后同一时间点比较,差异有显著性(P<0.01和P<0.05)。结论:为期16天的预热适应对离心运动所致骨骼肌损伤有明显的保护作用,并能纠正其自由基代谢失调。     

Effect of sulphurous mineral water in haematological and biochemical markers of muscle damage after an endurance exercise in well-trained athletes

Abstract

To investigate the effects of sulphurous mineral water (SMW) after a hydroponic treatment on muscle damage, antioxidant activity and peripheral blood changes induced by submaximal exercise. Thirty well-trained male triathletes were supplemented with SMW or placebo: 3 weeks of placebo, 30 days of wash out and 3 weeks of SMW. After both periods, participants ran for 2 h at 70% maximal aerobic speed. Antioxidant enzymes, lipid peroxidation, antioxidant capacity and blood cell markers were compared between placebo and SMW at pre-exercise (T₀), immediately post-exercise (T₁), 24 h post-exercise (T₂) and 48 h post-exercise (T₃). Total thiols decreased until T₃ vs. T₀ for both placebo and SMW; transient red blood cells, haemoglobin and haematocrit increased were shown at T₁ vs. T₀ and for leucocytes until T₂ vs. T₀, only for placebo group. Total thiols increased significantly in SMW vs. placebo at T₀; Thiobarbituric acid reactive species was significantly higher at T₀, T₁, T₂ and T₃; catalase increased significantly at T₁; creatine phosphokinase decreased significantly at T₁, T₂ and T₃, although no significant differences were found at T₀. Furthermore, red blood cells, haemoglobin and haematocrit were significantly higher and leucocytes were significantly lower at T₀ and T₁ in SMW group vs. placebo group. This study suggests that three weeks of SMW supplementation may protect from exercise-induced muscle damage.     

Comparative efficacy of active recovery and cold water immersion as post-match recovery interventions in elite youth soccer

ABSTRACT

The current study compared cold-water immersion (CWI) and active recovery (AR) to static stretching (SS) on muscle recovery post-competitive soccer matches in elite youth players (n = 15). In a controlled crossover design, participants played a total of nine competitive soccer games, comprising three 80 minute games for each intervention (SS, CWI and AR). Muscle oedema, creatine kinase (CK), countermovement jump performance (CMJA) and perceived muscle soreness (PMS) were assessed pre-, immediately post-, and 48 hours post-match and compared across time-intervals and between interventions. Following SS, all markers of muscle damage remained significantly elevated (P < 0.05) compared to baseline at 48 hours post-match. Following AR and CWI, CMJA returned to baseline at 48 hours post-match, whilst CK returned to baseline following CWI at 48 hours post-match only. Analysis between recovery interventions revealed a significant improvement in PMS (P < 0.05) at 48 hours post-match when comparing AR and CWI to SS, with no significant differences between AR and CWI observed (P > 0.05). Analysis of %change for CK and CMJA revealed significant improvements for AR and CWI compared to SS. The present study indicated both AR and CWI are beneficial recovery interventions for elite young soccer players following competitive soccer matches, of which were superior to SS.     

Relationship between physiological parameters and performance during a half-ironman triathlon in the heat

Abstract

Triathlon is a popular outdoor endurance sport performed under a variety of environmental conditions. The aim of this study was to assess physiological variables before and after a half-ironman triathlon in the heat and to analyse their relationship with performance. Thirty-four well-trained triathletes completed a half-ironman triathlon in a mean dry temperature of 29 ± 3ºC. Before and within 1 min after the end of the race, body mass, core temperature, maximal jump height and venous blood samples were obtained. Mean race time was 315 ± 40 min, with swimming (11 ± 1%), cycling (49 ± 2%) and running (40 ± 3%) representing different amounts of the total race time. At the end of the competition, body mass changed by ?3.8 ± 1.6% and the change in body mass correlated positively with race time (r = 0.64; P < 0.001). Core temperature increased from 37.5 ± 0.6ºC to 38.8 ± 0.7ºC (P < 0.001) and post-race core temperature correlated negatively with race time (r = ?0.47; P = 0.007). Race time correlated positively with the decrease in jump height (r = 0.38; P = 0.043), post-race serum creatine kinase (r = 0.55; P = 0.001) and myoglobin concentrations (r = 0.39; P = 0.022). In a half-ironman triathlon in the heat, greater reductions in body mass and higher post-competition core temperatures were present in faster triathletes. In contrast, slower triathletes presented higher levels of muscle damage and decreased muscle performance.     

Effect of cold water immersion on repeat cycling performance and thermoregulation in the heat

Abstract

To assess the effect of cold water immersion and active recovery on thermoregulation and repeat cycling performance in the heat, ten well-trained male cyclists completed five trials, each separated by one week. Each trial consisted of a 30-min exercise task, one of five 15-min recoveries (intermittent cold water immersion in 10°C, 15°C and 20°C water, continuous cold water immersion in 20°C water or active recovery), followed by 40 min passive recovery, before repeating the 30-min exercise task. Recovery strategy effectiveness was assessed via changes in total work in the second exercise task compared with that in the first. Following active recovery, a mean 4.1% (s = 1.8) less total work (P = 0.00) was completed in the second than in the first exercise task. However, no significant differences in total work were observed between any of the cold water immersion protocols. Core and skin temperature, blood lactate concentration, heart rate, rating of thermal sensation, and rating of perceived exertion were recorded. During both exercise tasks there were no significant differences in blood lactate concentration between interventions; however, following active recovery blood lactate concentration was significantly lower (P < 0.05; 2.0 ± 0.8 mmol · l^?1) compared with all cold water immersion protocols. All cold water immersion protocols were effective in reducing thermal strain and were more effective in maintaining subsequent high-intensity cycling performance than active recovery.     

运动诱导的呼吸链ROS生成及抗氧化物功能研究进展

线粒体呼吸链是运动产生自由基和ROS的主要场所,并构成机体主要的氧化系统。ROS的过量产生会对机体造成氧化损伤。呼吸链中存在对抗ROS的CoQ和细胞色素C等抗氧化体系,但作用有限。各种外源性抗氧化营养素的补充能起到对抗ROS的作用,联合补充的效果可能更佳。     

耐力训练及限食对老龄大鼠骨骼肌线粒体氧化及抗氧化水平影响的比较研究

目的:观察长期耐力训练及限食对老龄大鼠骨骼肌线粒体氧化及抗氧化水平的影响,比较其单独及协同作用,为"线粒体衰老"学说提供一定的理论依据。方法:32只17月龄雄性SD大鼠分为4组:安静组(Control,C)、限食组(Caloric-Restricted,CR)、运动组(Exercise,E)和限食加运动组(Caloric-restricted and Exercise,E+CR),训练方式为跑台运动,中等运动强度(64%VO2max,15m/min,60分钟/天,每周5天),限食摄入的标准为正常摄入组的60%,共训练及限食12周,相同月龄对照组正常饲养。12周后于末次训练后取大鼠骨骼肌分别进行线粒体氧化损伤水平及抗氧化水平测定。结果:CR组、E组和CR+E组骨骼肌线粒体丙二醛(malondialdehyde,MDA)含量显著降低,锰超氧化物歧化酶(manganese-containing superoxide dismutase,MnSOD)活性显著增加,谷胱甘肽过氧化物酶(glutathion peroxidase,GSH-PX)活性显著增加;E组和CR+E组骨骼肌线粒体过氧化氢酶(catalase,CAT)活性显著增加。结论:耐力训练提高机体的抗氧化水平,同时使细胞机能节省化,耗氧量相对下降而减少了自由基的产生,限食减弱了机体的氧化应激,减少了自由基的产生,阻止了脂质过氧化,同时限食动员了一系列的适应性的网络防御机制,增加了抗氧化水平,加强了防御。耐力运动在机体抗氧化能力上明显强于限食作用,而耐力运动与限食的协同作用对某些抗氧化酶的影响强于其单独作用的影响。     

运动对骨骼肌、心肌中热休克蛋白表达影响的研究进展

热休克蛋白是一组结构高度保守的多肽,几乎所有生物体受到某种额外程度的应激时都有热休克蛋白的表达,因此又称为应激蛋白.热休克蛋白赋予细胞或生物体从各种应激中恢复的能力和保护他们免遭这些应激因素的伤害.其中,表现最为明显的是热耐受能力.热休克蛋白作为一种分子伴侣,能维持细胞的正常结构.热休克蛋白在抗氧化、抗细胞凋亡中也具有重要作用.运动也能诱导心肌、骨骼肌等组织中热休克蛋白的表达,并与运动方式、运动强度密切相关,在骨骼肌中的表达表现出肌纤维特异性.     

A bioengineering analysis of human muscle and joint forces in the lower limbs during running

A two‐dimensional, dynamic bioengineering model of the lower limbs was developed in order to estimate muscle and joint forces present during running at 4.5 m s ^‐1. Data were collected from four subjects using a force platform and cine film. Individual X‐rays and anthropometric data from the lower limbs were utilized to produce accurate bone models of the subjects’ legs. Electromyographic verification of the model was undertaken while a runner was undergoing treadmill running at 4.5 m s^‐1. Results indicate that peak muscle forces of 22 times subject body weight (22 BW) could be present in the quadriceps muscle group and 7 BW in the gastrocnemius. The anterior shin muscles were found to be active for the first 9% of stance phase only, and compressive loads of 33 BW were found in the knee joint. The relationship between these nigh forces in the lower limbs and running related injuries is discussed.     

The effects of verbal encouragement and conscientiousness on maximal voluntary contraction of the triceps surae muscle in elite athletes

Abstract

We investigated the effect of verbal encouragement on maximal voluntary contraction (MVC) level of the triceps surae muscle group. Our secondary focus was to examine whether the effect of verbal encouragement on MVC level varies as a result of conscientiousness. While the participants performed plantar flexion, MVCs of the triceps surae muscle group were measured using rectified and smoothed surface electromyography (rsEMG) during the absence and presence of verbal encouragement. Participants completed questions from the Five Factor Personality Inventory concerning conscientiousness and were divided into high- and low-conscientiousness groups according to a median split. The sample included 30 female and 53 male elite athletes. In the entire cohort, there was no significant difference in MVCs with and without verbal encouragement. When the sample was partitioned by conscientiousness scores, verbal encouragement led to a significant increase in MVC in the low-conscientiousness group, whereas verbal encouragement led to a non-significant decrease in MVC in the high-conscientiousness group. Percentage change in MVC across experimental conditions was significantly different between the groups, with a 9.72% increase during verbal encouragement of the low-conscientiousness group, and a 2.47% decrease during verbal encouragement of the high-conscientiousness group.     

不同强度的耐力运动对糖尿病大鼠肾脏氧化应激与TIMP-1表达的影响

目的:探讨不同运动强度的耐力运动对糖尿病大鼠肾脏氧化应激及基质金属蛋白酶组织抑制物-1(TIMP-1)的影响。方法:以体重190±15 g SD雄性大鼠为研究对象,经6周高脂高糖膳食喂养并腹腔注射链脲佐菌素建立糖尿病模型后,将糖尿病大鼠分为糖尿病对照组(DMC),糖尿病运动Ⅰ组(DME1,跑速为10 m/min),糖尿病运动Ⅱ组(DME2,跑速为15 m/min),糖尿病运动3组(DME3,跑速为20m/min),运动组每天1小时跑台运动,每周5天,持续6周。6周末检测血糖、胰岛素,肾脏组织内MDA、SOD、CAT及TIMP-1的含量或活性。结果:与对照组相比,运动组血糖均著下降(P<0.01),而运动组血清胰岛素均呈上升趋势,且DME3组显著上升(P<0.05),但运动1组、运动2组胰岛素抵抗指数显著下降(P<0.05);而运动1组与运动2组MDA显著下降(P<0.05,P<0.01);同时,各运动组抗氧化酶均呈上升趋势,其中T-SOD含量上升均具有显著性或极显著性差异,低强度、中强度运动组CAT含量显著高于对照组(P<0.01);而运动组TIMP-1表达水平显著或极显著下降(P<0.05,P<0.01)。结论:10 m/min、15 m/min强度耐力运动可有效地控制降低血糖,改善胰岛素抵抗,提高糖尿病大鼠抗氧化防御系统,防止肾脏纤维化,有利于控制糖尿病进一步恶化。     

Long-term effects of the 11+ warm-up injury prevention programme on physical performance in adolescent male football players: a cluster-randomised controlled trial

This study examined the long-term effects of the 11+ on physical performance in adolescent male football (soccer) players. Eighty-two 14- to 16-year-old male football players (11+ = 42 players, control = 40 players) participated. Teams were randomised to control (CON) and intervention (INT) groups. INT applied the 11+ injury prevention programme for 30 weeks at least twice a week as a warm-up. CON performed their standard warm-up. Motor performance tests were conducted 1 week prior and 1 week after the competition season. We used magnitude-based inferences and linear mixed-effects models to analyse performance test results. INT showed superior results compared to CON in the vertical jump height 7.5% (95%-CI 4.4%, 10.7%), the Bosco 15-s-jump test 7.2% (95%-CI 2.2%, 12.4%), and the Illinois agility test ?2.6% (95%-CI ?4.1%, ?1.1%). Possibly beneficial effects in favour of INT were found in the 9.1 m sprint test ?3.1% (95%-CI ?6.1%, 0.1%). Possibly harmful effects (i.e. in favour of CON) were observed in the dribbling test 2.8% (95%-CI ?0.8%, 6.4%). The 11+ warm-up programme can improve different performance measures in football players. Coaches might implement additional dribbling drills next to the 11+ to achieve improvements observed in dribbling ability when using a regular warm-up programme.