倍力方抗运动性疲劳作用的实验研究

目的:研究倍力方对运动训练大鼠抗疲劳的作用。方法:将运动筛选后的大鼠分组,除安静组外其他各组均按计划进行运动训练。每天对各组体重食重进行称量。五周后对各组大鼠的生化指标进行测试。结果:复方Ⅰ能够明显延长力竭运动时间,并且抑制食欲和降体重。同时复方Ⅰ可明显提高肝糖元及肌糖元的含量;复方Ⅱ组在力竭运动即刻后,血中肌酐(CREA)的浓度明显小于Ⅰ即刻和对照即刻组。结论:倍力方能明显提高糖原储备,运动时糖供能增多,有助于节约蛋白质,减少蛋白质的分解。并对肾脏有明显的保护作用。     

The dynamic control ratio at the equilibrium point (DCRe): introducing relative and absolute reliability scores

Analytical methods to assess thigh muscle balance need to provide reliable data to allow meaningful interpretation. However, reproducibility of the dynamic control ratio at the equilibrium point has not been evaluated yet. Therefore, the aim of this study was to compare relative and absolute reliability indices of its angle and moment values with conventional and functional hamstring–quadriceps ratios. Furthermore, effects of familiarisation and angular velocity on reproducibility were analysed. A number of 33 male volunteers participated in 3 identical test sessions. Peak moments (PMs) were determined unilaterally during maximum concentric and eccentric knee flexion (prone) and extension (supine position) at 0.53, 1.57 and 2.62 rad · s^–1. A repeated measure, ANOVA, confirmed systematic bias. Intra-class correlation coefficients and standard errors of measurement indicated relative and absolute reliability. Correlation coefficients were averaged over respective factors and tested for significant differences. All balance scores showed comparable low-to-moderate relative (<0.8–0.9) and good absolute reliability (<10%). Relative reproducibility of dynamic control equilibrium parameters augmented with increasing angular velocity, but not with familiarisation. At 2.62 rad · s^–1, high (moment: 0.906) to moderate (angle: 0.833) relative reliability scores with accordingly high absolute indices (4.9% and 6.4%) became apparent. Thus, the dynamic control equilibrium is an equivalent method for the reliable assessment of thigh muscle balance.     

Effects of different warm-up modalities on power output during the high pull

This study compared the effects of six warm-up modalities on peak power output (PPO) during the high-pull exercise. Nine resistance-trained males completed six trials using different warm-ups: high-pull specific (HPS), cycle, whole body vibration (WBV), cycle+HPS, WBV+HPS and a control. Intramuscular temperature (T_m) was increased by 2°C using WBV or cycling. PPO, T_m and electromyography (EMG) were recorded during each trial. Two high-pulls were performed prior to and 3 min after participants completed the warm-up. The greatest increase in PPO occurred with HPS (232.8 ± 89.7 W, P < 0.001); however, this was not different to combined warm-ups (cycle+HPS 158.6 ± 121.1 W; WBV+HPS 177.3 ± 93.3 W, P = 1.00). These modalities increased PPO to a greater extent than those that did not involve HPS (all P < 0.05). HPS took the shortest time to complete, compared to the other conditions (P < 0.05). EMG did not differ from pre to post warm-up or between modalities in any of the muscles investigated. No change in T_m occurred in warm-ups that did not include cycling or WBV. These results suggest that a movement-specific warm-up improves performance more than temperature-related warm-ups. Therefore, mechanisms other than increased muscle temperature and activation may be important for improving short-term PPO.     

Nrf2在有氧运动训练中对小鼠骨骼肌抗氧化能力的作用

摘要：目的：Nrf2是机体氧化还原平衡的主要调节因子,本研究试图探讨Nrf2在有氧运动训练中对小鼠骨骼肌抗氧化能力的作用。方法：8周龄野生C57BL/6J小鼠和Nrf2敲除小鼠40只,雌雄各半。进一步各为安静组和运动组,每组10只,共4组：分别为野生安静组（WC）,野生运动组（WE）,敲除安静组（KC）和敲除运动组（KE）。运动组进行4周运动强度为70%VO2max跑速的跑台运动,每周运动6 d,每天运动1 h。运动组最后一次运动后休息48 h脱颈处死,取小鼠后腿骨骼肌。RT-PCR测量Nrf2及Nrf2介导的抗氧化基因mRNA表达量;Western blot法测定骨骼肌Nrf2及抗氧化蛋白含量; GSH试剂盒测量GSH/GSSG比值。结果：1）在安静情况下,KC组和WC组相比,骨骼肌中GSR、NQO1、GCLc、GPX、HO-1和SOD2这6个抗氧化蛋白表达以及GSH/GSSG值没有显著性改变。 2）4周有氧运动训练之后,Nrf2敲除运动组的大部分抗氧化蛋白（CAT, NQO1-1, GCLc, HO-1 and SOD2）和GSH/GSSG值都要显著低于野生运动组。结论：4周70%VO2max强度的有氧运动训练,增加了成年Nrf2敲除和野生鼠骨骼肌抗氧化蛋白表达量和GSH/GSSG比值的差异,而在无训练安静情况下在两种鼠中这些指标的差异不大。说明Nrf2对有氧运动训练中骨骼肌的抗氧化反应起着非常重要的作用。     

大剂量补充亮氨酸对抗阻运动所致骨骼肌损伤的影响

摘要：目的：探讨补充亮氨酸对无训练史被试进行抗阻运动所致骨骼肌损伤的影响。方法：16名青年男性大学生据体重随机分为补充亮氨酸组与安慰剂对照组,亮氨酸和安慰剂组被试从测试日深蹲抗阻运动前3周直至运动后4 d分别以每千克体重150 mg剂量摄入150 mL亮氨酸或糊精溶液。测试日各组被试以50% 1RM负荷完成5组深蹲运动,每组20次,组间间歇2 min。深蹲运动前于肘正中静脉采集血样,测量大腿围、纵跳高度、膝关节活动幅度与肌肉酸痛程度,并于运动后即刻、24 h、48 h、72 h和96 h重复测试。ELISA法检测血清CK-MM、Mb与血浆IL-6,胶乳增强免疫比浊法检测血清CRP。结果：与安慰剂组被试相比,补充亮氨酸显著降低了亮氨酸组被试运动后延迟性肌肉酸痛水平、大腿中段周长及血清CK-MM、Mb、CRP与血浆IL-6含量,而深蹲1-RM值、纵跳高度及膝关节ROM组间差异则并无统计学意义。结论：1）每千克体重150 mg剂量亮氨酸能够削弱抗阻运动所导致的骨骼肌损伤与疼痛,该效应可能与对炎症反应的抑制有关,且推测亮氨酸对骨骼肌蛋白质代谢平衡的调节作用在其中亦有贡献;2）该剂量亮氨酸不能明显促进工作肌机能恢复。     

Specific tackling situations affect the biomechanical demands experienced by rugby union players

Tackling in Rugby Union is an open skill which can involve high-speed collisions and is the match event associated with the greatest proportion of injuries. This study aimed to analyse the biomechanics of rugby tackling under three conditions: from a stationary position, with dominant and non-dominant shoulder, and moving forward, with dominant shoulder. A specially devised contact simulator, a 50-kg punch bag instrumented with pressure sensors, was translated towards the tackler (n = 15) to evaluate the effect of laterality and tackling approach on the external loads absorbed by the tackler, on head and trunk motion, and on trunk muscle activities. Peak impact force was substantially higher in the stationary dominant (2.84 ± 0.74 kN) than in the stationary non-dominant condition (2.44 ± 0.64 kN), but lower than in the moving condition (3.40 ± 0.86 kN). Muscle activation started on average 300 ms before impact, with higher activation for impact-side trapezius and non-impact-side erector spinae and gluteus maximus muscles. Players’ technique for non-dominant-side tackles was less compliant with current coaching recommendations in terms of cervical motion (more neck flexion and lateral bending in the stationary non-dominant condition) and players could benefit from specific coaching focus on non-dominant-side tackles.     

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing

‘A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge’s merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors’ muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30–40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking.

Highlights

• Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University.

• Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time. Hiking generates large stresses in the anterior muscles that cross the knee and hip joint.

• Hiking is considered as a quasi-isometric bilateral knee extension exercise. Muscle activity measurements during sailing, recorded by means of EMG, show a mean contraction intensity of 30-40% maximal voluntary contraction with peaks exceeding 100%.

• Hiking performance is strongly related to the development of neuromuscular fatigue in the quadriceps muscle. Since maximal strength is an important determinant of neuromuscular fatigue during hiking, combined strength and endurance training should be incorporated in the training program of dinghy sailors.

     

振动力量训练对跳远运动员膝关节肌力变化影响的实验

为了拓宽专项力量训练途径,丰富和创新力量训练方法,通过振动力量训练组(II组)和传统力量训练组(I)对比实验研究来探索振动力量训练对跳远运动员下肢肌肉力量训练效果的影响规律,为进一步振动力量训练发展和应用提供实验依据。实验结果表明:振动力量训练法能在同等的负荷条件下,能更有效地发展运动员膝关节屈肌群的最大力量、快速力量、爆发力,其中伸肌表现不明显;振动力量训练也提高了运动员的膝关节肌群力量耐力水平,同时使膝关节屈伸肌群得到协调发展。     

高强度运动对心脏的冲击影响及信号提取研究

设计实时的肌肉组织血氧量和瞬时心率无损同步检测方案与设备,为研究高强度运动心脏的冲击影响、探讨高强度运动中代谢规律提供测试手段。方法:采用连续双波长近红外光测量肌肉中血红蛋白与肌红蛋白含氧量的变化情况;采用芬兰SUUNTO心率带和自行设计的转发器及配套PC软件测量瞬时心率,进行了100m跑同步实测试验。结果:100m跑以无氧代谢为主。起跑后的前7s为无氧代谢的非乳酸功能,肌氧饱和度曲线变化不大。7s后开始消耗肌肉中储存的氧。结论:双波长近红外光组织氧测试法和运动心率无线实时采集系统能够正确实时同步地检测高强度运动时血氧和心率,揭示了高强度运动过程中肌肉中氧的运输与消耗及心率之间的动力学过程。     

城市高龄老人肌力、柔韧、平衡能力的分析——以南京市城区老龄人口为例

通过调查测定544名70岁以上南京市城市高龄老人身体机能的部分指标,结果表明:南京市城市高龄老人的肌力、柔韧性、平衡能力等均处于一个较低的水平,并且在70岁高龄之后各项机能指标仍然呈现下降的趋势.有运动习惯者在握力以及柔韧性方面优于无运动习惯者.