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

Jan G. Bourgois  Jasmien Dumortier  Margot Callewaert  Bert Celie  Carlo Capelli  Gisela Sjøgaard 《European Journal of Sport Science》2017,17(5):611-620

‘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.

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Nrf2在有氧运动训练中对小鼠骨骼肌抗氧化能力的作用     

何诗依  张缨 《北京体育大学学报》2017,40(12):50-54

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。  相似文献   

Effects of heat acclimation on hand cooling efficacy following exercise in the heat     

Elizabeth L. Adams  Lesley W. Vandermark  J. Luke Pryor  Riana R. Pryor  Rachel M. VanScoy  Craig R. Denegar 《Journal of sports sciences》2017,35(9):828-834

This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO₂ max], 54.1 ± 1.3 ml·kg^?1·min^?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO₂ max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO₂ max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min^?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min^?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min^?1) was similar to NC (0.025 ± 0.002°C·min^?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min^?1) was similar to when NHA (0.020 ± 0.003°C·min^?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.  相似文献   

我国男子高水平三级跳远运动员专项力量训练安排研究     

袁晓毅  丁振峰  关长亮  郭元奇 《北京体育大学学报》2016,39(1):112-118

摘要：男子三级跳远是我国参加奥运会田径比赛的潜优势项目，专项力量是影响三级跳远比赛成绩和技术水平提升的关键因素，运用文献资料法、专家访谈法、实地调查等研究方法，分析研究我国最优秀的6名男子三级跳远运动员专项力量训练安排。结论：1）我国男子高水平三级跳远运动员的力量训练内容、方法手段、计划与负荷基本符合世界潮流，但训练中缺少单腿支撑进行的蹲、拉、提、举等练习，不够贴近专项需要；2）专项力量训练器材与世界发达国家相比科技化含量不高；3）专项力量负荷调整控制主要依赖教练员经验与身体素质指标推算。  相似文献   

下肢离心练习对提高女排运动员移动速度作用的实验研究     

张明 《北京体育大学学报》2016,39(6):127-132

摘要：旨在探讨下肢离心负荷练习对排球运动员移动制动的影响,在现有发展运动员下肢力量常用手段的基础上,加入了离心训练手段,来提高排球运动员移动制动的效果。研究主要采用实验法，对28名高水平排球运动员（10名国家级健将和18名国家一级运动员）进行对照组与实验组研究，进行为期8周的下肢离心力量训练和传统下肢力量训练，并进行对比分析。研究结果表明,实验组和对照组下肢离心力量指标有差异。实验组下肢离心力量指标、专项移动速度的提高均显著优于对照组,具体结论如下:下肢离心力量训练与传统下肢力量训练均能改善下肢肌肉的最大离心力量。下肢离心力量训练对移动制动能力的改善效果显著优于进行传统力量训练。  相似文献   

Kinematic analysis of the drag flick in field hockey     

Rony Ibrahim  Gert S. Faber  Jaap H. van Dieën 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):45-57

Attaining high speed of the stick head and consequently of the ball is essential for successful performance of the drag flick in field hockey, but the coordination pattern used to maximise stick head speed is unknown. The kinematics of the drag flick was studied in ten elite hockey players who performed twenty shots each towards a target located 1.5 m high. A 150 Hz active marker motion analysis system was used, alongside two force plates to detect foot touchdown. Angular velocity and contribution to stick endpoint speed of upper body joints were analysed. Repeated measures ANOVA was used to compare timing of onset and peak angular velocities between joints. Participants used a kinematic pattern that was close to a proximal-to-distal sequence. Trunk axial rotation and lateral rotation towards the target, right wrist flexion and left wrist extension were the main contributors to stick endpoint speed. Coaches should emphasise trunk rotations and wrist flexion and extension movements for maximising stick head speed. Given the high level of the participants in this study, the coordination of joints motions, as reported here, can serve as a guideline for drag flick training.  相似文献   

谈悬吊训练在篮球运动员体能训练中的应用     

黎伟军  曹洁 《湖北体育科技》2010,29(5):543-544

核心力量训练作为篮球运动中较新的体能训练观念正在逐渐被重视。通过探索悬吊训练手段方法在篮球运动员的体能训练中的应用,帮助运动员提高体能素质和竞技水平。  相似文献   

Reliability of arterial spin labelling measurements of perfusion within the quadriceps during steady-state exercise     

Jonathan Fulford  Anni Vanhatalo 《European Journal of Sport Science》2016,16(1):80-87

Arterial spin labelling (ASL) provides a potential method to non-invasively determine muscle blood flow and examine the impact of interventions such as supplementation and training. However, it's a method with intrinsically low signal, leading to limitations in accuracy and temporal resolution. To examine these limitations, the current study measured perfusion via ASL on three occasions in the rectus femoris of 10 healthy adults, during light and moderate exercise, over three different exercise durations. For data sampled over 9 min, light intensity exercise gave an average perfusion of 35.0 ± 5.1 ml/min.100g^?1 with a coefficient of variation (COV) of 16% and single intraclass correlation coefficient (ICC) of 0.67. For the moderate bout, perfusion was 51.3 ± 5.6 ml/min.100g^?1 (COV 10%, ICC 0.82). When the same data were analyzed over 5 min 24 s, perfusion was 37.8 ± 11.13 (COV 30%, ICC 0.13) during light and 49.5 ± 8.8 ml/min.100g^?1 (COV 18%, ICC 0.52) during moderate exercise. When sampling was reduced to 1 min 48 s, perfusion was 41.2 ± 13.7 (COV 33%, ICC 0.26) during light and 49.5 ± 13.6 ml/min.100g^?1 (COV 28%, ICC 0.04) during moderate exercise. For 9 min a significant perfusion difference was found between the exercise intensities; however, this was not the case for sampling over 5 min 24 s or 1 min 48 s. Such findings illustrate the potential of ASL to non-invasively monitor muscle perfusion under steady-state conditions, but highlight that extended exercise protocols are necessary in order to generate date of sufficient reliability to be able to discriminate intervention dependent perfusion differences.  相似文献   

超高强铝合金的回顾与展望   总被引：3，自引：0，他引：3  

宁爱林  曾苏民  莫亚武  罗玉梅 《邵阳学院学报(社会科学版)》2003,2(5):90-92

综述了超高强铝合金的三个发展阶段，评述了超高强铝合金的熔体净化技术和强韧化技术，并对其发展趋势进行了展望．  相似文献   

浅谈女子竞技健美操力量训练方法   总被引：2，自引：0，他引：2  

徐胜 《广东技术师范学院学报》2004,(6):108-110

竞技健美操对力量素质的要求越来越高 ,它已成为决定运动成绩的主要因素之一 ,本文就女子竞技健美操运动员在力量训练中手段的选择以及上肢力量、下肢力量、腰腹力量训练的方法和注意事项进行了论述 .  相似文献