Description of the finger mechanical load of climbers of different levels during different hand grips in sport climbing

Abstract

Currently, direct empirical evidence exists about the amount of mechanical load that climbers apply to each finger during several hand grips specific to sport climbing, but not yet in a specific hanging position.

The objectives of this study are a) to draw and build a solid and rigid support that simulates the real action of a hand grip in a hanging position in sport climbing, to enable the measurement of the mechanical load endured by the fingers in a hanging position and in addition, b) to describe the distribution of mechanical load among fingers as a function of the level of climbing during different hand grips in a hanging position.

Thirty young male participants took part in the initial phase of reliability of the measurements, while another 64 male climbers participated in the subsequent study phase to check the relations between independent and dependent variables. The level of on sight climbing and the total practice experience were used to define the groups. The research task consisted of performing hanging positions on the created support in order to measure the mechanical load endured by the fingers in the three most characteristic hand grips in climbing (crimp, half crimp and slope). It has been concluded that the performance level of the climbers had no influence on the production of a pattern of differentiated finger mechanical load during the research task.     

Fingertip force and electromyography of finger flexor muscles during a prolonged intermittent exercise in elite climbers and sedentary individuals

Abstract

The aim of this study was to characterize forearm muscle fatigue identified by the decrease in electromyogram median frequency and/or fingertip force during intermittent exercise. Nine elite climbers (international competitive level, USA 5.14a on sight) and ten non-climbers were instructed to maintain a fingertip force of 80% of their maximal voluntary contraction force on a dynamometer mimicking a rock climbing grip during a 5 s effort/5 s rest cycle for 36 repetitions (i.e. 6 min of exercise). Elite climbers lasted twice as long as non-climbers (climbers: 3 min; non-climbers: 1 min 30 s) before the force could no longer be maintained (i.e. the failure point). After this moment, fingertip force decreased and stabilized until the end of the exercise around 50% maximum voluntary contraction force in non-climbers and 63% in elite climbers. Electromyogram median frequency showed a greater decrease in non-climbers than in elite climbers before the failure point. No change in median frequency was observed after the failure point in elite climbers or in non-climbers. These results confirm that elite climbers are better adapted than non-climbers for performing the intermittent fingertip effort before the failure point. After this point, the better fingertip force of elite climbers suggests different forearm muscle properties, while the electromyography results do not provide any indication about the fatigue process.     

Body fat measurement in elite sport climbers: Comparison of skinfold thickness equations with dual energy X-ray absorptiometry

Abstract

The aim of this study was to compare equations for estimating percentage body fat from skinfold thickness in elite sport climbers by assessing their agreement with percentage body fat measured using dual-energy X-ray absorptiometry (DXA). Skinfold thickness was measured in a convenience sample of 19 elite sport climbers [9 women and 10 men; mean age 31.2 years (s = 5.0) and 28.6 years (s = 3.6), respectively]. Percentage body fat was estimated using 17 different equations, and it was also measured by DXA. A significant inter-methods difference was observed for all equations, except for Durnin's equation in men (inter-methods difference: ?0.57% and ?0.29%; 1.96 s: 5.56 and 5.23 for Siri's and Brozek's equation, respectively) and women (inter-methods difference: ?0.67% and ?1.29% for Siri's and Brozek's equation, respectively), and for Wilmore's equation using Siri's body fat equation in women (inter-methods difference: ?1.86%). In women, the limits of agreement were lower when using Durnin's equation compared with Wilmore's equation (1.96 s: 3.86% and 5.13%, respectively). In conclusion, of the 17 studied equations, Durnin's equation was the most accurate in estimating percentage body fat in both male and female elite climbers. Therefore, Durnin's equation could be used to assess percentage body fat in elite sport climbers if more accurate methods are not available. The generalizability of the results is limited by the fact that the sample was not selected at random.     

体育运动中结缔组织生长因子对肌腱干细胞分化的影响

运用实验法和数理统计法探究体育运动中结缔组织生长因子对肌腱干细胞分化产生的影响。将周围结缔组织从活体中进行细胞分离及培养;取P2代细胞爬片进行免疫细胞化学检测细胞表型抗原标记CD44、CD29。取P3代细胞进行肌腱干细胞多向分化能力鉴定,收集未处理的肌腱干细胞和分化后的肌腱细胞,分别用实时荧光定量PCR和Western印迹检测I型胶原和Tenascin-C m RNA和蛋白水平的表达。实验结果表明:细胞免疫荧光染色CD44、CD29阳性,表明我们分离提取的组织细胞为肌腱干细胞;肌腱干细胞可以向脂肪细胞、骨细胞、软骨细胞分化;分化后的肌腱细胞,I型胶原的m RNA水平含量升高了5.3倍,Tenascin-C升高了2.1倍(P<0.01),I型胶原的蛋白表达升高了3.3倍,Tenascin-C的表达升高了1.8倍(P<0.05)。结论:结缔组织生长因子可以促进肌腱干细胞分化。     

Active recovery of the finger flexors enhances intermittent handgrip performance in rock climbers

This study aimed to (1) evaluate the effect of hand shaking during recovery phases of intermittent testing on the time–force characteristics of performance and muscle oxygenation, and (2) assess inter-individual variability in the time to achieve the target force during intermittent testing in rock climbers. Twenty-two participants undertook three finger flexor endurance tests at 60% of their maximal voluntary contraction until failure. Performances of a sustained contraction and two intermittent contractions, each with different recovery strategies, were analysed by time–force parameters and near-infrared spectroscopy. Recovery with shaking of the forearm beside the body led to a significantly greater intermittent test time (↑ 22%, P?P?P?相似文献   

以项目本质特征为核心导向提升我国竞技体育训练科学化水平

项目本质特征是指运动项目在比赛规则的允许下,以获得最佳运动效益为目标,在生物力学、生物化学、运动生理学、运动心理学和运动智能学等方面表现出的主要特征。在我国的竞技训练过程中存在着“重形不重质”的问题。只有对项目本身内在的、微观的和动态变化的细节进行剖析,正确理解项目本质特征,才能不断提升我国竞技运动训练科学化水平,为提高竞技成绩提供理论依据。     

A motivational model of performance in the sport domain

Abstract

Using a visual Go/Nogo paradigm and subtraction methods, we examined detailed developmental changes in the cognitive reaction times of 153 healthy children aged 6–12 years. Three conditions were studied: simple reaction, even rate reaction (50% Go), and high rate reaction (80% Go). The subtraction of simple reaction time from even rate reaction time was considered to reflect discrimination time, while the subtraction of simple reaction time from high rate reaction time was considered to reflect the time required for inhibition. We found that simple reaction time, even rate reaction time, and high rate reaction time all declined significantly with months of age (P < 0.01). Furthermore, the times for both discrimination and inhibition also showed significant declines (P < 0.01), which could be considered developmental changes in neural mechanisms involved in discrimination and inhibition processes. The time for inhibition showed a weaker correlation (P < 0.01), which could indicate that the degree of developmental change is larger for the discriminative processes than for the inhibititory processes required for our task in the age range studied.     

Education in the Chinese national sport system: experiences of professional wushu athletes

Abstract

Within the Chinese national sport system, the government provides resources and funding to train athletes from a young age to become high-performance competitors. Though athletes are well supported to excel in their sport, during their years of intense physical training, athletes generally receive little to no formal education to prepare them for life outside of sport. The sacrifice of forgoing formal education to compete in elite level sport is not uncommon for athletes within centralized sporting systems and has been widely documented; however, there is little research that focuses on the impact of the team’s educational systems from the perspective of the athletes. To add to the growing body of research in this area, the authors utilized in-depth interviews to examine professional wushu athletes’ education experiences whilst training on their team. Thematic analysis of the findings revealed that athletes who committed themselves to sport training in the Chinese national system had to negotiate a number of factors related to time, motivation, social influences, and resources when it came to education and academia. Findings highlight the ways in which these athletes experience and come to terms with limited academic opportunities, preparation and support from their team and the training environment.     

我国青少年体育训练和竞赛组织模式改革与创新对策的研究

运用献资料和访问调查法，对国内外青少年体育训练和竞赛体制的现状进行了综述分析，认为针对扩大我国青少年业余体育训练和竞赛活动规模以及提高青少年业余体育训练的质量问题，一直进行着以青少年运动队组织设置为重点的青少年业余体育训练和竞赛制度改革，尝试过多种组织形式。每一种组织形式都在实践过程中暴露出新的矛盾和问题。提出了构建社会主导、以“横向联系”为结构关系．使竞技体育后备人才的培养、交流、使用的服务体系完全社会化的青少年业余体育训练和竞赛组织模式，     

大学生业余田径训练中运动损伤情况的调查分析

对大学生在业余田径训练中的运动损伤进行了调查，并对损伤在项目上的分布情况、损伤性质及损伤原因作了重点分析。大学生在田径业余训练和比赛中，不同运动项目受伤的情况各有不同。同时对其预防措施进行了探讨，使运动员与教练员明确预防运动损伤的有效办法，从而提高田径训练的效率和水平。     

男性青少年骨密度与下肢跳跃能力的关系及运动训练对其影响

探讨青春发育期男性青少年在生长发育过程中骨密度(bone mineral density，BMD)值与下肢跳跃能力的关系及运动训练对其影响。对10～20岁男性青少年63名，依据年龄分为10～15岁和16～20岁组；依据是否从事规律的运动训练，再分为运动员组和非运动员组。超声法测量跟骨BMD，下肢跳跃能力指标使用日产Rebound Jumping测跳仪测量。结果：男性青少年的BMD在整个青春期呈上升趋势，且10～15岁和16～20岁组BMD有显著性差异；运动组和非运动组的BMD也呈显著性差异，提示早期运动训练可以改变骨密度；男性青少年的BMD与反映下肢跳跃能力的指标具有明显相关性，且此相关度受运动训练的影响，运动训练具有正向促进作用。     

普通高校体育特长生与体育院校运动系学生训练意愿比较

通过问卷时影响普通高校运动系学生训练意愿的因素做了调查与比较，用多因素分析法找出4个主成分(学校、个人、社会和家庭)因子；并在此基础上时高校体育特长生和运动系学生训练意愿的得分进行了t检验。结果表明运动系学生进校后运动成绩提高优于高校体育特长生，在影响训练意愿的4个主因中，个人主因时运动系学生的影响高于体育特长生；而在社会主因方面，体育特长生则明显高于运动系学生。     

我国田径传统优势项目下滑的成因与解决对策

对我国田径传统优势项目下滑的现状进行了分析,认为原因在于田径传统优势项目后备人才乏人、地方体育管理决策层避重就轻思想严重、现行的竞赛制度减少了现役优秀运动员参加大赛磨练的机会、田径传统优势项目训练存在闭门造车现象、田径传统优势项目教练员执教水平的局限等。结合目前国内外田径发展趋势,就存在的问题提出一些解决对策与建议。