Resultant muscle torque and electromyographic activity during high intensity elastic resistance and free weight exercises

Abstract

The purpose of this study was to quantify and compare Resultant Muscle Torque (RMT) and muscle activation (EMG) pattern, during resistance exercise comprising eight repetitions maximum (8 RM) biceps curl with elastic resistance and free weight exercise. Sixteen male and female recreationally active subjects completed 8 RM biceps curl by each of three modalities of resistance exercise: (i) dumbbell (DB), (ii) elastic tubing with original un-stretched length at the commencement of contraction (E0), and (iii) elastic tubing with 30% decrement of original length (E30) at the commencement of contraction. The magnitude of muscle activation, external force, acceleration as well as range of motion (ROM) were quantified and synchronised by specific software. The data were collected from all eight repetitions but the first (initial), the fifth (middle) and the eighth (last) repetitions were selected for further data analysis. Each selected repetition was partitioned into a concentric and eccentric phase and then each phase was further divided into three equal segments (3 concentric and 3 eccentric = 6 segments per repetition). The EMG and RMT data demonstrated a bell-shaped muscle activation and muscle torque production pattern for the three modes of exercise. The E30 resulted in 15.40% and 14.89% higher total EMG (µV) as well as 36.85% and 17.71% higher RMT (N · m) than E0 and DB, respectively (all P <0.05). These findings support the contention that an elastic resistance device (E30) has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of elite athletes.     

Nike Pro Ultimate Thermal

随着体育竞技标准的与日俱增,高档运动服的技术性能也日新月异。如今,各个领域的运动员都已经意识到了高性能运动内衣能帮助他们提高竞赛状态和训练水平。而Nike Pro Ultimate Thermal作为诸多创新的Nike Pro产品之一,旨在帮助运动员能够毫无顾虑     

Study of Thermal Conductivity of Hydrogen-argon Mixture at Different Temperatures for Thermal Insulation Pipes in Petroleum Industry

In this paper, through the study of thermal conductivity of hydrogen- argon mixture at different temperatures for thermal insulation pipes in petroleum industry, a good method for determining the therm...     

五人制足球射门点的热图分析

采用热图分析方法对2004年、2008年和2012年五人制足球世界杯60支球队的射门得分点进行描述。结果表明五人制足球得分点分布呈层级递减的扇形分布,大部分的进球分布在夹角60°内,热图分析能够非常直观呈现出球队进攻点的分布情况,可以作为五人制足球的统计分析方法。     

汽车热管理系统基础问题分析

热管理是汽车控制的一个重要组成部分,可以影响车辆的经济性能.本文介绍了汽车热管理系统比较重要的研究内容,包括智能化电控热管理系统,新材料技术和热管理仿真技术.分析了各种技术的先进性,这些高效的技术将会是将来发展的目标.     

备战第32届夏季奥运会视域下基于Fanger模型的运动中热环境对人体热感觉及能量消耗的影响研究

基于传热学领域的Fanger模型计算与模拟第32届夏季奥运会比赛中可能出现的极端热环境条件下人体热感觉和能量消耗的变化。有关运动中热环境与人体热感觉的研究表明:环境温度对于人体热感觉的影响最大,环境温度每增加1℃可引起热感觉0.20~0.25个等级的升高;其次为环境风速对人体热感觉的影响,环境风速从0增加至0.2 m/s可引起热感觉约0.10个等级的降低,随着环境风速的增加对人体热感觉的影响越小;环境相对湿度对人体热感觉的影响最小,环境相对湿度每增加10%可引起热感觉约0.10个等级的升高。有关运动中热环境与人体能量消耗的研究表明:环境温度对人体代谢当量的影响最大,环境温度每上升1℃可引起代谢当量约0.20 METs的增加;环境风速对人体代谢当量的影响次之,当环境风速从0增加至0.2 m/s,人体代谢当量增加了约1.70 METs;环境相对湿度对人体代谢当量的影响最小,环境相对湿度每上升10%可引起人体代谢当量约0.09 METs的增加。     

玄武岩纤维对油井水泥石韧性改善的室内研究

为解决油井水泥石脆性大的缺点,使用玄武岩纤维对油井水泥石进行增韧改性及性能评价,以抗压强度、抗折强度、抗冲击性能来评价玄武岩纤维的增韧性能.室内评价结果表明:玄武岩纤维对油井水泥石具有很好的增韧效果,掺入纤维后,不同温度下养护的水泥石抗折强度、抗冲击性能均有所提高,但抗压强度略有下降.     

Effects of Football Equipment on Thermal Balance and Energy Cost during Exercise

Abstract

Central core temperature, energy cost and pulmonary ventilation, heart rate, and sweat loss were measured on 5 football players while exercising on a motor driven treadmill at 6 mph for 20 min. Comparisons were made while subjects wore a football uniform and a hospital scrub suit. Core temperature was measured by a rectal thermistor inserted 4 in. into the rectum, energy cost and pulmonary ventilation by open circuit spirometry, heart rate by telemetry, and sweat loss by pre- and postexercise weight changes.

Core temperature, sweat loss, and peak exercise and end recovery heart rates while running in the uniform were significantly elevated compared to the scrub suit controls. Energy cost and pulmonary ventilation were greater (not significant) in the uniform primarily because of the added weight and, to a lesser degree, the reduction in available evaporative surface area.     

气候热应激对大学生运动生理及心理影响的实验研究

环境对体育锻炼者参加体育活动的影响日益受到关注。通过观察普通大学生在高温环境中上体育课时的生理及心理变化，研究热环境对运动者的生理及心理影响，为合理安排高校体育实践课提供参考．     

基于分布式光纤的特高混凝土拱坝导热系数反演分析

反演分析是主要利用监测资料的正分析成果,应用数学方法反求大坝及其基础的热力学参数,可以评价计算模型和结果的精度,从而提高计算成果的准确性。基于分布式光纤的测温优势,结合西南某施工期特高拱坝河床坝段,通过在其特殊浇筑仓距表层下60cm内不同深度处埋设分布式光纤测温,并对其测温结果分别取平均值,从而反求大坝混凝土导热系数。计算结果表明,比大坝设计初期拟定值略高,符合实际情况,其结果更加真实可靠。     

空调机组对体育馆室内局部热环境控制的研究

体育馆室内合理热环境既要满足人体需求,也是满足合理地使用与节约能源的需要。利用CFD技术对大型体育馆气流组织进行模拟和预测,得到体育馆室内空气的速度、温度等物理量分布情况。研究发现:处于送风口双重影响区域的位置风速较大,影响观众的热舒适性;体育馆比赛区域上方四周环绕式送风形成的速度场分布均匀,处于0~0.5 m/s之间,可满足比赛要求;四周环绕送风方式可在入场观众较少时通过安排观众集中就坐,达到节能减排的目的。空调机组对体育馆室内热环境营造研究结果将为体育场馆非均匀热环境研究打下基础,为体育馆节能措施提供理论支持。     

基于运动人体热舒适的体育场馆环境温度参数优化研究

体育场馆作为体育教学的主要场所,其热环境直接影响到运动人体的舒适健康和运动效果。为了获得运动人体热舒适,需维持人体与环境热交换之间产热和散热的动态传热平衡。夏季舒适的体育场馆热环境通常要消耗大量的空调能耗制冷,由此可见,体育场馆具有巨大的节能潜力。以1200名在西安某高校体育场馆内进行羽毛球活动的大学生为研究对象,监测大学生经过羽毛球训练后的生理参数以及对热舒适、疲劳感觉的评价,利用SPSS 23.0和ORIGIN进行数据统计分析,采用描述性统计、多元回归、方差分析等统计方法分析客观和主观数据之间的相互关系,建立不同环境温度工况对运动人体热舒适的定量影响关系。研究结果表明,环境温度对学生的舒适感受、疲劳感觉认知以及生理参数存在交互作用,形成热感觉满意率、疲劳感觉满意率与环境温度之间的定量影响关系。同时,以运动人体平均皮肤温度、血压、心率三类评价因子表征生理参数,进而反映体育场馆环境温度对其的显著性差异。通过兼顾运动人体热舒适和疲劳感觉满意率的综合影响,提出舒适的环境温度参数推荐范围,较国家标准中的室内空调环境温度的低限制值提高了2℃,有效降低了体育建筑夏季空调系统能耗。     

The Relationship Between Physical Activity and Thermal Protective Clothing on Functional Balance in Firefighters

We investigated the relationship between baseline physical training and the use of firefighting thermal protective clothing (TPC) with breathing apparatus on functional balance. Twenty-three male firefighters performed a functional balance test under four gear/clothing conditions. Participants were divided into groups by physical training status, and task performance was analyzed. There was an effect of equipment and training status on performance with the group reporting both aerobic and resistance training performing better than the group reporting no physical training. In conclusion, firefighters walk more slowly as a strategy to maintain balance when wearing TPC, which may be suboptimal given the emergent nature of fire suppression. This result was most prominent in the group reporting no physical training.     

Validity of a Tympanic Thermometer and Thermal Imaging Camera for Measuring Core and Skin Temperature during Exercise in the Heat

ABSTRACT

This study compared criterion to minimally invasive, practical measures of core (T_c) and skin (T_sk) temperature during 30 min of moderate-intensity cycle exercise in a heat chamber (35°C, 60% rH). T_c was monitored using a core temperature pill (T_c(Pill)) and tympanic thermometer (T_c(Tymp)) during rest, exercise, and recovery in 15 participants. T_sk was monitored using hard-wired skin thermistors attached to a data logger (T_sk(T)) and a thermal imaging camera (T_sk(IR)) in 11 participants. T_c measurement resulted in no significant difference (p > 0.05), a mean bias of 0.1°C, coefficient of variation (CV%) of 1.0%, and correlation of r = 0.74 between devices. T_sk measurement resulted in a significant difference (p = 0.01), a mean bias of 0.6°C, CV% of 2.3%, and correlation of r = 0.61 between devices. T_c(Tymp) demonstrated acceptable agreement with T_c(Pill); however, caution is advised when using T_sk(IR) to give accurate measures of T_sk during exercise.     

热环境下的降温时机与降温部位对运动表现的影响:系统评价与Meta分析

目的：通过系统评价与Meta分析对36项降温方法的不同降温时机和降温部位进行定量合成与分析,为热环境下运动员降温策略的制定提供科学依据。方法：依据PRISMA声明控制研究过程,对国内外数据库进行文献检索,对纳入文献进行质量评价、定量合成、亚组分析、敏感分析等。结果：共纳入文献36篇,合并365名受试者;Meta分析结果发现混合降温（运动前与运动中）的合并效应量最大（SMD=1.28）,其次为运动中降温（SMD=0.85）和运动前降温（SMD=0.51）;躯干降温（SMD=1.45）>体内降温（SMD=0.75）>下肢降温（SMD=0.74）>颈部降温（SMD=0.44）>全身降温（SMD=0.42）>口腔降温（SMD=0.31）>手部降温（SMD=0.17）>面部降温（SMD=-0.54）。结论：在降温时机的选择方面,采取连续性降温措施更有利于运动员的运动表现,尤其是在运动中以及间歇期间采取降温措施能更好延续降温效果,从而维持或提高运动表现;在降温部位的选择方面,采取不同的降温部位进行降温对运动表现提升的效果有所不同,身体局部降温和体内降温均能...     

中国传统武术话语权危机与提升策略

在梳理中国传统武术话语权发展历程的基础上,分析当前中国传统武术话语权式微问题的主要表现,即本质功能淡化、表层利益化严重、媒介记忆影响受众现实的真实性、媒介记忆受大众审美的影响等。进而提出话语权提升策略：传播主体方面,由"走出去"转为"互动化";受众方面,提高审美能力;媒介方面,关注社会记忆的责任与义务。     

脑力、体力劳动者足底压力参数分布特征及评定

通过分析脑力、体力劳动者自然行走过程中峰力值（maxforce,MF）、达峰力值时间（time to max force）、冲量（impulse）等参数特征,探讨职业对足底压力分布的影响。采用比利时Footscan USB2平板式足底压测试系统对50名普通健康脑力劳动者和63名普通健康体力劳动者进行自然行走过程中动态足底压力测试。结果显示：脑力、体力劳动者左脚Toel、Toe2-5、Heel Lateral区域平均峰值（MF）存在显著性差异,右脚Mid foot、Meta5区域MF差异存在非常显著性（P〈0．01）,左、右双足平均峰力值（MF）最大值均出现在足跟内侧（Heel Medial）。脑力、体力劳动者足底各区域达峰力值的时间（TMF）,左右双足差异均存在非常显著性（P〈0．01）。脑力劳动者与体力劳动者行走过程中左足在Toel、Toe2-5、Meta1、Heel Medial、Heel Lateral区域的冲量（Impulse,IP）,体力劳动者明显大于脑力劳动者且具有显著性差异〈0．01）,体力劳动者与脑力劳动者的足底MF与足弓接触面积及足角度存在不同程度的相关。结果说明：脑力劳动者与体力劳动者行走过程中左右双足的平均峰力值、接触面积、冲量等参数都存在不同程度的差异,可能与长期从事的职业不同有关,建议经常进行体育锻炼或定制矫形鞋垫,可以缓解足底压力高压区的过度集中,不断维护足健康水平。     

武术的文化进程探析

对武术由一项原始格斗技术发展成文化载体的演进历程进行研究。认为:先秦文化的繁荣使武术初具文化特色;集中国传统文化之大成的宋明理学的世俗化,促使武术成为成熟的文化载体,具有多方面文化特色;西方文化及竞技体育改变武术发展中的不良趋向,但降低了武术的层次。     

绿道体育健身环境规划初探

本文阐述了绿道体育健身环境概念和特点,提出建设绿道体育健身环境的最大效益、相对独立和分散集中的规划原则以及层级建设模式,阐述了绿道健身环境的景观设计。