Markers of isometric training intensity and reductions in resting blood pressure

Abstract

In this study, we examined the correlations between selected markers of isometric training intensity and subsequent reductions in resting blood pressure. Thirteen participants performed a discontinuous incremental isometric exercise test to volitional exhaustion at which point mean torque for the final 2-min stage (2min-torque_peak) and peak heart rate peak (HR_peak) were identified. Also, during 4 weeks of training (3 sessions per week, comprising 4 × 2 min bilateral leg isometric exercise at 95% HR_peak), heart rate (HR_train), torque (Torque_train), and changes in EMG amplitude (ΔEMG_amp) and frequency (ΔEMG_freq) were determined. The markers of training intensity were: Torque_train relative to the 2min-torque_peak (%2min-torque_peak), EMG relative to EMG_peak (%EMG_peak), HR_train ΔEMG_amp, ΔEMG_freq, and %MVC. Mean systolic (?4.9 mmHg) and arterial blood pressure (?2.7mmHg) reductions correlated with %2min-torque_peak (r = ?0.65, P = 0.02 and r = ?0.59, P = 0.03), ΔEMG_amp (r = 0.66, P = 0.01 and r = 0.59, P = 0.03), ΔEMG_freq (r = ?0.67, P = 0.01 and r = ?0.64, P = 0.02), and %EMG_peak (systolic blood pressure only; r = ?0.63, P = 0.02). These markers best reflect the association between isometric training intensity and reduction in resting blood pressure observed after bilateral leg isometric exercise training.     

Reliability and validity of the Yo-Yo intermittent recovery test level 1 in young soccer players

Abstract

The present study investigated the test-retest reliability from the Yo-Yo IR1 (distance and heart rate responses), and the ability of the Yo-Yo IR1 to differentiate between elite and non-elite youth soccer players. A total of 228 youth soccer players (11–17 years) participated: 78 non-elite players to examine the test-retest reliability within 1 week, added with 150 elite players to investigate the construct validity. The main finding was that the distance covered was adequately reproducible in the youngest age groups (U13 and U15) and highly reproducible in the oldest age group (U17). Also, the physiological responses were highly reproducible in all age groups. Moreover, the Yo-Yo IR1 test had a high-discriminative ability to distinguish between elite and non-elite young soccer players. Furthermore, age-related standards for the Yo-Yo IR1 established for elite and non-elite groups in this study may be used for comparison of other young soccer players.     

Lower limb joint kinetics during the first stance phase in athletics sprinting: three elite athlete case studies

Abstract

This study analysed the first stance phase joint kinetics of three elite sprinters to improve the understanding of technique and investigate how individual differences in technique could influence the resulting levels of performance. Force (1000 Hz) and video (200 Hz) data were collected and resultant moments, power and work at the stance leg metatarsal-phalangeal (MTP), ankle, knee and hip joints were calculated. The MTP and ankle joints both exhibited resultant plantarflexor moments throughout stance. Whilst the ankle joint generated up to four times more energy than it absorbed, the MTP joint was primarily an energy absorber. Knee extensor resultant moments and power were produced throughout the majority of stance, and the best-performing sprinter generated double and four times the amount of knee joint energy compared to the other two sprinters. The hip joint extended throughout stance. Positive hip extensor energy was generated during early stance before energy was absorbed at the hip as the resultant moment became flexor-dominant towards toe-off. The generation of energy at the ankle appears to be of greater importance than in later phases of a sprint, whilst knee joint energy generation may be vital for early acceleration and is potentially facilitated by favourable kinematics at touchdown.     

The Application of a Multiple Measurement Approach to Investigate the Effects of a Dance Program on Educable Mentally Retarded Adolescents

Abstract

Little evidence exists to assess the effects of dance training on special populations. Research in this field has relied on pretest-posttest methods for gathering data. While such data gathering methods may be appropriate for particular research problems, alone they may be inadequate for broad-based, exploratory investigations of programs and effects. The present study is an example of a multiple measurement approach that uses eight measurements, in combination, to answer four research questions regarding the physical and social effects that occur when a group of educable mentally retarded adolescents is exposed to a 10-week dance program. The findings revealed that four students showed improvement in both social and physical behaviors, seven students showed improvement in either social or physical behaviors, and two students showed no improvement. There was no evidence of a “transfer effect” due to participation in the program, and some students' behaviors were affected by external factors. The authors found the approach useful for identifying multiple effects and generating hypotheses for further study.     

南狮运动员膝关节屈伸肌群生物力学特征分析

南狮运动是我国南方地区广泛开展的民族传统体育项目,具有广大的群众基础,其发展前景甚为广阔。文章采用等速力量测试系统对广州体育学院12名高水平舞狮运动员进行测试,分析比较南狮运动员膝关节屈伸肌群等速收缩肌群峰力矩、屈伸肌比值(H/Q或F/E)、功率(Avg.Power,W)等指标及其肌力的生物力学特征,并应用运动生物力学的原理揭示动作技术特征,旨在为舞狮运动员的选材和教练员的科学训练提供参考依据。     

运动水平和认知风格对网球运动员接发球预判绩效的影响

采用3(运动水平)×2(认知风格)的混合实验。实验被试总人数56人,平均年龄18.68±6.47岁。经过ANOVA、T-test、相关分析、多重比较等方法对实验数据进行分析。结果显示:不同认知风格运动员接发球预判准确性(P=.015)、预判速度(P=.012)存在显著性差异;不同运动水平运动员接发球预判的准确性上的差异具有非常显著性(p=.001),不同运动水平运动员接发球预判速度上的差异具有显著性(p=.017)。得出:场独立型认知风格网球运动员在接发球预判绩效较好于场依存型认知风格的网球运动员;高水平网球运动员在接发球预判准确性和速度上具有绝对的优势,不仅远远高于低水平组,而且也明显高于中水平组。     

江苏省田径赛事市场现状与对策分析

本文以南京、苏州、扬州、无锡四个城市的田径赛事市场为研究对象,客观分析了江苏省田径赛事的现状。本文认为,要提高江苏省的田径赛事市场运作水平,首先必须提高运动员参赛竞技水平,其次是吸引社会力量共同开发田径市场,与此同时还必须培养和引进相关方面的人才,进一步完善田径市场发展的政策法规。     

基于知识图谱的领域新兴主题研究现状分析*

发现和追踪领域新兴主题是研究人员发现和追踪本领域内最新研究趋势和研究方向的一个重要途径。新兴主题探测可以探测、识别、发现这些新兴趋势和新兴主题。本文对ISI Web of Science数据库中收录的关于新兴主题研究的文献进行收集,然后从文献计量学的角度进行定量分析;利用CiteSpaceII对国家、机构、作者的合作关系做出对应的知识图谱;并对共被引文献的关键节点文献进行了研读和分析;最后利用CiteSpaceII生成的本研究领域中的研究主题聚类图、时序图对研究内容及现状进行了分析和预测。     

关于人类年龄分段的体育学研究

人类年龄分段自古有之,然而古今中外关于人年龄的分段受当时时代的限制和地域文化的不同而有很大的差别。我国成立以来,在中国人年龄的分段定义中,也有新的改动。本文利用文献资料法、调研法以及归纳总结的方法,纵向对比了中国历史和现代关于年龄分段的基本情况,也参考了国外和世界卫生组织对于人类年龄分段的定义,从体育学的角度,阐述了科学的符合时代的人类年龄分段对于体育学的积极意义,明确指出中国人由于经济的繁荣使我们的饮食水平有了很大的提高,从而使得国人的青春期有所提前这一现象。同时,指出了由于人们养生知识的普及和医疗卫生事业的进步,中国已经进入老龄社会这一实际情况,结合中国传统养生文化,建立了时代特色比较鲜明的人类年龄分段模式构想,以期能从生理锻炼和心理影响方面提高国人的身体素质,为我们终身体育的发展和延长人民寿命做出一份努力。     

10kV与110kV混压并架线路带电作业人员安全防护研究

10kV与110kV混压并架输电线路可以有效集约土地资源,充分利用线路走廊。为了评估带电作业人员检修10kV配电线路时,上方110kV输电线路对其安全影响,采用有限元电场计算与电场实测的方法研究混压线路空间电场分布和作业人员体表电场分布规律,在此基础上提出了10kV与110kV混压并架输电线路检修作业安全防护方法。