How much does lower body strength impact Paralympic running performance?

Objectives: Development of evidence-based methods of Paralympic classification requires research quantifying the relative strength of association between ratio-scaled measures of impairment and athletic performance. The purpose of this study was to quantify the extent to which muscle strength affects running performance in runners with and without brain impairment. Design: Cross-sectional study. Methods: Participants were 41 male runners: 13 with brain impairments (RBI) and 28 non-disabled (NDR). All participants completed a maximal 60-m sprint and a novel battery of three lower limb isometric strength tests. Results: RBI showed significantly lower strength scores compared with NDR on the more affected side in leg flexion (176 vs. 243?N), leg extension (993 vs. 1661?N) and plantarflexion (824 vs. 1457?N). Significant differences were also seen on the less affected side in plantarflexion (1072 vs. 1508?N). RBI were significantly slower in the acceleration phase (0–15?m) (3.2?s?±?0.3?vs. 2.8?s?±?0.2) and top speed phase (30?60?m) (4.3?s?±?0.6?vs. 3.8?s?±?0.3). Correlation analysis showed stronger relationships between strength and running performance in RBI than NDR; however, the correlations were not significant. Conclusions: This study evaluated measures to assess strength for the purposes of classification and found that the measures were significantly different in RBI compared with NDR indicating the tests were able to capture strength impairment in this population. This study indicates that strength may be an important impairment type to assess in this population, as impairments of muscle strength may influence the outcome of running performance in athletes with more severe impairments.     

Ground reaction forces of Olympic and World Championship race walkers

Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p < .001), resulting in a flattened profile. Athletes with narrower stride widths experienced reduced peak braking forces (r = .49, p = .046), peak propulsive forces (r = .54, p = .027), peak medial forces (r = .63, p = .007) and peak vertical push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency.     

Effects of load mass carried in a backpack upon respiratory muscle fatigue

Purpose: The purpose of this study was to investigate whether loads carried in a backpack, with a load mass ranging from 0 to 20?kg, causes respiratory muscle fatigue. Methods: Eight males performed four randomised load carriage (LC) trials comprising 60?min walking at 6.5?km?h^?1 wearing a backpack of either 0 (LC₀), 10 (LC₁₀), 15 (LC₁₅) or 20?kg (LC₂₀). Inspiratory (P_Imax) and expiratory (P_Emax) mouth pressures were assessed prior to and immediately following each trial. Pulmonary gas exchange, heart rate (HR), blood lactate and glucose concentration and perceptual responses were recorded during the first and final 60?s of each trial. Results: Group mean P_Imax and P_Emax were unchanged following 60-min load carriage in all conditions (p?>?.05). There was an increase over time in pulmonary gas exchange, HR and perceptions of effort relative to baseline measures during each trial (p?p?>?.05). Conclusions: These findings indicate that sub-maximal walking with no load or carrying 10, 15 or 20?kg in a backpack for up to 60?min does not cause respiratory muscle fatigue despite causing an increase in physiological, metabolic and perceptual parameters.     

钢结构材料在高温(火灾)条件下的力学性能试验研究

从基本的钢结构材料在高温下的力学性能着手 ,进行高温条件下钢结构材料的性能试验 ,建立高温下钢材的屈服强度、极限强度、弹性模量和极限应变随温度变化的力学模型 ,为高温 (火灾 )条件下钢结构的结构分析提供依据。     

我国高等教育层次结构的现状、问题及对策

文章在论述我国高等教育层次结构现状的基础上,分析了其存在的问题,各层次比例不合理、缺乏特色、衔接性差等。并针对这些问题提出了相应的对策,如调整各层次之间的比例;明确目标,办特色教育;构建高等教育的立交桥等等。     

常熟高专中高级知识分子健康状况调查

根据2001年高中级知识分子体检资料，对他们的健康状况进行了详细的分析，指出了存在的普遍问题，提出了一些有益的建议。     

积极创造条件进一步完善学分制

本文在分析了用学分制替代学年制的诸多优越性之后，提出了建立学分制的种种措施和条件。     

高职"产学研"联盟策略探析

文章在分析高职“产学研”联盟现状的基础上，探讨了协议联盟、订单式联盟、中介联盟、合资联盟、官产学联盟等不同形式的联盟策略，并指出高职“产学研”联盟应该注意的几个问题。     

高等职业教育实践教学体系的构建

实践教学体系是高职人才培养模式中十分重要环节，能否建立科学合理的实践教学体系，直接影响应用型人才培养的质量。合理构建实践教学体系首先应明确其指导思想、基本原则和目标要求，完善体系的构成元素和管理，并以师资建设为保证。     

高职高专人才培养中图书馆评估指标探析

作者在对高职高专人才培养工作水平评估标体系进行分析的基础上,就如何科学、合理地评价一所图书馆提出了一些粗浅的建议和看法,以期抓住各类型评估的良好机遇,推动图书馆事业的发展.