血液有形成分对足球运动员有氧能力的影响

目的：分析血液有形成分某些指标对足球运动员有氧能力的影响,比较不同有氧能力运动员联赛期间血液有形成分变化特点。方法：测定18名足球运动员联赛前和联赛中期血液有形成分指标;采用递增负荷跑台运动方式,测定联赛前反映最大有氧能力的相关生理指标。结果：1,红细胞比容、平均红细胞体积与最大摄氧量显著负相关。2,联赛中期,一般有氧能力组运动员血液有形成分变化比优秀有氧能力组明显。结论：1,血液有形成分在一定范围内影响运动员有氧能力。2,优秀有氧能力运动员对足球联赛大强度运动适应能力强,生理反应较平稳。     

A Coding System to Quantify Powerful Actions in Soccer Match Play: A Pilot Study

Purpose: The powerful activity profile of elite soccer match play has not been documented appropriately to inform specific maximal power assessment and development criteria. The aims of the current study were to develop a reliable soccer-specific powerful action (SSPA) notational analysis coding system that could be used to compare frequency and durations of powerful actions during elite youth soccer match play. Methods: Sixteen elite male English Premier League (EPL) Academy players (19 ± 1 yrs) were recorded by an individual camera during 16 competitive EPL U18 and U21 games. Video footage was analyzed using performance analysis software and SSPAs were coded according to the following categories: initial acceleration, leading acceleration, sprint, unilateral jump and bilateral jump. Results: The SSPA coding system demonstrated very good inter- and intra-rater reliability (kappa coefficients ≥ 0.827). Elite youth EPL soccer players undertook significantly more initial (31 ± 9) and leading (37 ± 12) accelerations than sprints (8 ± 3; p = .014, d = 1.7, and p < .001, d = 1.7, respectively) and jumps (6 ± 5; p = .002, d = 1.7 and p < .001, d = 1.7, respectively). Players performed a significantly greater number of initial and leading accelerations with action durations below 1.5 s compared to above 1.5 s (p = .001, d = 1.6, and p = .002, d = 1.4), respectively. Conclusions: Our SSPA coding system provides a reliable observational instrument for quantifying the frequency and duration of powerful actions performed during elite soccer match play. In our sample of elite youth soccer players, horizontal accelerations of short duration (< 1.5 s) from different starting speeds appear the most dominant powerful action in elite youth soccer match play.     

TG-4036A打包机液压故障分析及排除方法

文章分析了油温稍高压力上不去的原因,介绍了排除故障的方法.着重强调油品清洁度的重要性以及液压元件的磨损,对系统性能的影响.