空勤人员疲劳致因及体育锻炼恢复方法探讨

空勤人员因工作紧张程度高、舱内环境密闭、光照规律多变、远离自然、静坐有余而活动不足等成为了慢性疲劳综合症的高危人群.为了进一步关注空勤人员的健康,从空勤人员的疲劳特点方面进行探讨并尝试着提出体育锻炼恢复方法,以期对空勤人员的疲劳恢复研究有所帮助.     

基于ANSYS的Au-Al引线键合热可靠性研究

采用ANSYS有限元分析软件建立Au-Al引线键合模型考察键合区在热循环加载下的应力应变情况;并采用Coffin-Manson方程计算了在热循环加载下焊点的疲劳寿命。结果表明：随着热加载循环次数的增加,模型的应力应变将增大;施加约束后,模型的应力将减小,引线键合的寿命延长。此方法可以比较各种不同情形下Au-Al引线键合热可靠性。     

主动肌肉收缩对缓解运动疲劳的实验分析

目的:研究主动肌肉收缩对缓解运动疲劳的作用,对人体的适当运动对缓解肌肉疲劳有一定的调节指导意义。传统的分析方法基于蛋白质的分析方法,通过对于人体中蛋白质的详细分析和测试,推理出人体主动肌肉收缩对缓解疲劳的机理分析,但只是结果定性分析,没有详细描述机体的肌肉收缩详细过程。方法:提出一种基于主动肌肉收缩特性的方法,通过实验测试了三种不同运动状态所造成的疲劳程度,等长训练,等张训练,等动训练下的训练特性与相应的主动肌肉收缩特性,并且调查分析了不同年龄段的人群对于主动肌肉收缩下的运动疲劳缓解调节能力。结果:实验结果表明,主动肌肉收缩能够在一定程度上降低运动的疲劳感,并且随着年龄的增长,疲劳缓解调节达到预期效果的比例在逐渐降低,同时主动肌肉收缩的机理特性也在降低。结论:主动肌肉收缩对缓解运动疲劳具有很好的指导意义。     

Augmenting performance feedback does not affect 4 km cycling time-trials in the heat

We compared the effects of (1) accurate and (2) surreptitiously augmented performance feedback on power output and physiological responses to a 4000 m time-trial in the heat. Nine cyclists completed a baseline (BaseL) 4000 m time-trial in ambient temperatures of 30°C, followed by two further 4000 m time-trials at the same temperature, randomly assigning the participants to an accurate (ACC; accurate feedback of baseline) or deceived (DEC; 2% increase above baseline) feedback group. The total power output (PO) and aerobic (P_aer) and anaerobic (P_an) contributions were determined at 0.4 km stages during the time-trials, alongside measurements of rectal (T_rec) and skin (T_skin) temperatures. There were no differences (P > 0.05) in any of the variables between BaseL, ACC and DEC, despite increases (P < 0.05) in T_rec and T_skin. Typical pacing profiles were demonstrated; however, there was no interaction (P > 0.05) between feedback condition and time-trial stage. Providing surreptitiously augmented performance feedback to well-trained cyclists did not alter their performance or physiological responses to a 4000 m time-trial in a hot environment. The assumed influence of augmented performance feedback was nullified in the heat, perhaps reflecting a central down-regulation of exercise intensity in response to an increased body temperature.     

Pacing profiles and pack running at the IAAF World Half Marathon Championships

The aim of this study was to describe the pacing profiles and packing behaviour of athletes competing in the IAAF World Half Marathon Championships. Finishing and split times were collated for 491 men and 347 women across six championships. The mean speeds for each intermediate 5 km and end 1.1 km segments were calculated, and athletes grouped according to finishing time. The best men and women largely maintained their split speeds between 5 km and 15 km, whereas slower athletes had decreased speeds from 5 km onwards. Athletes were also classified by the type of packing behaviour in which they engaged. Those who ran in packs throughout the race had smaller decreases in pace than those who did not, or who managed to do so only to 5 km. While some athletes’ reduced speeds from 15 to 20 km might have been caused by fatigue, it was also possibly a tactic to aid a fast finish that was particularly beneficial to medallists. Those athletes who ran with the same competitors throughout sped up most during the finish. Athletes are advised to identify rivals likely to have similar abilities and ambitions and run with them as part of their pre-race strategy.     

Effects of forward trunk lean on hamstring muscle kinematics during sprinting

This study aimed to investigate the effects of forward trunk lean on hamstring muscle kinematics during sprinting. Eight male sprinters performed maximal-effort sprints in two trunk positions: forward lean and upright. A three-dimensional musculoskeletal model was used to compute the musculotendon lengths and velocity of the biceps femoris long head, semitendinosus, and semimembranosus muscles during the sprinting gait cycle. The musculotendon lengths of all the three hamstring muscles at foot strike and toe-off were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. In addition, a positive peak musculotendon lengthening velocity was observed in the biceps femoris long head and semimembranosus muscles during the late stance phase, and musculotendon lengths at that instant were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. The present study provides significant evidence that a potential for hamstring muscle strain injury involving forward trunk lean sprinting would exist during the stance phase. The results also indicate that the biceps femoris long head and semimembranosus muscles are stretched during forward trunk lean sprinting while contracting eccentrically in the late stance phase; thus, the elongation load on these muscles could be increased.     

学生篮球运动疲劳产生机理及恢复方法

为使学生篮球运动后疲劳尽快恢复,更好地投入到学习、工作中,利用学生篮球运动实践及观察方法、文献资料法及篮球运动理论进行研究发现,休息、睡眠、按摩、补充营养、物理疗法、心理恢复几种疲劳恢复方法可以使学生篮球运动疲劳得到很好的恢复,且多种恢复方法一起使用效果更佳。     

肌肉运动疲劳的生物标志物研究进展

肌肉疲劳是指在进行肌肉收缩活动期间产生的做功能力下降现象,在运动过程中很常见,也是限制运动员提高成绩的主要原因之一。肌肉疲劳产生生物标志物可以评估在运动期间肌肉的疲劳程度和运动对骨骼肌的影响。肌肉疲劳主要是由于能量物质耗尽,氧化应激增加,炎症反应激活等机制造成的。此外,还涉及了脱水、高氨血症、线粒体生物发生和遗传反应,文章通过梳理,把肌肉疲劳的生物标志物分为两类:一类是非侵入式的生物标志物,主要包括肌肉功率输出测量、电生理测量、心脏功能测量和摄氧量等;另一类是侵入式的生物标志物,主要包括ATP代谢、氧化应激和炎症等相关的生化指标。以期对以后运动疲劳的诊断和新的生物标志物的开发提供有价值的信息。     

某型号飞机前机身普通框接头R区疲劳分析

在民用飞机设计中,疲劳性能是飞机设计中要考虑的一个重要因素。而接头破坏可能是引起飞机结构失效的最常见的根源,且接头的疲劳强度分析在飞机结构分析中占有非常重要的地位。本文通过算例介绍了某型号飞机前机身普通框接头R区的疲劳分析方法,为接头的疲劳特性评估提供依据,以帮助结构工程师设计能够满足疲劳强度要求的接头尺寸,亦可为飞机的疲劳强度验证试验提供支持。     

竞技健美操运动员运动性疲劳与营养恢复探究

针对竞技健美操运动员产生疲劳的特点,文章采用文献资料法,专家访谈法,现场观察法,针对健美操运动员运动性疲劳的产生原因及消除方法进行了全面的调查研究与分析,并从运动营养学的角度对此提出行之有效的措施,最大可能地在最短时间内,运动员可以消除运动性疲劳,加快机体的恢复,从而保证运动员的训练可以正常进行。