The oxygen-conserving potential of the diving response: A kinetic-based analysis

We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics [heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation [oxyhaemoglobin ([HbO₂]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO₂) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (?0.86 bpm.%^?1) while HR kinetics in NDs steadily decreased throughout BH (?0.47 bpm.%^?1). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower [HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a [tHb] drop that NDs did not at the end of BH (?7.3 ± 3.2 vs. ?3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an “oxygen-conserving breaking point” in the human diving response.     

情感组织者技术对教师抑郁症的心理治疗

采用情感组织者技术对一名患有重度抑郁症的新上岗青年教师实施临床诊断和治疗.研究者向其大脑中输入一组"情感先行组织者"的程序性知识,使其在非药物干预条件下不仅能在短时间内改变原来的重度抑郁和过敏性焦虑情绪反应,而且迅速塑造了这位新教师的积极生活态度和健康的认知行为系统,根本性地结束了其抑郁症的所有临床症状.此个案初步证明了情绪组织者技术在抑郁症治疗中的有效性.     

传统武术劲的生理机制研究

目的：探索传统武术劲的系统训练方法及科学原理;方法：在对传统武术站桩练劲进行科学创新再指导6名运动员训练;结果：接受站桩训练的学员训练100小时后全身主要肌肉均建立一种反射,此反射能在特定的姿势下被激活,并且此反射被激活后使肌肉贮存弹性势能而增加出拳、出腿的速度和力量;结论：传统武术劲是符合现代生理学的一门科学的运动技术,它的原理就是人体在紧张性牵张反射的基础上通过训练建立的一个高级的运动条件反射。     

Abnormalities of masseter inhibitory reflex in patients with episodic tension-type headache

Objective: To investigate the masseter inhibitory reflex (MIR) and its eventual changes in patients with episodic tension-type headache (TTH). Methods: MIR was studied in 21 patients with episodic TTH and 30 healthy subjects, with age and sex matched to the study cohort. Median age of patients was 17,0 years (ranged 16～49 years), median duration of disease 12 months (1～5 years), and median frequency of headache 7.5 d per month. Results: The second period of suppression (S2) of MIR was reduced in intensity and duration in 10% of controls and 66.7% (confidence interval (CI)=45.3%～85%; P<0.05) of patients with episodic TTH (χ2=74.9; P<0.001). In 3 (14.3%) of patients with episodic TTH, S2 was completely absent. No significant correlation between the duration of disease and headache frequency was found. Conclusion: Our results confirm the link between episodic TTH and reduction or absence of S2. Teenage patients with episodic TTH may exhibit marked pathological changes in S2 in contrast to older individuals.     

Effects of neuromuscular function and split step on reaction speed in simulated tennis response

Abstract

The purpose of this study was to examine whether split step (small hop before step) would be more beneficial than no-split condition in simulated tennis response situation. In addition, it was studied if movement time of the response is related to separately measured force production capabilities and reflex sensitivity of the players. Nine skilled male tennis players participated in this study. Subjects stood on a force plate and reacted to a light signal and moved to appointed direction as fast as possible. With split step the participants were 13.1% faster (P <0.05) than without split step from the start to the distal end of the so called close range movement continuum (2.70 m). This was mainly explained by 43.6% faster time (P <0.05) from the signal to the onset of force production. Greater vertical forces were observed with split step: 15.7% greater F(z) mean force (P <0.05), 60.0% greater F(z) peak force (P<0.01). In split step both mean (r= ? 0.813, P <0.01) and peak (r=?0.765, P <0.05) vertical forces (Fz) correlated negatively with the time from the onset of the force production to the photocell. With split step higher EMGs were observed in muscles responsible for ankle joint movement indicating that different strategies were used. Due to the split step the players were able to start the movement faster which mostly explains the advantages over the no-split step condition. Split step condition may also benefit from stretch shortening type of muscle action.     

足底反射区脉冲电刺激对慢性运动性疲劳大鼠的影响

目的：选择最适宜的脉冲电流频率,研究观察足底脉冲电刺激对大鼠抗运动性疲劳力的影响。方法：实验于动物研究中心完成。选用6-8周龄健康雄性Wister大鼠60只。采用大鼠慢性运动疲劳（游泳力竭）模型。随机将大鼠分成边游泳边刺激组（A 组）、造模后即时刺激组（B组）、游泳后刺激组（C组）,这三类称为运动训练刺激组,外加造模组D（全程不予刺激）和对照组E（未进行游泳训练）,每组10只,实验过程中前后观察电流脉冲对大鼠游泳运动的血糖（葡萄糖氧化酶法测定）、血清乳酸含量（对羟基联二苯法测定）、红细胞超氧化物歧化酶活性（黄嘌呤氧化酶法测定）及体质量（早晨未进食前测试）的影响。利用统计学方法,结合SPSS分析软件探究最终结果。结果：排除大鼠在游泳训练中意外淹死的情况,实验大鼠全部计入结果分析。（1）血清血糖浓度：第1周末D组和B组大鼠低于B组,而A组无明显变化。浓度降低幅度A相似文献   

车灯线光源的优化设计

交通是城市发展的重要组成部分,作为交通元素的汽车无疑是重中之重,因此,车灯光源的设计对交通的顺畅与安全更是举足轻重.好的车灯设计不仅可以使车辆在夜间的行驶顺畅,更能有效的避免对驾驶员的影响,从而减少交通事故.本文通过对光在旋转抛物面中反射的分析,总结出其中的规律,如:线光源反射光发散域、会聚域对测试屏光强的影响.利用几何光学作图,设计了一套简明的计算,提高了实际应用的效率.得到了线光源长度为3.12(mm)的优化解.并充分利用了计算机绘图的优势得到了十分精确的屏上亮区.为讨论测试规范的合理性提供了依据.文章还详尽讨论了设计规范的合理性,突出了设计线光源具有的重要意义.     

向心训练与离心训练对大鼠腓肠肌H反射的影响

目的:探讨不同运动方式对大鼠神经肌肉系统H反射的影响.方法:选择72只SD大鼠随机分为向心组、离心组和对照组,3组各24只,其中向心组在4°的动物跑台上进行向心训练,离心组在-14°的动物跑台上进行离心训练,对照组不参加训练,训练8周后对大鼠右侧腓肠肌进行肌电图测试,采集H反射的主要指标.结果:离心组的Mmax波值显著高于对照组和向心组;离心组的Hmax波值显著高于对照组.3组之间的Hmax/Mmax值并不存在显著性差异;离心组Mmax波和Hmax波出现的时间要显著迟于向心组.结论:不同运动方式对大鼠H反射产生不同程度的影响,特别是离心训练后大鼠神经肌肉适应性得到改善.     

跆拳道运动员的技能及其训练

根据“从实战出发”的原则 ,对跆拳道运动员的技术训练与运用能力的区别、技术规范的变化与调节、身体活动的状态、动作之间“相生相克”的本质规律等方面进行了分析 ,同时 ,提出了提高运动员技能水平的相关要素、行动对策和训练要求     

乒乓球运动员反应速度和动作速度的发展特征及其评价的研究

本文采用简单反应时、简单反应手动作时等7项指标测试了乒乓球运动员341名、普通学生466名,分析论述了上述指标的快速发展阶段、缓慢发展阶段和稳定发展阶段等三个明显的发展特征;并建立了男、女子健将级、1级、2级和3级乒乓球运动员上述指标的优、良、中、差评价标准,以期能为运动员的选材和训练提供参考依据。