不同高度的手臂运动与心率变化的研究

目的：通过小样本实验研究,对运动中手臂高度与心率变化的机制进行探析。方法：监测15名受试者在运动中两臂直臂侧上摆和侧下摆的心率变化;两臂侧上屈伸和侧下屈伸的心率变化。结果：运动中手臂高度超过心脏能够促使心跳加速。结论：运动中手臂高度超过心脏能够促使心跳加速主要与重力势能、动力肌肉群做功、运动强度和心脏供血量等参数的变化有关。     

不同形式肌肉收缩时肌电参数变化特征及机制

研究目的：探讨动力性与静力性肌肉收缩时EMG各参数的变化特征及疲劳时各指标的差异,比较不同项目运动员肌肉收缩特征对EMG参数的影响及与该项目的关系。研究方法：27名受试者分为两组,第一组为赛艇运动员（组一）,第二组为田径爆发性力量项目（跳跃、短跑）专选运动员（组二）。受试者以2／3Mvc做静力性持续等长收缩,动力性持续肌肉收缩则采用本人的MVC,同时记录EMG信号,分析IEMG、E／T值和MF。研究结果：持续静力性肌肉收缩时,随疲劳的发展赛艇运动员与田径运动员IEMG、E／T值均显著升高。但赛艇运动员从运动开始至80％时段一直保持平稳,此后迅速上升。静力性收缩时两组运动员随疲劳发展MF从高频向低频转移,但田径运动员频率下降速率要快于赛艇运动员。结论：赛艇运动训练促使大脑皮层动员运动单位工作更具有时间耐久性。快速、爆发式运动使疲劳时大脑皮层兴奋性下降更快,肌肉更易于疲劳。     

Principal components analysis to characterise fatigue-related changes in technique: Application to double under jump rope

The upper extremities play an important role in managing the rope-turning technique required to perform continuous double unders. However, acute adaptions in this technique may occur as a jumper fatigues. The purpose of this study was to examine how turning technique is adapted with fatigue. Three-dimensional kinematic data of the upper extremity were collected from 10 trained athletes as they performed consecutive double unders to volitional fatigue. Time series wrist, elbow and shoulder joint angles were calculated where joint angle waveforms representing 10 unique trials from the beginning (“fresh”) and end (“fatigued”) of the continuous jumping protocol for all participants were analysed using principal component analysis. Participants reported stopping due to cardiovascular and shoulder muscular fatigue. From a kinematics perspective, with fatigue athletes used a more internally rotated range of motion at the shoulder, which we believe prompted a series of more distal adaptions in order to maintain rope turning, preserving consecutive double under performance. The presence of a maladaptive adaptation at the shoulder may increase the risk of developing shoulder injuries. Coaches should consider helping jumpers develop appropriate shoulder muscle endurance such that they can continue to maximise their training and proficiency, while protecting against potential fatigue-related maladaptation.     

Stability of pedalling mechanics during a prolonged cycling exercise performed at different cadences

The aim of this study was to analyse the effect of pedalling rate on the pattern of mechanical torque application and on neuromuscular fatigue during prolonged cycling exercise. Eleven well-trained individuals performed three 1-h pedalling sessions, at 50 rev?·?min^?1, 110 rev?·?min^?1 and a freely chosen cadence, at an intensity corresponding to 65% of their maximal aerobic power. The mechanical torque applied on the right pedal was recorded for 30?s every 5?min while pedalling. Contractile and neural properties of the quadriceps and hamstring muscles were analysed before and immediately after each of the three pedalling sessions. The post-exercise reduction in knee extensors maximal voluntary contraction was significant (P <?0.01) irrespective of the cadence, but no difference was found between cadences. The use of a particular cadence did not lead to preferentially central or peripheral fatigue. An increase in cadence resulted in greater positive and negative work generated during pedalling. The mechanical pattern was not altered during the exercise, whatever the selected cadence. The present study demonstrates that despite the occurrence of neuromuscular fatigue, trained individuals maintained a stable pedalling pattern throughout an endurance cycling exercise for cadences ranging from 50 to 110 rev?·?min^?1.     

武术长拳运动员不同强度练习后心率及血乳酸变化的研究

通过武术长拳运动员不同训练强度下心率和血乳酸的测定,分析研究运动员训练水平与心率及血乳酸的关系,并探讨不同训练负荷下血乳酸与运动员训练水平的关系,为科学训练提供依据。     

从规则变化探析新奥运周期我国女子体操训练对策

通过文献资料法、录像观察统计法、查阅有关体操规则变化情况。分析了国际体操规则变化特点，探讨了世界女子体操发展态势与我国女子体操现状及其与世界先进水平的差距，提出了新奥运周期的训练对策，旨在为我国女子体操在2008年北京奥运会上再创辉煌提供参考建议。     

周期训练中不同水平男子皮艇运动员血浆内皮素的变化

观察了20名不同水平男子皮艇运动员在一个周期训练中血浆内皮素(ET)的变化.结果提示:高水平男子皮艇运动员血浆ET水平与运动训练持续的时间及运动负荷成正相关,说明长时间、大强度训练能有效增加高水平运动员血浆ET的含量,运动员的心脏内分泌功能对周期训练适应性强,具有良好的心力储备和泵血功能,然而也不排除运动员有心脏功能的损伤.     

Adding omega-3 fatty acids to a protein-based supplement during pre-season training results in reduced muscle soreness and the better maintenance of explosive power in professional Rugby Union players

Evidence suggests that omega-3 fatty acid supplementation could reduce muscle soreness and maintain muscle function following eccentric exercise-induced muscle damage. The aim of this applied field study was to investigate the effectiveness of consuming a protein-based supplement containing 1546?mg of omega-3 polyunsaturated fatty acid (PUFA) (551?mg eicosapentaenoic acid (EPA) and 551?mg docosahexaenoic acid (DHA)) twice daily (FO) compared to a protein-based placebo (P) on muscle soreness, countermovement jump (CMJ) performance and psychological well-being in 20 professional Rugby Union players during 5 weeks of pre-season training. Players completed a 5-point-Likert soreness scale with 5 indicating “no soreness” and a questionnaire assessing fatigue, sleep, stress and mood each morning of training, plus they performed CMJ tests once or twice per week. Data were analysed using magnitude-based inferential statistics and are presented as percent beneficial/trivial/harmful. On day 35, there was a likely (% beneficial/trivial/harmful: 94/5/1) moderate (0.75, standardized mean difference (SMD)) beneficial effect of FO vs. P on the change in lower body muscle soreness compared with day 0 (FO: ?3.8?±?21.7%; P: ?19.4?±?11.2%). There was a likely (92/7/0) moderate (SMD: 0.60) beneficial effect of FO vs. P on CMJ performance (change from baseline to day 35, FO: +4.6?±?5.9%; P: ?3.4?±?8.6%). From day 20, a moderate beneficial effect of FO on fatigue was observed. In terms of practical relevance, the moderate beneficial effect of adding fish oil to a protein-based supplement on muscle soreness translated into the better maintenance of explosive power in elite Rugby Union players during pre-season training.     

Individualised training at different intensities,in untrained participants,results in similar physiological and performance benefits

This study compared effects of training at moderate, high, or a combination of the two intensities (mixed) on performance and physiological adaptations, when training durations were individualised. Untrained participants (n = 34) were assigned to a moderate, high, or mixed group. Maximal oxygen uptake (V?O_2max), power output at V?O_2max (MAP), time-to-exhaustion and gross efficiency were recorded before and after four weeks of cycling training (four times per week). The moderate group cycled at 60% MAP in blocks of 5 min with 1 min recovery, and training duration was individualised to 100% of pre-training time-to-exhaustion. The high group cycled at 100% MAP for 2 min with 3 min recovery, and training duration was set as the maximum number of repetitions completed in the first training session. The mixed group completed two moderate- and two high-intensity sessions each week, on alternate days. V?O_2max, MAP, and time-to-exhaustion increased after training (P < 0.05), but were not different between groups (P > 0.05). The mixed group improved their gross efficiency at 50% MAP more than the other two groups (P = 0.044) after training. When training is individualised for untrained participants, similar improvements in performance and physiological measures are found, despite marked differences in exercise intensity and total training duration.     

射箭运动员在不同训练时期血液氨基酸变化的研究

目的：观察射箭运动员在不同运动负荷状态时的血液氨基酸的变化。方法：用高效液相法测定射箭运动员冬训期间不同的训练时期血液中四种氨基酸——门冬氨酸（Asp）、谷氨酸（Glu）、甘氨酸（（Gly）和r-氨基丁酸（GABA）的含量。结果：在进行中等强度训练期和大强度训练期运动后1h血浆中谷氨酸的血浆浓度明显升高（P〈0．01）。而在大强度训练期后明显下降,甚至低于安静值;门冬氨酸在中等强度训练后血浆浓度也升高（P〈0．05）,在疲劳期则呈下降趋势,但仍高于安静值;在进行中等强度训练期和大强度训练期运动1h后血浆中r-氨基丁酸、甘氨酸均上升。大强度训练期明显升高,与训练前期安静值相比有显著意义（P〈0．01）。结论：射箭运动员在长时间大强度大运动量训练后,血液中的氨基酸会发生变化,中枢疲劳可能从血浆氨基酸的变化反映出来。     

Acute effects of small changes in crank length on gross efficiency and pedalling technique during submaximal cycling

ABSTRACT

The main purpose of this study was to assess the acute effects of small changes in crank length (assumable by competitive cyclists) on metabolic cost and pedalling technique during submaximal cycling. Twelve amateur road cyclists performed three sets of submaximal pedalling (150, 200 and 250 W) at a constant cadence (91.3 ± 0.8 rpm) in a randomised order with three commonly used crank lengths, preferred (172.5–175 mm), +5 mm and ?5 mm. Energy cost of pedalling, kinetic and kinematic variables were simultaneously registered. Changes in crank length had no significant effect on heart rate (144 ± 13, 145 ± 12 and 145 ± 13 bpm, respectively) and gross efficiency (GE) (20.4 ± 2.1, 20.1 ± 2.2 and 20.3 ± 2.4%, respectively). A longer crank induced a significant (P < 0.05) reduction of positive impulse proportion (PIP) (0.9–1.9%) due to a greater maximum (1.0–2.3 N · m) and minimum torque (1.0–2.2 N · m). At the same time, the maximum flexion and range of motion of the hip and knee joints were significantly increased (1.8–3.4° and P < 0.05), whereas the ankle joint was not affected. In conclusion, the biomechanical changes due to a longer crank did not alter the metabolic cost of pedalling, although they could have long-term adverse effects. Therefore, in case of doubt between two lengths, the shorter one might be recommended.     

不同等级女子背越式跳高助跑技术的生物力学分析

通过高速摄影获取部分不同等级女子背越式跳高弧线助跑技术的数据,运用生物力学的研究方法分析她们倒数第三步到起跳时,身体重心的前倾角、后倾角、内倾角、助跑方向角以及它们的变化,支持时间、腾空时间、步频步长、蹬伸离地瞬间水平速度以及它们的变化.进一步找出她们之间技术相同和差别的生物力学特征.     

Changes in swimming technique during time to exhaustion at freely chosen and controlled stroke rates

Abstract

The aim of this study was to assess technical changes during constrained swimming in time-to-exhaustion tests. Ten swimmers of national standard performed a maximal 400-m front crawl and two sets of exhaustion tests at 95%, 100%, and 110% of mean 400-m speed. In the first set (free), swimmers had to maintain their speeds until exhaustion and mean stroke rate was recorded for each test. In the second set (controlled), the same speed and individual corresponding stroke rate were imposed. The durations of the exhaustion tests, relative durations of the stroke phases, and arm coordination were analysed. For each speed in the “controlled” set, the exhaustion tests were shorter. Moreover, variables were consistent, suggesting a stabilization of stroke technique. Under the free condition, stroke rate increased to compensate for the decrease in stroke length. At the same time, swimmers reduced the relative duration of their non-propulsive phases in favour of the propulsive phases. Thus, swimmers changed their arm coordination, which came close to an opposition mode. These two constraints enable swimmers both to maintain their stroking characteristics and develop compensatory mechanisms to maintain speed. Moreover, stroke rate can be seen as a useful tool for controlling arm technique during paced exercise.     

Differences in lower-limb coordination and coordination variability between novice and experienced runners during a prolonged treadmill run at anaerobic threshold speed

This study investigated differences in lower-limb coordination and coordination variability between experienced and novice runners during a prolonged run. Thirty-four participants were categorised as either experienced (n = 17) or novice runners (n = 17). All participants performed a 31-min treadmill run at their individual anaerobic threshold speed, and lower-limb kinematic data were acquired in the sagittal plane at the beginning, middle, and end of the run. Lower-limb coordination and variability during the stance phase were quantified using a vector coding technique for hip-knee, knee-ankle, pelvis-thigh, thigh-shank, and shank-foot couplings. Repeated-measure analysis of covariance revealed that running experience and time had significant interactions on the coordination patterns for hip-knee and pelvis-thigh couplings. During the midstance, experienced runners exhibited a higher percentage of in-phase motion for pelvis-thigh and knee-ankle couplings while novice runners displayed a higher percentage of distal motion for pelvis-thigh coupling and anti-phase motion for hip-knee coupling. Experienced runners displayed more variability in hip-knee and shank-foot couplings, and novice runners had more variability in hip, knee, and thigh motion. Experienced and novice runners adapted to progressive fatigue through different lower-limb coordination patterns. Throughout the prolonged run, experienced runners demonstrated greater coordination variability and novice runners displayed greater joint and segment variability.     

递增负荷运动大鼠卵巢子宫超微结构变化及其恢复过程观察

众所周知,女性性腺卵巢通过周期性分泌女性激素,调控和影响女性生殖系统的功能,维持规律的月经周期。在长期大运动量作用影响下,女运动员出现以低性腺类固醇和低促性腺皮质激素水平为特征的适应性反应,进而导致AMI的高发病率[1,2,3,4]。为了阐释AMI的病理机制,搞清训练影响下HP     

模拟不同海拔高原训练对大鼠骨骼肌蛋白质与糖原含量的影响

用低压氧舱模拟海拔２０００米、３０００米高度进行１周耐力训练,观察对骨骼肌细胞蛋白质和肌糖原含量的影响,验证１周时间高原训练的效果,同时观察各高度训练１周后平原效应期２周间的变化。结果表明：高原耐力训练可导致骨骼肌蛋白质分解代谢增强,蛋白质净降解,并有随高度升高而加剧的趋势,同时可提高骨骼肌中肌糖原贮量;不同海拔高度１周耐力训练后的平原效应期间,骨骼肌蛋白质含量第１周即可完全恢复,第２周保持稳定水平,肌糖原含量第１周下降,第２周显著回升。本研究支持高原训练的高度应在２０００～３０００米之间,回平原参赛时间应选择在下高原３天以内或２周以后的观点