静态拉伸训练不同阶段对男性排球运动员踝关节动力学及下肢缓冲特征的影响

目的:测试静态拉伸训练前、后男性青年排球运动员踝关节跖-背屈动作和落地缓冲动作生物力学参数,分析静态拉伸对踝关节动力学及下肢缓冲特征影响的机制及意义。方法:22名健康男性青年高水平排球运动员随机分为实验组和对照组,对实验组进行36组下肢静态拉伸训练。分别于训练前、12组训练后、24组训练后、36组训练后、停训4周恢复期后测试踝关节跖-背屈动力学和缓冲期下肢及下肢各关节动力学、运动学数据,同步测试小腿后肌群影像学。结果:12组训练后至恢复期踝关节跖-背屈范围增加非常显著(P<0.01),小腿后肌群被动刚度显著降低(P<0.05),二者的增加/降低率%于36组训练后改变最明显(P<0.05),且变化率%之间呈非常显著正相关(P<0.01)。训练后小腿后肌群滞后%明显降低(P<0.05),肌腱弹性回缩率%明显升高(P<0.05),且二者之间呈显著负相关(P<0.05)。下肢刚度显著降低(P<0.05),髋、膝、踝关节做功均显著增加(P<0.05),训练各阶段踝关节做功贡献度均最大(P<0.05)。结论:静态拉伸训练早期即可通过降低肌...     

Biomechanical differences in double poling between sexes and level of performance during a classical cross-country skiing competition

Biomechanical differences in double poling (DP) between sex and performance level were investigated in female and male cross-country skiers during a classical race (10/15 km). Skiers were divided into faster and slower on basis of race performance: females faster (n=20), females slower (n=20), males faster (n=20), and males slower (n=20). Based on video analysis while DP in a flat section of the track, joint and pole angles at pole plant (PP) and pole-off, cycle characteristics and the use and coordination pattern of heel-raise (raise of heels from the ground to have a higher body position at PP) were analysed. Faster females and males had 4.3% and 7.8% higher DP velocity than their slower counterparts (both P<0.001). Faster males had 6.5% longer cycles than slower males (P<0.001). Faster skiers stopped heel-raise later than slower skiers (females: 2.0±3.4% vs. ?1.0±3.5%, P<0.05; males: 3.9±2.4% vs. 0.8±3.2% of cycle time in relation to PP, P<0.001). At PP, faster skiers and male skiers had a smaller pole angle and greater ankle to hip and ankle to shoulder angle with respect to vertical, resulting in a more distinct forward body lean. However, the majority of the differences are likely due to higher DP velocity.     

Comparison of methods for determining power generated on a rope-braked cycle ergometer during low-intensity exercise

This study compares the instrumentation and analysis techniques used when determining the power expended pedalling a rope-braked ergometer manufactured by Monark (Sweden) during a low intensity test. Power values were generated by eight subjects. The instrumentation consisted of load cells to measure the rope brake forces, a tachometer to measure the flywheel velocity and instrumented pedal cranks manufactured by Schoberer Rad Messtechnik (SRM). The subjects pedalled a rope-braked ergometer at 60 rev min^-1, against a resistance of 3 kg, for 5 minutes. Three different measurements of the mean power were recorded and these were compared with the value given by Monark. The SRM cranks provided two sets of results using different software packages supplied with the cranks. SRM standard software is used for taking measurements during training and cycle races over long time periods. An additional piece of software is provided by SRM called Ptnew, which gives readings of torque and pedal cadence over periods up to 30 seconds. Using the values supplied by Monark each subject generated 180 W of power. The mean power for the eight subjects, measured using the SRM cranks, was 170.36 W (SD 4.11) using the alternative SRM software (Ptnew) over a 30 second period and 173.68 W (SD 2.21) using the standard SRM software. From the direct measurement of the brake forces and flywheel velocity the mean power across the eight subjects was 148.90 W (SD 5.89). The SRM cranks measure the input power, whereas the direct measurement system measures the power output excluding mechanical losses. These values give a figure for the mechanical efficiency for the roped-braked ergometer of 88%. It was found that Monark overestimates the power generated by the subjects when compared with both the SRM systems and the direct measurement instrumentation.     

Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

长三角地区大学生体质状况静态分析

对长三角地区部分高校20009名学生2011年《大学生体质健康标准》测试数据进行静态分析,结果显示：超重或肥胖现象呈增长趋势发展;肺活量体重指数,女生优秀率和达标率与在校时间呈正相关性;耐力素质总体情况不理想,＂低分多高分少,且两端极点突起＂较明显,男生耐力素质与在校时间呈负相关;男生在速度灵巧类通过率高于女生,各年级呈负增长趋势;柔韧力量素质总体情况较好,男生通过率略好于女生,但及格率与在校时间呈负相关,女生优秀率与在校时间呈正相关。     

女子花样滑冰优秀运动员跳跃动作的运动生物力学分析

运用艾利尔软件,通过对2003年中国杯世界花样滑冰大奖赛我国优秀运动员以及国外优秀运动员跳跃动作的技术录像解析,分析所获得的起跳时水平速度、空中水平位移、腾空高度、空停时间、腾起角、关节角度等参数,并与国外优秀运动员作比较。结果显示,我国运动员起跳时水平速度与国外优秀选手还有差距,需提高滑行技术和蹬冰力量;提高起跳技术、腿部蹬伸力量和爆发力,使水平速度有效地转化为垂直速度;我国部分运动员腾起角偏大,在提高水平速度的同时,人体重心腾起角应逐渐减小;助滑末期运动员支撑腿应积极屈膝,充分后引浮腿;起跳时支撑腿应积极蹬伸,形成“小摆臂,早收臂”。     

第11届全运会女子铅球项目前8名运动员关键运动技术参数三维录像分析

本文采用文献研究法、三维录像解析法和统计分析法对第11届全运会女子铅球决赛前八名运动员最好成绩投次进行关键运动技术研究,获取她们的部分关键运动学参数,同时和世界级优秀运动员的相应参数进行比较分析,得出相应的研究结果。本论文的主要研究结论为1.背向滑步转身跳投技术按整体动作结构可分为后摆、滑步、过渡、双支撑和最后出手投掷五个阶段。2本研究再次证明了出手速度与比赛成绩呈高度正相关,相关系数达到0.95。而出手角度和其他运动学参数与成绩呈中低度相关。3.本届全运会中冠军巩立娇6次试投平均成绩为19.60±0.46m;平均出手速度为13.47±0.24m/s,与世界级选手接近;平均出手角度为33.99±1.23°,低于世界级优秀运动员;平均出手高度为2.03±0.03m,距离抵制板的水平距离平均为-0.03±0.08m。4.前3名运动员李玲、李梅菊和巩立娇最好成绩投次质心最大分别为速度为2.84m/s、2.65m/s和2.91m/s,质心最大速度与成绩相关性不大。铅球的出手速度为12.69m/s,13.31m/s和13.84m/s,出手角度为38.5°、35.5°和33.9°,铅球的出手高度为2.09m、1.98m和2.06m。     

The influence of water depth on kinematic and spatiotemporal gait parameters during aquatic treadmill walking

The purpose of this study was to investigate kinematic and spatiotemporal variables of aquatic treadmill walking at three different water depths. A total of 15 healthy individuals completed three two-minute walking trials at three different water depths. The aquatic treadmill walking was conducted at waist-depth, chest-depth and neck-depth, while a customised 3-D underwater motion analysis system captured their walking. Each participant’s self-selected walking speed at the waist level was used as a reference speed, which was applied to the remaining two test conditions. A repeated measures ANOVA showed statistically significant differences among the three walking conditions in stride length, cadence, peak hip extension, hip range of motion (ROM), peak ankle plantar flexion and ankle ROM (All p values < 0.05). The participants walked with increased stride length and decreased cadence during neck level as compared to waist and chest level. They also showed increased ankle ROM and decreased hip ROM as the water depth rose from waist and chest to the neck level. However, our study found no significant difference between waist and chest level water in all variables. Hydrodynamics, such as buoyancy and drag force, in response to changes in water depths, can affect gait patterns during aquatic treadmill walking.     

Effect of Toe Clips during Bicycle Ergometry on [Vdot]O2 max

Abstract

Previous investigators have yielded conflicting results in testing the hypothesis that the use of toe clips during bicycle ergometry produces a higher maximal oxygen uptake ([Vdot]O ₂ max) than testing without toe clips. Eight men, four competitive cyclists and four competitive distance runners volunteered to participate in three randomized [Vdot]O ₂ max tests: 1) a treadmill running lest, 2) a bicycle ergometer test using standard toe clips, and 3) a test on the same ergometer without toe clips. The highest mean [Vdot]O ₂ max was observed in the treadmill condition as expected. However, no statistically significant difference in mean [Vdot]O ₂ max or performance time was observed between the toe-clip and no toe-clip conditions. Based on these results, the research hypothesis was rejected and no favorable physiological effect may be attributed to the use of toe clips.     

高原运动员在次高原比赛期间静息心率及体重变化状况的分析

本文通过青海业余运动员云南昆明比赛期间晨静息心率、晨空腹体重和问卷调查的分析,发现：高原地区运动员即使向高原地区较低海拔移动较少的高度,也会产生有利于心血管方面的影响,运动员本体感觉好于原居住地;返回原居住地后,缺氧对机体也有刺激作用;在身体机能的变化中,机体对心血管系统的变化更为敏感,     

Differential effects of speed on two-dimensional foot strike pattern during barefoot and shod running in recreationally active men

ABSTRACT

The majority of barefoot running studies have not considered speed as an influential factor on foot strike pattern. The aim of this study was to investigate differences in foot strike pattern and spatiotemporal characteristics between barefoot and shod overground running at varying speeds. We first determined maximal running speed (Vm) over 50 m in 15 recreationally active men who self-reported as habitual rearfoot strikers. Participants then completed shod and barefoot running trials at different speeds equivalent to approximately 90%, 80%, 70% and 60% of Vm. Sagittal plane two-dimensional (2D) foot-ground contact angle, ankle plantar-dorsi flexion angle, contact time, flight time, step length and step rate variables for each trial were recorded. A significant interaction effect of running speed and footwear condition (p < 0.05) on foot-ground contact angle, ankle plantar-dorsi flexion angle and contact time was observed. There was a main effect of running speed (p < 0.01) on flight time, step length and step rate. There was a main effect of footwear condition on step length (p < 0.01). Participants were more inclined to plantarflex the ankle and contact the ground with the forefoot at higher percentages of Vm, especially when running barefoot.     

滕海滨双杠屈体后空翻2周下运动学分析

通过文献资料调研、视频观察和运动学研究方法揭示了我国优秀运动员滕海滨完成双杠屈体后空翻2周下的技术特点及运动学规律,从支撑摆动、腾空屈体2周和落地3个阶段剖析了它们之间的因果关系和技术细节.研究结果显示,支撑摆动推离杠的时机和方向、身体重心抛物线腾起的角度和速度、腾空的高度和向后屈体2周的翻转速度以及落地前伸髋的幅度和落地时的缓冲动作是完成好该动作的关键技术环节.     

绿色奥运年对我国竞技体育中“阴盛阳衰”现象的剖析

“阴盛阳衰”是中国竞技体育的一种独特现象,中国女子竞技体育运动以发展快、项目多、实力强、潜力大的特点,优于男子的发展。分析“阴盛阳衰”现象形成的诸因素,有利于女子竞技体育成绩的保持和发展,并能为男子竞技体育成绩的提高提供参考。     

贵州省体育科学深度和广度的分析--基于2001-2011年贵州体育科研论文引文的文献计量考察

用文献计量法、数理统计法考察2001-2011年贵州省体育科研工作者发表的体育期刊论文的引文。结果显示：引用文献的数量少,质量也有待提升;引文主要集中在期刊论文和专著两种文献类型上;引文语种单一,英文是贵州体育科研论文的唯一外语引文,个体作者之间的外语引文量呈两极分化态势;少数作者引用了其他学科的文献。但从引文各项指标的纵向发展趋势可以预料,今后,贵州体育科学的深度和广度将会得到进一步的发掘和拓展。     

近两届奥运会中国男篮后卫线得分能力的比较与分析

运用文献资料、数理统计等方法,对中国男篮后卫线在第28届和第29届奥运会上临场比赛数据进行比较,结果发现：中国男篮后卫线在得分能力上有较大提升;而同与赛队对手比较发现：两者在得分能力上仍然存在非常显著差异,主要是由于中国男篮后卫线近篮得分能力相对较差所致;对体现得分能力的各指标进行了比较研究,并作出了客观分析,旨在反映我国男篮后卫线在奥运会大赛上临场得分能力状况,为教练员对其针对性地训练提供参考依据。     

Examining the influence of grip type on wrist and club head kinematics during the golf swing: Benefits of a local co-ordinate system

Wrist movements have been identified as an important factor in producing a successful golf swing, with their complex motion influencing both club head velocity and orientation. However, a detailed analysis of wrist angles is lacking in the literature. The purpose of this study was to determine kinematics across wrists and club head characteristics during the golf swing under weak, neutral and strong grip conditions. Twelve professional male golfers executed 24 shots using a driver under three grip conditions. A six degrees of freedom analysis of the hand with respect to the distal forearm was performed using a 10-camera three-dimensional motion capture system. Differences in joint angles were explored using repeated measures ANOVAs at key swing events (onset, top of backswing and impact), in addition club head velocity and clubface angle at impact were also explored. Main findings revealed significant differences in flexion/extension and internal/external rotation for both wrists at all swing events, whereas fewer significant interactions were found in ulnar/radial deviation across grips for both wrists at all events. Clubface angle only differed significantly between the weak and the strong and neural grips, presenting a more ‘open’ clubface to the intended hitting direction. This study is the first to explore tri-planar wrist movement and the effect of different grips, such analysis has implications for coaching knowledge and practice and should inform future research into different aspects of skill, technique analysis and may inform injury mechanisms/prevention.     

第2届环青海湖国际公路自行车赛技术统计分析

以 2 0 0 3年第 2届环青海湖国际公路自行车比赛成绩资料为样本 ,运用相关分析、离差比较、聚类分析等研究方法 ,研究了自行车公路竞赛技术 ,探讨了公路竞赛技术和组队比赛的策略问题。结果表明 ,环湖赛的比赛成绩与赛道难度有关 ;运动队的团体成绩不是仅靠个别优秀运动员 ,而取决于队内运动员成绩的差异。中国队要在环湖赛中取得良好成绩 ,建议最好采用每人每赛段争先 1km的比赛策略