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1.
This study analyzed the joint torque and the mechanical energy flow in the support legs of skilled male race walkers. Twelve race walkers were videotaped using a high-speed camera at a frame rate of 250 Hz set perpendicular to the sagittal plane of motion; their ground reaction forces were measured with two force platforms. A two-dimensional, 14-segment, linked model was used to calculate the kinetics of the support leg joints. In the initial part of the support phase, the mechanical energy flowed into the thigh and shank by the torque of the large hip extensors and knee flexors. In the middle part, the mechanical energy generated by the torque of the large plantar flexors flowed to the foot and from the foot to the shank by the ankle joint force. The mechanical energy flow by the forward joint force of the support hip was significantly related to the walking speed in the final part of the support phase. Our findings suggest that race walkers in the final part of the support phase should exert the torque of the knee extensors and hip flexors to transfer the mechanical energy more effectively to the support thigh and shank.  相似文献   

2.
Abstract

The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles.  相似文献   

3.
十运会男、女20 km竞走前5名运动员运动技术分析   总被引：7，自引：0，他引：7  
竞走是我国田径传统的优势项目，但近年来男、女竞走运动员在国际比赛中成绩下滑。针对十运会我国男、女20km竞走前5名运动员的运动技术表现，采用新的标尺标定方法，通过二维录像平面解析研究运动员的运动技术特征。主要研究结果：竞走阶段的合理划分；步长、步频；头部速度特征；关键身体环节角度变化特征；角速度变化特征；身体垂直位移特征和运动技术视频图像信息等7个方面，并得出相应的结论。  相似文献   

4.
Aim: The aim of this study was to determine the relationships between biomechanical parameters of the gait cycle and race walking economy in world-class Olympic race walkers.

Methods: Twenty-One world-class race walkers possessing the Olympic qualifying standard participated in this study. Participants completed an incremental race walking test starting at 10 km·h?1, where race walking economy (ml·kg?1·km?1) and spatiotemporal gait variables were analysed at different speeds.

Results: 20-km race walking performance was related to race walking economy, being the fastest race walkers those displaying reduced oxygen cost at a given speed (R = 0.760, p < 0.001). Longer ground contact times, shorter flight times, longer midstance sub-phase and shorter propulsive sub-phase during stance were related to a better race walking economy (moderate effect, p < 0.05).

Conclusion: According to the results of this study, the fastest race walkers were more economi cal than the lesser performers. Similarly, shorter flight times are associated with a more efficient race walking economy. Coaches and race walkers should avoid modifying their race walking style by increasing flight times, as it may not only impair economy, but also lead to disqualification.  相似文献   

5.
李泽龙 《辽宁体育科技》2004,26(4):60-60,80
通过对一个竞走复步的分析，发现中外优秀男子运动员在后摆、前摆、前支撑、后支撑阶段中的运动学参数存在一定差异，找出我国运动员在技术方面存在的不足，为提高和完善我国男子运动员竞走技术提供理论支持。  相似文献   

6.
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8.
Race walking is an event where the knee must be straightened from first contact with the ground until midstance. The aim of this study was to compare knee angle measurements between 2D videography and 3D optoelectronic systems. Passive retroreflective markers were placed on the right leg of 12 race walkers and 3D marker coordinate data captured (250 Hz), with 2D video data (100 Hz) recorded simultaneously. Knee angle data were first derived based on the markers’ coordinates, and separately by using a 3D model that also incorporated thigh and shank clusters; the video data were analysed using both automatic tracking and manual digitising, creating four conditions overall. Differences were calculated between conditions for stance (using root mean square values), and at discrete events. There were few differences between systems, although the 3D model produced larger angles at midstance than using automatic tracking and marker coordinates (by 3 – 6°, P < 0.05). These differences might have occurred because of how the 3D model locates the hip joint, and because of the addition of marker clusters. 2D videography gave similar results to the 3D model when using manual digitising, as it allowed for errors caused by skin movement to be corrected.  相似文献   

9.
我国男子竞走运动员的技术特征及生物力学分析   总被引：10，自引：1，他引：9  
采用文献研究及生物力学分析等方法,对我国男子竞走运动员的技术进行分析,发现在1996年前的竞走规则和定义的影响下,我国男选手逐步形成了小步幅、快频率的技术特征。生物力学分析表明,髋的水平速度与摆动时间里高度相关,适当增加髋关节围绕身体垂直轴转动的速度,对提高步长有积极效果。控制足触地的角度和加强前摆着地技术的训练应引起重视。  相似文献   

10.
三维定点摄像方法在竞走运动中的应用研究   总被引：1，自引：0，他引：1  
通过查阅大量竞走运动相关文献资料发现,竞走技术的研究方法主要为平面摄影或摄像,对于竞走技术的深入研究在方法上存在明显不足,而在竞走规则修改后的十多年里,中国竞走运动员的＂小步幅、高步频＂技术受到巨大挑战。为了进一步深入探讨竞走运动技术特征,研究方法必须有所改进,对于竞走关键技术的研究,宜采用三维定点摄像方法,本文对三维定点摄像方法在竞走运动中的应用进行了探讨。  相似文献   

11.
The aim of this study was to explore the relationships between lower limb joint kinetics, external force production and starting block performance (normalised average horizontal power, NAHP). Seventeen male sprinters (100 m PB, 10.67 ± 0.32 s) performed maximal block starts from instrumented starting blocks (1000 Hz) whilst 3D kinematics (250 Hz) were also recorded during the block phase. Ankle, knee and hip resultant joint moment and power were calculated at the rear and front leg using inverse dynamics. Average horizontal force applied to the front (r = 0.46) and rear (r = 0.44) block explained 86% of the variance in NAHP. At the joint level, many “very likely” to “almost certain” relationships (r = 0.57 to 0.83) were found between joint kinetic data and the magnitude of horizontal force applied to each block although stepwise multiple regression revealed that 55% of the variance in NAHP was accounted for by rear ankle moment, front hip moment and front knee power. The current study provides novel insight into starting block performance and the relationships between lower limb joint kinetic and external kinetic data that can help inform physical and technical training practices for this skill.  相似文献   

12.
Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.  相似文献   

13.
关于竞走裁判员与一般人的肤视力和标准视力的比较研究   总被引：1，自引：0，他引：1  
采用测量、概率统计和逻辑思维方法等对竞走裁判员与一般人的肤视力和标准视力进行了比较研究。结果表明 :标准视力与肤视力是不同的 ,作为竞走裁判员不仅标准视力要好 ,而且肤视力也要好。各种肤视力之间存在着统计学差异 ,这表明 3种肤色运动员同场比赛时 ,竞走裁判员的肤视力是不同的。单一肤色运动员在一起比赛时 ,同一竞走裁判群体的黄肤视力、白肤视力和黑肤视力是不同的 ;不同肤色运动员在一起比赛时 ,同一竞走裁判群体的肤视力也是不同的。  相似文献   

14.
我国优秀女子竞走运动员竞走技术的生物力学分析   总被引：11，自引：0，他引：11  
采用摄像及录像解析等研究方法 ,对我国优秀女子竞走运动员的技术进行生物力学研究与分析。研究表明 ,我国女子竞走运动员的步长、步频、着地角及支撑腿各阶段的膝角合理 ,但身体重心上下起伏偏大 (>5cm) ,并且单步腾空时间在模糊腾空时限 ,如果竞走技术不连贯、协调、轻松 ,容易造成犯规 ,需要在以后的训练中予以纠正。  相似文献   

15.
Abstract

This study analysed the first stance phase joint kinetics of three elite sprinters to improve the understanding of technique and investigate how individual differences in technique could influence the resulting levels of performance. Force (1000 Hz) and video (200 Hz) data were collected and resultant moments, power and work at the stance leg metatarsal-phalangeal (MTP), ankle, knee and hip joints were calculated. The MTP and ankle joints both exhibited resultant plantarflexor moments throughout stance. Whilst the ankle joint generated up to four times more energy than it absorbed, the MTP joint was primarily an energy absorber. Knee extensor resultant moments and power were produced throughout the majority of stance, and the best-performing sprinter generated double and four times the amount of knee joint energy compared to the other two sprinters. The hip joint extended throughout stance. Positive hip extensor energy was generated during early stance before energy was absorbed at the hip as the resultant moment became flexor-dominant towards toe-off. The generation of energy at the ankle appears to be of greater importance than in later phases of a sprint, whilst knee joint energy generation may be vital for early acceleration and is potentially facilitated by favourable kinematics at touchdown.  相似文献   

16.
The study examined the differences between boys and adults after an intense stretch-shortening cycle fatigue protocol on neuromechanical parameters of the lower limb. Thirteen boys (9–11 years old) and 13 adult men (22–28 years old) were tested for maximal isometric voluntary knee extension torque and drop jump (DJ) performance from 30 cm before and immediately after a fatigue protocol, consisted of 10 × 10 maximum effort vertical jumps. Three-dimensional kinematics, kinetics and electromyographic (EMG) parameters of the lower extremities muscles were recorded during DJs before and after the fatigue test. The results indicated that reduction in maximal isometric torque and jumping performance was significantly higher in adults compared to boys. Vertical ground reaction forces, contact time and maximum knee flexion increased in a greater extend in adults than in boys. In addition, preactivation, EMG agonist activity, knee joint stiffness and stretch reflex decreased more in adults than in boys at all the examined phases of jumping tasks. It is concluded that employed fatigue protocol induced acute reduction in performance and altered motor control during jumping in both age groups. However, the differences in the level of fatigue between the 2 groups could be attributed to neuromuscular, mechanical and kinematic parameters observed between groups.  相似文献   

17.
我国优秀女子竞走运动员技术特征研究   总被引：7，自引：0，他引：7  
采用高速摄影机定点拍摄了2000年全国竞走锦标赛女子20 km竞走比赛前7名运动员的技术影片,并采用"TYF-2"型影片分析系统对影片进行解析,对运动员在比赛中程(10 km)的一个单步的各个阶段和各个技术环节进行了定量和定性的分析和研究.揭示了当今我国优秀女子竞走运动员的共性技术特征.结论我国优秀女子竞走运动员腾空时间为(48.8±9.8) ms;重心上下起伏距离为(6.0±1.3) cm,7名运动员身体重心的最高点均出现在支撑腿脚尖离地时,身体重心的最低点出现在垂直支撑时;前腿在触地瞬时的膝角为181.0°±2.0°,垂直支撑时膝角为185.7°±3.4°, 并保持157.0 ms的膝关节完全伸直状态,直至过渡到身体重心垂直面;优秀运动员均采用"足踵触地、踝关节背屈"滚动式着地技术,以及后蹬腿脚尖离地技术,符合当今世界竞走运动发展趋势.  相似文献   

18.
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.  相似文献   

19.
训练成效的突破很大程度上取决于训练理念的创新,而训练结构与训练实施则是训练理念得以实现的载体。竞走是对技术有特殊要求的田径运动,技术是竞走的生命。运用观察、调查、文献调研及数理统计等方法从竞走技术的规范性、实效性及经济性要求入手,在建构优秀竞走运动员技术训练结构的同时,提出优秀竞走运动员技术能力训练时应以根源性训练要素为主,常规性训练手段为辅的技术训练新理念。  相似文献   

20.
Technique changes in cyclists are not well described during exhaustive exercise. Therefore the aim of the present study was to analyze pedaling technique during an incremental cycling test to exhaustion. Eleven cyclists performed an incremental cycling test to exhaustion. Pedal force and joint kinematics were acquired during the last three stages of the test (75%, 90% and 100% of the maximal power output). Inverse dynamics was conducted to calculate the net joint moments at the hip, knee and ankle joints. Knee joint had an increased contribution to the total net joint moments with the increase of workload (5–8% increase, p < 0.01). Total average absolute joint moment and knee joint moment increased during the test (25% and 39%, for p < 0.01, respectively). Increases in plantar flexor moment (32%, p < 0.01), knee (54%, p < 0.01) and hip flexor moments (42%, p = 0.02) were found. Higher dorsiflexion (2%, for p = 0.03) and increased range of motion (19%, for p = 0.02) were observed for the ankle joint. The hip joint had an increased flexion angle (2%, for p < 0.01) and a reduced range of motion (3%, for p = 0.04) with the increase of workload. Differences in joint kinetics and kinematics indicate that pedaling technique was affected by the combined fatigue and workload effects.  相似文献   

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