Joint torque and mechanical energy flow in the support legs of skilled race walkers

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.     

我国男子竞走运动员的技术特征及生物力学分析

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。     

Analysis of lower limb internal kinetics and electromyography in elite race walking

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.     

广州亚运会20km竞走运动员速度变化特征

采用数理统计法,对2010年广州亚运会上男子20km、女子20km优秀竞走选手的速度特征进行研究。结果表明：在20 km竞走比赛的最后阶段,大多数男子选手的速度呈下降趋势,获得前3名的女子选手的速度也呈下降趋势。优秀男子20km选手的最低平均速度出现在12~14km段,最高平均速度出现在14~16km段;获得前3名的女子运动员最低平均速度出现在18~20km段,最高平均速度出现在8~10km段;男子各段速度起伏较大,女子各段平均速度起伏较小。     

中国精英女子赛艇运动员划桨技术特点分析

目的：以国家队和赛艇优势省队运动员为测试对象，总结分析我国精英女子赛艇运动员的划桨技术特点。方法：27名运动员参与本研究，利用"BioRow Tel"系统测试五种桨频（20、24、28、32、36桨/分）下的划桨技术，测试参数包括划桨节奏、桨叶轨迹、桨力特征等。结果：拉桨时间百分比随桨频的提高显著提高；入水角、出水角和划幅在中低桨频下非常稳定，但在接近比赛桨频时显著下降；抓水打滑和出水打滑均随桨频的增加而显著增加；与桨力相关的参数对桨频的变化相对不敏感。结论：我国运动员较为注重桨叶入水和拉桨前段，表现出的技术较好，而在拉桨后段特别是桨叶出水阶段暴露出的问题比较大；临近比赛桨频时的技术同中低桨频时相比存在比较明显的下降。训练中要解决好拉桨后段和桨叶出水的问题，并注重提高运动员在比赛桨频时的划桨技术。     

关于核心力量训练提高竞走“训练质量”的可行性分析

在对竞走运动项目特点和训练规律全面、准确认识的基础上,从运动生物力学、运动解剖学、运动生理学、运动康复医学四个方面探究竞走运动员核心力量训练对提高"训练质量"的可行性。分析表明:竞走运动员的核心力量训练可有效加强核心稳定性和协调性、增大躯干小肌群力量、提高神经对肌肉的控制和支配能力、预防损伤及加快体育康复等方面的作用,对竞走运动的经济省力、增大步长、加快步频,提高竞走"训练质量"具有重要的意义。     

十运会男、女20 km竞走前5名运动员运动技术分析

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。     

我国优秀女子竞走运动员竞走技术的生物力学分析

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。     

Athletics

The purposes of this study were to investigate (1) the relationships between official distance and selected ground reaction measures during discus throwing; and (2) the relationships between selected ground reactions and selected lower extremity joint kinetics. Three high‐speed video cameras and three force plates were used to collect three‐dimensional videographic and force plate data in this study. An inverse dynamic model was used to determine the lower extremity kinetics. Multiple regression analyses were conducted to determine relationships of the selected kinematic and kinetic measures with the official distance. Official distance was significantly correlated with ground reaction forces on the left foot during the first single‐support phase, on the right foot during the second single‐support phase and delivery phase, and on the left foot during the delivery phase. Also, the right‐hip extension and internal rotation moments and left‐knee extension moment during the delivery phase were significantly correlated with official distance. These results suggest that discus throwers should drive vigorously forward during the first single‐support phase and increase the landing impact force on the right foot after flight. Also they should increase forward and rightward ground reaction force on the right foot and backward and vertical force on the left foot by powerful right‐hip extension and internal rotation and left‐knee extension during the delivery phase. These results provide critical information regarding the training of discus‐throwing techniques, and the direction of future biomechanical studies on this event.     

我国男子竞走后备运动员技术的运动学分析

运用因素分析的方法对我国竞走后备运动员高速走系统分析。结论显示:依赖后支撑位移的变化获取单步水平速度的变化是符合竞走项目特点的技术特征;稳定的较高步频是高速走的基本特征之一;依赖腾空位移的增加来增大单步步幅对腾空时间不利;影响单步重心水平速度的运动学因素依主次排列为瞬时速度与空间特征因子、时间特征因子、腾空空间特征因子。     

竞走项目最大速度能力和足底压力特征研究

通过二维录像解析和足底压力分布实验测试,对竞走项目运动员最大速度能力和足底压力分布特征进行相关的基础研究,以获得竞走项目运动员在特定的技术规则规定下,世界级优秀竞走运动员的极限最大速度能力、关键运动学参数和足底压力分布特征参数情况,并对这些运动学和动力学参数进行了相关分析.     

Race walking gait and its influence on race walking economy in world-class race walkers

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.     

Effect of walking speed on lower extremity joint loading in graded ramp walking

Lower extremity joint loading during walking is strongly affected by the steepness of the slope and might cause pain and injuries in lower extremity joint structures. One feasible measure to reduce joint loading is the reduction of walking speed. Positive effects have been shown for level walking, but not for graded walking or hiking conditions. The aim of the study was to quantify the effect of walking speed (separated into the two components, step length and cadence) on the joint power of the hip, knee and ankle and to determine the knee joint forces in uphill and downhill walking. Ten participants walked up and down a ramp with step lengths of 0.46, 0.575 and 0.69 m and cadences of 80, 100 and 120 steps per minute. The ramp was equipped with a force platform and the locomotion was filmed with a 60 Hz video camera. Loading of the lower extremity joints was determined using inverse dynamics. A two-dimensional knee model was used to calculate forces in the knee structures during the stance phase. Walking speed affected lower extremity joint loading substantially and significantly. Change of step length caused much greater loading changes for all joints compared with change of cadence; the effects were more distinct in downhill than in uphill walking. The results indicate that lower extremity joint loading can be effectively controlled by varying step length and cadence during graded uphill and downhill walking. Hikers can avoid or reduce pain and injuries by reducing walking speed, particularly in downhill walking.     

优秀男子竞走运动员个性特征的调查研究

运用Cattell－16PF量表对优秀男子竞走运动员的个性特征进行了测量与评价。通过分析及与大学生、优秀女子竞走运动员的比较,揭示优秀男子竞走运动员的个性特征,为竞走的选材和训练提供参考。     

Kinematic characteristics of elite men's and women's 20 km race walking and their variation during the race

The aim of this study was to analyse the important kinematic variables in elite men's and women's 20 km race walking. Thirty men and 30 women were analysed from video data recorded during the World Race Walking Cup. Video data were also recorded at four points during the European Cup Race Walking and 12 men and 12 women analysed from these data. Two camcorders operating at 50 Hz recorded at each race for 3D analysis. The two main performance determinants of speed were step length and cadence. Men were faster than women because of their greater step lengths but there was no difference in cadence. A reduction in step length was the initial cause of slowing down with later decreases in speed caused by reductions in cadence. Shorter contact times were important in optimising both step length and cadence, and faster athletes tended to have longer flight times than slower athletes. It was less clear which other kinematic variables were critical for successful walking, particularly with regard to joint angles. Different associations were found for some key variables in men and women, suggesting that their techniques may differ due to differences in height and mass.     

Kinematic characteristics of elite men's 50 km race walking

Abstract

Race walking is an endurance event which also requires great technical ability, particularly with respect to its two distinguishing rules. The 50 km race walk is the longest event in the athletics programme at the Olympic Games. The aims of this observational study were to identify the important kinematic variables in elite men's 50 km race walking, and to measure variation in those variables at different distances. Thirty men were analysed from video data recorded during a World Race Walking Cup competition. Video data were also recorded at four distances during the European Cup Race Walking and 12 men analysed from these data. Two camcorders (50 Hz) recorded at each race for 3D analysis. The results of this study showed that walking speed was associated with both step length (r=0.54,P=0.002) and cadence (r=0.58,P=0.001). While placing the foot further ahead of the body at heel strike was associated with greater step lengths (r=0.45,P=0.013), it was also negatively associated with cadence (r= ?0.62,P<0.001). In the World Cup, knee angles ranged between 175 and 186° at initial contact and between 180 and 195° at midstance. During the European Cup, walking speed decreased significantly (F=9.35,P=0.002), mostly due to a decrease in step length between 38.5 and 48.5 km (t=8.59,P=0.014). From this study, it would appear that the key areas a 50 km race walker must develop and coordinate are step length and cadence, although it is also important to ensure legal walking technique is maintained with the onset of fatigue.     

对我国部分现役竞走运动员技术分析

依据高速摄影及国际田联竞走规则,对第５届全国大学生运动会男子２０公里 竞走比赛的运动员进行技术分析,结论如下：１．摆动腿摆动时间长于支撑腿支撑时 间。２．摆动腿方向和线路应低平,增加髋绕人体垂直轴的扭转幅度。３．应控制摆动 腿的膝角的最小角度。４．为了减少摆动时间应提高髋和踝的水平速度,５．减少后蹬 角提高重心水平移动速度,提高单步效率。     

优秀竞走运动员技术训练结构与训练实施研究

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。     

对我国优秀竞走运动员高速走技术速度特征的分析

运用高速摄影等方法，对第4届城市运动会男子20km竞走运动员的高速走技术的速度特征进行分析研究。结果表明，我国优秀竞走运动员重心速度回升的方式明显不同，在高速走时，高质量的摆腿动作比蹬地的用力程度更为重要。建议运动员增加髋关节肌群的力量练习。     

优秀男子举重运动员专项成绩与下肢等速肌力相关回归分析

采用德国IsoMed 2000等速肌力测试仪，对17名健将（健将组）和18名一级（一级组）男子举重运动员进行双侧髋、膝和踝关节60°/s、120°/s、180°/s和240°/s向心、离心（每种角速度5次）测试。探讨优秀男子举重运动员下肢关节不同角速度等速肌力的特征，比较健将与一级组间差异，对健将组下肢关节相对峰力矩与相对专项成绩进行Pearson相关分析，并建立抓、挺举与峰力矩多元线性回归方程。结果显示，优秀男子举重运动员的髋关节相对伸爆发力与相对抓举呈高度显著正相关，髋关节中速（120°/s）、膝踝关节相对伸爆发力与相对抓举呈中度显著正相关，而踝关节相对屈绝对力呈中度显著负相关；髋关节相对伸爆发力与相对挺举呈高度显著正相关，左膝（挺举弓步腿）相对中速（120°/s）、爆发力和踝关节相对爆发力与相对挺举呈中度显著正相关。