首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 656 毫秒
1.
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.  相似文献   

2.
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.  相似文献   

3.
以国际田联规定的竞走定义为依据, 采用高速摄影及影片解析的方法对高红苗在1994 年全国竞走锦标赛和1995 年世界杯竞走赛的竞走技术进行诊断。技术诊断结果如下: (1) 高在10km 赛程中能够保持稳定的步长, 且步长与步频合理; (2) 高的单步技术中腾空时间处于模糊腾空时限。躯干前俯角较大, 身体重心上下起伏较大, 存在被判罚腾空技术犯规的可能性; (3) 高的单步技术中前脚着时脚掌与地面的仰角合理, 支撑腿至垂直部位的膝角正确。  相似文献   

4.
以国际田联规定的竞走定义为依据,采用现场技术动作录像及技术动作高速摄影的方法,对俄罗斯的尼科拉耶娃在1995年世界杯竞走赛的比赛技术进行诊断。技术诊断结果如下:(1)在10km赛程中能够保持稳定的步长,且步长与步频合理;(2)单步技术中腾空时间处于不可见腾空时限,且躯干角合理,身体重心上下起伏较小;(3)单步技术中前脚着地时脚掌与地面的仰角合理,支撑腿至垂直部位的膝角正确。  相似文献   

5.
国际田联的“竞走定义”规范了竞走比赛的技术动作标准。如果运动员违反“竞走定义”受到3名不同裁判员的严重警告，将被取消比赛资格，因此“竞走定义”成为竞走的关键技术。在第27届奥运会上王丽萍荣获女子20公里竞走项目金牌，但仍受到2名裁判员的严重警告。世界杯赛和世界锦标赛的双赛冠军刘洪宇，在第27届奥运会女子20公里比赛中于16公里处，因受到3名不同裁判员的严重警告，被取消比赛资格，失去争夺金牌的机会。因此，对王丽萍、刘宏宇竞走关键技术的解析是必要的，对符合“竞走定义”的技术给予巩固，对违反“竞走定义”的技术给予改进。  相似文献   

6.
采用摄像及录像解析等研究方法,对2002年"海尔斯"杯全国竞走锦标赛暨亚运会选拔赛少年女子5000米场地赛前3名运动员(年龄在17岁以下)的技术进行分析,分别拍摄每个运动员在比赛进行到1150米处、2750米处、4350米处的技术图片资料,并进行解析,以取得每个运动员一个复步的各个阶段和各个技术环节的定量数据。研究结果表明:有2名运动员的腾空时间超过了合理的腾空时限;单步身体重心垂直位移和头顶垂直位移均较大;躯干前倾后仰幅度较大;膝关节技术动作符合竞走定义的要求;运动员的足掌触地角较小。  相似文献   

7.
The aim of this study was to analyse gait variability and symmetry in race walkers. Eighteen senior and 17 junior athletes race walked on an instrumented treadmill (for 10 km and 5 km, respectively) at speeds equivalent to 103% of season’s best time for 20 km and 10 km, respectively. Spatio-temporal and ground reaction force (GRF) data were recorded at 2.5 km, and at 4.5, 6.5 and 8.5 km for a subsection of athletes. Gait variability was measured using median absolute deviation (MAD) whereas inter-leg symmetry was measured using the symmetry angle. Both groups showed low variability for step length (<0.9%), step frequency (<1.1%), contact time (≤1.2%) and vertical peak force values (<5%), and neither variability nor symmetry changed with distance walked. Junior athletes were more variable for both step length (P = 0.004) and loading force (P = 0.003); no differences for gait symmetry were found. Whereas there was little mean asymmetry overall, individual analyses identified asymmetry in several athletes (symmetry angle ≥ 1.2%). Importantly, asymmetrical step lengths were found in 12 athletes and could result from underlying imbalances. Coaches are advised to observe athletes on an individual basis to monitor for both variability and asymmetry.  相似文献   

8.
Abstract

The aims of this study were to examine ground contact characteristics, their relationship with race performance, and the time course of any changes in ground contact time during competitive 800 m and 1500 m races. Twenty-two seeded, single-sex middle-distance races totalling 181 runners were filmed at a competitive athletics meeting. Races were filmed at 100 Hz. Ground contact time was recorded one step for each athlete, on each lap of their race. Forefoot and midfoot strikers had significantly shorter ground contact times than heel strikers. Forefoot and midfoot strikers had significantly faster average race speed than heel strikers. There were strong large correlations between ground contact time and average race speed for the women's events and men’s 1500 m (r = ?0.521 to ?0.623; P < 0.05), whereas the men's 800 m displayed only a moderate relationship (r = ?0.361; P = 0.002). For each event, ground contact time for the first lap was significantly shorter than for the last lap, which might reflect runners becoming fatigued.  相似文献   

9.
ABSTRACT

The aims of this study were to estimate the walking cadence required to elicit a VO2reserve (VO2R) of 40% and determine if fitness status moderates the relationship between walking cadence and %VO2R. Twenty participants (10 male, mean(s) age 32(10) years; VO2max 45(10) mL·kg?1·min?1) completed resting and maximal oxygen consumption tests prior to 7 x 5-min bouts of treadmill walking at increasing speed while wearing an Apple Watch and measuring oxygen consumption continuously. The 7 x 5-min exercise bouts were performed at speeds between 3 and 6 km·h?1 with 5-min seated rest following each bout. Walking cadence measured at each treadmill speed was recorded using the Apple Watch “Activity” app. Using Bayesian regression, we predict that participants need a walking cadence of 138 to 140 steps·min?1 to achieve a VO2R of 40%. However, these values are moderated by fitness status such that those with lower fitness can achieve 40% VO2R at a slower walking cadence. The results suggest that those with moderate fitness need to walk at ~40% higher than the currently recommended walking cadence (100 steps·min?1) to elicit moderate-intensity physical activity. However, walking cadence required to achieve moderate-intensity physical activity is moderated by fitness status.  相似文献   

10.
全国竞走锦标赛成年女子20km竞走全程速度节奏研究   总被引：1，自引：0，他引：1  
速度节奏是影响体能类竞速项目运动成绩的重要因素。通过文献资料法、数理统计法和访问调查等研究方法对2010年全国竞走锦标赛成年女子20km竞走全程速度节奏的研究结果表明:①此次比赛前六名选手呈现出的速度节奏是加速—调整—再加速—降速—冲刺;②年轻选手的战术选择存在较大问题,缺乏对个体竞技能力和竞赛环境的正确认识和把握;③与2007年相比,目前我国成年女子20km竞走项目处于全面落后状态,集团竞争力差,次最大速度下的耐力水平急待于提高。  相似文献   

11.
我国优秀女子竞走运动员关键技术的生物力学研究   总被引：4，自引：0，他引：4  
用１６ｍｍ高速摄影机进行比赛现场单步技术动作拍摄，拍摄频率为１２２幅／ｓ。采用国家体委体育科研所运动生物力学研究室影片解析系统，对国家竞走集训队运动员王妍、谷燕的竞走技术进行解析。研究结果，王妍、谷燕竞走技术符合国际田联新竞走定义。  相似文献   

12.
当今世界竞走技术的10个特征   总被引：12，自引：1，他引：11  
运用运动生物力学和体育统计学的方法、对1995年国际田联/锐步世界杯竞走赛女子10km、男子20km和男子50km3个项目前8名运动员的技术进行了定量和定性分析研究,归纳出符合竞走规则新定义的当今世界竞走技术的10个特征。  相似文献   

13.
Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p < .001), resulting in a flattened profile. Athletes with narrower stride widths experienced reduced peak braking forces (r = .49, p = .046), peak propulsive forces (r = .54, p = .027), peak medial forces (r = .63, p = .007) and peak vertical push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency.  相似文献   

14.
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.  相似文献   

15.
Abstract

The aim of this study was to assess the extent to which measures derived from the new FIFA referees’ fitness tests can be used to monitor a referee's match-related physical capacity. Match-analysis data were collected (Prozone®, Leeds, UK) from 17 soccer referees for 5.0 (s = 1.7) FA Premier League matches per referee during the first 4 months of the 2007–08 season. Physical match performance categories included total distance covered, high-intensity running distance (speed >5.5 m · s?1), and sprinting distance (>7.0 m · s?1). The two tests were a 6 × 40-m sprint test and a 150-m interval test. Heart rate demand was correlated with total match distance covered (r = ?0.70, P = 0.002) and high-intensity running (r = ?0.57, P = 0.018) in the interval test. The fastest 40-m sprint was related to total distance covered (r = ?0.69, P = 0.002), high-intensity running (r = ?0.76, P < 0.001), and sprinting distance (r = ?0.75, P = 0.001), while mean time for the 40-m sprints was related to total distance covered (r = ?0.70, P = 0.002), high-intensity running (r = ?0.77, P < 0.001), and sprinting distance (r = ?0.77, P < 0.001). The referees who recorded the best interval-test heart rate demand and fastest 40-m time produced the best physical match performances. However, only the sprint test and in particular the fastest 40-m time had appropriate construct validity for the physical assessment of soccer referees.  相似文献   

16.
Irisin is a myokine that is thought to be secreted in response to exercise that may help to prevent obesity and maintain normal glucose metabolism. In this study we investigated the associations between irisin and glucose homeostasis in middle-aged, overweight and obese men (n?= 144) with impaired glucose regulation, and the impact of exercise training on these relationships. The participants underwent 12 weeks of resistance or aerobic (Nordic walking) exercise training three times per week, 60 minutes per session. Venous blood (n?=?105) and skeletal muscle samples (n?=?45) were obtained at baseline and post-intervention. Compared to controls, Nordic walking, but not resistance training, increased irisin levels in plasma (9.6?±?4.2%, P?=?0.014; 8.7?± 4.9%, P?=?0.087; respectively) compared to controls. When considering all subjects, baseline irisin correlated positively with atherogenic index of plasma (r?=?0.244, P?=?0.013) and 2-hour insulin levels (r?=?0.214, P?=?0.028), and negatively with age (r?=??0.262, P?=?0.007), adiponectin (r?=??0.240, P?=?0.014) and McAuley index (r?=??0.259, P?=?0.008). Training-induced FNDC5 mRNA changes were negatively correlated with HbA1c (r?=??0.527, P?=?0.030) in the resistance training group and with chemerin in the Nordic walking group (r?=??0.615, P?=?0.033). In conclusion, 12-weeks of Nordic walking was more effective than resistance training in elevating plasma irisin, in middle-aged men with impaired glucose tolerance. Thus, the change in irisin in response to exercise training varied by the type of exercise but showed limited association with improvements in glucose homeostasis.  相似文献   

17.
The relationship between muscle co-activation and energy cost of transport and risk of injury (initial loading rate and joint stiffness) has not been jointly studied. Fourteen elite Kenyan male runners were tested at two speeds (12 and 20 km · h?1), where oxygen consumption, kinematic, kinetic and electromyography were recorded. Electromyography of seven lower limb muscles was recorded. Pre-activation and ground contact of agonist:antagonist co-activation was determined. All muscles displayed higher activity during pre-activation except rectus femoris (RF). Conversely, no differences were found during ground contact except for higher biceps femoris (BF) at 20 km · h?1. Knee stiffness was correlated to RF–BF co-activation during both pre-activation and ground contact at both running speeds. However, energy cost of transport was only positively correlated to the above-mentioned muscle pairs at 20 km · h?1 (r = 0620, P = 0.032; r = 0.682, P = 0.015, respectively). These findings emphasise the influence of neuromuscular control and performance and its support to musculoskeletal system to optimise function and modulate risk of injury. Further, neuromuscular activity during terminal swing is also important and necessary to execute and maintain performance.  相似文献   

18.
Abstract

The purpose of the present study was to determine if field-based variables associated with cardiovascular and neuromuscular stress could be used to accurately monitor and predict middle-distance running. Eleven middle-distance runners (age 21.3±1.6 years) completed three trials of steady-state running at 11, 13, and 15 km · h–1, and test performance was compared with competitive performance (personal best times converted to standardized Mericer scores). Oxygen uptake, heart rate (HR), and stride characteristics (ground contact time [Ct], flight time, step length, and step frequency) were monitored during treadmill running with the ratio of HR:1/Ct calculated. Heart rate and stride characteristics were significantly altered (all P<0.05) with increased running speed, while the HR:1/Ct index was unchanged. Stride characteristics, heart rate, and the HR:1/Ct index were reliable measures with no mean bias and low levels of random variation. The HR:1/Ct index was strongly related to competitive performance (r=–0.80 to 0.88, P<0.01). This was primarily attributed to the association between heart rate and Mercier scores (r=–0.81 to 0.87, P<0.01), whereas ground contact time was only moderately related to competitive performance at the fastest running speed (r=–0.60, P<0.05). Simple measures associated with cardiovascular and neuromuscular stress can be reliably monitored in middle-distance runners. A HR:1/Ct index provides a stable measure at any given submaximal running speed and may provide a useful tool for monitoring and predicting middle-distance running.  相似文献   

19.
Abstract

The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg · kg?1 body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time × condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg · kg?1 body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.  相似文献   

20.
ABSTRACT

Non-propulsive work demand has been linked to reduced energetic economy of cross-country mountain biking. The purpose of this study was to determine mechanical, physiological and performance differences and observe economy while riding a downhill section of a cross-country course prior to and following the metabolic “load” of a climb at race pace under two conditions (hardtail and full suspension) expected to alter vibration damping mechanics. Participants completed 1 lap of the track incorporating the same downhill section twice, under two conditions (hardtail and full suspension). Performance was determined by time to complete overall lap and specific terrain sections. Power, cadence, heart rate and oxygen consumption were sampled and logged every second while triaxial accelerometers recorded accelerations (128 Hz) to quantify vibration. No differences between performance times (P = 0.65) or power outputs (P = 0.61) were observed while physiological demand of loaded downhill riding was significantly greater (P < 0.0001) than unloaded. Full suspension decreased total vibrations experienced (P < 0.01) but had no effect on performance (P = 0.97) or physiological (P > 0.05) measures. This study showed minimal advantage of a full suspension bike in our trial, with further investigations over a full race distance warranted.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号