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1.
The speed attained by a track cyclist is strongly influenced by aerodynamic drag, being the major retarding force in track events of more than 200 m. The aims of this study were to determine the effect of changes in shoulder and torso angles on the aerodynamic drag and power output of a track cyclist. The drag of three competitive track cyclists was measured in a wind tunnel at 40 kph. Changes in shoulder and torso angles were made using a custom adjustable handlebar setup. The power output was measured for each position using an SRM Power Meter. The power required by each athlete to maintain a specific speed in each position was calculated, which enabled the surplus power in each position to be determined. The results showed that torso angle influenced the drag area and shoulder angle influenced the power output, and that a low torso angle and middle shoulder angle optimised the surplus power. However, the lowest possible torso angle was not always the best position. Although differences between individual riders was seen, there was a strong correlation between torso angle and drag area.  相似文献   

2.
ABSTRACT

Sprint cycling performance depends upon the balance between muscle and drag forces. This study assessed the influence of upper body position on muscle forces and aerodynamics during seated sprint cycling. Thirteen competitive cyclists attended two sessions. The first session was used to determine handlebar positions to achieve pre-determined hip flexion angles (70–110° in 10° increments) using dynamic bicycle fitting. In the second session, full body kinematics and pedal forces were recorded throughout 2x6-s seated sprints at the pre-determined handlebar positions, and frontal plane images were used to determine the projected frontal area. Leg work, joint work, muscle forces and frontal area were compared at three upper body positions, being optimum (maximum leg work), optimal+10° and optimal-10° of hip flexion. Larger hip (p = 0.01–0.02) and reduced knee (p = 0.02–0.03) contribution to leg work were observed at the optimal+10° position without changes at the ankle joint (p = 0.39). No differences were observed in peak muscle forces across the three body positions (p = 0.06–0.48). Frontal area was reduced at optimum+10° of hip flexion when compared to optimum (p = 0.02) and optimum-10° (p < 0.01). These findings suggest that large changes in upper body position can influence aerodynamics and alter contributions from the knee and hip joints, without influencing peak muscle forces.  相似文献   

3.
The effect on drag of a Speedo Fast-skin suit compared to a conventional suit was studied in 13 subjects (6 males, 7 females) swimming at different velocities between 1.0 and 2.0 m.s-1. The active drag force was directly measured during front crawl swimming using a system of underwater push-off pads instrumented with a force transducer (MAD system). For a range of swimming speeds (1.1, 1.3, 1.5 and 1.7 m.s-1), drag values were estimated. On a group level, a statistically non-significant drag reduction effect of 2% was observed for the Fast-skin suit (p = 0.31). Therefore, the 7.5% reduction in drag claimed by the swimwear manufacturer was not corroborated.  相似文献   

4.
采用文献资料法、数理统计法,对2007年女足世界杯运动员平均身高、体重、年龄指标进行比较分析。结果表明：各洲运动员在平均身高、体重和年龄方面存在显著性差异;前六名球队在体重和年龄方面存在显著性差异;不同位置运动员的平均身高、体重存在着显著性的差异,平均年龄不存在差异;旨在为足球运动的选材和训练提供可借鉴的科学参考依据。  相似文献   

5.
The aims of this study were to measure the aerodynamic drag in professional cyclists, to obtain aerodynamic drag reference values in static and effort positions, to improve the cyclists' aerodynamic drag by modifying their position and cycle equipment, and to evaluate the advantages and disadvantages of these modifications. The study was performed in a wind tunnel with five professional cyclists. Four positions were assessed with a time-trial bike and one position with a standard racing bike. In all positions, aerodynamic drag and kinematic variables were recorded. The drag area for the time-trial bike was 31% higher in the effort than static position, and lower than for the standard racing bike. Changes in the cyclists' position decreased the aerodynamic drag by 14%. The aero-helmet was not favourable for all cyclists. The reliability of aerodynamic drag measures in the wind tunnel was high (r > 0.96, coefficient of variation < 2%). In conclusion, we measured and improved the aerodynamic drag in professional cyclists. Our results were better than those of other researchers who did not assess aerodynamic drag during effort at race pace and who employed different wheels. The efficiency of the aero-helmet, and the validity, reliability, and sensitivity of the wind tunnel and aerodynamic field testing were addressed.  相似文献   

6.
The purposes of this investigation were to determine if increasing the bending stiffness of sprint shoes increases sprinting performance and to determine whether simple anthropometric factors can be used to predict shoe bending stiffness for optimal performance. Thirty-four athletes were tested using four different shoe conditions--a standard condition consisting of their currently used footwear and three conditions where the bending stiffness was increased systematically. The sprinters performed maximal effort 40 m sprints and their sprint times were recorded from 20 to 40 m. On average, increasing the shoe bending stiffness increased sprint performance. The stiffness each athlete required for his or her maximal performance was subject specific but was not related to subject mass, height, shoe size or skill level. It is speculated that individual differences in the force-length and force-velocity relationships of the calf muscles may influence the appropriate shoe stiffness for each athlete to obtain their maximal performance.  相似文献   

7.
Swimming     
Abstract

The effect on drag of a Speedo Fast‐skin suit compared to a conventional suit was studied in 13 subjects (6 males, 7 females) swimming at different velocities between 1.0 and 2.0 m?s‐1. The active drag force was directly measured during front crawl swimming using a system of underwater push‐off pads instrumented with a force transducer (MAD system). For a range of swimming speeds (1.1, 1.3, 1.5 and 1.7 m?s‐1), drag values were estimated. On a group level, a statistically non‐significant drag reduction effect of 2% was observed for the Fast‐skin suit (p = 0.31). Therefore, the 7.5% reduction in drag claimed by the swimwear manufacturer was not corroborated.  相似文献   

8.
运用骨龄评定预测方法,对珠江三角洲2191 名青少儿运动员现身高和未来身高的预测进行了分析研究,论证了其身高、运动员特点及发育提早、未来身高预测趋势的整体评价女高于男等现状特征,为该地区今后青少儿运动员科学选材的研究提供依据  相似文献   

9.
This study analysed the acute mechanical and metabolic responses to a sprint training session focused on maintaining maximal speed until a given speed loss was reached. Nine male high-level sprinters performed 60 m running sprints up to a 3% in speed loss with 6 min rests between sets. Mechanical responses (countermovement jump (CMJ) height and speed loss) and metabolic responses (blood lactate and ammonia concentrations) were measured pre-exercise and after each set was performed. Jump height loss showed almost perfect relationships with both lactate (r = 0.91) and ammonia (r = 0.91) concentrations. In addition, nearly perfect relationships were observed for each athlete between CMJ height loss and lactate (r = 0.93–0.99) and ammonia (r = 0.94–0.99). Very large correlations were found between speed loss and lactate (r = 0.83), and ammonia (r = 0.86) concentrations. Furthermore, close relationships were observed for each athlete between speed loss and lactate (r = 0.86–0.99), and ammonia (r = 0.88–0.98). These results suggest that the CMJ test may allow more accurate setting of training loads in sprint training sessions, by using an individualised sprint dose based on mechanical and physiological responses rather than a standard fixed number of sprints for all athletes.  相似文献   

10.
Cross-country mountain bike suspension reportedly enhances comfort and performance through reduced vibration and impact exposure. This study analysed the effectiveness of three different front fork systems at damping accelerations during the crossing of three isolated obstacles (stairs, drop, and root). One participant completed three trials on six separate occasions in a randomised order using rigid, air-sprung, and carbon leaf-sprung forks. Performance was determined by time to cross obstacles, while triaxial accelerometers quantified impact exposure and damping response. Results identified significant main effect of fork type for performance time (p < 0.05). The air-sprung and leaf-sprung forks were significantly slower than the rigid forks for the stairs (p < 0.05), while air-sprung suspension was slower than the rigid for the root protocol (p < 0.05). There were no differences for the drop protocol (p < 0.05). Rigid forks reduced overall exposure (p < 0.05), specifically at the handlebars for the stairs and drop trials. More detailed analysis presented smaller vertical accelerations at the handlebar for air-sprung and leaf-sprung forks on the stairs (p < 0.05), and drop (p < 0.05) but not the root. As such, it appears that the suspension systems tested were ineffective at reducing overall impact exposure at the handlebar during isolated aspects of cross-country terrain features which may be influenced to a larger extent by rider technique.  相似文献   

11.
目的:应用仿生摩擦学原理制备皮肤减阻材料,并分析其减阻性能。方法:制备水减阻材料、油减阻材料、仿鲨鱼黏液减阻材料,进行包裹物漂浮测试和运动员泳池测试,分析减阻材料性能。结果:漂浮实验表明,与对照组相比,涂覆水减阻材料、油减阻材料和仿鲨鱼黏液减阻材料均有明显减阻效果(P<0.01),仿鲨鱼黏液材料减阻效果最佳。结论:利用仿生摩擦学原理,应用聚乙烯吡咯烷酮(PVP)、聚乙烯醇(PVA)和聚丙烯酰胺(PAM)等超高分子量聚合物制备的仿鲨鱼黏液减阻材料有明显减阻效果。  相似文献   

12.
Reviews of the sport psychology literature have identified a number of models of athlete development in sport (Alfermann & Stambulova, 2007; Durand-Bush & Salmela, 2001). However, minimal research has investigated the origins of knowledge from which each model was developed. The purpose of this study was to systematically examine the influential texts responsible for providing the basis of athlete development models in sport. A citation path analysis of the sport psychology literature was used to generate a knowledge development path of seven athlete development models in sport. The analysis identified influential texts and authors in the conceptualization of athlete development. The population of 229 texts (articles, books, book chapters) was selected in two phases. Phase 1 texts were articles citing seven articles depicting models of athlete development (n=75). Phase 2 included texts cited three or more times by Phase 1 articles (n=154). The analysis revealed how the scholarship of Benjamin Bloom (1985) has been integrated into the field of sport psychology, and how two articles appearing in 1993 and 2003 helped shape present conceptualizations of athlete development.  相似文献   

13.
On a kayak ergometer, an accurate simulation of the athlete-paddle-kayak system kinematics is essential for analysing the relationship between technique and performance. The purpose of this study was to establish a strong relationship between performances on flatwater and performances on an ergometer by means of propulsive force measurement and drag models. Two trials were performed by 12 kayakers in which they were first timed over 250 m of flatwater kayaking (the reference test) and were then asked to perform a trial of the same duration on the ergometer with the same perceived physical exertion. Three techniques for measuring propulsive force and three drag models generated nine combinations, which were all evaluated for their ability to estimate kayak velocity. For each combination, the distance covered by the athlete on the ergometer was simulated. A kayakers’ ergometer ranking was based on the average velocity in the ergometer trial. Both distance and ranking were compared to the on-water results. The simulation with the best combination of force measurement and drag model gave an accurate estimate of distance (253 ± 10.5 vs. 250 m) and ranking compared to the reference test.  相似文献   

14.
The aim of this study was to determine if critical parameters for elite performance could be identified among a population of female shot putters. The performance of seven of the top women shot putters competing at the 2002 USA National Championships was examined. Video data were captured using two Panasonic 60 Hz cameras and the best throws of each athlete were digitized and analyzed using a Peak Motus three-dimensional motion analysis system. Thirty variables were examined for their effect on the distance of the throw. Correlation analysis indicated that measured distance was positively correlated with release speed (r = 0.97, p < 0.0003) and shoulder-hip separation (r = 0.72, p < 0.06) and negatively correlated with release angle (r = -0.74, p < 0.056), rear knee angle at rear foot touchdown (r = -0.93, p < 0.003) and rear knee angle at release (r = -0.76, p < 0.047). Greater knee flexion angle at both rear foot touch down and release along with a neutral shoulder-hip angle at release were identified as the most critical parameters for success among this sample of elite women shot putters. The unique observation about the knee positions at specific events should assist in new training and coaching developments.  相似文献   

15.
Weassessed the net forces created when towing swimmers while gliding and kicking underwater to establish an appropriate speed for initiating underwater kicking, and the most effective gliding position and kicking technique to be applied after a turn. Sixteen experienced male swimmers of similar body shape were towed by a motorized winch and pulley system. A load cell measured net force (propulsive force - drag force) at speeds of 1.6, 1.9, 2.2, 2.5 and 3.1 m· s-1 . At each speed, the swimmers performed a prone streamline glide, a lateral streamline glide, a prone freestyle kick, a prone dolphin kick and a lateral dolphin kick. A two-way repeated-measures analysis of variance revealed significant differences between the gliding and kicking conditions at different speeds. The results demonstrated an optimal range of speeds (1.9 to 2.2 m· s-1 ) at which to begin underwater kicking to prevent energy loss from excessive active drag. No significant differences were found between the prone and lateral streamline glide positions or between the three underwater kicking techniques. Therefore, there appears to be no significant advantage in using one streamlining technique over another or in using one kicking style over another.  相似文献   

16.
In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles.  相似文献   

17.
Aerodynamic drag in cycling: methods of assessment   总被引：1，自引：0，他引：1  
When cycling on level ground at a speed greater than 14 m/s, aerodynamic drag is the most important resistive force. About 90% of the total mechanical power output is necessary to overcome it. Aerodynamic drag is mainly affected by the effective frontal area which is the product of the projected frontal area and the coefficient of drag. The effective frontal area represents the position of the cyclist on the bicycle and the aerodynamics of the cyclist-bicycle system in this position. In order to optimise performance, estimation of these parameters is necessary. The aim of this study is to describe and comment on the methods used during the last 30 years for the evaluation of the effective frontal area and the projected frontal area in cycling, in both laboratory and actual conditions. Most of the field methods are not expensive and can be realised with few materials, providing valid results in comparison with the reference method in aerodynamics, the wind tunnel. Finally, knowledge of these parameters can be useful in practice or to create theoretical models of cycling performance.  相似文献   

18.
Aerodynamic efficiency is one of the important criteria for racing bicycle helmets, especially in time trial event. The physical characteristics of a bicycle helmet especially its venting geometry, position and number of vents play a crucial role in the aerodynamic efficiency of the helmet. Despite the importance of this, little information on aerodynamic behaviour of racing bicycle helmets is available. In this study, a series of commercially available time trial helmets were investigated in a wind tunnel environment over a range of wind speeds, and yaw and pitch angles to understand their aerodynamic behaviour. In order to obtain as realistic a data as possible, an instrumented mannequin was used in the wind tunnel testing. The experimental findings indicate that the aerodynamic performance of current production time trial helmets varies significantly. The results also show that helmet length as well as vent geometry and vent area have significant effects on aerodynamic drag of a time trial helmet. A time trial helmet having longer length and smooth vents with minimum vent area can reduce aerodynamic drag significantly.  相似文献   

19.
Abstract

In elite sport, to remain competitive at the international level, it is critical to understand the game demands on players to ensure sport specific training programmes are designed for optimal athlete preparation and conditioning. In netball, recent research examining the activity patterns of players at the elite level is lacking, with only one study undertaken on this level of competition in the past 30 years. Therefore, the aim of this study was to provide coaches with up to date knowledge of player activity patterns as a basis for the design of optimal sport specific training programmes. The Australian female netball team were analysed using video footage of three international test matches. Player activity was categorised into five movement and eight game-based activities; and further classified as work or rest. Results suggest that differences in the current game exist when compared to the previous analysis. Positional differences were also found with regard to player activity confirming the need for an individualised component of training based on player position.  相似文献   

20.
采用开放式访谈法对损伤运动员康复过程中的三个阶段进行了访谈研究.运动员将在损伤后的第一周,损伤后的15～20天及损伤后的30天接受访谈.这三次开放性的访谈是让运动员在没有任何前提约束的情况下自由地谈论他们的经历.被试是美国东南部大学的NCAA一级运动员（5名）.对访谈结果的分析揭示了四个主题：视点情绪反应,损伤应对及人际关系和几个次级主题.结论：第一,运动损伤在很大程度上影响了运动员的生活;第二,运动损伤对于本研究中的每名运动员都是一次独特的经历;最后,通过多重现象访谈法给运动员提供了公开谈论他们损伤康复经验的机会.  相似文献   

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