The effects of wind and altitude in the 400-m sprint

In this paper I use a mathematical model to simulate the effect of wind and altitude on men's and women's 4400-m race performances. Both wind speed and direction were altered to calculate the effect on the velocity profile and the final time of the sprinter. The simulation shows that for a constant wind velocity, changing the wind direction can produce a large variation in the race time and velocity profile. A wind of velocity 2 m x s(-1) is generally a disadvantage to the 400-m runner but this is not so for all wind directions. Constant winds blowing from some directions can provide favourable conditions for the one-lap runner. Differences between the running lanes can be reduced or exaggerated depending on the wind direction. For example, a wind blowing behind the runner in the back straight increases the advantage of lane 8 over lane 1. Wind conditions can change the velocity profile and in some circumstances produce a maximum velocity much later than is evident in windless conditions. Lower air density at altitude produces a time advantage of around 0.06 s for men (0.07 s for women) for each 500-m increase in elevation.     

The Effects of Muscular Fatigue on the Kinetics of Sprint Running

Abstract

In order to compare the kinematic and kinetic effects of fatigue on the mechanics of sprint running, 15 male subjects were filmed in the saggital plane while performing a short (50 meter) maximal exertion sprint and a long (400 meter) fatiguing sprint. The short sprint was filmed at 40 meters, while the long sprint was filmed at 40 and 380 meters. The films were reduced utilizing a digitizer coupled to a computer terminal. Analysis results were generated via a human motion analysis program. Kinematic and kinetic results were entered into the statistical analysis as differences between non-fatigued and fatigued values. Initially, quality of the performance (measured by the change in horizontal velocity of the body center of gravity) was statistically related to change in the kinetic variable of integrated muscle moment at each of the body joints. The kinetic variables found to be significant were then statistically compared to logically related changes in kinematic variables (temporally adjacent or concurrent). Changes in the generated moments about the hip and knee during ground contact were found to be related to the quality of the performer. Kinematic changes related to the significant moment changes indicated that, while the better sprinter (smaller velocity loss) closely maintained the kinetic and kinematic patterns, the poorer sprinter (larger velocity loss) inefficiently deviated in both areas. The lack of significance between the changes in upper limb moments and change in average velocity indicated that productive arm effort does not affect the level of performance in the fatigued condition.     

The effect of track geometry on 200- and 400-m sprint running performance

This study looked at how the geometry of the running track affects performances in the 200- and 400 m sprint running events. Although an athletics track must be designed with two parallel straights and two curved bends, the lengths of the straights and bends are not fixed and may vary within an approved set of limits. The bend can be semi-circular or a double-curve consisting of arcs of two different radii. A mathematical model was used to calculate the effect of track geometry on race times for six different track designs; three with semi-circular bends (encompassing the extremes of the permitted designs), and the three permitted double-curve designs. The calculations revealed substantial differences among the track designs. The time difference (in the inside lane) between the fastest and slowest tracks is about 0.1 s in the 200-m race and 0.2 s in the 400-m race. The time differential between the outside and inside lanes for a double-curve track can be up to 0.08 s greater than for a standard track with semi-circular bends.     

Changes in force production, blood lactate and EMG activity in the 400-m sprint.

The neural activation (iEMG) and selected stride characteristics of six male sprinters were studied for 100-, 200-, 300- and 400-m experimental sprints, which were run according to the velocity in the 400 m. Blood lactate (BLa) was analysed and drop jumps were performed with EMG registration at rest and after each sprint. Running velocity (P less than 0.001) and stride length (P less than 0.05) decreased and contact time increased (P less than 0.01) during the 400-m sprint. The increase in contact time was greatest immediately after runs of 100 and 300 m. The peak BLa increased and the rate of BLa accumulation decreased with running distance (P less than 0.001). The height of rise of the centre of mass in the drop jumps was smaller immediately after the 300 m (P less than 0.05) and the 400 m (P less than 0.01) than at rest, and it correlated negatively with peak BLa (r = -0.77, P less than 0.001). The EMG and EMG:running velocity ratio increased with running distance. It was concluded that force generation of the leg muscles had already begun to decrease during the first quarter of the 400-m sprint. The deteriorating force production was compensated for until about 200-300 m. Thereafter, it was impossible to compensate for fatigue and the speed of running dropped. According to this study, fatigue in the 400-m sprint among trained athletes is mainly due to processes within skeletal muscle rather than the central nervous system.     

The effect of resisted sprint training on maximum sprint kinetics and kinematics in youth

Abstract

Resisted sled towing is a popular and efficient training method to improve sprint performance in adults, however, has not been utilised in youth populations. The purpose therefore was to investigate the effect of resisted sled towing training on the kinematics and kinetics of maximal sprint velocity in youth of different maturation status. Pre- and post-intervention 30 metre sprint performance of 32 children, 18 pre-peak height velocity (PHV) and 14 mid-/post-PHV, were tested on a non-motorised treadmill. The 6-week intervention consisted of ～12 sessions for pre-PHV and 14 for mid-/post-PHV of resisted sled towing training with each sessions comprised of 8–10 sprints covering 15–30 metres with a load of 2.5, 5, 7.5 or 10% body mass. Pre-PHV participants did not improve sprint performance, while the mid-/post-PHV participants had significant (P < 0.05) reductions (percent change, effect size) in sprint time (?5.76, ?0.74), relative leg stiffness (?45.0, ?2.16) and relative vertical stiffness (?17.4, ?0.76) and a significant increase in average velocity (5.99, 0.76), average step rate (5.65, 0.53), average power (6.36, 0.31), peak horizontal force (9.70, 0.72), average relative vertical forces (3.45, 1.70) and vertical displacement (14.6, 1.46). It seems that sled towing may be a more suitable training method in mid-/post-PHV athletes to improve 30 metre sprint performance.     

Lactate and Phosphagen Levels in Muscle Immediately after a Maximum 300 m Run at Sea Level

Abstract

The relative effectiveness of six intensive training programs on the development of four selected skills was studied, with emphasis on limited time encountered within the semester organizational plan. One hundred and twenty college freshmen men volunteers were randomly assigned to training groups of 30 members each, which met for two sessions a week for 16 weeks.

Results indicated that: (a) direct practice jumping, alone or combined with repetitive sprinting or weight training, was significantly superior to weight training alone on standing broad jump development; (b) direct practice of a zigzag run was superior to both weight training and repetitive sprinting; and (c) when group acquisition of “adequate” skill is the objective, performance improvements educed over the first nine weeks were great enough to question the merits of persisting at an activity over a full semester. Only the zigzag run was adversely affected by the spring vacation cessation of training.     

高原训练对运动能力影响的机制

随着竞技体育的不断发展和运动技术水平的提高，高原训练作为一种辅助手段引起国内外体育界的重视。高原训练的实践经验和基础理论的研究得到了重视和完善，形成了较为丰富的理论和实践体系。就高原训练对生理、生化机能的影响等方面的研究进行综述。     

"放松跑"在短跑中的运用及训练

对“放松跑”原理在短跑中的运用奈件进行了分析，从理论上探讨了“放松跑”对短跑运动能力的影响，并提出了具体的训练方法，可采用减阻训练法、节奏训练法、波浪跑训练法、放松大步跑训练法等。     

Arm coordination and performance level in the 400-m front crawl

The purpose of this study was to determine whether the Index of Coordination (IdC) and the propulsive phase durations can differentiate performance level during a maximal 400-m front crawl swim trial. Sixteen male swimmers constituted two groups based on performance level (G1: experts; G2: recreational). All participants swam the 400-m front crawl at maximal speed. Video analysis determined the stroke (swimming speed, stroke length, stroke rate) and coordination (IdC) parameters for every 50 m. Both stroke and coordination parameters discriminated performance level. The expert group had significantly higher values for speed and stroke length and lower values for the relative propulsive phase duration and IdC (p < .05). However there was no significant change in coordination parameters for either group throughout the trial. This suggests that, when associated with greater stroke length, catch-up coordination can be an efficient coordination mode that reflects optimal drag/propulsion adaptation. This finding provides new insight into swimmers' adaptations in a middle-distance event.     

A critical review of the current evidence examining whether resistance training improves time trial performance

A number of reviews have concluded that resistance training is beneficial for improving sports performance despite the inclusion of studies which do not actually measure a performance outcome (i.e. a timed trial). The purpose of this review was to examine only those studies which would allow us to infer the benefits of resistance training on improving time trial performance. Of the nine studies meeting all inclusion criteria only three demonstrated an additive effect of adding resistance training to the current activity-specific training being performed. These three studies demonstrated improvements in either 5 or 10 km time trial among recreationally skilled athletes (i.e. non-elite level time). Previous reviews have included studies which did not include: (1) performance outcomes; (2) control groups; and/or (3) equal volumes of activity-specific exercise among the resistance training and control groups. Presently, there is little evidence that adding resistance exercise to a sport-specific training program will augment time trial performance. While it is difficult to perform such long-term studies assessing the effects of resistance training among time trial athletes, the statement that resistance training is efficacious for improving time trial performance should be tempered until sufficient evidence is presented to support such claims.     

短跑途中跑动力来源论的对比研究

就短跑途中跑动力来源的各种观点加以对比分析，认为后蹬不是短跑途中跑的唯一动力来源，对途中跑中动力的各种来源不能片面讨论，应辨证地来看待与分析。     

The influence of pacing strategy on marathon world records

The aim of this study was to analyse the influence of the pacing strategy adopted by elite marathon runners when setting every marathon world record in the last 50 years. We divided former marathon record holders into two groups: classic athletes (record holders between 1967 and 1988) and contemporaneous athletes (record holders between 1988 and 2018). The total distance of the marathon was divided into 8 sections of 5?km and 1 last section of 2.195?km, and the relative average speed of each section was calculated individually. On average athletes were slightly faster in the first half-marathon than in the second one, where they slowed down progressively (ES?=?0.28, small effect). However, when comparing classic vs. contemporaneous athletes, we observed that classic athletes started significantly faster (p?相似文献   

攻击行为与现代短跑战术

用耦合振荡子与生物同步的理论，可以证明：无论是史前的动物在捕食的追击中，或是现代的运动员在争取优胜的跑步中，都可以从步伐频率的同步耦合中节约自己的体能，提高运动时奔跑的效率。     

世居高原中长跑运动员营养状况调查

对21名云南省世居高原的中长跑男运动员进行了5天的营养调查工作。结果显示动物性食品和油脂类摄入量偏高;热源质分配比不适宜,蛋白质和脂肪含量偏高,碳水化合物偏低;部分维生素和无机盐摄入不足。体格检查显示有55%的运动员BMI<20。生化检查显示有36.4%的运动员体内维生素B1营养水平不足或缺乏。     

Endurance and sprint benefits of high-intensity and supramaximal interval training

Abstract

This study examined the effect of two different interval training programs–high-intensity interval training (HIT) and supramaximal interval training (SMIT)–on measures of sprint and endurance performance. Physically active individuals (Females: n=32; age 19.3, s=2.2 years; mass 67.6, s=9.1 kg; stature 172.7, s=6.6 cm. Males: n=23; age 20.0, s=2.7 years; mass 71.3, s=8.3 kg; stature 176.6, s=5.8 cm) completed pre-testing that comprised (1) 3000 m time-trial, (2) 40 m sprint, and (3) repeated sprint ability (RSA–6×40 m sprints, 24 s active recovery) performance. Participants were then matched for average 3000 m running velocity (AV) and randomly assigned to one of three groups: (i) HIT, n=19, 4 min at 100% AV, 4 min passive recovery, 4–6 bouts per session; (ii) SMIT, n=20, 30 s at 130% AV, 150 s passive recovery, 7–12 bouts per session; and (iii) control group, n=16, 30 min continuous running at 75% AV. Groups trained three times per week for six weeks. When time to complete each test were compared among groups: (i) improvements in 3000 m time trial performance were greater following SMIT than continuous running, and (ii) improvements in 40 m sprint and RSA performance were greater following SMIT than HIT and continuous running. In addition, a gender effect was observed for the 3000 m time trial only, where females changed more following the training intervention than males. In summary, for concurrent improvements in endurance, sprint and repeated sprint performance, SMIT provides the greatest benefits for physically active individuals.     

男子铁人三项运动员高原训练期跑步训练的科研监控

铁人三项虽然包括游泳、骑车和长跑三个项目,但是跑步对总成绩的影响最大,我国男子铁人三项运动员在游泳和骑车赛段中并不逊色于国外的优秀运动员,但是跑步赛段中的差距却很明显。在本次高原训练中迫切需要建立科研与训练相结合的模式,发掘优秀队员的潜能,提高单项成绩,创造我国男子铁人三项最好成绩。     

现代体育教学模式在体育课中的运用

根据现代体育教学的模式的教学特点,体育教师在体育课的教学中应怎样来运用先进的教学模式。现代体育教 学的模式对体育教学有何作用。面对学校体育形势发展的需要和所存在的问题,还应处理好那些关系。及时找出它们的 共性以及特点,分析其优势与不足,对体育课教学的进一步深化改革有那些重要意义。     

对我国女子铁人三项运动员高原训练负荷的实证研究

方法:运用文献资料法、数理统计法、实验法等,以我国女子铁人三项运动员为研究对象,对高原训练期间的训练负荷进行研究。结果:训练负荷量与训练周期成反比,铁人三项中各单项训练量从大到小的顺序依次为自行车、跑步和游泳;在训练强度上,是有氧训练为主,混氧训练为辅;高原训练的效果与训练负荷、训练周期相关,但是与训练周期不完全相关。结论:1)适当缩短高原训练周期,提高有效负荷训练;2)根据运动员的具体情况,合理安排铁人三项中各单项的训练负荷;3)在训练负荷量较小的前提下,加大重点课次的训练负荷强度,加深对机体的刺激深度,从而提高训练效果。     

我国男子500米速度滑冰优秀运动员KLAP刀起跑技术的运动学研究

运用标准的三维摄像DLT法测量和录像解析的方法,以参加全国第十届冬季运动会速度滑冰比赛前6名的 男运动员为研究对象,对其500米比赛起跑阶段下肢蹬冰技术进行运动学研究。旨在揭示运动员在起跑阶段下肢蹬 冰过程中蕴含的运动学规律,为丰富速度滑冰技术理论,为教学、训练和科研提供参考依据。     

浅谈我国优秀女子400米跨栏跑运动员栏间跑节奏的时空特征

运用影片拍摄及解析的方法，对10名中国优秀女子400m跨栏跑运动员栏间跑节奏的时空特征进行分析，并与前苏联400m跨栏跑运动员斯捷潘诺娃的栏间跑节奏进行对比。研究表明：中国优秀女子运动员栏间跑时间特征表现为“忽快忽慢”、速度变化不稳定，同时栏间跑空间特征表现也不稳定、栏间跑步数变化起伏太大，指出逐步减少栏间跑步数是提高女子400m跨栏跑成绩的趋势。