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1.
Abstract

The purpose of this study was to compare response times among four starting techniques—cross-over step, jab-step, standing sprinter's start, and the momentum start—to determine the fastest start for optimum speed in base running in slow pitch softball. The subjects were 30 adult male amateur softball players. Response time was recorded to the nearest 1/100 second using a Dekan Automatic Performance Analyzer arranged with two starting lights and a stop gate. A one way repeated measures ANOVA indicated that the momentum start was significantly (p < .01) faster than the other starts compared while there were no significant differences among the other starts. Reliability coefficients ranging from .90 to .95, obtained using the intraclass correlation coefficient for multiple trial data, signified no trends among trials and high reliability of the testing procedures and equipment. The results suggested that the momentum start was the fastest starting technique for optimum speed for running bases in slow pitch softball.  相似文献   

2.
The main objectives of the present research were (1) to examine the relationships between the distances travelled underwater during the start and turn segments with swimming race performance at the elite level and (2) to determine if the individualised-distance start and turn parameters affect the overall race performance. The race parameters of the 100 and 200?m events during 2013 World Championships were measured by an innovative image-processing system (InThePool® 2.0). Overall, 100?m race times were largely related to faster start velocities in men's breaststroke and freestyle events. Conversely, overall, 200?m race times were largely related to longer starting distances in the women's butterfly events, to longer turn distances in men's and women's backstroke and women's butterfly events and to shorter turn distances in women's freestyle events. Changes on the start or turn velocities could represent moderate time improvements in most of the 100?m events, whereas modifications on the start or turn distances (especially in the last turn) could provide elite swimmers with time improvements of practical importance on the 200?m events. The evaluation of races by individualised-distance parameters should be provided to elite swimmers in order to decide the most appropriate race segment configuration for each event.  相似文献   

3.
Starting block performance in swimming is of crucial importance in the individual competitions for the shorter swimming distances as well as for the relay events. The significance of this swim start performance will increase with the introduction of a new starting block with a longer and slightly steeper surface in conjunction with a push-off support for the feet and laterally adjustable handles. As grab starts and track starts were equally observed in international swimming competitions there are good reasons to assume that only the latter will remain the dominant starting technique. This report aims to summarize existing knowledge on the biomechanics of the swim start performed on a traditional starting block as a new starting block is introduced and new starting techniques are going to be developed. Following some introductory remarks on the assessment of the swim start performance, results will be discussed on the merit of different take-off techniques, on the entry behaviour, and on the force development profiles on the starting block. In conclusion, a tendency in favour of the rear-weighted track start was found in conjunction with a flat entry. In addition, it could be shown that an angular momentum around the transverse body axis combined with a dolphin kick (and a previously hyperextended hip joint) may provide hydrodynamic conditions to enter the water with a rather steep centre of mass trajectory. Finally, existing biomechanical knowledge will be presented on the relay start as well as on a possible change in the starting technique using the new block.  相似文献   

4.
Abstract

This study aimed to understand the kinematic and kinetic differences between two sprint starts: block and split-stance standing. Fourteen sub-elite male sprinters (100 m time: 11.40?±?0.39?s) performed block and split-stance standing starts sprints over 30 m of in-ground force platforms in a randomised order. Independent t-tests and repeated measures mixed model analysis of variance were used to analyse the between-condition variables across conditions, and over four step phases. Block start sprints resulted in significantly (p?<?.05) faster 5 m (5.0%, effect size [ES]?=?0.89) and 10?m (3.5%, ES?=?0.82) times, but no significant differences were found at 20 and 30?m. No significant differences were found in any kinematic measure between starting positions. However, block starts resulted in significantly (p?<?.001) greater propulsive impulses (6.8%, ES?=?1.35) and net anterior-posterior impulses (6.5%, ES?=?1.12) during steps 1–4, compared to the standing start. Block starts enable athletes to produce a greater amount of net anterior-posterior impulse during early accelerated sprinting, resulting in faster times up to 10 m. When seeking to improve initial acceleration performance, practitioners may wish to train athletes from a block start to improve horizontal force production.  相似文献   

5.
Abstract

The purpose of this study was to investigate the effect of load on swimming endurance in humans. Twenty male subjects between the ages of 17 and 24 swam in a vertical to semi-vertical position (treaded water using arms and legs) until exhausted or until an hour had elapsed. This was done with loads of 0, 2, 4, 6, 8, 10, 15, 20, 25, and 30 percent of the body weight. The lead used as a weight was placed around the waist of the swimmer. The times were recorded at each load and the means determined and plotted. The relationship between load and endurance was close and curvilinear. Heavier individuals were at a slight disadvantage in this swimming test which used percentage of body weight as a measure of load. Among good swimmers a load of 4 percent of the body weight did not decrease swim time appreciably, while a load of 30 percent reduced swim time to a matter of seconds.  相似文献   

6.
Abstract

In an effort to determine the better method of starting and running to the right, two methods, the jab step and the cross-over step, were compared. Thirty male students, 13–17 years old, were timed at four testing stations, 5, 11, 22, and 37 feet from the start. Reliabilities were very high. Analysis of variance revealed the cross-over step to be significantly faster than the jab step at each timing station.  相似文献   

7.
Abstract

The sprint starts of 12 skilled collegiate sprinter!hurdlers were filmed for four different sprint start conditions. Ground reaction forces were collected for the first step out of the blocks and velocities through a 2-m speed trap immediately following the first support phase were recorded. The subjects employed their preferred right-left leg placement in the blocks, while the anterior–posterior spacing of the front block with respect to the starting line and the amount of forward lean in the set position were varied. Four positions were constructed that accounted for anthropometric differences. The four positions consisted of combinations of two arm orientations (forward lean and perpendicular to ground) and two front block to starting line distances (bunched and elongated). Kinematic data were reduced to provide center of mass position and velocity measures and analyzed for critical periods throughout the starting action. Selected critical events from the first step kinetic records were also analyzed. The results indicated that the elongated starting positions resulted in greater horizontal displacement, greater propelling impulse, increased first step toe-off velocity, and greater average velocity through a 2-m speed trap. Arm orientation effects were less well defined. Forward lean tended to result in greater vertical velocity at block clearance and horizontal velocity at first step toe-off, whereas perpendicular arm positioning resulted in greater 2-m speed trap velocity.  相似文献   

8.
Abstract

This study was designed to investigate the swimming endurance trainability of smokers as compared to nonsmokers. Nonsmokers (N = 47) and smokers (N = 34) of college age were selected from intermediate swimming classes and timed while swimming distances of 100 yd. and 200 yd. prior to participation in an 8-week training program. After 4 weeks of training, swimming times were again recorded for these same distances. At the end of eight weeks, swimming times were taken for distances of 100, 200, and 400 yards. The mean changes of both smokers and nonsmokers during the pretraining to 4-week period, the 4-week to 8-week period, and the pretraining to 8-week period were all significant at the .05 level. However, no significant differences were found between the mean swimming times of smokers and nonsmokers for any of the pretraining, 4-week, or 8-week distances.  相似文献   

9.
Abstract

Four measures of elapsed time were secured on a sample of 76 male physical education majors during a 50-yd. sprint. The subjects were timed during two sprints and measurements were secured at 20, 30, 40, and 50 yd. Ten different measurement schedules were developed from the four measurements. Data revealed that the greatest source of measurement error existed in the first 20 yd. of the sprint. The intraclass reliability estimates of the 10 measurement schedules ranged from .79 to .98.  相似文献   

10.
Abstract

Forearm flexion strength of 65 college men was measured at two distances from the elbow at each of three angles of the forearm. The speed of forearm flexion movement was measured through an arc of 85°. Ebel intraclass reliabilities for strength and speed were high, i.e., .95 to .99. The extremely low correlations between limb strength and speed of movement, which ranged from —.06 to .14, are in agreement with the majority of the low correlations reported in earlier studies. The findings of this study support the theory of specificity in that individual differences in the speed of a limb involving a single joint are predominantly independent of strength measures associated with that limb and joint.  相似文献   

11.
Abstract

Work presented in this paper provides a methodology for categorising swimming start performance based on peak force production on the main block and footrest components of the Omega OSB11 starting block. A total of 46 elite British swimmers were tested, producing over 1000 start trials. Overwater cameras were synchronised to a specifically designed start block that allowed the measurement of force production via two sets of four, tri-axis, force transducers; one set in the main block and one in the footrest. Data were then analysed, segregating trials for gender. Each start was categorised, with respect to the peak force production in horizontal and vertical components, into one of nine categories. Three performance indicators, i.e. block time, take-off velocity and distance of entry, were used to assess whether differences in performance could be correlated with these categories. Results from these data suggest that swimmers generating higher than average peak forces were more likely to produce a better overall start performance than those who produced forces lower than the average, for this population of athletes.  相似文献   

12.
Purpose:This study aimed to determine the accuracy of a 4 split time modelling method to generate velocity-time and velocity-distance variables in elite male 100-m sprinters and subsequently to assess the roles of key sprint parameters with respect to 100-m sprint performance.Additionally,this study aimed to assess the differences between faster and slower sprinters in key sprint variables that have not been assessed in previous work.Methods:Velocity-time and velocity-distance curves were generated using a mono-exponential function from 4 split times for 82 male sprinters during major athletics competitions.Key race variables-maximum velocity,the acceleration time constant(τ),and percentage of velocity lost(vLoss)-were derived for each athlete.Athletes were divided into tertiles,based on 100-m time,with the first and third tertiles considered to be the faster and slower groups,respectively,to facilitate further analysis.Results:Modelled split times and velocities displayed excellent accuracy and close agreement with raw measures(range of mean bias was-0.2%to 0.2%,and range of intraclass correlation coefficients(ICCs)was 0.935 to 0.999)except for 10-m time(mean bias was 1.6%±1.3%,and the ICC was 0.600).The 100-m sprint performance time and all 20-m split times had a significant near-perfect negative correlation with maximum velocity(r≥-0.90)except for the 0 to 20-m split time,where a significantly large negative correlation was found(r=-0.57).The faster group had a significantly higher maximum velocity andτ(p<0.001),and no significant difference was found for vLoss(p=0.085).Conclusion:Coaches and researchers are encouraged to utilize the 4 split time method proposed in the current study to assess several key race variables that describe a sprinter’s performance capacities,which can be subsequently used to further inform training.  相似文献   

13.
This study aimed to determine if starting with the feet above the water (FAW) in male backstroke swimming resulted in faster start times (15-m time) than when the feet were underwater (FUW). It was hypothesised that setting higher on the wall would generate increased horizontal force and velocity, resulting in quicker starts. Twelve high-level male backstrokers performed three trials of the FAW and FUW techniques. A biomechanical swimming testing system comprising one force plate (1,000 Hz), four lateral-view (100 Hz), and five overhead (50 Hz) video cameras captured the swimmers' performance. Data for each participant's fastest trial for each technique were collated, grouped, and statistically analysed. Analysis included Wilcoxon, Spearman Rho correlation, and regression analysis. Wilcoxon results revealed a significantly faster start time for the FAW technique (p < 0.01). Peak horizontal force was significantly smaller for FAW (p = 0.02), while take-off horizontal velocity was significantly greater (p = 0.01). Regression analysis indicated take-off horizontal velocity to be a good predictor of start time for both techniques, and the horizontal displacement of the centre of mass for the FAW start.  相似文献   

14.
Abstract

Five subjects were tested three times in each of three static and three phasic work tests involving leg extensions in the semi-reclining position. Oxygen uptake, net oxygen consumption, ventilation rate, pulse rate, and systolic and diastolic blood pressures were consistently higher in phasic work than in static effort with a comparable resistance. The patterns of systolic and diastolic blood pressure and pulse rate response and recovery did not seem to differ in the two modes of work. While the ventilation rate—oxygen uptake relationship was similar in both forms of effort, the pulse rate—oxygen uptake relationship differed in that the static pulse exceeded the phasic rate at a comparable level of oxygen uptake.  相似文献   

15.
Abstract

The objective of this study was to determine the relationship between different variables measured with a force plate during the swimming start push-off phase and start performance presented by times to 5, 10 and 15?m. Twenty-one women from the Slovenian national swimming team performed two different swim starts (freestyle and undulatory) on a portable force plate to a distance further than 15?m. Correlations between push-off variables and times to 5, 10 and 15?m were quantified through Pearson's product-moment correlation coefficient (r). The variables that significantly correlated (p?<?.05) to all times measured in the two starts performed were: average horizontal acceleration (freestyle: r?=??0.58 to ?0.71; and undulatory: r?=??0.55 to ?0.66), horizontal take-off velocity (freestyle: r?=??0.56 to ?0.69; and undulatory: r?=??0.53 to ?0.67) and resultant take-off velocity (freestyle: r?=??0.53 to ?0.65; and undulatory: r?=??0.52 to ?0.61). None of the variables derived from the vertical force were correlated to swimming start performance (p?>?.05). Based on the results of this study, we can conclude that horizontal take-off velocity and average horizontal acceleration (calculated as the average horizontal force divided by swimmer's body mass) are the variables most related to swimming start performance in experienced swimmers, and therefore could be the preferred measures to monitor swimmers’ efficiency during the push-off phase.  相似文献   

16.
Abstract

Twelve male subjects with no specialized training in sprint running were used to study effects upon the sprinter's start when hand spacing and rear knee angle were systematically altered. Results indicated that hand spacing had an effect on the start during the first 10 yd. of the sprint. The effect of rear knee angle was present at 10 yd. and the advantage gained at 10 yd. was still present at 30 yd.  相似文献   

17.
通过对国家男子轮椅竞速队4×100m接力运动员接力每棒最佳起动时机的分析,以获取接力队员独立的每棒距离速度时间变化及相应的起动时间,用数值积分法计算最佳的接棒起动距离时机并和实际接力训练中的接棒起动距离时机进行比较.认为国家男子轮椅竞速队接力训练中出发距离偏小,启动时机过晚;根据最佳起动距离时机范围作接力测试时,交接棒可在前接力区完成,接力成绩有所提高.提出国家男子轮椅竞速队接力训练中要延长起动距离时机;计算的最佳出发起动时机可作为接力技术训练中起动距离时机设置的参考.  相似文献   

18.
ABSTRACT

Purpose: This study aimed to examine the effect of gradual self-control of task difficulty and feedback on accuracy and movement pattern of the golf putting sport skill. Method: Sixty students were quasi-randomly assigned to four groups under a varying combination of the two factors of task difficulty control (self-controlled or yoked) and feedback control (self-controlled or yoked). The participants in the two groups (dual-factor gradual self-control and self-controlled task difficulty group) that granted control over task difficulty in the acquisition phase were told they could choose any of the pre-set distances from the target. All groups were given 100% feedback in the first half of the acquisition phase, but the participants in the two groups (dual-factor gradual self-control group and self-controlled feedback) that could control their feedback were told that in the second half of the acquisition phase they would be able to ask for feedback when needed. The practice schedule of each member of the dual-factor gradual self-control group was used as a basis to plan the practice of predetermined distances and feedback presentation to the corresponding participants in the yoked conditions. Results: ANOVA with repeated measures showed that the practice method involving gradual self-control of two factors had a positive impact on accuracy and movement pattern of golf putting in the retention and transfer tests compared to other methods (ps < .05). Conclusion: The advantages of self-control practice presumably come from better adjustment of challenge points by the learner in the course of the practice.  相似文献   

19.
Abstract

The aim of the current study was (1) to investigate whether the number of accelerations is a more precise estimate of performance decline in soccer compared to distances with high-speed running (HSR) and (2) to compare changes in the number of accelerations and HSR distances across playing positions in order to examine whether the match profiles of the physical measures are consistent or demonstrate high interposition variability. The dataset includes domestic home games (N?=?34) over three full seasons (2012–2014) for a team in the Norwegian Elite League. The change in the number of accelerations throughout the match demonstrates a more clear pattern compared to the distance covered by HSR. In numbers of accelerations, a systematic and linear decrease can be observed throughout the match, with 34% less accelerations from the first to the last 5-minute period of the game (6.7 vs. 4.4 accelerations). This pattern of results captures the change in the number of accelerations across all positions. HSR distance had more variability during the match. All five positions investigated displayed a similar trend in accelerations and HSR profiles after the peak periods in each half. In contrast to the absolute number of accelerations, there were major positional differences in the mean HSR distance during the match. Our data suggest a more visible performance decline in the number of accelerations from the start to the end of the game, than the decline in the distance covered by HSR distance.  相似文献   

20.
Abstract

Few studies have focused on the effect of posture during sprint start. The aim of this study was to measure the effect of the modification of horizontal distance between the blocks during sprint start on three dimensional (3D) joint angular velocity. Nine trained sprinters started using three different starting positions (bunched, medium and elongated). They were equipped with 63 passive reflective markers, and an opto-electronic Motion Analysis® system was used to collect the 3D marker trajectories. During the pushing phase on the blocks, norm of the joint angular velocity (NJAV), 3D Euler angular velocity (EAV) and pushing time on the blocks were calculated. The results demonstrated that the decrease of the block spacing induces an opposite effect on the angular velocity of joints of the lower and the upper limbs. The NJAV of the upper limbs is greater in the bunched start, whereas the NJAV of the lower limbs is smaller. The modifications of NJAV were due to a combination of the movement of the joints in the different degrees of freedom. The medium start seems to be the best compromise because it leads, in a short pushing time, to a combination of optimal joint velocities for upper and lower segments.  相似文献   

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