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1.
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   

2.
Abstract

Four sprint starting positions—the bunch, medium, elongated, and hyperextended—were compared on mean elapsed times at distances of 10 and 30 yd. Averages of three starts for each of 30 inexperienced college undergraduate males on each type of start were derived from electronically-controlled measures, the times for both distances being recorded from the same start. Statistical analyses indicated significantly lower elapsed times with the hyperextended starting position.  相似文献   

3.
PurposeThe purpose of this study was to compare the effects of intermittent sprint training and plyometric training on endurance running performance.MethodsFourteen moderately trained male endurance runners were allocated into either the intermittent sprint training group (n = 7) or the plyometric training group (n = 7). The preliminary tests required subjects to perform a treadmill graded exercise test, a countermovement jump test for peak power measurement, and a 10-km time trial. Training included 12 sessions of either intermittent sprint or plyometric training carried out twice per week. On completion of the intervention, post-tests were conducted.ResultsBoth groups showed significant reduction in weekly training mileage from pre-intervention during the intervention period. There were significant improvements in the 10-km time trial performance and peak power. There was also significant improvement in relative peak power for both groups. The 10-km time trial performance and relative peak power showed a moderate inverse correlation.ConclusionThese findings showed that both intermittent sprint and plyometric training resulted in improved 10-km running performance despite reduction in training mileage. The improvement in running performance was accompanied by an improvement in peak power and showed an inverse relationship with relative peak power.  相似文献   

4.
Abstract

The purpose of this report was to introduce and validate a method to account for variable fatigue rates during cycle sprinting by incorporating decline from peak power (30%) as a test termination criterion. Fifteen healthy men performed three maximal sprint tests separated by 20 min (Bouts 1 and 2) and 48 hours (Bout 3). Power curves were analyzed for peak power, time to peak, time to fatigue (decline of 30% from peak), total work, total test time, fatigue rate, and the fatigue index. High test-retest reliability was demonstrated for all variables (R = 0.85–0.98). No significant differences were detected between variables (Bouts 1, 2 and 3; p > 0.01). Fatigue rates varied widely among participants (range = 24.7–65.4 W·s-1), but the fatigue index was consistent (31.1 ± 0.16; mean ± standard error of measurement, range = 30.1–32.5%). Our data show that variable fatigue responses among participants are normalized to the percentage of decline from peak power by incorporating a relative fatigue cutoff criterion. This approach might inform mechanisms relating to short-term fatigue and recovery during consecutive sprint bouts.  相似文献   

5.
Abstract

Seven 6 s sprints with 30 s recovery between sprints were performed against two resistive loads: 50 (L50) and 100 (L100) g · kg?1 body mass. Inertia-corrected and -uncorrected peak and mean power output were calculated. Corrected peak power output in corresponding sprints and the drop in peak power output relative to sprint 1 were not different in the two conditions, despite the fact that mean power output was 15–20% higher in L100 (P < 0.01). The effect of inertia correction on power output was more pronounced for the lighter load (L50), with uncorrected peak power output in sprint 1 being 42% lower than the corresponding corrected peak power output, while this was only 16% in L100. Fatigue assessed by the drop in uncorrected peak and mean power output in sprint 7 relative to sprint 1 was less compared with that obtained by corrected power values, especially in L50 (drop in uncorrected vs. corrected peak power output: 13.3 ± 2.2% vs. 23.1 ± 4.1%, P < 0.01). However, in L100, the difference between the drop in corrected and uncorrected mean power output in sprint 7 was much smaller (24.2 ± 3.1% and 21.2 ± 2.7%, P < 0.01), indicating that fatigue may be safely assessed even without inertia correction when a heavy load is used. In conclusion, when inertia correction is performed, fatigue during repeated sprints is unaffected by resistive load. When inertia correction is omitted, both power output and the fatigue profile are underestimated by an amount dependent on resistive load. In cases where inertia correction is not possible during a repeated sprints test, a heavy load may be preferable.  相似文献   

6.
Abstract

The aim of this study was to assess the efficacy of electromyography (EMG) normalization methods for a high-speed 20-m sprint. Comparisons were based on intra-individual reliability and magnitude of normalized EMG signals from three repeat sessions separated by 1 day (between days) and 1 week (between weeks) from the initial test. Surface EMGs were recorded (n=16) from the medial and lateral gastrocnemius and soleus during the normalization methods (isometric: maximum/sub-maximum/body weight; isotonic: maximum/sub-maximum/body weight; isokinetic: 1.05 rad · s–1, 1.31 rad · s–1, 1.83 rad · s–1; squat jump). The EMG data from the 20-m sprint were normalized using each method and using the within-sprint peak EMG (sprint peak). Intra-individual reliability of the EMG was assessed using typical error of measurement as a percentage of intra-individual coefficient of variance (TEMCV%). Sprint peak normalization improved intra-individual reliability of EMG (soleus: <4.91CV%; medial gastrocnemius: <6.2CV%; lateral gastrocnemius: <7.1CV%) compared with un-normalized EMG (soleus: <13.3CV%; medial gastrocnemius: <16.5CV%; lateral gastrocnemius: <16.3CV%) both between days and between weeks. Squat jump normalization improved the soleus (<11.2CV%) and medial gastrocnemius (<15.7CV%) reliability between days and weeks and provided a representative measure of triceps surae muscle activation. The intra-individual reliability of the medial gastrocnemius EMG data was improved both between days and weeks when using isotonic normalization. Isometric and isokinetic normalization showed no improvement in intra-individual reliability either between days or weeks for any muscle. The method of normalization influenced the between-stride muscle interaction during the 20-m sprint. The results of this study suggest that peak normalization can be used to normalize high-speed muscle actions, while normalizing EMG to a squat jump may provide an alternative method to represent relative muscle activation.  相似文献   

7.
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   

8.
Abstract

Five trials spaced a minute apart were secured on 50 male subjects three days in succession on an apparatus designed to isolate action of the right wrist flexor muscle group. Reliability of measurement was assessed through the intraclass correlation technique. Although an acceptable level of reliability was obtained (R = .93), nonpertinent factors apparently intruded. These were tentatively identified as a trial effect due to depletion of energy reserves for strength exertion, and a day effect due to either strength development, a learning effect, or a combination of strength development and learning effects. Consideration of such factors in measurement programs was noted.  相似文献   

9.
Abstract

This study investigated the association between explosive force production during isometric squats and athletic performance (sprint time and countermovement jump height). Sprint time (5 and 20 m) and jump height were recorded in 18 male elite-standard varsity rugby union players. Participants also completed a series of maximal- and explosive-isometric squats to measure maximal force and explosive force at 50-ms intervals up to 250 ms from force onset. Sprint performance was related to early phase (≤100 ms) explosive force normalised to maximal force (5 m, r = ?0.63, P = 0.005; and 20 m, r = ?0.54, P = 0.020), but jump height was related to later phase (>100 ms) absolute explosive force (0.51 < r < 0.61; 0.006 < P < 0.035). When participants were separated for 5-m sprint time (< or ≥ 1s), the faster group had greater normalised explosive force in the first 150 ms of explosive-isometric squats (33–67%; 0.001 < P < 0.017). The results suggest that explosive force production during isometric squats was associated with athletic performance. Specifically, sprint performance was most strongly related to the proportion of maximal force achieved in the initial phase of explosive-isometric squats, whilst jump height was most strongly related to absolute force in the later phase of the explosive-isometric squats.  相似文献   

10.
Abstract

In recent years the classic Margaria step-test for anaerobic power has been largely replaced by bicycle ergometer tests, the most popular of these being the Wingate Anaerobic Test (WAnT). The purpose of this study was to examine the relationship between the WAnT and sprint-run times and to determine the influence of age and weight on the WAnT scores. The 56 male volunteers (age 10–15 years) recruited from a track club and junior high school represented a wide range of athletic abilities. Subjects were tested for anaerobic power (5 sec output) and capacity (30 sec output) using the Wingate test procedures. Wingate scores for anaerobic power and capacity were only moderately correlated with 50 yd dash times (r = ?.53 and ?.53) and with the 600 yd run (r = ?.26 and ?.29). Partial correlations between these variables were lower when age adjusted and higher when adjusted for body weight. Results of this study indicate that the Wingate anaerobic test is only a moderate predictor of dash or run times, but becomes a stronger predictor when WAnT scores are adjusted for body weight. The high correlation of the WAnT with body weight must be taken into account when comparing the anaerobic capacity of individuals. The standing long jump would be the preferred field test of sprint-related ability because of its simplicity, but the Wingate lest has the advantage of providing a quantitative measurement of anaerobic fitness.  相似文献   

11.
ABSTRACT

This study aimed to examine the effects of two jump squat (JS) training programs involving different loading ranges in under-20 soccer players during a preseason period. Twenty-three elite young soccer players performed sprint speed (at 5-, 10-, and 20-m), change-of-direction (COD) speed, JS peak-power (PP), and countermovement jump (CMJ) tests pre and post four weeks of training. Athletes were pair-matched in two groups according to their optimum power loads (OPL) as follows: lower than OPL (LOPL; athletes who trained at a load 20% lower than the OPL) and higher than OPL (HOPL; athletes who trained at a load 20% higher than the OPL). Magnitude-based inferences were used to compare pre- and post-training measures. Meaningful increases in the PP JS were observed for both groups. Likely and possible improvements were observed in the 5- and 10-m sprint velocity in the LOPL group. Meanwhile, possible and likely improvements were observed in the CMJ, 5- and 10-m sprint velocity, and COD speed in the HOPL group. Overall, both training schemes induced positive changes in athletic performance. Soccer coaches and sport scientists can implement the JS OPL-based training schemes presented here, either separately or combined, to improve the physical performance of youth soccer players.  相似文献   

12.
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   

13.
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.  相似文献   

14.
Abstract

The aim of this study was to investigate spatiotemporal and kinematic changes between the initial acceleration, transition and maximum velocity phases of a sprint. Sagittal plane kinematics from five experienced sprinters performing 50-m maximal sprints were collected using six HD-video cameras. Following manual digitising, spatiotemporal and kinematic variables at touchdown and toe-off were calculated. The start and end of the transition phase were identified using the step-to-step changes in centre of mass height and segment angles. Mean step-to-step changes of spatiotemporal and kinematic variables during each phase were calculated. Firstly, the study showed that if sufficient trials are available, step-to-step changes in shank and trunk angles might provide an appropriate measure to detect sprint phases in applied settings. However, given that changes in centre of mass height represent a more holistic measure, this was used to sub-divide the sprints into separate phases. Secondly, during the initial acceleration phase large step-to-step changes in touchdown kinematics were observed compared to the transition phase. At toe-off, step-to-step kinematic changes were consistent across the initial acceleration and transition phases before plateauing during the maximal velocity phase. These results provide coaches and practitioners with valuable insights into key differences between phases in maximal sprinting.  相似文献   

15.
ABSTRACT

Successful sprinting depends on covering a specific distance in the shortest time possible. Although external forces are key to sprinting, less consideration is given to the duration of force application, which influences the impulse generated. This study explored relationships between sprint performance measures and external kinetic and kinematic performance indicators. Data were collected from the initial acceleration, transition and maximal velocity phases of a sprint. Relationships were analysed between sprint performance measures and kinetic and kinematic variables. A commonality regression analysis was used to explore how independent variables contributed to multiple-regression models for the sprint phases. Propulsive forces play a key role in sprint performance during the initial acceleration (r = 0.95 ± 0.03) and transition phases (r = 0.74 ± 0.19), while braking duration plays an important role during the transition phase (r = ?0.72 ± 0.20). Contact time, vertical force and peak propulsive forces represented key determinants (r = ?0.64 ± 0.31, r = 0.57 ± 0.35 and r = 0.66 ± 0.30, respectively) of maximal velocity phase performance, with peak propulsive force providing the largest unique contribution to the regression model for step velocity. These results clarified the role of force and time variables on sprinting performance.  相似文献   

16.
The purpose of this study was to assess the effect of periodized resistance training on accelerative sprint performance. Sixteen physically active men participated in a randomized controlled study. An experimental group (n = 10) completed an 8-week periodized resistance training intervention, while a control group (n = 6) did not train. Pre- and post-training measures of 20-m straight-line sprint time, including a 10-m split, maximum strength, and explosive strength, were recorded. Flight time, stance time, stride length, and stride frequency were quantified from digitized video recordings of the first three strides of the 20-m sprint. Resistance training resulted in significant increases in maximum strength (parallel back squat: 19%) and explosive strength (6–10%). However, both groups increased 0–10 m sprint times (experimental group = 6%; control group = 3%) while 10–20 m times were reduced (experimental group = 7%; control group = 4%), highlighting the mechanical differences between the distinct sprint phases. The change during the 0–10 m interval was accompanied by a reduction in stride frequency during the first three strides. Strength coaches should be aware that the potential benefits of increased muscular strength during short sprints are likely to be affected by mechanical specificity and that improvements in sprinting performance may not occur immediately after a period of resistance training.  相似文献   

17.
Abstract

There is evidence that the digit ratio (2D:4D) is a negative correlate of prenatal levels of testosterone, but there is no association between 2D:4D and the circulating levels of both total and free testosterone. Sports provide a physical challenge and participants often show increased levels of free testosterone immediately preceding and during competition. We tested this hypothesis of a link between 2D:4D and testosterone under challenge in 79 professional rugby players using the following procedures; (i) 25 players were physically challenged using a repeated sprint agility test, and saliva samples were assayed for testosterone immediately preceding the repeated sprint agility test (time 1) and 5 minutes (time 2) and 20 minutes after completion of the repeated sprint ability (time 3); (ii) 54 players were also tested for salivary testosterone in an unchallenged condition. We found that right-left 2D:4D was significantly and negatively related to testosterone concentrations at times 1, 2 and 3 following the repeated sprint agility test (P < 0.05) and there was no association between the 2D:4D and basal testosterone levels in the unchallenged group. We suggest that low right–left 2D:4D is a predictive marker of free testosterone responsiveness when trained men are physically challenged, and that this association is programmed by the action of prenatal testosterone.  相似文献   

18.
Background:In a sprint cross-country(XC)ski competition,the difference in recovery times separating the first and the second semi-final(SF)heats from the final(F)may affect performance.The aim of the current study was to compare the effects of longer vs.shorter recovery periods prescribed between the 3 knock-out races of a simulated sprint XC ski competition involving a prologue(P),quarter-final(QF),SF,and F.Methods:Eleven well-trained XC ski athletes completed 2 simulated sprint XC ski competitions on a treadmill involving 4×883-m roller-ski bouts at a 4°incline using the gear 3 ski-skating sub-technique.The first 3 bouts were completed at a fixed speed(PFIX,QFFIX,and SFFIX)corresponding to~96%of each individual’s previously determined maximal effort.The final bout was performed as a self-paced sprint time trial(FSTT).Test conditions differed by the time durations prescribed between the QFFIX,SFFIX,and FSTT,which simulated real-world XC ski competition conditions using maximum(MAX-REC)or minimum(MIN-REC)recovery periods.Results:The FSTT was completed 5.4±5.5 s faster(p=0.009)during MAX-REC(179.2±18.1 s)compared to MIN-REC(184.6±20.0 s),and this was linked to a significantly higher power output(p=0.010)and total metabolic rate(p=0.009).The pre FSTT blood lactate(BLa)concentration was significantly lower during MAX-REC compared to MIN-REC(2.5±0.8 mmol/L vs.3.6±1.6 mmol/L,respectively;p=0.027),and the pre-to-post FSTT increase in BLa was greater(8.8±2.1 mmol/L vs.7.1±2.3 mmol/L,respectively;p=0.024).No other differences for MAX-REC vs.MIN-REC reached significance(p>0.05).Conclusion:Performance in a group of well-trained XC skiers is negatively affected when recovery times between sprint heats are minimized which,in competition conditions,would occur when selecting the last QF heat.This result is combined with a higher pre-race BLa concentration and a reduced rise in BLa concentration under shorter recovery conditions.These findings may help inform decision making when XC skiers are faced with selecting a QF heat within a sprint competition.  相似文献   

19.
Abstract

Six female collegiate swimmers were used to evaluate the hypothesis that the recovery procedure after exercise will not only affect subsequent performance, but will also affect the recovery process after the subsequent performance. Each swimmer exercised for two minutes at 90% [Vdot]O2 max on a swimming ergometer, recovered for 15 minutes by walking on land or swimming, then swam 200 yds. for time. Oxygen uptake was measured for 15 minutes after the 200 yd. swim. Venous blood, obtained after the ergometry swim, and before and after the 200 yd. swim, was analyzed for lactate. Two hundred yard swim times were not significantly affected by either the walking or swimming recovery procedures. Blood lactate after the ergometry swim averaged 96.7 ± 18 mg/100 ml. The swimming recovery reduced the lactate levels by 53.3% compared to a 38.5% reduction during the walking recovery. Significant differences in blood lactate were also noted after the 200 yd. swim, with the trials in which swimming recovery protocol was used yielding less than the trials involving the walking recovery (99 ± 8 mg/100 ml compared to 113 ± 8 mg/100 ml, respectively). The post 200 yd. swim oxygen uptakes averaged 7.74 ± 1.51 liters and were not affected by protocol. It was concluded that a 15 minute recovery period may be sufficient for repeated bouts of high intensity work lasting less than three minutes. It was also concluded that self-selection of the mode of recovery is not always the most effective for removal of blood lactate.  相似文献   

20.
The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40–50 years) as well as compare the adaptations to younger adults (20–30 years). Twenty-eight inactive participants – 14 young 20–30-year-olds (n = 7 males) and 14 middle-aged 40–50-year-olds (n = 5 males) – completed 4 weeks of running sprint interval training (4 to 6, 30-s “all-out” sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO2max (young = 3.9, middle-aged = 5.2%; P < 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P < 0.001), peak sprint speed (young = 9.3, middle-aged = 2.2%; P < 0.001), and average sprint speed (young = 6.8, middle-aged = 11.6%; P < 0.001) in both young and middle-aged groups from pre- to post-training on the 30-s sprint test. The current study demonstrates that a 4-week running sprint interval training programme is equally effective at improving aerobic and anaerobic fitness in younger and middle-aged adults.  相似文献   

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