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1.
Kicking is a key component of freestyle swimming yet the optimum combination of kick rate and kick amplitude remains unknown. For Paralympic swimmers, with upper and lower limb disabilities, the influence of the kick plays an important role in net force production. To determine optimum kick characteristics, 12 Paralympic swimmers aged 19.8 ± 2.9 years (mean ± s) were towed at their individual peak freestyle speed. The experimental conditions were (i) a prone streamline glide for passive trials and (ii) maximal freestyle kicking in a prone streamline for active trials at different speeds and kick amplitudes. Kick rate was quantified using inertial sensor technology. Towing speed was assessed using a novel and validated dynamometer, and net force was assessed using a Kistler force-platform system. When peak speed was increased by 5%, the active force increased 24.2 ± 5.3% (90% confidence limits), while kick rate remained at approximately 150 kicks per minute. Larger amplitude kicking increased the net active force by 25.1 ± 10.6%, although kick rate decreased substantially by 13.6 ± 5.1%. Based on the current kick rate and amplitude profile adopted by Paralympic swimmers, these characteristics are appropriate for optimizing net force.  相似文献   

2.
The aim of this study was to evaluate the influence of dry-land inertial training (IT) on muscle force, muscle power, and swimming performance. Fourteen young, national-level, competitive swimmers were randomly divided into IT and control (C) groups. The experiment lasted four weeks, during which time both groups underwent their regular swimming training. In addition, the IT group underwent IT using the Inertial Training Measurement System (ITMS) three times per week. The muscle groups involved during the upsweep phase of the arm stroke in front crawl and butterfly stroke were trained. Before and after training, muscle force and power were measured under IT conditions. Simultaneously with the biomechanical measurements on the ITMS, the electrical activity of the triceps brachii was registered. After four weeks of training, a 12.8% increase in the muscle force and 14.2% increase in the muscle power (p?<?.05) were noted in the IT group. Moreover, electromyography amplitude of triceps brachii recorded during strength measurements increased by 22.7% in the IT group. Moreover, swimming velocity in the 100?m butterfly and 50?m freestyle improved significantly following the four weeks of dry-land IT (?1.86% and ?0.76%, respectively). Changes in the C group were trivial. Moreover, values of force and power registered during the ITMS test correlated negatively with the 100?m butterfly and 50?m freestyle swimming times (r value ranged from ?.80 to ?.91). These results suggest that IT can be useful in swimming practice.  相似文献   

3.
In this study, we examined the reliability and construct validity of new soccer skills tests. Twenty soccer players (10 professional and 10 recreational) repeated trials of passing, shooting, and dribbling skills on different days. Passing and shooting skills required players to kick a moving ball, delivered at constant speed, towards one of four randomly determined targets. Dribbling required players to negotiate seven cones over 20?m. Each trial consisted of 28 passes, 8 shots, and 10 dribbles. Ball speed, precision, and success were determined for all tests using video analysis. Systematic bias was small (<9% in all measures) and all outcome measures were similar between trials. Test-retest reliability statistics were as follows: ball speed (passing, shooting, dribbling; coefficient of variation [CV]: 6.5%, 6.9%, 2.4%; ratio limits of agreement [RLOA]: 0.958?×/÷ 1.091, 0.990?×/÷ 1.107, 0.993?×/÷ 1.039), precision (passing, shooting, dribbling; CV: 10.0%, 23.5%, 4.6%; RLOA: 0.956?×/÷ 1.147, 1.030?×/÷ 1.356, 1.000?×/÷ 1.068), and success (passing, shooting, dribbling; CV: 11.7%, 14.4%, 2.2%; RLOA: 1.017?×/÷ 1.191, 0.913?×/÷ 1.265, 0.996?×/÷ 1.035). Professional players performed better than recreational players in at least one outcome measure for all skills. These findings demonstrate the reliability and validity of new soccer skill protocols.  相似文献   

4.
The effectiveness of the swimming turn is highly influential to overall performance in competitive swimming. The push-off or wall contact, within the turn phase, is directly involved in determining the speed the swimmer leaves the wall. Therefore, it is paramount to develop reliable methods to measure the wall-contact-time during the turn phase for training and research purposes. The aim of this study was to determine the concurrent validity and reliability of the Pool Pad App to measure wall-contact-time during the freestyle and backstroke tumble turn. The wall-contact-times of nine elite and sub-elite participants were recorded during their regular training sessions. Concurrent validity statistics included the standardised typical error estimate, linear analysis and effect sizes while the intraclass correlating coefficient (ICC) was used for the reliability statistics. The standardised typical error estimate resulted in a moderate Cohen’s d effect size with an R2 value of 0.80 and the ICC between the Pool Pad and 2D video footage was 0.89. Despite these measurement differences, the results from this concurrent validity and reliability analyses demonstrated that the Pool Pad is suitable for measuring wall-contact-time during the freestyle and backstroke tumble turn within a training environment.  相似文献   

5.
This study examined the validity of isometric strength tests for evidence-based classification in Para swimming. Thirty non-disabled participants and forty-two Para swimmers with physical impairment completed an isometric strength test battery designed to explain activity limitation in the freestyle discipline. Measures pertaining to dominant and non-dominant limb strength and symmetry were derived from four strength tests that were found to be reliable in a cohort of non-disabled participants (ICC = 0.85–0.97; CV = 6.4–9.1%). Para swimmers had lower scores in strength tests compared with non-disabled participants (d = 0.14–1.00) and the strength test battery successfully classified 95% of Para swimmers with physical impairment using random forest algorithm. Most of the strength measures had low to moderate correlations (r = 0.32 to 0.53; p ≤ 0.05) with maximal freestyle swim speed in Para swimmers. Although, fewer correlations were found when Para swimmers with hypertonia or impaired muscle power were analysed independently, highlighting the impairment-specific nature of activity limitation in Para swimming. Collectively, the strength test battery has utility in Para swimming classification to infer loss of strength in Para swimmers, guide minimum eligibility criteria, and to define the impact that strength impairment has on Para swimming performance.  相似文献   

6.
The aim of this study was to examine the influence of level of skill and swimming speed on inter-limb coordination of freestyle swimming movements. Five elite (2 males, 3 females; age 18.9?±?1.0 years, height 1.71?±?0.04?m, body mass 62.1?±?7.0?kg) and seven novice (age 22.0?±?2.0 years, height 1.77?±?0.04?m, body mass 74.8?±?9.0?kg) swimmers swam a sprint and a self-paced 25?m freestyle trial. The swimming trials were recorded by four digital cameras operating at 50 Hz. The digitized frames underwent a three-dimensional direct linear transformation to yield the three-dimensional endpoint kinematic trajectories. The spatio-temporal relationship between the upper limbs was quantified by means of the peak amplitude and time lag of the cross-correlation function between the right and left arm's endpoint trajectories. A strong anti-phase coupling between the two arms, as confirmed by peak amplitudes greater than 0.8, was noted for both groups and swimming speeds. Significantly higher (P <?0.05) peak amplitudes were observed for the sprint compared with self-paced swimming. No significant differences in the strength of inter-limb coupling were noted between the elite and novice swimmers (P >?0.05). Time lags were very close to 0?ms and did not differ between groups or swimming speeds. We conclude that in freestyle swimming, the intrinsic anti-phase (180° phase difference) inter-limb relationship is strongly preserved despite the physically powerful environmental influence of the water and this “preferred” pattern is not affected by level of skill. In contrast, increasing movement speed results in stronger inter-limb coupling that is closer to the anti-phase inter-limb relationship.  相似文献   

7.
Performances often vary between the heats and finals of breaststroke swimming competitions possibly because the swimmers try to conserve their energy, or for other tactical reasons. Additionally, coaches might advise either a 'positive' or 'even' pace race strategy during the final. The effect of such pacing changes on metabolism (blood lactate, heart rate, ventilation), ratings of perceived exertion, stroke kinematics and turning times have not been investigated. Nine male competitive breaststroke swimmers swam three paced (Aquapacer) 200-m trials, 48 h apart and in random order, at 98%, 100% and at an attempted 102% of their maximal 200-m time-trial speed. Responses in metabolic variables were similar between the 98% and 100% trials, but higher post-exercise blood lactate concentrations and respiratory exchange ratios were observed following the 102% trial. As the pace of trials increased, stroke rate was found to increase proportionately with stroke count. However, during the latter stages of the 100% trial, a disproportionate increase in the stroke count was observed, which led to a significant pacing error. This feature was more obvious in the 102% trial, where participants demonstrated 'positive pacing' and reported higher ratings of perceived exertion than for the 98% trial. During the early stages of the trials, turning times were initially shorter the faster the pace of the trial; however, as the trials progressed, this pattern was found to reverse. We conclude that a slight reduction in pace during near maximal breaststroke swimming altered kinematic but not post-exercise metabolic responses, while an increase in pace led to positive pacing and an increase in both kinematic responses and anaerobic metabolism.  相似文献   

8.
Abstract

Opportunities for ball passing in water-polo may be brief and the decision to pass only informed by minimal visual input. Since researchers using point light displays have shown that the walking or running gait of familiars can be identified, water-polo players may have the ability to recognize team-mates from their swimming gait. To test this hypothesis, members of a water-polo team and a competition swim team viewed two randomized sets of video clips, each less than one second long, of swimmers from both teams sprinting freestyle past a fixed camera. The arm stroke clip sequence showed only the upper body, and the kick sequence showed only the lower body. After viewing each video clip, observers rated their level of certainty as to whether the swimmer presented was a team-mate or not. Discrimination was significantly above chance in both groups. Water-polo players were better able to identify team-mates from their kick, whereas swimmers were better able to do so by viewing arm stroke. Our results suggest that, as with walking and running gait, small amounts of visual information about swimmers can be used for recognition, and so raise the possibility that specific training may be able to improve team-mate classification in water-polo, particularly in newly formed teams.  相似文献   

9.
采用文献资料法、运动影像解析法等方法,对第7届全国残疾人运动会游泳比赛S8级别100m自由泳冠军王晓福自由泳下肢技术的运动学特征进行分析。结果表明：王晓福自由泳下肢技术属于非常典型的鞭状打水动作;在交替打水阶段他通过加大左腿的动作幅度来帮助控制身体的平衡,他的腿部打水动作是推进力的主要来源;其自由泳的海豚腿打水阶段膝关节的角度较小。  相似文献   

10.
Opportunities for ball passing in water-polo may be brief and the decision to pass only informed by minimal visual input. Since researchers using point light displays have shown that the walking or running gait of familiars can be identified, water-polo players may have the ability to recognize team-mates from their swimming gait. To test this hypothesis, members of a water-polo team and a competition swim team viewed two randomized sets of video clips, each less than one second long, of swimmers from both teams sprinting freestyle past a fixed camera. The arm stroke clip sequence showed only the upper body, and the kick sequence showed only the lower body. After viewing each video clip, observers rated their level of certainty as to whether the swimmer presented was a team-mate or not. Discrimination was significantly above chance in both groups. Water-polo players were better able to identify team-mates from their kick, whereas swimmers were better able to do so by viewing arm stroke. Our results suggest that, as with walking and running gait, small amounts of visual information about swimmers can be used for recognition, and so raise the possibility that specific training may be able to improve team-mate classification in water-polo, particularly in newly formed teams.  相似文献   

11.
We analysed stroke phases and arm and leg coordination during front crawl swimming with and without a wet suit. Twelve nationally and internationally ranked French male triathletes performed three swim trials in randomized order using the front crawl stroke with and without a wet suit. All triathletes swam at three different swim velocities, corresponding to the paces appropriate for the 800?m (V800), 100?m (V100) and 50?m (V50) events. The different stroke phases and arm and leg coordination were identified by video analysis. Arm coordination was quantified using a new index of coordination, which expresses the three major modalities of opposition, catch-up and superposition in swimming. At all swim velocities, no significant differences in leg movements with or without the wet suit were noted. However, the wearing of the wet suit was associated with a significantly greater stroke length at the paces appropriate for the 100 and 50?m events (+3.46% and +3.10% at V100 and V50, respectively; P?<0.01); a significantly greater stroke index at all three velocities (+5.18%, +5.21% and +5.91% at V800, V100 and V50, respectively; P?<0.01); a significantly shorter pulling phase (?10.97%; P?<0.05) and lower index of coordination (?21.87%; P?<0.01) at the pace appropriate for the 800?m; and a significantly greater entry and catch phase (+9.81%; P?<0.05) at the pace appropriate for the 100?m. We conclude that the wet suit amplified the coordination mode of the triathletes (i.e. catch-up coordination) without modifying stroke rate, recovery phase or leg movements.  相似文献   

12.
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   

13.
Objective: Effective warm-ups are attributed to several temperature-related mechanisms. Strategies during the transition phase, preceding swimming competition, have been shown to prolong temperature-related warm-up effects. The purpose of this study was to evaluate the effects of two different clothing strategies during the transition phase, on subsequent 100-m maximal swimming performance. Methods: Nine competitive swimmers (3 female, 21?±?3?yrs; 6 male 20?±?2?yrs, mean performance standard 702 FINA Points, mean 100-m seasons best time 61.54?s) completed their own 30-min individual pool warm-up, followed by 7-min changing time and a 30-min transition phase, straight into a 100-m maximal effort time-trial. During the transition phase, swimmers remained seated, either wearing warm or limited clothing. Swimmers returned 1 week later, where clothing conditions were alternated. Results: Post-transition phase skin and core temperature remained higher in the warm clothing condition compared to the limited clothing condition (Mean Core: 36.90?±?0.17°C, 36.61?±?0.15°C, P?P?P?Conclusion: Wearing warm clothing during a 30-min transition phase improved swimming performance by 0.6%, compared to limited clothing.  相似文献   

14.
The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross-country skiing techniques. Eight skilled male cross-country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross-country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self-selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross-country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross-country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross-country skiing techniques.  相似文献   

15.
Abstract

In this study, we examined the reliability and construct validity of new soccer skills tests. Twenty soccer players (10 professional and 10 recreational) repeated trials of passing, shooting, and dribbling skills on different days. Passing and shooting skills required players to kick a moving ball, delivered at constant speed, towards one of four randomly determined targets. Dribbling required players to negotiate seven cones over 20 m. Each trial consisted of 28 passes, 8 shots, and 10 dribbles. Ball speed, precision, and success were determined for all tests using video analysis. Systematic bias was small (<9% in all measures) and all outcome measures were similar between trials. Test–retest reliability statistics were as follows: ball speed (passing, shooting, dribbling; coefficient of variation [CV]: 6.5%, 6.9%, 2.4%; ratio limits of agreement [RLOA]: 0.958 ×/÷ 1.091, 0.990 ×/÷ 1.107, 0.993 ×/÷ 1.039), precision (passing, shooting, dribbling; CV: 10.0%, 23.5%, 4.6%; RLOA: 0.956 ×/÷ 1.147, 1.030 ×/÷ 1.356, 1.000 ×/÷ 1.068), and success (passing, shooting, dribbling; CV: 11.7%, 14.4%, 2.2%; RLOA: 1.017 ×/÷ 1.191, 0.913 ×/÷ 1.265, 0.996 ×/÷ 1.035). Professional players performed better than recreational players in at least one outcome measure for all skills. These findings demonstrate the reliability and validity of new soccer skill protocols.  相似文献   

16.
The aim of this study was to examine the influence of level of skill and swimming speed on inter-limb coordination of freestyle swimming movements. Five elite (2 males, 3 females; age 18.9+/-1.0 years, height 1.71+/-0.04 m, body mass 62.1+/-7.0 kg) and seven novice (age 22.0+/-2.0 years, height 1.77+/-0.04 m, body mass 74.8+/-9.0 kg) swimmers swam a sprint and a self-paced 25 m freestyle trial. The swimming trials were recorded by four digital cameras operating at 50 Hz. The digitized frames underwent a three-dimensional direct linear transformation to yield the three-dimensional endpoint kinematic trajectories. The spatio-temporal relationship between the upper limbs was quantified by means of the peak amplitude and time lag of the cross-correlation function between the right and left arm's endpoint trajectories. A strong anti-phase coupling between the two arms, as confirmed by peak amplitudes greater than 0.8, was noted for both groups and swimming speeds. Significantly higher (P<0.05) peak amplitudes were observed for the sprint compared with self-paced swimming. No significant differences in the strength of inter-limb coupling were noted between the elite and novice swimmers (P>0.05). Time lags were very close to 0 ms and did not differ between groups or swimming speeds. We conclude that in freestyle swimming, the intrinsic anti-phase (180 degrees phase difference) inter-limb relationship is strongly preserved despite the physically powerful environmental influence of the water and this "preferred" pattern is not affected by level of skill. In contrast, increasing movement speed results in stronger inter-limb coupling that is closer to the anti-phase inter-limb relationship.  相似文献   

17.
The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross‐country skiing techniques. Eight skilled male cross‐country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross‐country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self‐selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross‐country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross‐country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross‐country skiing techniques.  相似文献   

18.
Research to enhance running performance has led to the design of a leaf spring-structured midsole shoe (LEAF). In treadmill running, it has been shown that LEAF led to an increased running economy and increased stride length (SL) through a horizontal foot shift during stance compared to a standard foam shoe (FOAM). The purpose of this study was to analyse whether (a) these findings can also be observed in overground running and (b) relations exist between spatio-temporal variables and running economy. Ten male long-distance heel-strike runners ran at their individual 2?mmol/l blood lactate speed with LEAF and FOAM in randomized order. Kinematic data were recorded with an inertial measurement unit synchronized with 2D video. Oxygen consumption was measured using an automated metabolic gas analysis system. Blood lactate was collected after each run. The strike pattern was unaffected by LEAF. SL was increased by 0.9?±?1.1?cm (95% CI 0.2 to 1.5; p?=?.040; dz?=?0.76), stride rate (SR) was reduced by ?0.4?±?0.3?strides/min (95% CI ?0.6 to ?0.1; p?=?.029; dz?=?0.82) and oxygen consumption tended to be reduced by 1% (?0.4?±?0.6?ml/min/kg; 95% CI ?0.8 to 0.0; p?=?.082; dz?=?0.62) when running with LEAF compared to FOAM. Changes in oxygen consumption in LEAF were correlated with SL (r?=?0.71; p?=?.022) and SR (r?=??0.68; p?=?.031). It can be concluded that LEAF has the potential to cause small changes in spatio-temporal variables during running. Runners increasing SL and decreasing SR in response to LEAF can achieve small improvements in running economy, which is beneficial in terms of performance.  相似文献   

19.
The aims of this study were to compare the physiological demands of laboratory- and road-based time-trial cycling and to examine the importance of body position during laboratory cycling. Nine male competitive but non-elite cyclists completed two 40.23-km time-trials on an air-braked ergometer (Kingcycle) in the laboratory and one 40.23-km time-trial (RD) on a local road course. One laboratory time-trial was conducted in an aerodynamic position (AP), while the second was conducted in an upright position (UP). Mean performance speed was significantly higher during laboratory trials (UP and AP) compared with the RD trial (P < 0.001). Although there was no difference in power output between the RD and UP trials (P > 0.05), power output was significantly lower during the AP trial than during both the RD (P = 0.013) and UP trials (P = 0.003). Similar correlations were found between AP power output and RD power output (r = 0.85, P = 0.003) and between UP power output and RD power output (r = 0.87, P = 0.003). Despite a significantly lower power output in the laboratory AP condition, these results suggest that body position does not affect the ecological validity of laboratory-based time-trial cycling.  相似文献   

20.
1500米自由泳是竞技游泳项目中距离最长的项目。运动员在各分段中速度变化的具体表现能够客观反应其比赛战术。本文运用文献分析法、录像观察法对北京奥运会和山东全运会1500米自由泳决赛运动员的战术进行分析和探讨,分析得出长距离游泳战术类型分为前慢后快、前快后慢、相随、匀速和变速共五种战术。前慢后快战术和变速战术是世界级游泳运动员的常规战术之一。我国游泳运动员应加强后半程的游进能力,加强战术模拟训练,提升赛扬的战术执行能力。  相似文献   

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