Kinematic analysis of butterfly turns of international and national swimmers

The aims of this study were (1) to evaluate the different turn phases of 200 m butterfly during competition in a 50 m pool, (2) to determine if wall contact times are related to swim speed and (3) to compare the turn variables of a European Champion with other swimmers. In the first part of the study, we assessed the turns of 22 swimmers ranked in three groups according to 200 m butterfly swim performance (fast group = 121.73 - 3.03 s, intermediate group = 126.25 - 0.55 s, slow group = 129.24 - 2.30 s). Two turn times were recorded: the first before the turn (i.e. the time it takes the swimmer's head to reach the wall from 7.5 m away) and the second after the turn (i.e. the time from the wall to the point at which the swimmer's head passes 7.5 m away). The third turn was performed significantly faster by the fast group than by the slow group, both before ( P ? 0.01) and after ( P ? 0.02) the turn. In the second part of the study, objectives (2) and (3) were evaluated among 15 swimmers based on a specific protocol. Three cameras (50 Hz) simultaneously recorded the turn; these were placed above the water 10 m before the wall, 5 m before and just above the wall. Longer contact times of the feet on the wall were associated with a faster push-off speed ( P ? 0.02). The European Champion achieved an improved contact time while performing a rapid pull-out speed.     

Comparison of starts and turns of national and regional level swimmers by individualized-distance measurements

The aim of this study was to compare the race characteristics of the start and turn segments of national and regional level swimmers. In the study, 100 and 200-m events were analysed during the finals session of the Open Comunidad de Madrid (Spain) tournament. The “individualized-distance” method with two-dimensional direct linear transformation algorithm was used to perform race analyses. National level swimmers obtained faster velocities in all race segments and stroke comparisons, although significant inter-level differences in start velocity were only obtained in half (8 out of 16) of the analysed events. Higher level swimmers also travelled for longer start and turn distances but only in the race segments where the gain of speed was high. This was observed in the turn segments, in the backstroke and butterfly strokes and during the 200-m breaststroke event, but not in any of the freestyle events. Time improvements due to the appropriate extension of the underwater subsections appeared to be critical for the end race result and should be carefully evaluated by the “individualized-distance” method.     

Kinematic effects of repeated turns while running

Abstract

In team sports, non-contact ACL and MCL injuries occur during abrupt changes of direction, like turns or cutting manoeuvres. Fatigue affects dynamic neuromuscular control and increases knee injury risk. This study analysed how lower limb joints and centre-of-mass kinematics are affected throughout a high-intensity running protocol involving repeated 180°-turns. Twenty young men (18–23 years, BMI: 20.8–24.4?kg?m^?2) completed a 5-m shuttle running trial lasting 5?min at an average speed of 75% of their maximum aerobic speed. During the test, cardio-metabolic parameters were obtained, together with joints and centre-of-mass kinematics, using a motion capture system. Kinematic data were compared between the first and the last minute of exercise. Perceived exercise intensity ranged from “hard” to “maximum exertion” and post-exercise lactate concentration ranged from 5.4 to 15.5?mM. The repetition of 180°-turns induced a substantial reduction of hip (?60%, p?<?.001, large effect) and knee flexion (?40%, p?=?.003, medium-to-large effect), and an increase of hip adduction and internal rotation (+25–30%, p?<?.05, medium-to-large effect). Since such movements are factors increasing the likelihood of non-contact knee injuries, we concluded that the prolonged repetition of turns may expose participants to increased risk of ligament failure. Prevention programmes should include discipline-specific neuromuscular training especially in late practices.     

Kinematic differences between front crawl sprint and distance swimmers at sprint pace

The purpose of this study was to use three-dimensional methods to determine whether there are distinct kinematic differences between sprint and distance front crawl swimmers when swimming at a sprint pace. Seven sprint and eight distance specialists performed four 25-m sprints through a 6.75-m(3) calibrated space recorded by six gen-locked cameras. The variables of interest were: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, shoulder and hip roll angles, duration of stroke phases, and the time corresponding to particular events within the stroke cycle relative to hand entry. Differences between sprint and distance swimmers were assessed with an independent t-test for each variable, in addition to effect size calculations. Differences between sprint and distance front crawl swimmers were generally small and not significant when swimming at a sprint pace. Differences were limited to temporal aspects of the stroke cycle. These findings suggest that coaches should not train sprint and distance specialists differently in terms of technique development.     

Kinematic differences between front crawl sprint and distance swimmers at a distance pace

The purpose of the study was to determine whether there are differences in kinematics between sprint and distance front crawl specialists when swimming at a distance pace using a six beat kick. Seven sprint and eight distance male specialists performed one maximum 400 m swim through a 6.75 m3 calibrated space recorded by six gen-locked cameras. The following variables were calculated: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, the shoulder and hip roll angle, duration of the stroke phases and time corresponding to particular events within the stroke cycle relative to hand entry. Differences between the groups were assessed by an independent t-test and effect size (d) calculations for each variable. The groups only differed significantly with respect to the average swim velocity, with the distance swimmers maintaining a greater velocity throughout the 400 m. However, effect sizes were moderate for elbow angle range during the pull phase (d = 0.78) and the total hip roll magnitude (d = 0.76). There was little evidence to suggest that sprint and distance swimmers using a six beat kick pattern differ in technique when swimming at a distance pace and therefore coaches should not encourage the development of different techniques between these groups.     

黄旭双杠支撑屈体后空翻2周成挂臂动作的运动学分析

通过运动学分析揭示了我国优秀运动员黄旭完成的双杠支撑屈体后空翻2周成挂臂动作的运动学规律和技术特点，为我国运动员发展和改进该类动作提供理论依据和技术参数。     

Kinematic differences between front crawl sprint and distance swimmers at a distance pace

Abstract

The purpose of the study was to determine whether there are differences in kinematics between sprint and distance front crawl specialists when swimming at a distance pace using a six beat kick. Seven sprint and eight distance male specialists performed one maximum 400 m swim through a 6.75 m³ calibrated space recorded by six gen-locked cameras. The following variables were calculated: average swim velocity, stroke length, stroke frequency, upper limb and foot displacement, elbow angle, the shoulder and hip roll angle, duration of the stroke phases and time corresponding to particular events within the stroke cycle relative to hand entry. Differences between the groups were assessed by an independent t-test and effect size (d) calculations for each variable. The groups only differed significantly with respect to the average swim velocity, with the distance swimmers maintaining a greater velocity throughout the 400 m. However, effect sizes were moderate for elbow angle range during the pull phase (d = 0.78) and the total hip roll magnitude (d = 0.76). There was little evidence to suggest that sprint and distance swimmers using a six beat kick pattern differ in technique when swimming at a distance pace and therefore coaches should not encourage the development of different techniques between these groups.     

An analysis of selected kinematic variables in national and elite male and female 100-m and 200-m breaststroke swimmers

The kinematic analysis of competition breaststroke swimming has tended to focus on the mean values of swimming speed, stroke rate and stroke length; values in individual lengths, as well as the start, turns and finish, have largely been ignored. This study includes all such variables and aims to improve the coach's holistic understanding of breaststroke racing by determining the relationships and differences between and within these selected kinematic variables. We also compare 100-m events with 200-m events to determine if there are characteristic differences between them. Competitive breaststroke swimming performances in 100-m events (males: n = 159, finishing time = 65.05 +/- 2.62 s; females: n = 158, finishing time = 74.04 +/- 3.66 s) and 200-m events (males: n = 159, finishing time = 141.47 +/- 6.15 s; females: n = 158, finishing time = 158.66 +/- 7.87 s) were collected and analysed from 12 world, international and national championships. The better 100-m and 200-m breaststroke swimmers were found to demonstrate greater competency in the kinematic variables measured, except stroke kinematics, which were unique to each individual. These findings suggest that coaches should place emphasis on all of the kinematic components in training and that they should attempt to identify the stroke rate to stroke length ratio most appropriate for the individual. Finally, characteristic differences do exist between the 100-m and 200-m events, which has implications for how swimmers might train for each event.     

An analysis of selected kinematic variables in national and elite male and female 100-m and 200-m breaststroke swimmers

The kinematic analysis of competition breaststroke swimming has tended to focus on the mean values of swimming speed, stroke rate and stroke length; values in individual lengths, as well as the start, turns and finish, have largely been ignored. This study includes all such variables and aims to improve the coach's holistic understanding of breaststroke racing by determining the relationships and diff erences between and within these selected kinematic variables. We also compare 100-m events with 200-m events to determine if there are characteristic diff erences between them. Competitive breaststroke swimming performances in 100-m events (males: n = 159, finishing time = 65.05 - 2.62 s; females: n = 158, finishing time = 74.04 - 3.66 s) and 200-m events (males: n = 159, finishing time = 141.47 - 6.15 s; females: n = 158, finishing time = 158.66 - 7.87 s) were collected and analysed from 12 world, international and national championships. The better 100-m and 200-m breaststroke swimmers were found to demonstrate greater competency in the kinematic variables measured, except stroke kinematics, which were unique to each individual. These findings suggest that coaches should place emphasis on all of the kinematic components in training and that they should attempt to identify the stroke rate to stroke length ratio most appropriate for the individual. Finally, characteristic diff erences do exist between the 100-m and 200-m events, which has implications for how swimmers might train for each event.     

Coping strategies and the influence of perceived parental support in junior national age swimmers

This study examines how national junior age group swimmers cope with poor performance and explores whether coping strategy use changes with perceptions of parental support. One hundred and four junior age group swimmers (mean age 14.2 years) completed a modified version of the COPE scale (Crocker & Issack, 1997) and the perceptions of Perceived Parental Support Scale (Van Yperen, 1995). Results showed that the swimmers in this sample used a mixture of behavioural and cognitive strategies with an emphasis upon individual or internally focused approaches. When analysing coping strategies and perceptions of parental support (high, medium and low), significant differences were found in the use of behavioural and cognitively orientated approaches. When perception of parental support was low, swimmers reported using less active and training-orientated mechanisms and a tendency to use strategies such as self-blame and venting of emotion. These findings suggest that the effectiveness and ability of coping strategies to adapt to differing situations may be contingent upon perceptions of perceived support for junior swimmers. This highlights an area for future research.     

我国优秀残疾人游泳运动员特质运动自信心和运动可能自我状况相关研究

采用特质运动员自信心量表(ASCI)及运动可能自我量表(EPSI),对我国优秀残疾人游泳运动员运动任务自信心、运动应对自信心以及目前与未来的可能自我状况进行测查,分别从残疾人运动员心理特征和游泳项目特点两个不同视角,分析自信心与积极的可能自我对于发挥成绩的重要作用,同时探讨特质运动员自信心对运动可能自我预测作用,以此提高我国优秀残疾人游泳运动员训练和参赛的动机,为我国优秀残疾人游泳运动员训练比赛心理的调节提供参考依据.     

我国游泳运动员官能流行病学的调查分析

对我国8省市110名二级以上游泳运动员进行耳、鼻、咽喉官能损伤调查,结果发现损伤发病率高达100%.相关损伤发病率最高的9种疾病依次为:中耳炎、迷路炎、外耳道炎、慢性鼻炎、急性化脓性鼻窦炎、鼻中隔歪曲、慢性咽炎、急性喉炎、慢性上颌窦炎等.疾患以慢性损伤为主,对运动员身体、训练及比赛影响较大.结合游泳运动的特点及游泳运动员的健康状况与培养价值,就发病率较高的9种损伤及其原因进行分析,并依据调查结果提出预防监督建议.     

优秀游泳运动员年龄特征分析

通过对悉尼奥动会、日本福冈世界锦标赛及全国九运会游泳比赛前8名游泳运动员年龄特征的分析，重点追踪典型运动员首次创造最佳运动成绩的年龄，并结合1980年以来历届奥运会，世界游泳锦标赛冠军年龄，对游泳运动员年龄进行全面，客观的研究。     

An analysis of the rollover backstroke turn by age-group swimmers

Kinetic (3-D force plate), kinematic (videography) and temporal characteristics of backstroke turns by 20 male and 16 female swimmers were recorded to identify and describe key elements of backstroke turning performance. Data were recorded during a 50 m maximum effort swim in a 25 metre pool. A Pearson product moment correlation matrix revealed that the 5 m RTT was significantly correlated with anthropometric measures of height, mass, trochanteric height and age; kinetic measures of horizontal impulse and peak force; and kinematic measures of wall contact time and peak velocity. The stepwise multiple regression equation to predict 5 m RTT was: 19.6-0.75 trochanteric height-1.8 wall exit velocity-0.03 peak vertical force. Four key factors were identified from a principle components factor analysis--anthropometry and force, post-turn velocity, force preparation and rotational skills. Implications from the findings were that age-group backstrokers should 'hit the wall hard' with relatively extended legs to reduce swim distance and push-off deceleration; use minimal wall contact time, and maximise forces to develop high horizontal velocities in a streamlined position.     

A 3D kinematic analysis of breathing patterns in competitive swimmers

Abstract

The purpose of this paper was to understand which differences long-term swimming training can cause on trunk mechanics during breathing and how these differences are related to the years of swimming training. The variations and coordination among trunk compartments were considered as target movement patterns. Video-based plethysmography was utilised for data acquisition and pre-processing. A group of swimmers, who followed a long-term intensive swimming training previously to this study, was compared with a non-swimmer control group. The participants of both groups performed quiet breathing and vital capacity tests. From the compartmental volumes associated with each breathing curves, the relative amplitude and cross-correlation among these volumetric time-varying signals were calculated, in order to analyse the relative partial volume variation and the coordination among trunk compartments involved in respiration. The results of a Mixed-ANOVA test (P ≤ 0.05) revealed higher coefficient of variation (P < 0.001) and correlations among trunk compartments in the swimmers group when vital capacity was performed. Significant linear regression was found between the years of swim training and the coefficients of variation and correlation. The results suggest that after long periods of intensive swim training, athletes might develop specific breathing patterns featuring higher volume variations in the abdominal region and more coordination among compartments involved in forced respiratory tasks such as vital capacity.     

Home advantage in southern hemisphere rugby union: national and international

This study evaluates home advantages both for national (Super 12) and international (Tri-nations) rugby union teams from South Africa, Australia and New Zealand, over the five-year period 2000 - 2004 using linear modelling. These home advantages are examined for statistical and practical significance, for variability between teams, for stability over time and for inter-correlation. These data reveal that the overall home advantage in elite rugby union has a mean of +6.7 points, and that this changes little from year to year. Closer scrutiny nevertheless reveals a high degree of variability. Different teams can and do have different home advantages, which ranges from a low of -0.7 to a high of +28.3 points in any one year. Furthermore, some team home advantages change up or down from one year to the next, by as much as -36.5 to +31.4 points at the extremes. There is no evidence that the stronger teams have the higher home advantages, or that a high home advantage leads to a superior finishing position in the competition.     

蹦床网上成套动作连接技术的运动学分析及诊断

采用文献资料、专家访谈和数理统计等研究方法,对蹦床网上成套动作技术进行了综合研究,提出了成套动作连接技术的概念,并从运动学的角度对连接技术各阶段的基本技术进行了分析,提出了主要诊断方法。研究表明,连接技术是蹦床网上成套动作技术环节的主要特征,是成套动作成功与否的关键技术,在蹦床成套动作编排与训练中应引起高度重视。     

Seasonal training and performance of competitive swimmers

To determine the relationship between prescribed training and seasonal-best swimming performance, we surveyed 24 swim coaches and 185 of their age-group and open-class swimmers specializing in sprint (50 and 100 m) and middle-distance (200 and 400 m) events in a summer and winter season. We expressed effects on training as either multiples of swimmers' standard deviations (effect size, ES) or as correlations ( r ). Coaches prescribed higher mileage and longer repetitions of lower intensity to middle-distance swimmers than to sprinters (ES = 0.4-1.5); as competitions approached, repetition intensity and duration of rest intervals increased (ES = 0.5-0.9), whereas session and repetition distances decreased (ES = 0.4-1.3). The 95% likely ranges of the true values for these effects were about - 0.3. Weekly mileage swum at an easy or moderate pace remained at almost 60% of the total throughout both seasons. Interval training reduced gradually from 40% of total distance in the build-up to 30% at the end of tapering. Older swimmers had shorter rests and swam more miles ( r = 0.5-0.8). After partialling out the effects of age on performance ( r = 0.7-0.8), better performance was significantly associated only with greater weekly mileage ( r = 0.5-0.8) and shorter duration of rest intervals ( r = 0.6-0.7) in middle-distance swimmers. Weconclude that periodization of training and differences in training between sprint and middle-distance events were broadly in accord with principles of specificity. Strong effects of specificity on performance were not apparent, but weak effects might have been detected with a larger sample.