Kinematic analysis of the backstroke start: differences between backstroke specialists and non-specialists

Abstract

The purpose of this study was to clarify factors to perform the hole-entry technique in the backstroke start. A total of 16 well-trained Japanese competitive swimmers were divided into two groups (backstroke specialists and non-specialists) to compare their backstroke start motions. Their backstroke motions were videotaped, and two-dimensional co-ordinates for the swimmers were obtained from the video images using direct linear transformation methods. A non-paired t-test and Mann–Whitney U-test were used to analyse the statistical difference of the kinematic variables between the groups. Backstroke specialists showed a significantly shorter 5 m time (P = 0.009, effect size = –1.54), a significantly higher position of the toe (P = 0.010, effect size = 1.47) at signal and of the hip at toe-off (P = 0.002, effect size = 1.94), a significantly larger hip joint angle at toe-off (P = 0.007, effect size = 1.60) and a significantly higher angular velocities of the hip joints (45–85%; P < 0.05) for the normalised time as compared to that of non-specialists. An earlier initiation of the extension and the maintenance of a higher extension speed at the hip joints were important factors in achieving an arched-back posture, which facilitated and water entrance with a small entry range.     

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。     

Stroke-coordination and symmetry of elite backstroke swimmers using a comparison between net drag force and timing protocols

Abstract

Stroke-coordination and symmetry influence the force fluctuations within any net drag force profile. The aim of this study was to analyse elite (FINA points 938) backstroke swimmers stroke-coordination using an instantaneous net drag force and timing protocols using a symmetry index tool. Ten male and nine female elite backstroke swimmers completed three maximum speed trials and five maximum speed net drag force swimming trials. Net drag force was measured using an assisted motorised dynamometer device. Each trial was filmed using three genlocked 50 Hz cameras, synchronised to the net drag force output from the force-platform. This methodology enabled the comparison of stroke-coordination timing symmetry index to net drag force symmetry index. The timing symmetry index and net drag force symmetry index yielded different results, the timing reflects the stroke-coordination, whilst the force index identified the effectiveness of the stroke. The only variable that was significantly different when comparing left and right stroke patterns was the location of minimum net drag forces. Conversely, gender influenced the location of maximum net drag force. Relationship analysis identified that location of maximum net drag force production was the only variable to correlate with speed within this cohort. Backstroke arm coordination was minimally influenced by gender.     

游泳运动员高原训练部分生理、生化指标的变化分析

高原训练可以提高运动员的运动能力,应用血氧饱和度、晨脉、体重及部分血液指标对高原训练进行科学的监控,可以了解运动员对运动训练的适应和恢复情况。     

广东省男子短距离自由泳一级运动员划臂技术分析

采用文献资料法、录像分析法、专家访谈法和数理统计法,对广东省男子短距离自由泳运动员的技术动作进行研究,以期为提高广东省男子短距离自由泳运动员的技术水平提供参考.     

湖北省优秀仰泳运动员赵菁的比赛成绩与技术的多维分析

采用文献资料、比较分析、数理统计等研究方法,对湖北省优秀仰泳运动员赵菁的比赛成绩与技术进行多维度分析比较,从中找出薄弱环节,为备战2009年全运会提供参考.     

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.     

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.     

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.     

篮球比赛反败为胜案例的分析与研究--决胜时刻的技战术分析

通过运用文献资料、录像观察、专家访谈、逻辑分析等研究方法,以最后时刻决定胜负的44场比赛及2012-2013赛季 NBA 季后赛的2场比赛为研究对象,并结合笔者所执教的山东财经大学男篮两场成功和失败案例,对决胜时刻的反败为胜做分析,分析出篮球比赛反败为胜时刻影响攻守技战术运用的因素：教练员因素、时间因素、比分因素、核心队员是否上场等。通过对比赛决胜时刻技战术的研究,探索出篮球比赛中落后队伍反败为胜的经验和影响因素,使篮球反败为胜时刻的攻防技战术应用有可靠的理论依据,对反败为胜时刻的攻防技战术应用具有极强的实战指导意义,从而使得篮球比赛更为精彩。     

Backstroke start performance: the impact of using the Omega OBL2 backstroke ledge

FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras. Starts performed with the OBL2 had a 0.13 s lower time to 10 m, 2.5% less variability in time to 10 m and 0.14 m greater head entry distance. The OBL2 provides a performance advantage by allowing an increased head entry distance rather than larger horizontal impulse on the wall. This may be due to the swimmers assuming different body positions during the start manoeuvre. Additional studies are needed to evaluate factors that contribute to improved performance when using the OBL2. Swimmers should train with the OBL2 and use it in competition to ensure optimal start performance.     

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.     

我国大众体育今后发展的理论转向

结合大众体育理论文献与我国现实存在的问题,对大众体育的本质核心进行了重新定位,并对以往研究中存在的问题进行了反思。提出以下几点理论转向：1）在发展中注重考察、分析和迎合参与者的差异性。2）对部分人群的体育评价标准和推广策略进行科学的调整,以推动大众体育的普及。3）建立以社区为单位,临近社区统筹互补的结构规划模式。     

乌鲁木齐都市体育圈构建的理论分析

在旅游资源的密集区，构建都市体育圈，从而发展区域体育旅游，建立体育产业与相关产业融合发展的平台，是当前一大趋势。依托乌鲁木齐都市圈，构建乌鲁木齐都市体育圈，探讨了乌鲁木齐都市体育圈概念、内涵和意义，分析了构建乌鲁木齐都市体育圈的条件，从指导思想、空间布局、形象定位、发展模式、建设内容5个方面提出了总体构想。