52 research outputs found
Effects of different swimming race constraints on turning movements
The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan
Arm–leg coordination during the underwater pull-out sequence in the 50, 100 and 200 m breaststroke start
To investigate the arm-leg coordination from different perspectives of motor control during the underwater start sequence to understand whether differences exist between the three competitive breaststroke swimming events
Arm - Leg coordination profiling during the dolphin kick and the arm pull-out in elite breaststrokers
In breaststroke races, the dolphin kick could finish before, at the same time, or during the arm pull-out, but it is unclear how swimmers perform this technique. The aim of this study was to investigate whether swimmers glide between the dolphin kick and arm pull-out, favour continuity or even overlap those two phases, as it would impact the active underwater sequence. Fourteen international and national male swimmers performed 100-m breaststroke with all-out effort in a pre-calibrated 25 m swimming pool. A multi-camera system tracked the head of the swimmers. Key points of the active underwater sequence were obtained from notational analysis. A hierarchical cluster analysis identified three coordination profiles. All swimmers started their dolphin kick before the arm pull-out. However, one swimmer started the arm pull-out before the end of the dolphin kick, seven swimmers started the arm pull-out after the end of the dolphin kick, and four swimmers synchronised the beginning of the arm pull-out and the end of the dolphin kick, while two other swimmers mixed two coordination profiles among the start and the three turns. Those different profiles allow achieving similar performance outcome, suggesting individual training regarding the underwater phase
Intra- and inter-individual variability in the underwater pull-out technique in 200 m breaststroke turns.
The purpose of the present study was to investigate the intra- and inter-individual variability in arm-leg coordination during the underwater phase of the turn segment in 200 m breaststroke. Thirteen male swimmers were recruited and performed a 200 m breaststroke in a pre-calibrated 25 m pool. Sub-phases during the underwater segment were obtained using a notational analysis, and the mean velocity, displacement and duration during each sub-phase were obtained. A hierarchical cluster analysis (HCA) was performed using the analysed variables in all phases to identify inter-individual variability and random intra-individual variability. In addition, a linear mixed model (LMM: lap as a fixed effect and the participant as a random effect) was conducted to investigate systematic intra-individual variability. HCA identified three coordination patterns that were distinguished by the timing of the dolphin kick relative to the arm pull-out and the duration of the glide with arms at the side. All swimmers except one performed the arm pull-out after the dolphin kick. Nine swimmers maintained one coordination pattern, but other swimmers switched their coordination during the trial, particularly by shortening the duration of the glide with arms at the side. LMM showed a linear decrease (from the first to the last turn) in the time gap between the end of the dolphin kick and the start of the arm pull-out (a glide with the streamlined body position; F = 9.64, p = 0.034) and the glide duration with the arms at the side (F = 11.66, p = 0.015). In conclusion, both inter- and intra-individual variabilities during the underwater phase were evident in 200 m breaststroke turns, which were categorised into three patterns based on the timing of the dolphin kick and the duration of glides
Two-dimensional video analysis in swimming: a tool for scientific purposes and coaching practicest
Two-dimensional video analysis in swimming: a tool for scientific purposes and coaching practices
Technical factors affecting speed fluctuations and performance in the underwater phase of breaststroke
Elite swimming races are usually decided by small margins, with the start and turn often being key determinants of race success. This thesis focuses on the underwater phase of the breaststroke start and turn. The first study used data from international competitions to illustrate that GB breaststrokers have room for improvement in their starts and turns, compared to international competitors. This was followed by a series of experimental studies utilising three-dimensional video to analyse the breaststroke underwater phase (BUP) techniques used by elite and sub-elite GB swimmers.
Participants differed in when they performed the fly kick within the BUP with the majority adopting the separated technique, where the fly kick was initiated and completed prior to Pull-down. In this group, time spent performing the breaststroke kick was the only temporal metric to correlate strongly with BUP performance (10 m time). Significant differences between elite and sub-elite swimmers were found in durations of Arm recovery and Arm to leg recovery.
Correlations were found between BUP performance and mass centre velocity variables in the Fly kick preparation, Pull-down, Glide 2 and Arm + leg recovery phases. Breakout distance, Fly kick preparation phase distance, Arm + leg recovery end of phase distance and Arm + leg recovery minimum velocity distance all correlated strongly with BUP performance.
Elite swimmers showed significantly higher mean velocities than sub-elite during the propulsive phases of the Pull-down and Kick, and the Arm + leg recovery. They travelled significantly further underwater during the complete BUP and during the Fly kick prep/recovery, Fly kick upbeat, and Arm + leg recovery phases. Pull-down hand speed correlated strongly with BUP performance for the combined cohort and was higher in the elite than the sub-elite group.
The thesis concludes by reporting a five-year technical intervention with a World leading breaststroker. The work demonstrated that through multiple, interdisciplinary interventions, positive changes in performance can be effected: the elite breaststroker reduced his breaststroke start time by 0.26 s
The use of technology to improve swimming performance: skill focus
When working with elite swimmers, it is necessary to determine areas in which small changes can result in improved performances during the pinnacle events each year as a culmination of improvements within the daily training environment. The swimming skills of starts and turns comprise approximately 30% of the total race time in events with distances up to 100m (Thayer and Hay, 1984) indicating the importance of skills to overall race performances. Data from the 2011 World Championships is presented to highlight the percentage of race time spent in the start and turn phases for all events. [Continues.
Development and Validity Assessment of the Max Power Model for the Detection, Separation, and Quantification of Differences in Resistive and Propulsive Forces in Swimming
Thesis (PhD) - Indiana University, School of Health, Physical Education and Recreation, 2006Purpose: The purpose of this study was twofold. First, a new method, the Max Power Model, for assessing resistive (Fres) and propulsive (Fprop) forces using tethered swimming was developed. The Max Power Model (MPM) is based on the maximum power that a swimmer can deliver to an external load while swimming (Pmax) and its relationship with the maximum velocity of the swimmer (vmax). The development of the MPM was accomplished in three ways: examination of the shape of the Pmax vs. vmax curve, development of a method of comparing Pmax vs. vmax curves, and finally testing the sensitivity of the method to large changes using the four competitive strokes and underwater dolphin kicking. Second, the validity of the MPM was assessed by comparison with the Velocity Perturbation Model (VPM) and response to independent changes in Fres and Fprop during swimming (as supplied by a pocketed dragsuit, a wetsuit, hand paddles, fist gloves).
Results: The MPM was developed effectively. The Pmax vs. vmax curve was found to be best described as an exponential function. Comparisons of Pmax vs. vmax curves were therefore made after linearization using the natural log of Pmax. If the slopes were similar, the comparisons were accomplished using ANCOVA with vmax as the covariate, otherwise a t-test for differences in slope was used. The MPM was sensitive to large changes in the swimming condition as seen through significant differences (p < 60; 0.05) in an ANCOVA for competitive stroke and a significantly different slope of ln(Pmax) vs. vmax for underwater dolphin kick in comparison with the competitive strokes. Assessment of the validity of the MPM yielded mixed results. The MPM showed a strong relationship to the VPM. However, the VPM showed no significant differences between any of the equipment treatment conditions in either the calculated Fres or the drag coefficient indicating an inability to detect small changes in Fres and Fprop. The MPM showed more promise, responding as expected to a majority of the equipment conditions.
Conclusion: While still in need of further exploration and validation, the MPM has promise as a simple method to detect, separate, and quantify differences in Fres and Fprop during swimming
Biomechanical analysis of backstroke to breaststroke turns in age-group swimmers: An intervention study (The interplay between the kinematics, dynamometric, hydrodynamics and electromyography factors)
Compreender a aquisição de experiência em habilidades de viragens na perspetiva de um jovem nadador em desenvolvimento, geralmente requer o desenvolvimento de uma relação e interação entre as características do movimento efetivo e o processo de ensino-aprendizagem. No entanto, poucas análises biomecânicas de viragens em nadadores de grupos de idade foram conduzidas para facilitar o diagnóstico biomecânico e a intervenção científica em técnicas de viragem nado costas para bruços. Os objetivos desta Tese foram: (1) identificar as características biomecânicas determinantes em cada uma das quatro diferentes técnicas de viragens de nado costas para bruços e (ii) investigar o efeito de 16 treinos de interferência contextuais sistemáticos de 40 minutos cada (quatro semanas), seguido de prática bloqueada, em série e aleatória sobre como facilitar e aprender as técnicas de viragem de nado de costas para nado bruços. Uma abordagem multidisciplinar, incluindo um sistema de captura de movimento, uma plataforma de força tri-axial subaquática personalizada, eletromiografia de superfície (EMG) e uma abordagem dinâmica inversa utilizando variáveis hidrodinâmicas, foi usada para atingir esse objetivo. Começamos (no primeiro estudo) identificando as principais características biomecânicas e determinantes das viragens open, somersault, bucket e crossover. O comportamento eletromiográfico (EMG) e as variáveis cinemáticas selecionadas das quatro técnicas de viragem foram comparadas no segundo estudo, com ênfase particular na eficácia de rotação e no empurrada da parede. O terceiro estudo comparou as características hidrodinâmicas e a estratégia de arrancamento relacionadas à eficácia fase de saída da viragem. O quarto estudo empregou os modelos de aprendizado de máquina linear e baseado em árvore para identificar os modelos altamente realistas de desempenho das viragens com base em variáveis temporais, cinemáticas e cinéticas abrangentes (incluindo hidrodinâmicas). Finalmente, vimos como um programa de intervenção de quatro semanas que ofereceu aumentos sistemáticos na interferência contextual permite que nadadores de grupos de idade melhorem as técnicas de viragens de nado de costas para nado bruços. Os resultados apontaram que um programa de intervenção de quatro semanas melhorou as técnicas de giro de nado de costas para peito de nadadores de grupos de idade. De acordo com os modelos lineares e não lineares previstos, o desempenho de torneamento otimizado foi alcançado por um compromisso e continuidade entre as fases de entrada e saída das viragens. A eficácia de virada foi diretamente influenciada pelas contribuições da velocidade de aproximação à parede e habilidades de rotação na melhoria da velocidade de rolamento e força de empurrão. A atividade eletromiográfica integrada de oito músculos foi semelhante em quatro variantes de rotação, o eretor da espinha e o gastrocnémio medial foram os mais ativados, com viragem crossover tendo os maiores valores de Iemg na rotação e empurre. Uma comparação de medidas cinéticas revela que a viragem bucket tem um pico de força mais alto, enquanto um impulso horizontal mais alto leva a uma velocidade de empurre mais alta na viragem crossover. A viragem somersault apresentou um deslizamento ligeiramente mais profundo, enquanto as características hidrodinâmicas e a estratégia de saída, como determinantes da eficácia da saída na viragem, não diferiram significativamente entre as quatro técnicas de viragem.
PALAVRAS-CHAVE: NATACAO, FAIXAS ETARIA, BIOMECHANICA, VIRAGENSUnderstanding the acquisition of expertise in turning skills from the perspective of a developing young swimmer generally requires the development of a relationship and interaction between characteristics of effective movement and the teaching-learning process. However, few turning biomechanical analyses on age-group swimmers have been conducted to facilitate biomechanical diagnosis and scientific intervention in backstroke to breaststroke turning techniques. The objective of this Thesis were twofold: (i) to identify the biomechanical features that have the greatest influence in each of the four different backstroke to breaststroke turning techniques and (ii) to investigate the effect of four weeks and 16 systematically contextual interference training sessions of 40 minutes each, followed by blocked, serial, and random practice on facilitating learning of the backstroke to breaststroke turning techniques. A multidisciplinary approach, including a motion capture system, a customized underwater tri-axial force plate, surface electromyography (EMG) and an inverse dynamic approach utilizing hydrodynamic variables, was used to accomplish this goal.
We began (in the first study) by identifying the key biomechanical features and determinants of open, somersault, bucket, and crossover turning performance. The electromyographic (EMG) behavior and selected kinematic variables of the four backstroke to breaststroke turning techniques were compared in the second study, with a particular emphasis on rotation and push-off efficacy. The third analysis compared the hydrodynamic characteristics and pull-out strategy related to turn out efficacy. The fourth study employed the linear and tree-based machine learning models to identify the highly realistic models of backstroke to breaststroke turn performance based on comprehensive temporal, kinematic, kinetic (including hydrodynamic) variables. Finally, we looked at how a four-week intervention program that offered systematic increases in contextual interference allows age-group swimmers to improve backstroke to breaststroke turning techniques. Results pointed out that a four-week intervention program improved age-group swimmers' backstroke to breaststroke turning techniques. According to the linear and nonlinear predicted models, optimized turning performance was achieved by a compromise and continuity between the turn-in and turn-out phases. Turn-in efficacy
was directly influenced by the contributions of approaching velocity to the wall and rotating abilities in improving rolling velocity and pushing-off force. The integrated electromyographic activity of eight muscles was similar across four turning techniques. The erector spinae and gastrocnemius medialis were the most activated muscles, with the crossover turn having the highest rotation and push-off iEMG values. A comparison of kinetic measures reveals that the bucket turn has a higher peak force, while a higher horizontal impulse leads to higher push-off velocity in the crossover turn. The somersault has a slightly deeper gliding depth, while hydrodynamic characteristics and pull-out strategy, as determinants of turn-out efficacy, did not differ between turning techniques
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