KINEMATICAL ANALYSIS OF THE SWIMMING START: BLOCK, FLIGHT AND UNDERWATER PHASES

The purpose of this study was to analyze, through kinemetry, the block, flight and underwater phases of the swimming start. The sample was composed by 4 swimmers. Four VHS video cameras were used. Analyzed variables: block time, flight time and distance, angle of entry, maximum depth achieved, time, distance and average velocity of the underwater phase and total start time in 15 meters. Pearson’s correlation was used to verify the relationship between the variables.Flight distance, angle of entry, depth achieved and average velocity under teh water presented significant correlation with the starting time (r = -0.482, 0.512, 0.515 and -0.645, respectively), being all important factors to be observed by athletes and coaches, who should look forward to reach best values of the variables in order to improve the execution of swimming starts

INSTRUMENTATION AND PADDLE RACKETS

Tennis rackets have long been studied, but just recently attention has been focused on paddle rackets. Knowledge of racket characteristics and properties will contribute to its improvement, better athletic performance and, most important, injury prevention. Compromise between a high coefficient of restitution and vibration absorption should be achieved. Paddle rackets are suitable to accept surface bonded sensors, thus making electronic instrumentation an efficient way to investigate mechanical problems such as impacts, vibrations, strains, and so on. The aim of this paper is the description of an instrumentation setup designed to investigate some important mechanical characteristics upon paddle rackets. Coefficient of restitution for a constrained racket setup was determined using a pneumatic ball cannon and a lab-designed laser and photo diode reflective window. The cannon shot was adjusted in order to provide ball speeds within expected competition values. The laser window consisted of a wooden frame with a pair of parallel mirror strips facing each other, reflecting a zigzag laser beam provided by a low power pointing device. The zigzag beam detected light interruptions during the ball passing through, anywhere inside the window. Processed and analyzed, the signal informed about the time interval between pre and post ball impact on the racket. Speeds could thus be calculated and used with the appropriate formulae to obtain the coefficients of restitution. Piezoelectric transducers were bonded to the racket surface and handle. Held by a wire, in a vertical position, rackets were hit by a magnetically driven hammer, at different heights on the longitudinal axis of symmetry, allowing us to locate vibration nodes. Two of them were detected; the first at about 110 mm from the free racket end and the second on the handle. These nodes are points which once impacted excite the lowest amplitude vibrations in the structure. Associated with suitable theory, our results are contributing to paddle racket improvements. New rackets have been designed taking those results into account. A hollow racket is an example; Laboratory tests have shown that the coefficient of restitution is higher and vibrations lower than those of compact rackets, as a consequence better performance and a reduction in injury are expected

INSTRUMENTAÇÃO E CALIBRAÇÃO DO APARELHO REFORMER DO MÉTODO PILATES PARA ANÁLISES BIOMECÂNICAS

Acompanhando programas de exercício em voga nosúltimos anos, observa-se que o método Pilates destaca-se.  Na contramão da sua popularidade, verifica-sefalta de informações quantitativas para a prescrição e progressão dosexercícios do método, que são subsídios importantes, em especial, para areabilitação. Este estudo tem como objetivo primário construirduas plataformas de força extensométricas, de baixo custo, para serem adaptadasao aparelho Reformer, do métodoPilates – o mais utilizado dos aparelhos; o segundo, realizar a calibraçãodesses instrumentos e determinar sua acurácia. Esse instrumento foi construídopara medir forças vertical e horizontal de membros inferiores durante exercíciosem cadeia cinética fechada, sobre o aparelho Reformer. Esse instrumento foi calibrado e testado e pode serconsiderado um aparato promissor para análises biomecânicas

LOAD DURING THE VERTICAL JUMP IN WATER: VALUES FOR PRESCRIPTION IN HYDROTHERAPY

This study aimed to analyse the vertical component of the ground reaction force (GRF) in the vertical jump in water performed by men and women at two levels of immersion. 11 men and 11 women performed three vertical jumps on a water-proof force plate at hip and chest levels of immersion. No effect of gender was observed. No difference between levels of immersion was found for peak of propulsion [1.85 and 1.89 units of body weight (BW) at the hip and chest respectively]. During the landing phase, the force peak was significantly higher at the hip level (2.62 BW) than at the chest level (2.07 BW). The force during the propulsion phase was similar between the immersions; however the vertical load on landing needs to be considered when prescribing this exercise, even in water

COMPARISON OF GROUND REACTION FORCES BETWEEN IN-PLACE AND FORWARD WATER RUNNING AT TWO LEVELS OF IMMERSION

This study compared GRF of in-place and forward water running at two levels of immersion. Twenty healthy subjects executed both exercises at a self selected speed at hip and chest immersion. Variables analyzed were: vertical peak (Fy), anterior peak (Fx anterior) and posterior peak (Fx posterior). Two-factor repeated measures ANOVA was used with

A DYNAMOMETRIC METHOD FOR THE EVALUATION OF HIKING IN LASER BOATS

This study aimed to develop a dynamometric method for the evaluation of hiking in Laser boats. The boat’s and sailor’s centres of mass, the hiking distance and the hiking moment were calculated from the ground reaction force, acquired by two force plates located under the boat hoof. Three sailors performed different hiking positions varying their hip and knee angles. Pearson’s coefficient was used to verify the correlation between the measures obtained through the dynamometric method and a kinematic method. A very high correlation was observed between the methods (r=0.99) and the mean error was approximately 1% for both hiking distance and moment. Thus, the new method seems to be valid and efficient since it measured the variables in a fast and precise way, facilitating the analysis and assisting sailors and coaches on decision taking

BIOMECHANICAL ANALYSIS OF SPINE MOVEMENTS IN HIKING ON SAILING: A PRELIMINARY STUDY

This study aimed to evaluate sailors’ vertebral spine movements and positioning during hiking position. One Laser Class sailor composed the sample. Four 60Hz Peak Motus System® cameras were used. To evaluate some spine angles the following points were chosen: in saggital plane - the neck flexion angle, thoracic kiphosis angle and lumbar lordosis angle; in frontal plane – the lateral inclination angle; in transversal plane – the trunk rotation. Data were analysed through descriptive statistics. The analysis shows great angle variations performed in a 10s hiking execution. It can be observed that the sailor’s trunk performs, in the three axes, a sum of movements during the technical gesture. It was demonstrated that hiking is not a static posture and to study this position researchers should not consider trunk as a fixed segment

Diferentes perspectivas da ação de membros inferiores nos quatro nados competitivos: uma revisão integrativa

It is currently known that the speed of swimming is a function of the propulsion generated from the lower limbs and not just the upper limbs. However, for years the action of the legs, during swimming, had its importance mitigated. Thus, the objective of this work was to raise, by means of an integrative literature review, the state of the art regarding the importance of the lower limbs in swimming. This research was delimited in the action of surface legs and underwater legs, excluding the analysis of exits and turns. Studies indexed in the following databases were analyzed: Web of Science, PubMed, Scopus, Lilacs and SciELO. The search system included reading of titles, abstracts and articles in full, found through blocks of descriptors that combined main and secondary terms. A total of 154 articles were found, of which 55 were included for qualitative analysis. The results showed that studies on the use of the lower limbs in swimming have a low sample value and a heterogeneous description of the levels of the participants. Breaststroke and underwater swells are the most studied variables. It is recommended to examine the effectiveness of other anthropometric, kinematic and coordination variables to better understand the production of maximum speed and to consider the importance of individual techniques in the action of the legs in swimming. Still, in the field of using the lower limbs in swimming, there are some gaps, which the articles themselves point out. These demands are due to the strength generated by these segments, in addition to the discussion of the importance of considering individual factors in the action of the legs for swimmers.Atualmente se sabe que a velocidade da natação é uma função da propulsão gerada a partir dos membros inferiores e não apenas dos membros superiores. No entanto, por anos, a ação das pernas, durante o nado, teve sua importância mitigada. Dessa forma, o objetivo deste trabalho foi levantar, por meio de uma revisão integrativa da literatura, o estado da arte acerca da importância dos membros inferiores na natação. Esta pesquisa foi delimitada na ação das pernas de superfície e pernas subaquáticas, excluindo-se as análises das saídas e viradas. Foram analisados estudos indexados nas seguintes bases de dados: Web of Science, PubMed, Scopus, Lilacs e SciELO. A sistematização de busca incluiu leitura de títulos, resumos e artigos na íntegra, encontrados por meio de blocos de descritores que combinaram termos principais e secundários. Um total de 154 artigos foi encontrado, dos quais 55 foram incluídos para análise qualitativa. Os resultados mostraram que os estudos sobre a utilização dos membros inferiores na natação possuem baixo valor amostral e descrição heterogênea dos níveis dos participantes. O nado peito e as ondulações subaquáticas são as variáveis mais estudadas. Preconiza-se examinar a eficácia de outras variáveis ​​antropométricas, cinemáticas e de coordenação para entender melhor a produção da velocidade máxima e considerar a importância de técnicas individuais na ação das pernas na natação. Ainda, no campo da utilização dos membros inferiores na natação, existem algumas lacunas, as quais os próprios artigos apontam. Essas  demandas ficam por conta da força gerada por esses segmentos, além da discussão da importância em se considerarem fatores individuais na ação das pernas para os nadadores

COMPARATIVE ANALYSIS OF TEMPORAL PARAMETERS OF DIFFERENT TECHNIQUES OF THE FREESTYLE FLIP TURN

This study aimed to describe and compare temporal parameters of four different turning techniques of Freestyle swimming flip turn. 17 national level swimmers participated in this study. After practicing sessions, the swimmers performed three times each of the four analyzed techniques. Performance was videotaped using six video cameras and the analyzed variables were: rolling time, wall contact time, pushing time, gliding time and total turn time. No differences were found between the techniques for any variable. Apparently, the choice of the technique can be made accordingly to the swimmer’s subjective preference, or based on the objective performance differences casuistically sustained. However, future studies are needed and additional performance indicators should be analyzed to provide a better understating regarding the different technique

Predição da força de reação do solo durante a corrida na água

Este estudo visou desenvolver um modelo para a predição da força de reação do solo na corrida subaquática. Participaram 20 sujeitos (9 homens e 11 mulheres), que realizaram corrida subaquática em dois níveis de imersão e três velocidades. Para cada sujeito foram coletadas seis passagens válidas em cada condição, com a utilização de uma plataforma subaquática de força. O modelo para predição da força foi construído por regressão linear múltipla. Foram consideradas variáveis dependentes a componente vertical e a componente ântero-posterior da força de reação do solo. As variáveis imersão, sexo, velocidade, massa corporal, densidade corporal e percentual de gordura foram consideradas independentes. Permaneceu no modelo final de regressão para a componente vertical a velocidade (pThis study aimed at developing a model to predict ground reaction force during deep-water running. A total of 20 subjects ((9 men, 11 women) ran in water at two immersion levels and three different speeds. Each subject performed six valid trials in each condition, data being captured by an underwater force plate. The force prediction model was build by multiple linear regression. Dependent variables were the vertical and anteroposterior components of the ground reaction force; independent variables were runners' immersion, sex, speed, body mass, body density, and percentage of fat. At the final regression model for the vertical component, only speed remained (