Biomechanical determinant factors in tennis forehand drive

The forehand drive in tennis is considered essential in the performance of athletes. Despite several studies in biomechanics, there are unexplored issues and methodologies that may contribute to a better understanding of the key factors in performance and greater efficiency to capture kinematic data contributing to a positive impact for tennis players. Therefore, the first study aimed to compare the contribution of the upper limb to racket speed among intermediate and experienced tennis players. The results showed that what differentiate the two groups is the contribution of the shoulder to the racket head velocity. In order to use the same method with elite athletes in real situation with a simpler methodology, the second study aimed to validate an inertial measurement unit system. The results of this study demonstrated a high degree of confidence to collect kinematic data in the forehand drive. After this validation, in the third study we determined the contribution of the upper limbs to the racket head velocity in elite players, in the field. The results showed some differences when compared to previous studies using the same methodology, these differences may be related to the level of the players or the type of the stroke. Finally, the fourth study aimed to determine the moments of force of the dominant upper limb between a forehand in a quasi-static stance and a dynamic frontal weight transfer stance forehand. The results showed a higher load on the joints during the forehand in quasi-static stance. We can conclude that the results obtained during the various studies may contribute to a greater knowledge of coaches to help athletes to achieve a better performance in the forehand drive, as well as health professionals to understand which techniques may be associated with a higher load on the joints.O batimento de direita no ténis é considerado decisivo na performance dos atletas. Apesar de vários estudos ao nível da biomecânica, existem questões e metodologias inexploradas que poderão contribuir para uma melhor compressão de fatores chave na performance dos tenistas. O primeiro estudo teve como objetivo comparar a contribuição do membro superior para velocidade da raquete entre jogadores de nível intermédio e experientes. Os resultados demonstraram que o que diferencia os dois grupos é a contribuição do ombro para a velocidade da cabeça da raquete. Para utilizarmos o mesmo método com atletas de elite em situação real e com uma metodologia menos pesada do ponto de vista da sua preparação, o segundo estudo teve como objetivo validar um sistema de sensores inercias. Os resultados deste estudo demonstraram que podemos recolher com confiança os dados cinemáticos neste movimento através de um sistema de sensores inerciais. Após esta validação, no terceiro estudo determinámos a contribuição dos membros superiores para a velocidade da cabeça da raquete em jogadores de elite, no campo. Os resultados demonstraram algumas diferenças quando comparados com estudos prévios utilizando a mesma metodologia, estas diferenças poderão estar relacionadas com a diferença do nível de jogadores ou o tipo de batimento. Por último, o quarto estudo teve como objetivo determinar os momentos de força do membro superior dominante entre um batimento apoiado e um batimento dinâmico. Os resultados demonstraram uma maior carga nas articulações durante o batimento em apoio. Podemos concluir que os resultados obtidos durante os vários estudos poderão contribuir para um maior conhecimento dos treinadores no sentido de ajudar os atletas a atingir uma melhor performance no batimento de direita, bem como os profissionais de saúde a perceber quais os batimentos que poderão estar associados a uma maior carga nas articulações

Sports Performance and Health

Sports performance is primarily associated with elite sport, however, recreational athletes are increasingly attempting to emulate elite athletes. Performance optimization is distinctly multidisciplinary. Optimized training concepts and the use of state-of-the-art technologies are crucial for improving performance. However, sports performance enhancement is in constant conflict with the protection of athletes’ health. Notwithstanding the known positive effects of physical activity on health, the prevention and management of sports injuries remain major challenges to be addressed. Accordingly, this Special Issue on "Sports Performance and Health" consists of 17 original research papers, one review paper, and one commentary, and covers a wide range of topics related to fatigue, movement asymmetries, optimization of sports performance by training, technique, and/or tactics enhancements, prevention and management of sports injuries, optimization of sports equipment to increase performance and/or decrease the risk of injury, and innovations for sports performance, health, and load monitoring. As this Special Issue offers several new insights and multidisciplinary perspectives on sports performance and health, readers from around the world who work in these areas are expected to benefit from this Special Issue collection

Quantifying the functional role of discrete movement variability: Links to adaptation and learning

Introduction: Movement variability can be defined as the variance in human movement from one trial or cycle to the next, often when attempting to maintain dynamic equilibrium (in the case of continuous skills) or achieve consistent movement outcome (for discrete skills). Some theoretical perspectives of motor control consider movement variability to be deleterious. However, the dynamical systems perspective proposes beneficial and functional roles for movement variability. Within this view variability has developed as an independent theme of research that has gained momentum over the past 25 years, attracting focus from various sub-disciplines within the field with a major contribution from sports biomechanics. The previous research within the field of movement variability has proposed that these functional roles include reducing the risk of injury, enabling coordination change and facilitating adaptation to varying task or environmental constraints. This thesis is primarily constituted of four sequential studies designed to further the method-related approach to, and theoretical understanding of, the interaction between variability in discrete movement and adaptation

El uso de la tecnología de captura de movimiento para el análisis del rendimiento deportivo

In sport performance, motion capture aims at tracking and recording athletes’ human motion in real time to analyze physical condition, athletic performance, technical expertise and injury mechanism, prevention and rehabilitation. The aim of this paper is to systematically review the latest developments of motion capture systems for the analysis of sport performance. To that end, selected keywords were searched on studies published in the last four years in the electronic databases ISI Web of Knowledge, Scopus, PubMed and SPORTDiscus, which resulted in 892 potential records. After duplicate removal and screening of the remaining records, 81 journal papers were retained for inclusion in this review, distributed as 53 records for optical systems, 15 records for non-optical systems and 13 records for markerless systems. Resultant records were screened to distribute them according to the following analysis categories: biomechanical motion analysis, validation of new systems and performance enhancement. Although optical systems are regarded as golden standard with accurate results, the cost of equipment and time needed to capture and postprocess data have led researchers to test other technologies. First, non-optical systems rely on attaching sensors to body parts to send their spatial information to computer wirelessly by means of different technologies, such as electromagnetic and inertial (accelerometry). Finally, markerless systems are adequate for free, unobstructive motion analysis since no attachment is carried by athletes. However, more sensors and sophisticated signal processing must be used to increase the expected level of accuracy.En el ámbito del rendimiento deportivo, el objetivo de la captura de movimiento es seguir y registrar el movimiento humano de deportistas para analizar su condición física, rendimiento, técnica y el origen, prevención y rehabilitación de lesiones. En este artículo, se realiza una revisión sistemática de los últimos avances en sistemas de captura de movimiento para el análisis del rendimiento deportivo. Para ello, se buscaron palabras clave en estudios publicados en los últimos cuatro años en las bases de datos electrónicas ISI Web of Knowledge, Scopus, PubMed y SPORTDiscus, dando lugar a 892 registros. Tras borrar duplicados y análisis del resto, se seleccionaron 81 artículos de revista, distribuidos en 53 registros para sistemas ópticos, 15 para sistemas no ópticos y 13 para sistemas sin marcadores. Los registros se clasificaron según las categorías: análisis biomecánico, validación de nuevos sistemas y mejora del rendimiento. Aunque los sistemas ópticos son los sistemas de referencia por su precisión, el coste del equipamiento y el tiempo invertido en la captura y postprocesado ha llevado a los investigadores a probar otras tecnologías. En primer lugar, los sistemas no ópticos se basan en adherir sensores a zonas corporales para mandar su información espacial a un ordenador mediante distintas tecnologías, tales como electromagnética y inercial (acelerometría). Finalmente, los sistemas sin marcadores permiten un análisis del movimiento sin restricciones ya que los deportistas no llevan adherido ningún elemento. Sin embargo, se necesitan más sensores y un procesado de señal avanzado para aumentar el nivel de precisión necesario

A Biomechanically Based Observational Tennis Serve Analysis Method Can be Used to Assess Serve Mechanics

Traditional sports science motion analysis techniques using three-dimensional (3D) kinematics have demonstrated that proper mechanics enhance serve performance and improper mechanics overload tissues resulting in injury. However 3D analysis is costly, time-consuming, and requires extensive knowledge of biomechanical properties and data analysis. Currently there are no simple, reliable, and valid observational methods for health care providers (HCP) and tennis professionals to evaluate tennis serve mechanics. Researchers investigating observational analyses have determined that superior reliability may be a result of specific operational definitions and the incorporation of educational training sessions on how to perform the analysis. The first purpose of this dissertation was to investigate the reliability of an observational tennis serve analysis (OTSA) tool between two HCPs that helped create the analysis method. The OTSA assesses nine key body positions/motions during the service motion. These specific body positions have been called “nodes.” The second purpose was to determine the OTSA reliability in a group of novice users unfamiliar with the analysis method undergoing two different forms of instructional training. The third purpose was to determine the discriminant and convergent validity of the OTSA in grading tennis serve mechanics among tennis players using the national tennis ranking program commonly used in the United States to evaluate level of tennis play. The first study demonstrated that reliability of the OTSA ranged from 0.36-1.0 across the nodes, with five out of the nine nodes displaying substantial reliability (\u3e0.61). In the second study results demonstrated there were no statistical differences in the intra-observer reliability values between the two instructional training groups. Additionally, the majority of the inter-observer kappa values were not statistically different between the two instructional training groups. In the third study, six of the nine nodes were able to discriminate between high and low ranked tennis players. Additionally, there was a strong correlation between the OTSA and ranking level, indicating that there is convergent validity and supports the construct of the OTSA as deficits in the service motion are associated with lower ranked tennis players. These results suggest that nearly all of the nodes associated with the OTSA are reliable and valid and can be used to assess tennis serve mechanics

DEVELOPMENT OF A TEST DEVICE TO MEASURE THE TRIBOLOGICAL BEHAVIOUR OF SHOE-SURFACE INTERACTIONS IN TENNIS

The aim of this thesis was to better understand the tribological mechanisms that occur during typical player movements, build further on this understanding and develop a robust, portable device to assess the friction characteristics of tennis surfaces that relate to playing performance and safety. To understand the tennis player’s response and adaptability to a tennis court surface, including friction in the shoe-surface interface, a series of friction experiments were carried out on three categories of tennis surface, grass, clay and hardcourt. For grass, parameters such as moisture, level of wear and height were found to have an effect on the shoe-surface friction. For clay, influence of clay particle size and the infill volume was established. In terms of biomechanical conditions, it was found that the shoe orientation during a slide affects the friction. It was demonstrated that matching applied pressures is a useful approach for shoe friction testing and analysis. Through video analysis, shoe landing and sliding were found to be two possible ‘risk’ movements. Material characterisation, combined with friction and temperature measurements have provided empirical knowledge into the manner in which shoes and surfaces behave. During a slide on hardcourts, temperature changes were found to be different along a shoe outsole. The front part experienced higher change of temperature compared to other positions. Three types of bespoke tread samples were produced and tested, resulting a ‘holed sample’ the optimal to use. These samples resulted relatively easy to manufacture and generate frictional results compared to tennis shoes. The final robust portable device resulting from this study, measures the friction characteristics of the shoe-surface interface representative of match-play tennis. The device can be used in two configurations to replicate a shoe landing and a sliding movement. The test shoe consists of a commercial rubber with a bespoke tread design with mechanical properties that match typical values to a tennis shoe. This device will aid the International Tennis Federation (ITF) and the sports surface research community to gain understanding of player-shoe-surface frictional interactions, and allow courts to be monitored around the world

Development and Application of 3D Kinematic Methodologies for Biomechanical Modelling in Adaptive Sports and Rehabilitation

Biomechanical analysis is widely used to assess human movement sciences, specifically using three-dimensional motion capture modelling. There are unprecedented opportunities to increase quantitative knowledge of rehabilitation and recreation for disadvantaged population groups. Specifically, 3D models and movement profiles for human gait analysis were generated with emphasis on post-stroke patients, with direct model translation to analyze equivalent measurements while horseback riding in use of the alternative form of rehabilitation, equine assisted activities and therapies (EAAT) or hippotherapy (HPOT). Significant improvements in gait symmetry and velocity were found within an inpatient rehabilitation setting for patients following a stroke, and the developed movement profiles for patients have the potential to address patient recovery timelines. For population groups, such as those following a cerebral incident, alternative forms of rehabilitation like EAAT and HPOT are largely unexplored. Within these studies, relevant muscular activations were found between healthy human gait and horseback riding, supporting the belief that horseback riding can stimulate similar movements within the rider. Even more, there was a strong correlation between the horse’s pelvic rotations, and the responsive joint moments and rotations of the rider. These findings could have greater implications in choosing horses, depending on the desired physical outcome, for EAAT and HPOT purposes. Similar approaches were also used to address another biomechanically disadvantage population, adaptive sport athletes. Utilizing similar methodologies, a novel 3D wheelchair tennis athlete model was created to analyze match-simulation assessments. Significant findings were present in the energy expenditure between two drill assessments. Overall, the quantitative results, coupled with the qualitative assessment chapter, provide a robust assessment of the effects of 3D movement analysis on rehabilitation and adaptive activities

The feasibility of sports grips customisation using rapid manufacturing methodologies

In many sports where an implement is used to strike a ball, the grip is typically the sole point of contact between the player and implement. The grip significantly influences how a player wields an implement and is also a means for a player to experience impact forces and vibration. This transmission of force and vibration to the hand can affect a player's control, perception of the equipment, and also expose a player to injury or provoke degeneration of existing maladies. In general, the grip is the least expensive component of an implement. Little development over the previous two decades has been invested on the grip when compared to the vast changes in design, geometry and materials used in the implements which they are attached to. The development and flexibility of a group of manufacturing processes collectively known as rapid manufacturing have begun to introduce customised products to the mass-market. The main advantage of rapid manufacturing processes is the lack of tooling required, allowing parts to be produced directly from 3D CAD models using an expanding range of polymers and other materials. The integration of rapid manufactured parts into recreational sports equipment has not previously been attempted and is the focus of this work, with tennis selected as the candidate sport. [Continues.

Subjective and objective assessment of tennis racket performance play

Assessment of wielded implement performance is important to a variety of human endeavours and often critical to success in a sports context, particularly so in the game of tennis. Tennis racket design and manufacture is a multimillion business involving 10 major international companies. Tennis participation is currently estimated at around 60 million individuals worldwide. Thus the importance of optimum racket performance to maximise competitive advantage and minimise the risks of injury is clear. This thesis presents work to enable advances in tennis racket performance with respect to player feel perception, measurement of physical phenomena and the correlation of these aspects within real play contexts. To investigate feel perception a methodology was adapted from the existing literature. Interview testing was conducted to elicit a comprehensive range of tennis specific vocabulary. The end goal was to create a perception relationship map or ‘feel map’. The inductive analysis was used to link all the related clustered themes identified from the vocabulary to sub and base themes describing the relationship. Further analysis introduced higher level general dimensions that unified common base themes. The resulting feel maps were created from both English and German sample groups, with a view to subsequent comparison. To complete the map and broaden its application a wide scale questionnaire was distributed to a tennis playing population. The responses provided data indicating percentile use of selected vocabulary within the tennis community and the relative importance players associate with assorted perception groups. Visual representations of the data were introduced to the map for quick and easy use and an associated lexicon compiled to provide a reference for more detailed information. The feel maps and lexicon provide users with a versatile tool in the form of a ‘perception relationship model’. The map itself can act as an overall research guide for future work in the field. The addition of percentile use and relative importance data mean the map can be used to create more informed and subtle player test questionnaires or as a design aid, with interdependency links indicating which additional factors should be considered or exploited for their influence on the characteristic areas in question. Interestingly the general dimensions of highest relative importance were sound and grip respectively. This may be due to the basic level of interaction between player and racket which ultimately has to be perceived either through the grip or from the sound. A perception test questionnaire was also created with the use of the feel map and later used to study the correlation between objective and subjective measures. To best attain objective measures from the racket an innovative instrumentation system was created. Two alternative systems were designed and tested, the first based on wired instrumentation and data capture the second based on wireless technologies as these became available. Both systems were required to take measures of grip pressure and acceleration with 6 degrees of freedom. The first system utilised uniaxial accelerometers mounted on an aluminium bracket, and a triaxial accelerometer inserted inside the butt of the racket arranged to allow measurement and calculation of acceleration from the required 6 degrees of freedom. The system could be adapted to include either TekScan multi-cell full grip coverage force measurement, or 2 single point higher sample rate single cell grip force sensors. All data was fed via 15 m of cable to data acquisition systems. This restricted the participants’ freedom of movement and encumbered the racket and thus the systems application, making it unsuitable for extensive perception or fatigue testing. The second system utilised a compact data logger with an integrated on board tri-axial accelerometer small enough to be mounted within the racket handle. A revised mount overcame the need for the aluminium throat bracket, moving the uniaxial accelerometers into a bulbous addition to the butt of the racket. The system was capable of capturing 8 channels simultaneously which allowed for the 6 accelerometers and two single cell grip force sensors to be located under the grip. The system was more difficult to adapt and maintain than the wired system, but improved freedom and reduced added weight to the racket made the system far more suitable for the planned perception and fatigue testing. Fatigue testing conducted with the wireless device investigated the effect of full body fatigue on players’ performance by monitoring the resultant effects in the racket. The protocol was based on the multistage fitness test, designed to progressively increase in difficulty until volitional fatigue. Heart rate data indicated that the protocol was successful in fatiguing the participants to a point at or near their VO2max. Unfortunately, with the wireless system in its early stages of development, the device failed mid way through testing. The limited data set that was collected indicated that technique was affected by fatigue. Further research is required to confirm this finding and to make comparisons between racket types during the fatiguing process. The wireless device was adapted to make it more durable and reliable before the planned perception testing was conducted. A protocol was developed to investigate the affect of changing racket moment of inertia on player perception and physical measures. The test questionnaire developed from the feel map was used to evaluate player perception ratings of various elements of racket feel, and the wireless instrumentation system was used as part of methodology designed to compile a set of comparable physical data. A detailed analysis of the results revealed that there was some evidence of correlation between the perceptions of power, balance, flexibility and control and the moment of inertia of the racket. In a design optimisation context, however, more definitive correlations would be more useful. These would be expected to be found with future testing utilising a wider range of racket properties. The research proves to a large extent the original hypothesis that through the use of non invasive instrumentation and improved player perception elicitation techniques it is possible to substantially and usefully improve the objective and subjective assessment of tennis racket performance in play to enable investigation of better design characteristics and fatigue related injury phenomena

Analysis of the backpack loading efects on the human gait

Gait is a simple activity of daily life and one of the main abilities of the human being. Often during leisure, labour and sports activities, loads are carried over (e.g. backpack) during gait. These circumstantial loads can generate instability and increase biomechanicalstress over the human tissues and systems, especially on the locomotor, balance and postural regulation systems. According to Wearing (2006), subjects that carry a transitory or intermittent load will be able to find relatively efficient solutions to compensate its effects.info:eu-repo/semantics/publishedVersio