Material and construction influences on football impact behaviour

The purpose of this work was to understand the influence of materials and construction on football performance. Two main areas identified as needing further work were post-impact rebound deviation and acoustic response. To further investigate these areas, football materials were tested in a lab with different loading scenarios and the resulting data was used in various characterisation methods to help define finite element models. The finite element models were used to efficiently explore a variety of material and construction variations. Acoustic data for a range of balls was collected in an anechoic chamber and advanced coupled Eulerian-Lagrangian simulations were developed to visualise the mode shapes of internal resonances. [Continues.

Advanced modelling of ovoid balls

Sports played with an ovoid ball may be considered as minority sports in comparison to the numerous games played with spherical balls, however the ovoid ball market is considerable, with $84million spent on the purchasing of American footballs in the US alone (SGMA 2007b). In comparison to spherical balls, it is apparent that little research has been performed on ovoid types, which presented an opportunity for a detailed study into their dynamic properties in game related situations. With the development of this knowledge new ball design concepts have been investigated to improve consistency and performance, allowing manufacturers to create balls with improved physical characteristics. Experimental procedures have been created which allow the dynamic behaviour of an ovoid ball to be characterised. It was found that the measured parameters varied depending upon the position of impact, orientation angle of the ball and the position of the valve at impact. The inclusion of the valve within a rugby ball creates a non uniform mass distribution resulting in unstable rotation about the axis with the intermediate moment of inertia. This unstable rotation results in the ball performing a series of half twists, thus increasing the drag force during the flight and wobble. Prototype rugby balls have been manufactured with various mass distributions, allowing the effect on the unstable rotation to be analysed. Results showed that the inclusion of multiple valves, within the dynamically balanced bladder, resulted in stable rotation about all ptinciple axes. FE models have been created with isotropic and anisotropic material properties, with all models validated using experimental procedures. Results suggest that the anisotropic FE simulation accurately predicts the coefficient of restitution, contact time and deformation during experimental testing, and as a result it can be used to predict the dynamic behaviour of a rugby ball during various impact scenarios. Using a thermo-bonded construction, it was shown that a novel rugby ball could be developed with a unique carcass configuration and outer panels with increased design flexibility. A number of carcass designs, based upon mathematical shapes, have been created which increase the consistency of the dynamic behaviour of the ball when impacted at different locations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Training Load and Performance Monitoring, Recovery, Wellbeing, Illness and Injury Prevention

This book represents the efforts of different authors to analyze and provide solid evidence that supports training regulations based on monitoring strategies. This Special Issue includes original articles with some diversity, i.e., considering that different age groups, competitive levels, expertise, and conditions were researched regarding the main topics of training load and performance monitoring, recovery, wellbeing, and illness and injury prevention. Psychophysiological aspects were considered, as were locomotor and mechanical demands and tactical responses. The myriad outcomes analyzed present the reader with an overview of the state of the art and possible new directions for future research. In this book, readers will be also able to find systematic reviews about the key topics

Sports Materials

To further improve the level of correlation between these finite element models and lab-simulated bat/ball impacts, the material behavior for these wood species must also be characterized at strain rates comparable to those experienced ..

Player protocols for football boot testing

Football is the most popular sport and played by more players worldwide than any other sport. The football boot industry is therefore big, competitive and still growing. Today, football boot designs are subcategorised into four categories, of which three are linked to specific skill performance enhancing claims: The power boot for enhanced shooting performance, the touch/control boot for enhanced ball control and the speed boot for enhanced speed generation. In comparison to the strong marketing claims, little research has been published on the impact of football boot design on performance, injury and comfort. Therefore, little is known about the importance and impact of changing boot design. The outcome of this thesis offers researcher and the football boot industry validated human test protocols for power boot, touch/control and speed boot designs. The outcome of the thesis also advances the knowledge of how the football boot impacts performance, comfort and highlights the potential links between plantar comfort and injury risk. Rule based system assessment was performed to validate a boot performance conceptual framework linking the player and their desired movements during a football match with the football boot and its different components. The three protocols for assessment of key performance aspects for power boots, touch/control boots and speed boots were validated using test-retest reliability assessment through relative and absolute reliability measures. The power boot protocols involved shooting assessment measuring ball velocity, offset from target, success and player perception of ball velocity and accuracy. The touch/control boot protocol involved dribbling and passing assessment measuring time, number of touches and radial distance from cones during completion of a complex dribbling drill, ball velocity and offset from target during flat and airborne passes. The speed boot protocols involved combined agility and acceleration sprinting time and jump height before and after a 90 min match simulation protocol. Throughout the match simulation heart rate, player perceived exertion, perceived muscle fatigue, overall foot comfort and specific regional foot comfort. The validated protocols were then applied to assess how boot parameters impact performance. For the power boot, boots with and without upper padding were compared II demonstrating a small favour for the non-padded boot. Similarly, boots with and without upper padding were compared for the touch/control boot scenario with no differences seen between the two designs. Finally, two commercially available speed boots were assessed for the speed boot scenario demonstrating significant differences in both comfort and performance measures. Indicating a potential link between decreased foot comfort and decreased ability to maintain performance throughout a 90 min game. The boot performance conceptual framework was developed with component at each level but no interactive links between levels were added due to the lack of evidence in the literature. The boot performance conceptual framework offers researchers and the football boot industry a visualisation tool to aid the general overview when assessing or designing football boots. The three validations of protocols demonstrated strong test- retest reliability for most measures assessed and can therefore be applied to assess the impact of altering boot designs like demonstrated in this study