Morphometrics for sports mechanics: Showcasing tennis racket shape diversity.

Tennis racket design has changed from its conception in 1874. While we know that modern tennis rackets are lighter and have larger heads than their wooden predecessors, it is unknown how their gross shape has changed specifically. It is also unknown how racket shape is related to factors that influence performance, like the Transverse and Polar moments of inertia. The aim of this study was to quantify how tennis racket shape has changed over time, with a view to furthering our understanding of how such developments have influenced the game. Two-dimensional morphometric analysis was applied to silhouettes extracted from photographs of 514 rackets dating from 1874 to 2017. A principal component analysis was conducted on silhouette outlines, to allow racket shape to be summarised. The rackets were grouped by age and material for further analysis. Principal Component 1 accounted for 87% of the variation in racket shape. A pairwise Pearson's correlation test indicated that head width and length were both strongly correlated to Principal Component 1 (r = 0.916 & r = 0.801, p-values<0.001). Principal Component 1 was also correlated to the Polar (r = 0.862, p<0.001) and Transverse (r = -0.506, p<0.001) moments of inertia. Racket age and material had a medium (p<0.001, η2p = 0.074) and small (p = 0.015, η2p = 0.017) effect on Principal Component 1, respectively. Mean racket shapes were also generated from the morphometric analyses for the material and age groupings, and we consider how these shape changes may have influenced performance and injury risk. These mean shape groupings could support the development of models, such as finite element analysis, for predicting how historical developments in tennis equipment have affected performance and injury risk.

Evolution of Sports-related Headgear.

The major focus of this review is to establish concussion in sport as a silent epidemic in our society that is not an accident. Brain injury has a definitive pattern and distinct nonrandom predictable characteristic. The development of successful head protection requires a scientific database approach to the mechanics of headgear. It is the responsibility of the health care clinician to help with the maintenance of protective standards for headgear and support rule changes to decrease the morbidity and mortality of athletes.

Injuries and Footwear (Part 1): Athletic Shoe History and Injuries in Relation to Foot Arch Height and Training in Boots.

This article traces the history of the athletic shoe, examines whether selecting running shoes based on foot arch height influences injuries, and examines historical data on injury rates when physical training (PT) is performed in boots versus running shoes. In the 1980s and into the 2000s, running shoe companies were advertising specialized shoes with "motion control," "stability," and "cushioning," designed for individuals with low, normal, and high arches, respectively. Despite marketing claims that these shoes would reduce injury rates, coordinated studies in Army, Air Force, and Marine Corps basic training showed that assigning or selecting shoes on this basis had no effect on injury rates. Consistent with this finding, biomechanical studies have shown that the relationships between arch height, foot joint mobility, and rear-foot motion are complex, variable, and frequently not as strong as often assumed. In 1982, the US Army switched from PT in boots to PT in running shoes because of the belief that boots were causing injuries and that running shoes would reduce injury rates. However, a historical comparison of injury rates before and after the switch to running shoes showed virtually no difference in injury risk between the two periods. It is not clear at this point if the type of footwear effects injury incidence.

Change in size and impact performance of football helmets from the 1970s to 2010.

Linear impactor tests were conducted on football helmets from the 1970s-1980s to complement recently reported tests on 1990 s and 2010 s helmets. Helmets were placed on the Hybrid III head with an array of accelerometers to determine translational and rotational acceleration. Impacts were at four sites on the helmet shell at 3.6-11.2 m/s. The four generations of helmets show a continuous improvement in response from bare head impacts in terms of Head Injury Criterion (HIC), peak head acceleration and peak rotational acceleration. Helmets of 2010 s weigh 1.95 ± 0.2 kg and are 2.7 times heavier than 1970s designs. They are also 4.3 cm longer, 7.6 cm higher, and 4.9 cm wider. The extra size and weight allow the use of energy absorbing padding that lowers forces in helmet impacts. For frontal impacts at 7.4 m/s, the four best performing 2010 s helmets have HIC of 148 ± 23 compared to 179 ± 42 for the 1990 s baseline, 231 ± 27 for the 1980s, 253 ± 22 for the 1970s helmets, and 354 ± 3 for the bare head. The additional size and padding of the best 2010 s helmets provide superior attenuation of impact forces in normal play and in conditions associated with concussion than helmets of the 1970s-1990 s.

Hacia atrás... ni para coger impulso / Always look ahead

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Motor sport in France: testing-ground for the world.

The birth of the automobile in the late nineteenth century was greeted with a mixture of awe, scepticism and sometimes even disdain from sections of the European public. In this article, the steps taken in France to pioneer and promote this new invention are examined. Unreliable and noisy, the early automobile owes a debt of gratitude to the French aristocracy who organised and codified motor racing in an effort to test these new inventions while at the same time introduce them to a wider public. City-to-city races demonstrated the potential of the automobile before the initiative of Gordon Bennett proved to be the catalyst for the birth of international motor sport as we recognise it today. Finally this article looks at the special connection between Le Mans and the automobile. Le Mans has, through its 24-hour race, maintained a strong link with the development of everyday automobile tourism and offers the enthusiast an alternative to the machines that reach incredible speeds on modern-day closed circuits. This article examines how French roads were veritable testing grounds for the earliest cars and how the public roads of Le Mans maintain the tradition to this day.

Daredevils and early birds: Belgian pioneers in automobile racing and aerial sports during the belle époque.

During the belle époque, Belgium was a trend-setting nation in many domains, including motorised sports. Belgian automobile racers and pilots shattered world records and became international stars. Striking was the shift in sports. Indeed, around 1896, sporting members of the leisure class stepped from the bicycle into the automobile and, around 1908, from the automobile into the airplane. Although these motorised sports were extremely expensive, this article shows that sportsmen and sportswomen from the working class could achieve upward social mobility through their performances. The achievements of these motorised pioneers had a major impact and wide-ranging significance. They laid the foundations for the expansion of the automobile industry and the emergence of civilian and military aviation.

Birth and evolution of the football helmet.

OBJECTIVE: To review the advent and evolution of the football helmet through historical, physiological, and biomechanical analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: Significant correlation exists between head injuries and the advent of the football helmet in 1896, through its evolution in the early to mid-1900s, and regulatory standards for both helmet use and design and tackling rules and regulations. With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. Not only is the material used important, but the protective design also proves essential in head injury prevention. Competition among leading helmet manufacturers has benefited the ultimate goal of injury prevention. However, just as significant in decreasing the incidence and severity of head injury is the implementation of newer rules and regulations in teaching, coaching, and governing tackling techniques. CONCLUSION: Helmet use in conjunction with more stringent head injury guidelines and rules has had a tremendous impact in decreasing head injury severity in football. Modifications of current testing models may further improve helmet design and hence further decrease the incidence and severity of head injury sustained while playing football.

The female dragons awake: women, sport and society in the early years of the new China.

This article, based on archival records, published documents, interviews with elite sportswomen and three regional case studies, deals with the radical social, economic, cultural and political changes in the early years of the Communist China, the consequent changes in women's lives and the eventual extraordinary impact on elite women's sport. It analyses the complicated relations between the communist system, gender ideology, sports policy, international politics and elite women's sport. With the establishment of a variety of sports institutions, systems and structures women in increasing numbers took part in competitive sport and produced even increasingly remarkable achievements.