A review of the physics of ice surface friction and the development of ice skating.

Our walking and running movement patterns require friction between shoes and ground. The surface of ice is characterised by low friction in several naturally occurring conditions, and compromises our typical locomotion pattern. Ice skates take advantage of this slippery nature of ice; the first ice skates were made more than 4000 years ago, and afforded the development of a very efficient form of human locomotion. This review presents an overview of the physics of ice surface friction, and discusses the most relevant factors that can influence ice skates' dynamic friction coefficient. It also presents the main stages in the development of ice skating, describes the associated implications for exercise physiology, and shows the extent to which ice skating performance improved through history. This article illustrates how technical and materials' development, together with empirical understanding of muscle biomechanics and energetics, led to one of the fastest forms of human powered locomotion.

World records: how much athlete? How much technology?

The quality of performance during international competitions such as the Olympic Games and various world championships is often judged by the number of world records attained. The simple fact that world records continue to improve is evidence that sports performance is progressing. Does this also mean that athletes are improving? Is the continual progression of world-record performances evidence that contemporary athletes are superior to the athletes who performed in the past? Technological developments may obscure insight into the athletic enhancement made by athletes over the years. This commentary tries to separate technological and athletic enhancement in the progression of world records by the use of a power balance model.

O segredo do sucesso: apontamentos sobre a trajetória social de skatistas profissionais / El secreto del succeso: apuntes sobre la trayectoria social de skatistas profesionales / The secret of success: notes on the social trajectory of professional skaterboarders

Este artigo aponta, a partir de casos concretos, para elementos acerca da trajetória social de skatistas que lograram estar no subuniverso dos patrocínios. Em se tratando de skate, isso significa praticamente a única possibilidade de profissionalização. São considerados detalhes da constituição e do funcionamento do campo do skate em sua totalidade e da vida dos informantes, de seu caminho para incorporar disposições e capitais válidos no contexto do skate. Os dados utilizados são provenientes de técnicas de pesquisa como a entrevista semiestruturada, a observação participante e a coleta de documentos.

The aim of this article is to look at specific real life cases of the social trajectory of skateboarders, who managed their skateboarding career whilst not being in the mainstream of sponsorship. In skateboarding sponsorship is almost the only viable means to be professionally and thus financially stable. This study is done by taking into consideration: the ins and outs of the skateboarding world, the lives of the people involved in the sport, and the means with which they exercise and manage their chosen profession. The data utilized is derived from techniques of research such as: semi structured interviews, participant observation and document-based research.

Este articulo trata de levantar, apartir de hechos concretos, elementos acerta de la trayectoria social de skatistas que lograron estar en el submundo de los patrocinios. Eso significa practicamente la unica posibilidad de profesionalización. Son considerados detalles de la constituición y del funcionamiento de la rama del skate en su totalidad y de la vida de los informantes y de su camino para incorporar disposiciones y capitales validos en el contexto del skate, los datos utilizados son provenientes de técnicas de pesquisa como la entrevista semiestructurada, las observaciones participantes y la colecta de documentos.

Human locomotion on ice: the evolution of ice-skating energetics through history.

More than 3000 years ago, peoples living in the cold North European regions started developing tools such as ice skates that allowed them to travel on frozen lakes. We show here which technical and technological changes determined the main steps in the evolution of ice-skating performance over its long history. An in-depth historical research helped identify the skates displaying significantly different features from previous models and that could consequently determine a better performance in terms of speed and energy demand. Five pairs of ice skates were tested, from the bone-skates, dated about 1800 BC, to modern ones. This paper provides evidence for the fact that the metabolic cost of locomotion on ice decreased dramatically through history, the metabolic cost of modern ice-skating being only 25% of that associated with the use of bone-skates. Moreover, for the same metabolic power, nowadays skaters can achieve speeds four times higher than their ancestors could. In the range of speeds considered, the cost of travelling on ice was speed independent for each skate model, as for running. This latter finding, combined with the accepted relationship between time of exhaustion and the sustainable fraction of metabolic power, gives the opportunity to estimate the maximum skating speed according to the distance travelled. Ice skates were probably the first human powered locomotion tools to take the maximum advantage from the biomechanical properties of the muscular system: even when travelling at relatively high speeds, the skating movement pattern required muscles to shorten slowly so that they could also develop a considerable amount of force.