Using appropriate boundary conditions in traction test devices

Previous authors have developed traction test devices with the aim of replicating the boundary conditions at the studded shoe-surface interface during movements in which the athlete is at risk of suffering injury or losing performance (Barry and Milburn, 2000; Cawley et al., 2003). While subject tests can provide loading and movement patterns which are more representative of key movements during competition, mechanical rest devices are repeatable, thus allowing the influence of different shoes and surfaces to be more clearly understood. However, replicating characteristic player loading conditions and movements is vital in order to note meaningful trends. For example, Nigg (1990) showed that a particular surface provided the highest traction forces when tested at a low normal force but gave the lowest traction when a higher, more representative, normal force was applied. Attention should be drawn to the loading conditions at the time within a movement when the player is at the highest risk of injury or loss in performance. The parameter obtained from mechanical tests which is used describe traction must also be carefully selected in order to be related to injury risk or performance for each particular movement. This study contains analysis of a forefoot push-off (performance) movement in which the player seeks sufficient traction in order to avoid slipping relative to surface.