Short-term kinematic adaptation to unanticipated sprint running conditions in field sport

An important characteristic of skilled behaviour in unanticipated conditions, such as sprinting in field sports, concerns the functional relationship between adaptive movement variability and performance outcome. The process of improving a skilled behaviour involves developing a stable performance under different conditions with a consistent performance reflecting mastery in a given task (Preatoni et al., 2012). The aim of this study was to extend insight into lower limb kinematic adaptation to unanticipated sprint running conditions in field sport. Methods An automatic marker tracking system (200 Hz) was used to track three-dimensional, bilaterally (lower limb) located active markers during the initial 20 m of sprint run acceleration trials performed by twenty university footballers. The performers were made aware of the final sprint distance prior to initiating the sprint in the anticipated 20 m (A20) condition. In the unanticipated 20 m (U20) and 40 m (U40) conditions, the performers were informed of the final sprint distance immediately after initiating the sprint. The groups mean step velocity was determined as the primary performance measure with its mechanical step determinants e.g. step frequency, being the kinematic measures of adaptation. Results No difference in performance outcome or individual variability of performance outcome between conditions was observed (mean step velocity m.s-1; A20: 6.71±0.20; U20: 6.69±0.19; U40: 6.71±0.20). Determinants of step velocity and their variability were significantly different (p