The relationship between foot-ball impact with kick outcome in football kicking

Across the football codes, kicking is the main skill used to score goals and pass between team members. Kicking with high ball velocity and high accuracy is required to kick to targets at far distances or reach a submaximal target in less time. The impact phase is the most important component of the kicking action: it is the only time a player forcefully contacts the ball to produce the flight path. Ensuring high impact efficiency and the appropriate combination of flight characteristics are imparted onto the ball during foot-ball impact is important for successful kicking. The aim of this thesis was to determine how foot-ball impact characteristics influences impact efficiency, ankle plantarflexion, ball flight characteristics and kicking accuracy. By using a mechanical kicking machine to systematically explore impact characteristics and performing an intra-individual analysis of human kickers, high-speed-video analysis of foot-ball impact found impact characteristics influenced impact efficiency, ankle plantarflexion, ball flight characteristics, and kicking accuracy. Increasing ankle joint stiffness, impact locations on the foot closer to the ankle joint, altering foot-ball angle and reducing foot velocity each increased impact efficiency. These results supported the coaching cue ‘maintaining a firm ankle’ during impact as effective at increasing impact efficiency. The impact location between the foot and ball across the medial-lateral direction, foot-ball angle and foot trajectory were each identified as influential to ball flight characteristics and/ or kicking accuracy. The oblique impact theory applied to the duration of impact provided a theoretical framework underpinning how each impact characteristic influenced ball flight characteristics. More consistent performing players produced less kick-to-kick variability in their impact characteristics, while lower kick accuracy was due to errors produced in the combination of impact characteristics. In conclusion, foot-ball impact characteristics were influential to impact efficiency, ankle plantarflexion, ball flight characteristics, and kicking accuracy