2 TYPES OF BALL-EFFECTOR INTERACTION AND THEIR RELATIVE CONTRIBUTION TO SOCCER KICKING

The study attempts a closer examination of the ball-foot interaction a t the instant of soccer kicking using high speed videotaping. This all ows a detailed biomechanical analysis of the collision. A central ques tion is whether the ball-foot interaction can be modeled as an elastic impact, or as a mixture of 'impact-like' and 'throwing-like' patterns . The findings prove that the theory of conservation of momentum alone is not adequate for modeling kicking: additional momentum and mechani cal energy is supplied to the system during the collision phase becaus e of the muscle work. This is due to the relatively long duration of c ollision (about 16 ms) and the large ball-foot displacement (about 26. 0 cm). More than 50% of the ball's speed and at least 30% of its kinet ic energy is imparted to the ball without any contribution of the pote ntial energy of the ball deformation.