ABSTRACT
In recent times, ball impact techniques have improved, and various ball impact point with the foot, swing motions, and more complicated curving kicks are being performed by football players. For example, top professional athletes who use the instep while kicking curve shots are often able to apply topspin in addition to sidespin. Such an intentional application of topspin to a ball is an extremely specialised technique that results in shots that drop more than conventional curve shots. A few top-level football players (e.g. C. Ronaldo) are also capable of kicking the knuckling shot, in which a ball is intentionally kicked with very low or no spin; due to the effects of random turbulence, such balls have an unpredictable wobble. Moreover, as a result of the excitation of an irregular vortex oscillation in the ball wake, the knuckleball results in the ball wavering or dropping unpredictably (Asai et al., 2008).
