The Punt Kick – Sweet Spot
It is well known that if the ball is contacted on a certain
part of the foot, the impact feels solid, full or ‘sweet’. This
point on the foot is therefore known as the ‘sweet spot’ or centre
of percussion. All levers such as a baseball bat, a tennis racket,
and body segments such as the arm or leg have a ‘sweet spot’
which is calculated in simple terms using the lever length, and
the mass of the body segment. An important prerequisite, of course,
is that the swinging limb is going to collide with another object
such as a ball otherwise the segment cannot have a sweet spot.
On a cricket bat the sweet spot is the point on the bat where
the batter feels no vibration at the hands when the bat and ball
collide, and is located some two thirds of the way down the blade.
Little force is, therefore, lost in the collision and the impact
is ‘meaty’ and solid. In a kicking action, the situation is more
complex. When a player swings the lower leg at the ball, the
linear speed at any point on the leg will increase with the distance
from the knee to the foot. In theory then, the highest linear
speed would be attained at the end of the foot next to the toes.
This would seem to be the appropriate point at which to make
contact with the ball. However, in practice, we know that if
contact is made with the ball at this point, the impact is likely
to jar the foot and result in ligament damage.
In theory, the ‘sweet spot’ of the lower leg is found around
the shin area, but we cannot, of course, kick a ball from this
part of the limb. However, in close proximity to the shin is
the hump, the part on the foot between the first two marbles,
where the impact seems to be free of any significant jarring
effect. While this part of the foot is not precisely located
at the sweet spot, it is close enough to ensure a sweet impact
with the ball.
In practical terms, the sweet spot or centre of percussion,
is roughly adjacent to the top two eyelets of the inside row
of the football boot. Contact at this point will result in the
greatest ball speed and distance off the foot. It is best facilitated
with an oblique approach, which places the body in a slight inward
lean position, and allows the foot to swing around to the ball,
thereby ensuring good contact with the boot.
If the leg has a sweet spot, does it also follow that the ball
has a sweet spot?
Find out more in ‘The Science of Kicking’