How does the jump affect the speed and accuracy of the ball? - Part 1 : Jumping Into the goal square.

In this section of the blog we will consider the bio-mechanical benefits of a player jumping at roughly 45 degrees into the circle and throwing the ball at the goals mid-air. The primary benefit of this is that the player is physically closer to the goals, thus giving the goal keeper less time to react to the shot.

As demonstrated above, this shot is only physically possible if there are no defenders in front of the shooter.

This type of shot also increases  the velocity of the ball by allowing handball players to maintain momentum by jumping forwards into the goal circle after running, instead of planting their foot down and stopping prior to throwing the ball.

In order to analyse how jumping  assists in adding speed to the throw, we first need to understand the concept of impulse. Impulse is described as the effect of force acting over time (Knudson, 2007.) When running,  there is breaking impulse when the foot initially lands and then a propulsion impulse when the foot pushes off the ground after landing.  The key difference between breaking impulse and propulsion impulse is the direction of force.

The picture above demonstrates the direction of force. Since the foot is applying force onto the ground, the ground is applying equal but opposite force to the foot according to Newton's third law: every action has an equal but opposite reaction. The direction of force is against the motion of the body and therefore, the body slows down.

In contrast to the breaking impulse, the propulsion impulse lasts longer and the vectors of force create a forward force which allow for increased velocity of the body.


In sports such as cricket, the bowler has to put their foot down before the crease, thus creating a equal but opposite force and reducing the momentum body (including the ball).












However, in handball, players are allowed to jump and throw the ball within the circle, as long as their foot is not within the circle when they let go of the ball. This essentially means there is no breaking impulse in mid-air (neglecting air resistance) and the players can throw at a higher speed than if their foot was planted on the ground.