How can a handball player manipulate his center of mass to achieve the best accuracy for a goal shot?

As described in the previous post, handball players achieve an advantage of additional speed and distance when jumping into the goal circle. However, in order to achieve maximum visual stability with the goals, the shooter needs to manipulate their center of mass. 


The center of mass is defined as the point (theoretical) where the mass is evenly distributed in all directions. (Blazevich, 2012.) For a male standing up straight, this is generally around the abdomen and may vary depending on physiological factors. In order to maximise hang time in sports such as handball, players use the following center of mass techniques:

Get the center of mass as low as possible prior to the jump- this can be done by lowering the torso. Additional bending of the knees as much as possible also creates a greater distance to exert force on the ground and accelerate, thus creating a better upward momentum. 

The player now drives their center of mass as high as possible by leaving the ground and getting their feet up as high as possible.

 At this stage of the jump the center of mass is now almost at maximum height.

It is important to note that visually (especially in sports like handball and basketball) it may seem like the player is floating sideways (aka. hang time), however the player's center of mass is always in a state of vertical
deceleration/acceleration due to Newton's 2nd law and its application to gravity. As we will find out in the next phase, it is only the top half of our body that 'hangs' in the air.

The final phase of the movement occurs just before the player's center of mass starts to accelerate downwards. Being the highest point in the maneuver, the player extends their hand and throws the ball while driving their legs downwards.

As the legs are extended downwards, there is a conservation of momentum and the upper body moves upwards. Since the overall center of mass starts moving downwards, while the upper body is relatively moving upwards, it gives the 'hang' effect to the upper body (Blazevich, 2012.) This split-second allows a well conditioned handball shooter to have improved aim since their head and eyes are at the same level for a moment longer. 


Additionally, handball players have to maneuver and shoot around multiple defenders. In order to do this successfully without loosing balance, they also need to manipulate their center of mass. For example in the instructional video below by Salming Handball, the shooter leans in to perform a 'feint' shot by tricking the defender into thinking he will shoot then twisting around his center of mass to evade the defender.
Notice that the defender also moved his center of mass towards where he initially believed that the ball will go, however, did not have sufficient time to go against his momentum and turn the other way.