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Just Jump System

The Just Jump System is one of many systems available for measuring vertical jump height. See the discussion and list of available methods.

About: The Just Jump System is an example of an electrical contact operated system. The Just Jump Mat is a 27 inch x 27 inch mat with a hand-held battery operated computer unit. The mat calculates vertical jump height by measuring the time that the feet are not in contact with the mat, and from this calculates explosive leg power. The hand-held computer displays height, and hang time for 1 jump, average height plus ground time for 4 jumps, computes explosive leg power rating, times sprints and foot quickness.

Instructions: With either the hands on the hips or allowed to swing freely, the subject stands on the mat, then when the equipment is ready jumps as high as possible. (see Vertical Jump Videos)

just jump mat

Disadvantages: the jump height is a calculated value based on the time the feet were off the mat. To be accurate, the feet must be together when they leave and return to the mat, and the amount of leg bend when landing can also affect the score (the laser system improves on this). Without a mark on the wall to aim for and motivate the subject, jump height using this method is often lower. This device is quite expensive. Movements of athlete on the floor can trigger the contacts and this can cause a jump height calculation without jumping.

Advantages: This device is very portable. The vertical jump measurement when using this device is not reliant on the subject timing their jump to touch something at the peak of the jump. The apparatus can be used indoors or outdoors. The mat can even be used for timing sprints and for foot quickness.

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