After introducing our force plate, the most common question from sports agents and parents is “So this device measures hang time?” Actually, a force plate measures the opposite of hang time, by calculating the amount of time athletes spend on the ground, as well as the force exerted over this period. These 2 factors of force and time combine to make an impulse. Basically, an impulse causes a change in momentum and is responsible for almost every facet of athleticism whether it is improving reaction time, vertical jump height, or sprinting speed.
There are generally 2 ways to improve impulse and the change of momentum during sport. The first method involves a small force applied for a long time, and the second option is applying a large force briefly. The latter tactic is more relevant to sporting movements, so training programs must seek to create these large forces or apply them very briefly. At Sparta, one of the chief uses of our force plate technology is to classify athletes as those who need more force or more time. A January 2010 study out of Marquette University found squats to be the best exercise at increasing impulse by prolonging the time factor of impulse. The study also concluded that jumping exercises are best for increasing the ability to apply force very quickly.
Not every facility has access to a force plate; in fact, this technology is usually only available in laboratories. Regardless of the facility, this plate is generally used to look at force characteristics, rather than to investigate time and impulse. These additional factors can relate much better to movements that require stability (i.e. changing direction), rather than just sheer explosion. For example, compare the controlled stop of an agility movement versus a sprint, or an approach jump versus a block jump in volleyball.
So make sure your program is seeking to improve the time or the force of your movements. And for “hang time” in the air, well my old football coach used to say, “spend as little time in the air as possible because you cannot do anything with your feet off the ground.”
But if you’re competing against our athletes, please continue to emphasize hang time because it is always more helpful to focus on mere results rather than the process of achieving greater results.