A 3-inch diameter baseball weighing 5 ounces routinely lights up 95 mph on the radar gun when thrown by Major League pitchers. This equates to a velocity of 139 feet per second during the 60-foot, 6-inch path to home plate with a flight duration of 4/10ths of a second. Aroldis Chapman threw a fastball 105 mph which reached home plate in 380 milliseconds.
The pitching motion is perhaps the most complex and forceful movement in all of sports. In fact, the pitching motion is the fastest human movement recorded. It breaks down to a series of synchronized body movements requiring precise coordination of close to 100 muscles, bones and soft tissue structures.
Pitch velocity starts in the large mass of the lower extremities as kinetic energy (energy from movement) that is eventually transferred to the ball like a whip snapping. “The kinetic chain” is a term used to describe the sequence of activation, mobilization and stabilization of different body segments.
The strongest and largest muscle in the body – the gluteus maximus initiates the throwing motion. Half of the total energy and force developed in throwing is produced in the legs and the trunk. Therefore, velocity correlates more with lower body strength than upper body strength. During wind-up, the pitcher loads his back leg in preparation for a forceful drive towards home plate. His shoulder and arm move into a position that ultimately creates a whipping action. The pitcher’s straight-line acceleration toward home plate carries his entire body mass, which, then, abruptly decelerates when his land leg strikes the front of the mound.
The tremendous momentum of his lower half quickly shifts all of the lower extremity and trunk momentum to the upper extremity, which has moved into the cocking position. The arm then rapidly rotates towards home plate accelerating the five-ounce ball. Arm rotation velocities as high as 7000 degrees per second have been recorded which is roughly how often the wheel of your car rotates when you are driving roughly 93 mph.