Willie M
Mechanics of the Baseball Throw
Boise State University
1996
Throwing is a fundamental skill that is often overlooked by coaches at all levels. Many coaches believe that throwing ability is innate: you have it, or you don’t. Although some athletes have more natural ability than others, almost anyone can improve his or her throwing by understanding and practicing proper throwing mechanics.
MECHANICS OF A PROPER THROW
An athlete doesn’t have to be large or exceptionally strong to throw hard. A high-velocity throw is a result of proper technique rather than brute strength.
An accurate, hard throw involves a synchronized sequence of four motions: a stride, hip rotation, trunk rotation, and arm movement. The goal of these sequences of motions is to achieve maximal hand (and ball) velocity.
The throwing sequence begins with a step (stride) in the direction of the throw. The length of stride should vary according to the athlete’s height. Generally, the length of the stride should be somewhat less than the athlete’s standing height technically, stride length should be about 80° of the athlete’s height. Over striding is a common fault that reduces proper hip rotation and detracts from the velocity of the throw.
As the stride foot hits the ground, the other (pivot) foot braces against the ground to provide stability and leverage for the remaining movements of the throw. Hip rotation is the next element in the throwing sequence. Hip rotation simply refers to the natural tendency for the hips to open toward the thrower’s target. It is important to remember that hip rotation must occur before trunk rotation. Unskilled throwers tend to rotate the hips and trunk at the same time.
Rotation of the hips before the trunk is important because it serves to stretch the muscles across the trunk eventually causing these muscles to contract more forcefully. This preloading of the trunk muscles enables the trunk to rotate rapidly setting the stage for a proper arm action.
As the trunk begins to rotate toward the target, the throwing arm should lag behind. The lagging arm stretches the shoulder muscles, which in turn further helps accelerate the arm.
As the upper arm begins its forward movement, the elbow should be bent to enable the upper arm to move more quickly. Two other arm actions also contribute to a very rapid increase in hand (and ball) velocity. The first of these actions is the turning of the upper arm around its long axis. This action is technically called inward rotation of the humerus, this is the same movement that occurs when an extended arm is turned from a position where the palm of the hand faces the sky to where the palm faces the ground.
The second action accompanying the forward movement of the arm is the straightening (extension) of the elbow joint. To make certain that maximal hand velocity is achieved, it is essential that the forward movement of the upper arm, the inward turning of the upper arm, and the extension of the elbow occur simultaneously.
A common held belief is that a good wrist snap is the secret to throwing hard. However, research indicates that the importance of the wrist snap has been overrated. High-speed photography shows that the ball is actually released from the thrower’s hand before most of the wrist flexion occurs. Nonetheless, the wrist snap does contribute somewhat to the velocity of the throw, and should be considered an important final component of the throwing motion.
Another common misconception is that an “overhand” throw is accomplished by allowing the arm to move above the shoulder joint. However, film analysis shows that the “overhand” throw depends primarily on the amount of trunk lean. For example, sidearm throwers use an erect posture, whereas players who throw “overhand” lean toward the side opposite of their throwing arm. An athlete should be taught to throw using a body position and arm angle that are most natural and comfortable for that particular player.
CONCLUSION
A high-velocity throw is made possible by rapidly accelerating the arm and hand. The most rapid acceleration of the arm and hand occurs when the thrower’s hips and trunk rotate in the proper order. Coaches should help athletes understand and practice the mechanics by ensuring that they 1) stride in the direction of the throw and keep the stride short enough to allow maximum hip rotation; 2) allow the arm to lag behind the hips and trunk so the athlete feels a slight stretch in the trunk and arm muscles; and 3) extend the elbow at the same time that the upper arm is moving forward and turning inward.
Ross E. Vaughn, Ph.D., is director of the Biomechanics Laboratory and a professor in the Department of Health, Physical Education and Recreation at Boise State University, Idaho. A former baseball player (pitcher) who coached college baseball for 11 years, Dr. Vaughn has extensively studied the mechanics of the pitching motion through high-speed film and computer analysis techniques.