How to throw a baseball

Click on Throwing Like a Girl for James Fallows’ 1996 article on the “kinetic chain” theory of how to throw a ball, by which the momentum of the weight of the body as a whole is transferred to the arm and then to the ball itself.

Click on Throwing Like a Tim Lincecum for his current update.

Here is the key paragraph of the 1996 article.

… The most useful description I’ve found of the mechanics of throwing comes from a man whose specialty is another sport: Vic Braden made his name as a tennis coach, but he has attempted to analyze the physics of a wide variety of sports so that they all will be easier to teach.

Braden says that an effective throw involves connecting a series of links in a “kinetic chain.” The kinetic chain, which is Braden’s tool for analyzing most sporting activity, operates on a principle like that of crack-the-whip. Momentum builds up in one part of the body. When that part is suddenly stopped, as the end of the “whip” is stopped in crack-the-whip, the momentum is transferred to and concentrated in the next link in the chain. A good throw uses six links of chain, Braden says. The first two links involve the lower body, from feet to waist. The first motion of a throw (after the body has been rotated away from the target) is to rotate the legs and hips back in the direction of the throw, building up momentum as large muscles move body mass. Then those links stop—a pitcher stops turning his hips once they face the plate—and the momentum is transferred to the next link. This is the torso, from waist to shoulders, and since its mass is less than that of the legs, momentum makes it rotate faster than the hips and legs did. The torso stops when it is facing the plate, and the momentum is transferred to the next link—the upper arm. As the upper arm comes past the head, it stops moving forward, and the momentum goes into the final links—the forearm and wrist, which snap forward at tremendous speed.

via The Atlantic.

Click on James Fallows for his web log.

Hat tip to Ezra Klein.

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