The Arm by Jeff Passan Read Free Book Online

stand up long-term to the single fastest movement the body can generate: the throwing motion. The arm moves thirty times faster than an eyeblink when it’s firing a baseball. It’s the final cog of a mechanism that steals energy from the legs, builds on it through the hips and butt, transfers it up the back and to the shoulder, and releases it with a whip of muscles and ligaments and tendons and bones that launch a five-ounce projectile at speeds of up to 105 miles per hour. It is beautifully chaotic and chaotically beautiful. It is different in every arm, from Harley Harrington’s emergent one to that of Greg Maddux, the Hall of Fame pitcher who never did break over a twenty-three-year, five-thousand-inning career. All the gurus of biomechanics—the science, as the pioneering biomechanist James G. Hay once said, of “internal and external forces acting on a human body and the effects produced by these forces”—concur that Maddux’s delivery was perfect, though one could argue that perfect mechanics are more than a series of proper motions. Perfection is the ability of a pitcher to find a delivery that keeps him productive and healthy.
    Pitching consists of six generally accepted phases: windup, stride, arm cocking, acceleration, deceleration, and follow-through. Throwing a baseball differs from all other athletic tasks. Footballs are about ten ounces heavier and require slightly dissimilar mechanics. Tennis serves and volleyball spikes come more over the top than most pitchers’ high three-quarters deliveries.Windmilling softball pitchers rarely need Tommy John surgery, because the force generated simply isn’t enough to rip the elbow apart.
    Overhand throwing isn’t in and of itself the villain or culprit. “When you grow up, that’s what we do. We throw,” said Chris Carpenter, the former St. Louis Cardinals ace. “It doesn’t have to be a ball. It can be a toy, a Cheerio. You grow up, you chuck shit around. That’s what I did anyway.” Throwing is eminently natural, positively symphonic, an inevitable result of human evolution. What’s unnatural is throwing a five-and-a-quarter-ounce sphere ninety-plus miles per hour one hundred times every five days.
    The traditional pitching motion starts with a leg lift into a stride. This activates what’s commonly known as the kinetic chain—a simplistic way of describing the sequential transfer of energy from body parts farther from the ball to ones closer. Something as simple as a leg lift starts building elastic energy, a type of potential energy that comes from the stretching of ligaments and tendons before it’s stored in muscles. When the stride foot lands, the muscles in the butt clench—scouts look for pitchers with big asses for a reason: they’re biomechanically advantageous—and start rotating the hips. Shortly thereafter, the muscles in the back activate, too, sending rapid signals from the brain to the muscles. Those nerve impulses open up calcium channels in the muscle. As calcium is released, muscles contract. The powerful contractions begin cascading up the chain to the torso. Good hip-to-shoulder separation—the opening of the hips while the torso stays in line with the plate, which creates even more elastic energy because hip rotation stretches its ligaments and tendons—is common in the hardest-throwing pitchers.
    Front foot down, hips rotated, torso starting to twist, pitchers cock their arms and prepare for twenty to thirty milliseconds of wonder. What happens next is difficult to see with the naked eye. The shoulder externally rotates, bringing the elbow forward,the hand behind the body, and the forearm almost parallel to the ground. All of the elastic energy rushes into the shoulder, loading the muscles and ligaments and tendons and bones, like a coiled spring pushed flat. The UCL is screaming for mercy, particularly in players whose weak shoulder muscles