Why a pitcher’s arm is a biological marvel,
In 1974, Tommy John, a pitcher with the Los Angeles Dodgers, walked off the mound in mid-game, his left elbow in fierce pain. It would lead to revolutionary surgery, surgery that would unexpectedly save John’s career and become known simply as ‘Tommy John
The ulnar collateral ligament is a finicky little bastard, ill equipped to stand up long-term to the single fastest movement the body can generate: the throwing motion. The arm moves 30 times faster than an eye blink 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 [12-year-old prodigy] Harley Harrington’s emergent one to that of Greg Maddux, the Hall of Fame pitcher who never did break over a 23-year, 5,000-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 10 ounces heavier and require slightly dissimilar mechanics. Tennis serves and volleyball spikes come more over the top than most pitchers’ high threequarters 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 s--t 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 51⁄ 4- ounce sphere 90-plus miles per hour 100 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 20 to 30 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 cannot withstand the onslaught of energy and spill it down to an already loaded elbow.
The UCL is triangular, and the energy affects each side differently; the posterior and transverse bundles, biomechanists believe, endure less stress, while the anterior — the side that in almost every injury is torn — is burdened to the cusp of failure.
When the ligaments and tendons tell the shoulder it cannot rotate further, the elastic energy turns into kinetic energy, and the shoulder sends it down the arm by rotating internally at up to 8,000 degrees per second. No movement in the body matches the internal rotation of the shoulder, and along with the extension of the elbow, it propels the arm forward.
“If you’re 1/30th of a second late or early, you’re basically, over time, doing damage,” said Brent Strom, the Houston Astros’ pitching coach. “And that’s how fine this thing is. It’s like hitting a golf ball. You’ve got to be right on time. Those that can maintain that timing can stay healthiest the longest.”
The UCL breathes a sigh of relief as the energy travels down the arm and through the ball. Shoulder muscles contract to help the arm decelerate safely, and the follow-through dissipates the remaining energy. And, if all goes well, pitchers do it 99 more times that day.
Baseball has seen its share of anomalies who could throw 150 pitches without any arm soreness or regular- ly top 100 miles per hour without incident. R.A. Dickey, the Toronto Blue Jays’ right-handed knuckleball pitcher, a 13-year major league veteran, throws a baseball for a living without a UCL, which is not supposed to be possible.
He does not know if he was born without one or it just vapourized at some point during all the innings he tossed in high school. He is not sure if the muscles in his arm learned how to contract to keep it stable. Dickey simply knows he is a freak. And freaks are confusing. They defy explanation. And they challenge the modern theories of the pitching arm, which hold it to be a delicate flower never to be mistreated.
“I believe it’s miraculous,” Dickey said.
Dickey isn’t wrong. Long before he mastered the knuckleball, he was a regular fastball pitcher, able to run it over 90 miles per hour. His arm’s ability to function without a UCL is extraordinary; though, for that matter, every arm is a little miracle. It doesn’t take an outlier to appreciate the arm’s ability to survive the rigours of baseball.
“Every time I throw, it’s a train wreck,” then Philadelphia Phillies starter Cole Hamels said on May 25, 2012. “I’m sore as heck. I don’t even want to know what’s going on inside me.”
Two months to the day after Hamels said that to me, the Phillies signed him to a six-year, $144-million contract extension.