Computer modelling at Waterloo Engineering shows professional baseball pitchers could make mechanical changes to avoid a common, career-threatening elbow injury without necessarily sacrificing competitive velocity.
"Our simulation found solutions that suggest there's untapped efficiency out there,” said Cedric Attias, who led the study while earning a master’s degree in mechanical engineering. “Our goal isn't to tell pitchers to throw softer. It's to help them throw smarter."
Researchers built a detailed digital skeleton with muscles, ligaments and joints to examine extreme twisting forces exerted during the throwing motion on the ulnar collateral ligament (UCL), a small band of tissue on the inside of the elbow that helps holds it together.
Their study, the first of its kind, revealed two main factors - a high arm slot, or angle, and tilting the torso away from the pitching arm during delivery of the ball - that put the most demand on the UCL.
With repetition of the explosive motion required to pitch at professional speeds, the UCL often breaks down and tears, resulting in Tommy John surgery to replace it and a long rehabilitation to get back on the field. Some pitchers never recover to play at elite levels.
“This ligament is especially vulnerable because it’s small, has a poor blood supply and wasn’t designed for movement this extreme or repetitive,” said Attias, who was supervised by Dr. John McPhee in the Motion Research Group (MoRG).
Although strain on the UCL is inevitable, the study results point to mechanical changes - particularly to arm slot and torso tilt, as well as lower body movements - that could help pitchers reduce injury risk while still throwing at high speeds.
“We confirmed that mechanics matters tremendously,” Attias said. “We showed that one pitcher throwing 93 miles an hour with controlled, upright mechanics puts meaningfully less stress on their UCL than someone using more extreme technique to reach the same speed.”
Go to Throwing smarter, not softer: how baseball pitchers can protect their elbows for the full story.
A digital skeleton developed by researchers at the Waterloo Engineering shows the stages in a typical baseball pitching delivery.