The Boston Herald reports on a fascinating computer simulation linking muscle strength to the risk of ulnar collateral ligament injuries:

“Our simulations illustrate that if the muscles were doing nothing, then the bones that make up the elbow joint could have been pulled apart during that single pitch,” said Murray, associate professor of biomedical engineering at Northwestern’s McCormick. “In contrast, we also were able to implement reasonable assumptions about muscle performance that showed how the very same pitch could result in no load on the UCL at all.”

The UCL is at the heart of many sports injuries, especially pitching injuries, and it is the focal point of the widely used procedure known as Tommy John surgery. The procedure is named after former Los Angeles Dodgers and Chicago White Sox pitcher Tommy John, on whom doctors first performed the surgery in 1974. The procedure uses tissue from elsewhere in the body to repair the UCL and has a high rate of success, but recovery typically takes up to a year.

It looks like mechanics doesn’t matter that much. Now they need to figure out if particular muscles matter more than others. Here is the abstract. I believe something similar has led to fewer shoulder injuries among pitchers. It would be nice if a set of exercises could cut down the need for Tommy John surgeries.