The researchers’ computer simulations enable them to estimate how much load the hamstrings are under and how much they’re stretched. In animal models, says Thelen, the mechanical strain a muscle is experiencing is a good predictor of injury potential.

Now the researchers can translate what they’ve learned about hamstring muscle mechanics into how best to rehabilitate the muscle after injury. Sherry and Thomas Best, an associate professor of biomedical engineering, family medicine and orthopedics and rehabilitation, have discovered that exercise programs that strengthen the core muscles-the abs and lower back-are related to fewer hamstring re-injuries. “Through our experiments and simulations, we’ve been able to show that these muscles can have a large influence on pelvic orientation, which affects hamstring stretch-and thus, presumably affects injury potential,” says Thelen.