A common and debilitating problem for athletes are anterior cruciate ligament (ACL) injuries. The study is published in the August 3 Journal of Biomechanics.
The anterior cruciate ligament provides stability to the knee joint. Most ACL injuries occur when coming down from a rebound, on a jump-stop lay-up, or when catching a pass. Even small jumps can cause tears in the ligament. David Hawkins, professor of neurobiology physiology, and behaviour at UC Davis says, "We focused on an easy intervention, and we were amazed that we could reduce shear load in 100 percent of the volunteers."
Basketball players from UC Davis and local high schools were fitted with instruments and digital cameras in order to measure muscle activity and movements. They also calculated the forces on their knees during several common basketball drills.
They then instructed the volunteers in a new technique that involved jumping higher and landing more steeply, toe landings, and bending their knees further before jumping again. After some practice, every volunteer reduced forces on their knees by an average of 56 percent. Interestingly, they were also able to jump about 2.5 centimeters higher than before.
In live practice, the researchers found that the athletes quickly slipped back into old habits, reducing the impact of the training changes. They note that more intensive off-court training would be needed to permanently change muscle memory and habits. In addition, they suggest teaching younger children these techniques while they are still learning how to move, so that bad habits do not have to be unlearned when they are older.
While full clinical trials will be needed to definitively prove that these techniques reduce ACL injuries, the scientists can recommend warm-ups that exercise the knee and landing on your toes and balls of the feet.