The anterior cruciate ligament (ACL) is one of the four ligaments in the knee that connect the upper and lower leg bones. Ruptures of the ACL are common in contact sports such as football and soccer. These sports injuries can lead to arthritis and other complications later in life. According to the Arthritis Foundation, research suggests that ACL and other traumatic knee injuries can be reduced by more than 50% by using a preventive training program that combines flexibility, balance, strength, plyometric, agility, and technique training into exercise selection. To help you prevent debilitating ACL injuries and their effects that could last a lifetime, we've outlined 4 ways to prevent ACL injuries.