The answer to this question would be: better-stabilized knee joint
The quadriceps femoris muscle is located in the anterior part of the femur. This group of muscle is used for extension. It has no role in flexion, abduction or adduction. In general, training a muscle will stabilize the nearby joint. In this case, the quadriceps will stabilize the knee joint.
There are two main types of adaptation: physical and behavioral. Physical adaptations are special body parts that help a plant or animal survive in an environment.