Ligaments are not activated in normal joint
movement, it is the job of surrounding tendons and muscles to stabilize the joints, with ligaments only activated in extreme circumstances (such as knee
twisting, etc.) Sudden sharp impacts or changes in force may also overwhelm the surrounding muscle's ability to tighten and stabilize the joint, which
requires the ligaments to intervene.
A good example is the Lunge &
Twist Sandbag Exercise; this simple looking
movement involves a full lunge with an upper body
twisting motion that
requires core strength, upper body mobility, and lower body balance.