Answer:
Decrease the range of motion involved in the exercise.
Step-by-step explanation:
A ball squats activity is the dorsoflexion of ankle and contraction of muscles around the joint to produce maximal contraction. People who have an unstable knee shall not perform ball squat in depth and shall decrease the range of motion. These people with knee instability shall have a knee flexion restricted to 50-60° so that shear forces applied on posterior joints are minimized.