Strengthening Exercises 
Step Up:  Stand parallel to a step.  Place the foot on the step and transfer your weight, stepping up.  Momentum will stress the weakened ankle and will cause the tendons to tighten, strengthening the response of these tendons for the stress created by a possible ankle sprain.

Step Up (continued)

Heel Raises: Using a chair or the wall for support, stand with both feet flat on the floor and slowly transfer your weight to your toes and raise your heels.  This will strengthens the calf and stabilizing ankle muscles.

Heel Raises: (Continued)