Activities such as walking, squatting, or lunging require coordinated movement between many areas of the body (e.g., the ankle must be able to bend to allow the shin to come forward over the foot and the knees to bend).  If motion is restricted in the ankle in any way it can cause pain and dysfunction to any number of structures in the body as they try to compensate.  Stretching the calf muscles on a BOSU Balance Trainer can help the ankle be able to dorsiflex (i.e., shin to come over the foot), thereby reducing the likelihood that possibly painful compensations will occur in other areas of the body like the knees, hips and back.