MUSCLES ENGAGED Quadriceps The quadriceps (quads) are a group of four muscles on the front of the thigh. They allow your knee to straighten and provide stability when standing. Your quads are the most important muscle group for maintaining the ability to stand and to walk independently. Calves Calves (calf muscles) influence the ankles and contribute to overall ankle strength. Strengthening your calf muscles will help your balance and performing movements such as running, walking and jumping. Equipment Used Bosu The BOSU balance trainer stands for "Both Sides Utilized" and is most often used for balance training, various athletic drills and aerobic activities. Exercise Instructions Step 1 Stand on one side of the Bosu with your feet shoulder width apart. Step 2 Step across the Bosu with your outside foot. Step 3 Once on the other side, step across the Bosu with the opposite leg.