Racquetball is a great indoor cardio exercise that can be played alone, with two people or in teams. It can burn up to 800 calories in a one-hour session when played vigorously. It can also help you get your steps in; some estimates suggest you can cover the distance of up to two miles going back and forth on the court for the ball. It can also improve your balance, coordination and flexibility. Click here for more great cardio ideas that can help you burn calories and lose weight. How many calories you burn doing racquetball casually depends on your speed, weight and gender. You can see how many calories you burn playing casual racquetball using the calculator below.