Those big exercise balls are a great addition to your workout. You can use them in several ways, depending on your exercise goals. Exercise balls are most often used for weight training, flexibility training and to develop core strength.

Choosing and using an exercise ball
When choosing your exercise ball, you want to get one that fits you. When you sit on the ball with your back straight, your feet should be firmly planted on the floor and your knees should be level with your hips.

If you are very heavy or if you plan to lift weights while on the ball, choose one that can handle the weight. This is not usually an issue, as most exercise balls will handle 600 pounds or more, but a poorly made, cheap ball may not work well for you.

Do remember, though, that using an exercise ball puts your body in an unstable situation and pay attention to what it is telling you. If you feel pain, change positions or try a different exercise, but don’t ignore it. If you feel insecure and unstable, deflate the ball slightly for a week or two. That makes it a little more stable. You can also hold onto something while you use the ball, or place it next to a wall or something to stabilize it a bit.

Core strength
The “core” muscles are those that support your spine—the abdominal, spinal, hip and pelvic floor muscles. These core muscles are the foundation and anchor for all movement; when your core is strong, your other muscles can produce more power. The core muscles also protect your spine and prevent back and joint injuries. They help you stand straight and tall, with good posture and body position and they improve your balance and coordination, preventing falls and injuries.

The primary use of exercise balls is to strengthen the core muscles. You can’t not develop core strength when you use an exercise ball; just sitting on one makes you work your core muscles because you automatically contract them to compensate for the instability. Watching TV or working at your desk while you sit on an exercise ball strengthens your core muscles. Doing crunches, twists or oblique exercises on the ball strengthens them even more.

Flexibility training
It’s easy to do hip stretches on an exercise ball—just move your hips side to side and forward and backward. Or rotate them in counterclockwise circles, and then in clockwise circles. You can use the ball with yoga or pilates, too, for added flexibility.

Weight training
Using a stability ball can improve the efficiency of your weight training. You use the ball like a weight bench, but it is unstable. When you are sitting or lying on the ball, you automatically contract your abdominal and back muscles and, because the ball is unstable, you use your muscles differently than with a weight bench. Both of these factors increase the intensity of your workout.

Incorporating an exercise ball into your workout is a great way to strengthen your core and to increase the effectiveness of flexibility and weight training.