Exercise Balls For Dummies
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Because you use the ball with so many different body positions while you're exercising, the size of the ball you use really does make a difference and can make or break your workout.

Size does matter. And although using smaller balls can enhance certain exercises and larger balls can support your body weight if you have a bad back, using the right ball for you, which means one that is measured by your height and/or your arm span, makes all the difference in the world.

Using your height to size up your ball

When you stand next to an exercise ball, it should be even or slightly above your knee level. The best way to size up your ball is by sitting on it. When you sit on the ball, your knees should be bent at a 90-degree angle and your thighs should be parallel or even with the floor. Find your height and see which ball size you should try first.

The following chart shows a slight variation of recommended heights for the different ball sizes you can choose from.


Recommended ball size

Under 4'8"

45 cm ball

4'8'' to 5'3''

55 cm ball

5'4'' to 5'10

65 cm ball

5'10 to 6'4

75cm ball

For kids who are 5 years and younger, always use a 45 cm ball.

Doing the sit test

The best way to tell whether or not your new ball is the correct height is to sit on it. The recommended height allows you to bend your knees at a 90-degree angle when you're sitting on the ball and your feet are flat on the floor. This angle allows your hips to be level or slightly higher than your knees.

A ball that's too small compromises the position of your hips and pelvis when you sit on it, whereas a ball that's too large doesn't allow your feet to touch the ground, making it unstable. Achieving a good balance between a ball that's too large or a ball that's too small provides you with the best workout. As Goldilocks once said, not too hard, not too soft, juuuuusssst right.

Lying on the ball

When you lie on your stomach on the ball, you want to make sure that your back doesn't arch. Your back should maintain the natural curve, otherwise known as neutral spine. If you arch your back at all when you lie face down with your stomach on ball, you need to get a smaller ball so you avoid injury from placing strain on your back. In addition, when you lie face down on the ball, your hands should be able to comfortably touch the floor in front of you.

Using your arm to size up your ball

Another way to find the correct size ball is to measure the length of your arm from your fingertip to your shoulder. Because people have different leg lengths (some have shorter legs and some have longer legs), using your arm span to find a ball that's just right for you can be a more accurate way to measure a ball. If you plan to use the ball for a lot of aerobic exercise and need to hold onto it, using your arm measurement can provide a better fit for your circumstances. However, using your arm-span measurement to buy your new ball can take a bit more time and a bit more skill because most people are more familiar with their height rather than their arm span. If you choose to use this method of measuring, take a look at the following chart to see where you fit in.

Arm length

Recommended ball size

22" to 25-1/2"

55 cm ball

26" to 31-1/2"

65 cm ball

31-3/4" to 35-1/2"

75 cm ball

About This Article

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About the book author:

LaReine Chabut is a well-known fitness expert who has her International Sports Sciences Association certification and her American Fitness and Aerobics certification.

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