Natural Fitness makes a variety of exercise balls out of non-toxic and phthalate-free material. Phthalates are chemicals used in everyday-type plastics like shower curtains and exercise balls. Debate over these chemicals heated up in 2010 when the Environmental Protection Agency placed them on its "concern list" of chemicals that may adversely affect your health or our environment. This chemical may disrupt hormone activity and, over time, cause demasculinizing of men. Phthalate-free Natural Fitness exercise balls that inflate to various sizes are available.
Small Size
Choose the 45-cm size ball if you are between 4-foot-8 and 5-foot-5, advises the American College of Sports Medicine. Check to make sure you can sit on your ball with your hips and your knees at 90 degrees. Natural Fitness makes one ball that inflates to this size as of 2011. It is burst resistant to 600 lbs.
Average Size
Use the Natural Fitness exercise balls that inflate to 55 cm if you are 5-foot-6 to 6 feet tall. When you inflate your ball, follow the instructions from Natural Fitness. Also, periodically check your ball's inflation regularly, recommends ASCM. Natural Fitness as of 2011 makes a 300-lb. burst-resistant ball and a 600-lb. burst-resistant ball in this inflation size.
Tall Size
If you are 6 feet tall to 6-foot-5, use a Natural Fitness ball that inflates to 65 cm. Natural Fitness offers a 300-lb. burst-resistant ball as well as a 600-lb. burst resistant ball in this inflation size as of 2011. If you are 6 feet tall and need more guidance, ASCM notes you should be able to comfortably sit on your ball with erect posture as well as knees at a 90-degree angle.
Extra Tall
Use a 75-cm ball if you are taller than 6-foot-5. The Natural Fitness balls in this size also come in 300-lb. and 600-lb. burst-resistant options. Many of the Natural Fitness exercise balls are sold in kits that include a ball pump, an exercise chart, an exercise DVD and a measuring tape so you can make sure you inflated your ball to the correct size.
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