How to Use an Exercise Ball As a Chair
Choose the right fitness ball for your height and weight. Measure your current chair and aim to have the diameter of the ball be about 4 inches (10.2 cm) higher than your current chair.
If you are of average weight and you are under 5'3" (160 cm), you should choose a 55 cm (21.7 inch) diameter exercise ball. If you are between 5'3" and 6' (160 and 182.9 cm) you should choose a 65 cm (25.6 inch) diameter exercise ball. If you are over 6 feet (182.9 cm) tall, you should probably use a 75 cm (29.5 inch) diameter exercise ball.
Pump up the ball, aiming to pump it up to maximum diameter so that you do not sink too far into the ball.
Sit up straight on the ball with your legs out in front of you. They should be at a 90 degree angle to your thighs and parallel to the ball.
Bend your elbows and place your forearms at a 90 degree angle. Reaching forward slightly, you should be able to rest them on the top of the desk or table.
Practice active sitting. This is the state when your body reacts to the prospect of falling off the ball by tightening your core muscles in your stomach and back. Flex the muscles in your abdomen to add an extra element of exercise.
Use the ball in 20 minute intervals. Do not get rid of your office chair. Just like exercise, it is important to give your muscles rest to prevent muscle fatigue and get the maximum benefit.
Work up to 30 minute intervals as you get used to the chair. Doctors do not recommend that you sit for longer than 30 minutes at a time. If you need to get up to change chairs frequently, this will also benefit your spine.