My desk chair is an exercise ball. I made this conversion a few months ago when I realized I was not getting enough crosstraining other than my walking. Walking does nothing to strengthen the abs, and posture is also very important for walking. Walkers need to work on those areas.
Benefits of Sitting on the BallSitting on an exercise ball, your body is constantly making small adjustments with the postural muscles, abdominals, gluteals and leg muscles. It is "active sitting" rather than the slumping and poor posture we develop even in ergonomic desk chairs.
Personally, I have seen dramatic improvements in my balancing and abdominal stability. Before sitting on the ball, I had difficulty maintaining a V-sit on a BOSU ball for 20 seconds. Now I can V-sit with no effort for a minute or more. Previously, I had sharp pain from a postural muscle in my back by the end of a 26.2 mile walking marathon. This year I had no such problem.
Update 2007: After a traffic accident, I had tailbone pain when using the exercise ball as a chair and discontinued using it. Stuart McGill, PhD. in "Low Back Disorders" cautions against use of an exercise ball as a chair for those with lower back pain. I have switched to a Fit Disc as a seat cushion rather than using the exercise ball as a chair.
But is it Ergonomic?Those who design and sell ergonomic desk chairs, which cost hundreds of dollars each, naturally caution you about using a $15-30 exercise ball instead. Certainly, those with back pain and other musculo-skeletal disorders need to use caution when changing chairs for hours of sitting. I have a friend whose chair must be precisely adjusted or it sends her into days of hip pain.
Update 2007: If you experience increased lower back pain when using the exercise ball as a chair, discuss with your medical provider and consider discontinuing use.
You must get the right size of ball. Your thighs should slope downwards slightly rather than be at 90 degrees. But the ball should not be so tall that you end up balancing on your wrists at the keyboard.
There have not been many studies on the benefits of using an exercise ball as a chair. However, the physical therapists and kinesiotherapists and personal trainers I have know all congratulate me on using the ball as a chair and say they do so themselves. Perhaps it is a fad, but it is one with many converts among the exercise and therapy experts.
ComfortWhen starting out using a ball, you should begin with a half hour or less and build up your time each day to see how you tolerate it. I have a desk job and I swiftly built up to sitting on the ball for 8-10 hours a day.
I find the ball to be far more comfortable than most desk chairs. I have a spendy ergonomic chair in my office which is nowadays shunted aside. The one in my home office is now inhabited mostly by my cat.