The issue surfaces periodically, particularly when the balls are advocated for mitigating or averting the musculoskeletal disorders that bedevil workers in many occupations. Experts quoted in an Ergonomics Today™ article in April 2005 and a round of expert comment in the Ergonomics Forum from the same period suggest the balls may do more harm than good.

“When someone tells you that a $19 ball will solve all of your back pain issues, you ought to be suspicious,” warned ergonomist Peter Budnick Ph.D., CPE, in Ergonomics Today™. “And when they have the audacity to label that ball ‘ergonomic,’ you should know better.”

Writing for the Forum from Canada, Jeff Pajot conceded that sitting on the exercise balls with no trunk support and the constant trunk movement does activate trunk musculature and therefore aids muscle tone. “However,” he added, “since the muscles shorten during contraction, there is a huge compression placed on the intervertebral discs. Prolonged compression is contraindicated, especially during sitting since the pelvis is rotated forward which flattens the lumbar lordosis adding a further compressive penalty to the discs.”

Writing for the Forum from the United Kingdom, John Ridd said that in his consultant capacity he advises against allowing the balls into the workplace. Apart from the spinal risks, he noted, the potential for injury is high because users can become unbalanced and fall off the ball. “In the UK, one of the criteria that office seating has to satisfy is that it should be 'stable'!”

Andrew L. Concors, a physiotherapist and ergonomist writing from the United States in the Forum advised against them for safety reasons and because, “the fitball is not primarily designed to be a sitting surface while chairs are.”

Forum comments from other experts cite similar objections.

In fairness, Jane Clapp, co-author of “Working on the Ball” doesn’t present the topic as “ergonomic sitting” in the Globe & Mail newspaper article. She calls it “active sitting,” and many of the anecdotes in the article describe valuable activity on the job for people whose day leaves little time for the gym.

"I was a total sceptic,” Canadian broadcast researcher Sharon Flynn told the newspaper. "That pain you get between the shoulder blades from hunching over a computer? I don't get that any more. Also, it's fun. You can bounce when you're waiting for something to download."

And then there is the benefit of exercise to sedentary workers. Al Letts’ movie production office is full of fitness balls. It’s “more comfortable than an office chair because it's got spring,” he told the Globe&Mail. At the end of the day, you've actually had a good workout and not even noticed."

There is no doubt Forum experts will have plenty to say about the book, particularly about Clapp’s claim that "balancing on the ball encourages spinal alignment and continuously engages back and abdominal muscles."

Sources: Globe&Mail; Ergonomics Today™; Ergoweb’s Ergonomic Forum http://forum.ergoweb.com