You know those large rubber balls found in health clubs and gyms? How about replacing the desk chair in your office with one? Though far from becoming the norm, these unconventional seating options are showing up in more and more workplaces.

And not just in companies like Google, who are well known for embracing the unconventional. (I mean how many places can you bring your dog to work with you?) But firms like BMW, Sprint Nextel, and many more, as well as several schools are trying them out.

The most vocal proponents for their use consider them the ultimate solution for eliminating persistent backaches and chronic back pain. Other benefits include improved posture because there's no back support to slouch against, and heightened ability to concentrate.

In addition, there is a substantial exercise benefit. Instead of sitting idle for roughly 8 hours every day, that time is transformed into a workout focused mainly on your lower back and abdominal muscles. Once the balancing activity becomes second nature, they say the minimal, but continuous exertion of maintaining stability increases toning and fitness.

However, there are some physical therapists and ergonomic consultants who offer a word of caution. They say that replacing your desk chair with a fitness ball isn't for everyone, and there are some risks to be aware of. Starting out slowly is advised, using the ball for increasing intervals of time until adapting to the exertion required for sustained periods.

They also suggest that older employees should avoid these type chairs and that even with younger workers tending to adapt more easily, there are still those that find the benefits don't outweigh the constant activity required over extended durations.

More obvious risks are the safety factors. After all, it's a ball, and it can roll. If your attention is elsewhere, or you're in deep concentration, you may fall off possibly injuring yourself and/or send the ball careening into someone else.

To solve this problem some manufacturers build frames for the exercise balls, making them more like regular chairs complete with arms and backs. Of course in gaining stability, this solution seems to defeat the original benefit, leaving the user with nothing but a bouncy seat.

There is no doubt a lousy desk chair makes for an uncomfortable, less productive workday. It will also make one susceptible to all manner of soreness and backaches. But while the exercise ball chair has certainly demonstrated itself to be a solution for many, those in need of a better seating option would be well advised to check out an ergonomically designed, well-made desk chair.

And not just one - find the one that fits you. Everybody is different and experience has proven there is no such thing as one size fits all. It's amazing how much difference a properly fitted, top of the line ergonomic chair will make - it's like sitting on air.

No, you won't be exercising, so if that's your goal, consider the ball. But if you don't want to even notice the chair, and your desire is to feel as good leaving at days end as when you arrived, spend some money on a real chair. I mean if you're spending a third of every day seated, why wouldn't you? You can still get the ball for diversion - it's only about $30.