While at my desk, is it better to sit on one of those pilates/gym balls than to sit in an office chair?

I have also heard that it's good for core strengthening (as you're using stomach/back muscles to hold yourself up) and is good for alignment/posture in a similar way.

If you google 'exercise ball' many sites describing the benefits come up. Be sure to buy one that's *exactly* the right size for your body (mainly based on leg length and therefore the angle of your hips while sitting on it).

We have some of these where I work. We mostly use them when we need to pair on something. They're easy (and fun!) to roll over to someone else's desk. But, maybe I should commandeer one for full-time use...

its suppose to help posture as well.

I've also seen balance ball chairs, which are basically a ball with a wheel base and some lower back support - they're supposed to give you the same core muscle benefits, but they're a lot easier move around the office in (if you need to be wheeling back and forth, instead of sitting in one place).

Here's a link to one:

http://tinyurl.com/2zyaj8

If you google "exercise ball chair" you can find a bunch more, I'm sure...

You are far less likely to fall asleep at work when sitting on a gym ball.