[KoZeN]

http://news.bbc.co.uk/1/hi/6187080.stm

Not a link to the source but a decent article surmising the findings.

[eevo]

I do sit like this on an aeron chair, leaned back as far as it can go. I almost never have back issues, but in this position (exactly like the far right picture in the article) my neck eventually starts to ache.

Good for back, bad for neck...

[maineldc]

You should check out the freedom chair with headrest. I have 3 and love them for exactly this reason, though now that my daughter has taken over my home office, I never get to actually use them...

http://www.amazon.com/HumanScale-Freedom-Chair-Headrest-Fabr...

[chrismealy]

That's what I do, except I put my feet on a chair and keep my legs straight.

Trying to sit up straight makes my shoulders hunch up. Slouching lets my shoulders and arms relax. Sitting on a hard unpadded chair is good too.

[roblund]

Pretty interesting article.