Bending back too much on squats?

[Mad Max]

What is the most one should bend their back on the squat. I often go as low as 45 degress from upright, which is lower than most. Thing is I'm tall, 6'4", so I find it hard to stay upright anyway, even on bodyweight squats. I've seen pic's of Arnie doing ATF, squats with his back bent forward a great deal.
Are there any risks?

[HardToSquat]

I am 6'3 and do ATfs. I have a medium-wide stance and get all the way to where my hams touch my calves and I can stay pretty much upright to a point. I've seem those pics of Arnie and they make me cringe as it looks like he is doing a good morning. He goes way forward when doing close stance ATFs. IMO if you go that much forward, that is an injury waiting to happen unless you are genetically gifted. I bend my back only slightly on the ATFs and my lower back is never sore from squats, only Deads.

[Big & Tall]

http://www.exrx.net/WeightExercises/Quadriceps/BBSquat.html

I'm 6'6", so I also find it difficult to stay upright on squats. But that doesn't mean it can't be done, or you shouldn't squat. Your lower back will just be a weak link for a while, so consider also doing deadlifts and hyperextensions to strengthen it. And keep squatting, paying careful attention to form.

[BG5150]

I'm not sure, but 45 degrees has got to be very bad.

Make sure you have an arch in your back. When you lose the arch, don't add weight.

[bschatz88]

Make sure you have an arch in your back. When you lose the arch, don't add weight.

I agree with that :)

[RBC13]

And keep those abs tight.

[bigsethmeister]

I have the same problem. Squats are a really difficult exercise for me because my natural tendency is to lean way forward and let my knees forward in order to keep from falling over backward. It really sucks.