Holy smokes. Here's a place to start:

http://startingstrength.com/article/strength-training-for-people-my-age

Lots more discussion to that end on that site. One upshot - frail people wither away, strong ones go like hell and drop dead, and a calculation of area under the time/quality of life curve shows the strong guy winning bigly.

Originally Posted by Brad
No one should be doing squats at any age... and it's definitely one of the worst things anyone over 30 can do.