I'm looking 40 in the face. I've had 2 nasty injuries, one a back injury, that after some years I still deal with with my lifting. Having said that, I'm a 500+ raw squatter and go heavy as I can as often as I can and still getting bigger and stronger (still feel like a beginner, though).
I go through phases of heavy low reps and higher rep schemes (about the same volume) depending on how I feel that day/week and what body part is acting up or feeling strong.
Check out the "Over 35" forum for some really strong 'old' people. There are 60 year old competive bodybuilders, a bunch of 5/3/1'ers, men, women powerlifters, olympic throwers, and a bunch of other strong folks doing a variety of things, each one with an entertaining and informative log.
One woman in her 40's at about 120-130 bw (sorry if I'm guessing high if you're reading this) is squatting 345 and repping 315-- effectively putting many of 'teh boyz' on this site to shame.
Listen to what your body tells you and stick with what works!