An addendum to Mondays's link -
The reason for guys and gals of any age to do total body resistance exercises like squats and deads is to maintain or build muscle and bone strength and overall functionality. They are not just for athletes, and yes, they are preferable to machine exercises which tend to isolate muscle groups rather than being full-body, functional exertions.
BUT proper technique is important. Beginners need to be trained to do those things correctly. Even with excellent training, I had a painful back during my first few months of deadlifting. As I grew stronger with the movement, the pain went away and never returned.
I began doing deads 3 years ago. I began with 95 lbs, with trainer. The bar weighs 45 lbs, and the lightest bumper plates weigh 25. I have the movement pretty-well grooved in by now so I do deads on my own. However, my trainer still programs what I do. Occasionally I use the trap bar, for no reason other than variety.
At this point (mind you, I am not a youngster, and do not have a husky lifter's build) my programming looks like the below note from my genius trainer - This is a strength program for a not-young guy, not an endurance program although I mix it up sometimes:
Think: after 115 lb. 5 rep warmup, with 90 second rests between sets.
Set 1—135 for 5 reps
Set 2—145 for 5 reps
Set 3—155 for 5 reps
Set 4—155 for 5 reps
Set 5—165 for 3-5 reps
If you add a 6th set add another set at 135.
Even if you feel you can/should do more weight, don’t. Master the weight(make 135-155 move smooth and easy, with no sticks)- Master the hold. Get to a point where 135-155 for 5 reps “feels” like you could do it for 15-20 reps.
Bonus links via reader: Dan at age 72 beginning squats, and two years later.