I think you guys are asking for things that just arent possible.....as far as comparing your 50 year old self with your 25 year old self
Post 50! Your past 50! Do you see any professional athletes in MLB, NFL, or NBA past 50? It is what it is....aging....and your looking for a culprit. And the culprit is your post 50!
Twenty year old Joe out playing full court basketball with the boys...I dont expect him to get hurt...if he does...bad luck
Fifty year old Joe out playing full court basketball with the boys and he tears his achilles or blows out his knee.....yea I am not surprised. Should fifty year old joe be blaming the court, his shoes, or anything else? He is fifty!
I cannot squat, deadlift or do anything poundage wise my 28-38 year old self could do in the gym...that guy was a stud...joints of steel...IM not trying to find any other reason for it than what is fact....my prime lifting years was probably 28-44ish...its just the reality of it
with that said I think the biggest mistake i see everyone do that develops knee problems is
1) Ballistic training...they bounce out of the hole on squats, hacks and whatever else in their younger years because they are trying to show off/use too much weight with shit form and they damage their knees
2) Shallow movements.....and we can argue all day about this but it is my experience that virtually every single guy Ive ever come across that did shallow nonfull movement squats to again (show off/use too much weight) ended up developing knee problems....while people who have always done deep full squats dont get those debilitating knee problems with time. Ive seen this time and time again...either ballistic out of the hole or non ass to bucket squats due to wanting to use weights that were truly too heavy to be used at that time.
I did the following when i was training people all the time and wrecked quite a few egos in the process....i had countless guys saying "my knees hurt...oh woe is me my knees etc"....and i would explain the above and you know what i would make them do? I told them im going to reteach you to squat properly and its going to be embarassing because we are starting with 25lb plates on each side and we are not going up the following weeks until you squat it deep/then a pause/and then raise (not ballistically) out of the hole for 10 reps...and we will only go up in weight until you learn how to squat properly......and you see the light goes on with them...with the "oh man i should have been doing this for all these years...I ruined myself trying to show off"
Ive squatted in probably 98% of my leg workouts for the last 30 years. Ive always squatted bigtime deep and im 6'1"....like Tenny said I have no idea how someone does half squats...my patella tendons feel like they want to snap across the room like that so no wonder so many people sacrificed knee health over form doing it that way for so many years.
Gone are the days of 450-575 squats for reps for me....thats gone. And mainly for the reasoning that I dont want to suffer a catastrophic injury at this point in my life. I do a boatload of hiking for cardio now so my whole deal is 20 reps with squatting. Ive gone over to smith squatting now because all the hiking and free squatting wears me out and again its all about injury prevention with me now. 315 for 20 rock bottom is right around the corner for me.
I do the same thing every time i train legs and have done for years...
16% menthol (FLEXALL) on my knees, with long cotton sweats under my normal sweats to keep warm
a) train hamstrings first..get a whole bunch of blood in the legs
b) always do leg press first for quads and again i do deep and use the warmup sets (deep) to get mobility in my knees....every warmup set is 12-16 reps and top work set is 12-16
c) smith squat (non counterweighted) trying to set my 20 reps record
d) one other exercise
e) adductor
f) abductor
(knee wraps on all my top end sets)
but again.....i think mostly people are expecting themselves to have the capacity their 25 year old self did....and its just not possible. I always tell people you better get some big quads when you are young (25-40ish) because you will not be able to build massive quads when you are older...you will be fighting to keep leg size at that point so you better get them large when you can.