I’m a 45 year old fart AND I only started working out a couple of years ago. Boy, did I get my share of problems. Tendonites in my left elbow, partially ruptured right patella tendon, right shoulder impingement. And I had a history of knee problems to start with.
I take glucosamine/chondroitin/MSM and fish oil. But it’s not only about the supplements.
I try to use balanced workouts, undulating, with a deload week every month.
And I NEVER suck up the pain. I learned that the hard way. I feel something I shouldn’t, I immidiatly stop the exercise. I sometimes do 1 extra rep just to be sure. Put cold water on it in the shower, head home, ice.
I ease new exercises in real slowly, using light weight, gradually increasing the weight and the reps. It could take an exercise up to 3 months to make it heavy enough to use it in my actual training.
Because of the partially torn patella tendon I had to stop doing any quad exercises. After the doctor told me the tendon should have healed I started on the leg press. Only because I could use sub-bodyweight on the legpress. Yup, I started pressing with 50kg on the press. Took me 3 months to work to a decent weight. Started doing Goblet Squats then. Went form 5kg db to 20kg db in about a month. Felt a strange pain in my right knee. Felt the pain when I came up from sitting in a chair.
Dropped any quad exercise untill a month after I could get up from sitting down again.
Then I returned to the leg press. Started doing the goblet squat again about a month ago, went from 5kg db with 8 reps to 8kg db for 12 reps.
I know I could increase the weight faster. I did do it faster. Wasted several months getting injured again after doing it faster.
Also, compound exercises. In isolation exercises, if something gives, you have a serious injury. In compound exercise, they tend to be less serious (in my limited experience).