As it's relevant to the sport I practice and just came back from armwrestling training I'd like to randomly comment: Armwrestling clubs have a LOT of people with tendon pain and injuries. The general approach to recovery and building tendon strength (beside lifting heavy) is to do static holds of 10 seconds+ of light to medium weight. Often paired with very large sets (50+ reps) of _extremely light_ weight; lifting almost nothing, just to get the blood through the tendon. You should not feel sore at all in either movement. The idea being that blood gets into tendons through movement. As for static holds; tendons expand during these static holds, so the idea is that they can then absorb more nutrients... Or something like that; I'm no expert by any means!

In the bouldering community there has also been a bit of an uproar where Emil Abrahammsson (find it on Youtube) did very light static holds 2+ times per day for ~30 seconds if I recall correctly for great tendon strength, this also had some influence on how people train for armwrestling. This style was nicknamed "Abrahangs".

No comment on the joint thing.

As far as tendons are concerned, they require proactive rehab and you have to load them. There are various loading strategies that a physio is best placed to advise on. Shockwave therapy has also been found to help.

Some pain during tendon loading during rehab is generally expected and not necessarily a negative sign, somewhere around a 4/10 at most.

Recovery is slow in the order of months, not weeks.

There is some evidence that taking a collagen peptide based protein along with vitamin c an hour before loading the tendon can help.

Maybe glucosamine, it’s pretty cheap and accessible.

I doubt it, it's not the area where creatine is helpful. It'll influence energy provision which helps your muscles recover, and even be a bit stronger in general. I'm in my 45's but I don't experience tendon or joint pain while lifting (my numbers are not going to impress anybody though, but I do train pretty hard). Were I in your shoes I'd take a trip to the GP to try and find out what the source of your pain is. I am tempted to say I would also start taking creatine, but not if you're increasing your load as a result.

Use compression sleeves if you mean knees / elbows. If you mean rotator cuff, do face pulls. This isn't medical advice, just speaking from experience.

Except for old injuries that never completely healed, you should not be suffering joint pain at your age. For starters, you likely should shift to lighter weights.

A general rule is that, after 26, any muscle or joint injury you suffer will never completely heal. So

- avoid injury scrupulously. Don't accept gym challenges (even your own). Be wary of odd exercises, machines, routines. Don't do anything hard at first, always start easy. Be lazy, build up and take your time: you have the rest of your life. Don't work out while under the influence of alcohol, especially when with friends. I avoid certain sports, e.g., any martial arts, soccer, football, even baseball, b/c the variety of situations(and consequent accidents) is so unpredictable as to be uncontrollable. Sprinting, hurdles, gymnastics and high jump are risky too.

- avoid over-stressing muscles and joints. Keep the cardio up - maybe try the gym classes with music (the crowd is better-looking and friendlier).

- See a doctor if you suffer pain unduly.

- Avoid all toe-lift weight machines and weight sleds (sleds that you push as if pushing a truck) like the plague. Never use them, otherwise you may experience pain so severe it will change your "fight or flee" response to 100% "fight" even in a life-threatening situation. Do NOT challenge this suggestion especially if above the age of 40. Explanation: look up the term "plantar fasciitis".

I anticipate "someday soon" cures for tendon/joint pain but I've been waiting too long to expect their arrival before I die!

Isometric holds. Tendons grow slow and recover slow, generally not as much circulation as muscle.

Big heavy holds will help encourage blood flow without stretching them / stressing them as hard as big lifts.

It seems weird because it goes again ROM ideas, but it has definitely helped protect my arms for rock climbing as well as less fatigue in my legs for big lifts.

I'm going to get yelled at, but eat bacon. Fat is good for tendons. Obviously don't eat immense amounts, but if you're eating none, try eatong a couple of slices on workout days.