My hope is that some of the arm exercises on here and other linked sites will help me strengthen my forearms and fix my tendons so I can get back to at least some of the training. Maybe starting back slowly just so I maintain instead of focusing on lifting more.
Yep - 54yo here, so I ain't what I used to be, and back then I wasn't what I could have been. I am eating better, so hopefully that will help.
Honestly? My suggestion to you would be as follows:
Commit... in your workouts... to FIRST after stretching to warm up minimum 10-15 minutes SOLID.. then.... doing PRECOR Elliptical on 9 or 10 incline and try starting at 10 resistance. And the idea is to see by how much you can pass 3.0 miles by the time you hit the 30 minutes mark!
If you feel yourself needing to let-off the resistance at times. Try to resist doing that as long as possible. The goal being get to 15 minutes at first. If bop it down. See if later on you can bop it back up! Then after awhile not even needing to at all! (over time)
And make sure to tell it your weight and age so it can give ya decent guess on calories burned.
THEN! .. Nope! Not weights yet!... Goto Leg Raise station. And try to do, in sets of 10x, as many as you can. I've gotten it up to 10 sets of 10x, at times, now with my back trauma and shoulder stuff and stomach hernia issue I'm waiting to get fixed, I can only do like maybe 6 x 10 these days.
THEN... you go do weights! But think of and use gorging principles and then only do your upper body stuff. So that way your body will focus getting blood to that region with several muscles near each other, so best chance for them all receiving the repairing nutrients that evening.
Then like on a "Leg Day". Try replacing doing weights on and off with INSTEAD... doing the Elliptical in similar fashion... only this time.. for a full 60 minutes! And the Goal is to see how much farther than 6.0 mi you can get to before times up! And be more lenient with yourself about allowing yourself to bump it down a notch. This time try like doing 5 mins reduced, 5 mins back up to the resistance you're trying to maintain from the start. And typically, I usually opted for the Interval training pattern it has. Cause those change-ups can help ya recover a bit while hoofin' it.
And on upper body days? END with shoulder work NEVER begin with shoulder work!
EDIT: RE: Tendon pain? NO.. naw man... at this age bracket you gotta give that tendon time to calm back down man. It's MUCH easier to RIP isht like tendons in this age bracket man. As they say "Belee 'Dat!" Learn to be cool with backing-off the intensity a lil, from what you "Know" you can do. Because, I believe especially with age, we develop even more so the ability to push past the pain when working out, far more than we should be. Before? The vibrant healthy nature of all our tissues could handle picking up that tab owed by us pushing past pain threshold limits being loudly signalled to us by Pain! but it's not as much like that any more. It's kinda like, in terms our workouts, we need to be more willing to admit "Your mouth is writin' checks your azz can't cash" anymore, when it comes to the level of intensity or heavy weight we should be trying to push it up to. Realistically.
You can acheive that Hypertrophy many different ways. Ya just need to push that muscle to failure. The only thing with that is... doing so with way lighter weights can feel tedious due to the high rep counts needed to achieve similar results. Cause I mean like... Dumbbell Chest presses with 25Lbs you're like "This is nothing, I could do this all day long!" But you'd be surprised how it hard it CAN feel after like 40-60 reps in one go! Thing of it is, that lighter weight? Can signal to you sooner, before damage is happening, that you're done now. It gives you a chance to NOTICE that pain/inflammation/soreness is increasing to that place where if you stop now... you'll still get a righteous pump and tighten up, but you didn't "cross the line" that day of what your joints and tendons and muscle tissue wanted to allow you to do that day.
Especially since at this age bracket, we tend to have a metric crap ton more things to be stressing about than we did back at 20-30s. And that has a very definitive effect on us! Cause you're in that "home stretch" towards hopefully retirement, so now you hopefully have a higher paying job than before but more responsibilities and demands on you, it's how it always is.
Think of it this way.... If you DON'T tone it down and start listening better to your body now at this age? You're going to pay an even higher cost in terms to the change in your quality of life, because we just don't heal as good the more we age. And things like tendons and trauma to spine? Speaking from experience, and comparing notes with others in that boat? You want to avoid the need for surgical intervention for anything at all costs. Once it's needed? It's been my experience that the area of fixing is never the same again.
There's also financial responsibility questions to answer and think about. How would that mess up your ability to do your line of work if you ended up jacking up your elbow, that tendon? What if it creates an issue for you, that will persist AFTER you're retired and no longer getting health insurance thru an employer?
If you need a surgery, now is the time to get that done. I figure we already know we're aging now, so best to get the work that needs done taken care of at youngest point in your timeline to encourage best healing outcome, ya know?