I was at the gym today with a friend who is 70. He hammers out 45lb dumbbell preacher curls with no problem. He doesn't look his age. I've read that muscle mass can be gained into one's 90's.
Further regarding age: I worry about tendon injuries far more than muscle injuries, and train accordingly. I'll be 57 in a few weeks.
Saw this article yesterday.
"Intensive Exercise Keeps Aging Muscles Young"
http://www.newsmax.com/Health/Health-News/intensive-exercise-aging-muscles/2016/04/06/id/722587/
Regarding injuries, I don't think I've ever had a muscle injury, and I'd probably remember if I did. Joints, on the other hand, are a different matter. And the only time I've ever experienced joint issues was when I lacked proper form and/or used momentum when going heavy, both of which should be relegated to the foolishness of youth even though I had made such errors well past my youth. Because I now (finally) use proper form and cadence, I no longer have any joint pain during any exercise, and have only residual shoulder issues from my impetuous past. Although you "worry" about it, I assume you don't experience any joint pain while working out or afterwards. My thinking is that, apart from residual pain from a past injury, if a person has joint pain during or after an exercise, then he's either doing the wrong exercise or doing the right exercise improperly.
As an aside, regarding your 70-year-old friend who hammers out dumbbell preacher curls, just a quick observation if I may. I don't understand the fascination with any isolation exercises, particularly for biceps. The bicep is probably the smallest muscle group that people spend an inordinate amount of time on. When I'm at the gym, this seems to be the muscle group that most people concentrate on, with variations of curls of one type or another. I don't see why people don't just focus on bang-for-the-buck compounds, which also provide a better metabolic effect, especially as we get older and have more limited resources to employ (i.e., recovery). Back exercises work the biceps plenty, so why paint with a pencil brush when you can use a roller? People can't really change the shape of the muscle, as I think that's genetically determined. As for strength and size, well-performed back exercises also leave your biceps spent, along with your back and rear delts. Thanks for letting me rant.
