As a member of the over 50 set I think it all comes down to what you brought to the dance. What is heavy for a 110 pound person may not be for a 230 pounder. I still do most of the crazy things I did in my youth and some like my current job as a fire fighter are perhaps more extreme in some respects. There are no absolutes in physical capabilities due to age except that you have to work much much harder as you age to keep fit vs when you were younger. I hit the weights for an hour a day and no I'm not as strong as I was at 20 but I am in better shape than most of the 25 years olds I work with. Eat right ,work out, listen to you body and lift with your legs not your back. It's much like training your horse for endurance if we just take the horse from hanging out in a paddock and try to top ten chances are we are going to hurt the horse and we all know that so we train them up. Some how I think a lot of us forget that the rider should do that too. Oh and
I do keep the bottle of Advil handy LOL
As someone who is over 50, here's my advice. Don't do it! Don't lift more than 30 lbs, period. I know that many of you out there will say how you can fling 100 lb sacks of grain over your shoulder every day....etc. That's great...until you can't and you do other serious damage that causes you to change all of your riding dreams. Use a cart, use a 4 wheeler, use a neighbor kid. Don't be macho. Plus, it's darn expensive to have all of your body parts put back together. Just think of how many LQ trailers I could have and how many XP rides I could attend for all the money I've spent on surgeries, physical therapy, doctors, medicine, etc. It's not worth it. BTW, I suggest Pilates with a really well trained instructor for developing your core strength...however, that does not mean you'll be 25 years old ever again :)