I made a short video in honor of three of my buddies, all mid sixties, who have been fishing fresh water for years in New England. Like me, they have grown complacent, and have forgotten that age happens when we least expect it.
They came down this year to throw flies at big tarpon, and were in for a rude awakening. One lasted two hours with a 12 wt, and spent the following 2 days on ibuprophen and ice and heat packs. The other two gave up and used spinning gear.
The same thing happened to me when I first got back down here, finally, for good. It gave me a big scare - the thought of being too old to throw a heavy rod.
All it took was isometric exercises done for 10 seconds throughout the day whenever I thought of it. That was after a 3 week layoff with ibuprophen for several days (after breaking out the old 12 wt) so that I could hold up my coffee cup.
If any here are planning throwing a heavy line and are used to trout rods, I would highly recommend exercising and practicing with heavy flies for a couple of months before a planned trip.
With isometrics, all that is required is two arms. With the rod arm bent 90 degrees at the elbow, and a fist made such as you would use holding a rod, place the line hand over the top of the rod hand and pull back with the rod arm as hard as you can for 10 seconds.
This simultaneously strengthens the hauling muscles as well. It is good to do exercises like this immediately before eating, as the carbs and protein will quickly be available to build new muscle rather than tear down what's already there.
The video shows the muscles that will get amazingly painfull from the backcast if one is not used to heavy rods and lines.