I think there is little doubt that Ken's recommendation regarding developing a strength building regimen is a good plan for us older sailors. At almost 59, I'm beginning to believe that I will have start a weight or conditioning training program to strengthen my back, as I find it becoming easier and easier to tweak it.
However, I did want to emphasize the importance of using a mechanical downhaul tool. Probably about 10 years ago I started have back problems that I think were nerve related, as I developed pain at my right hip and along my lower right torso, and it started becoming increasingly difficult to walk normally. I ultimately discovered that the stress I was putting on my right side while downhauling my sails was the source of my problems. Although I had no problems of any kind for many years earlier, the affects of age started getting the better of me. By regularly using a mechanical downhaul tool, my problem literally disappeared.