I'm 57 years old, and this is what i did:
I changed the problem, rather than find the cure.
1. Lightest equipment: Gardiner Xtreme pole and brushes, (sill brushes are good). I put 30m of reinforced pole hose on my main reel (easy to use and reel in). I also purchased a waterworks electric reel (one of the best things i've done).
2. Work out the side of the van (in 90% of cleans, this works ideal, straight out and straight back, no going round corners.
3. Bin off all the awkward houses. I only take on easy houses or bungalows (no reaching over large connys to get to crap).
4. Price increase, I can now earn the same money for less hours per day.
I had tennis elbow, golfers elbow, a dodgy shoulder and a dodgy wrist (no jokes please). By changing the way I work, all these are no longer a problem.
I have done all I can do to make my work (easier!). This year I will focus on me...maybe Pilates, Krav Maga I fancy (I used to do boxing) but I need some form of external fitness or exercise that I find interesting. My diet is good and I eat healthy so I can't really improve on that but I will drink less alcohol. (no more wiskey).
Ps The red wine stays.