Is it bad to wash your hands after a strenous activity?

I've had older people tell me that you may speed up painful arthritis if you wash your hands after a strenuous activity such as writing or drawing for a couple of hours or using them to mage. I do mage therapy & wash my hands regularly to avoid cross-contaminiation. I am woried I may be damaging my hands by doing so. I have ony minor aches & pains in the hands from normal wear & tear but am woried that they might get worse. Is there anything medical to back this up? Or is it plainly a superstitious belief? thanks!