I have developed knee pain after about 2 hours of hiking. It is most painful on the downhill but uphill hurts, too. Putting weight on it is not the problem, flexing is what hurts. Does this sound like an overuse issue also related to age? I'm 60 and want to do MORE hiking. Just walking around does not make it hurt, I walk about 2 - 3 miles a day at my work. It is perhaps the ultra flexing for climbing that triggers it? Anybody else develop this problem and what do you do for it?