(I am reposting my response from an old hiking pole thread )
"I am a recent convert myself. Before I always hiked without them, thinking that the poles would get in the way.
As I got older, I realized that my knees were giving out on me,. On my last hike to the top of Mt. Whitney, hiking poles made a huge difference: I was able to go down the mountains with ease, and my uphill speed increased dramatically.
I have Black Diamond hiking poles. They are easy to adjust if you are switching from uphill to downhill, unlike the Leki kind.
Here is an old knee support/hiking poles thread "