I remember reading once (in regards to trekking poles) that the human arm can weigh 5 or more pounds, on average I think the number was 7 pounds. I think the argument was that just by swinging around hiking poles and resting your arms on them while you walk, you are in effect taking 10-15 lbs off of your legs. Just a thought/theory. Obviously most of us use them much more effectively than just this. I see benefits from proper technique, pushing off or pulling up on uphill, putting weight on them on downhill (easing impact on knees), and more importantly, I use them for most of my balance in uneven and loose terrain. Ever tried some new sport that requires balance and woke up the next morning feeling sore muscles you never knew you had? Alot of fatigue in the legs comes from them constantly steadying and balancing your body and pack load. Transfer the balancing act to the arms (poles) when the terrain is uneven and the legs go much longer now that they are just supplying raw go power!