It is amazing to know, but not surprising, that we evolved in a such way to spend as few energy as possible. Walk and run is one the activities where we spend lots of energy and in order to avoid waist we swing our arms synchronized with our legs naturally. Watch this video and discover how to spend up to 26% more energy just walking "out of phase". Unfortunately researchers did not tested the really weird silly walks done by Monty Python's John Cleese at this video. Certainly those silly walks spends more than that.

Source: guardian.co.uk