Sorry, I should have been more explicit. On a forum I use it was a genuine question asked by someone else. I thought it a wind up too. She asked if walking a mile used more energy than running a mile. Every reply laughed at her but she would insist on trying to get a scientific answer, which I couldn't provide. Thanks for your replies.
Ahh.. ok. I did hear it touted that you were quite well off 'briskly walking' one mile, almost as much as running it. As I said, running is more efficient, mostly due to conservation of momentum, and also there is the springing motion involved. So given the amount of work you do to walk a mile, I wouldn't be surprised that it comes close to running, even though running feels more energetic.