Good piece on double-amputee Pistorius (video)

http://sports.espn.go.com/oly/trackandfield/news/story?id=2938043

Anyone have a link to a study saying the prosthetic legs produce less energy than flesh and bone legs? I’m having a hard time being convinced the drag reduction of a prosthetic offsets (or exceeds?) the energy loss in the same leg. But seeing numbers would be nice.