Some engineers at Russia's Ufa Aviation Technical University are walking with an extraordinary spring in their step. Gasoline-powered boots, originally conceived to scoot Soviet soldiers across a battlefield, allow them to take 14-foot strides and jog at up to 23 miles per hour, according to Boris Rydoi, chief of the project that developed the technology. Each time a brave soul wearing the boots takes a step, the gas in a cylinder fires, pushing a metal plate away from the bottom of the boot and shooting the walker into the air. Rydoi hopes to sell the über-boots for $400, pitching them as an alternative to in-line skates.