In 1974, Soviet engineer Viktor Gordeyev decided he was done with running. So he designed a boot to do the work for him. Using tiny, gasoline-powered pistons, Gordeyev’s boots propelled the runner away from the ground, turning each footfall into an explosive stride.

As nutty as the idea sounds, Gordeyev’s prototype worked. In tests, runners bounded along at nearly 22 miles per hour. The Soviet military promptly seized Gordeyev’s concept and classified it a state secret. With the help of the boots, Russian super soldiers would be able to run down their tank-driving Western enemies! Best of all, the boots got great mileage: Each pair could go 70 miles on a single gallon of gas.

So why aren’t we all racing around on rocket boots? Hard as it may be to believe, gasoline-powered shoes aren’t particularly safe. The New York Times noted that the engines “tend to throw a wearer off balance or cause knees to buckle.”

If the timing of a runner’s stride is even slightly off, the piston can fire just as the foot is making impact with the ground, causing serious injury instead of a super step. Still, if you desperately need to win a footrace (with a hungry cheetah, for instance), rocket boots may be a risk worth taking.

Want more amazing stories like this? Subscribe to mental_floss magazine today!