Walking on Air

American engineer Marion "Frank" Rudy created the world's first shock-absorbing sole system for athletic footwear. Marketed by Nike as the "Air" system, the technology inspired countless follow-ups by rival shoemakers.

Inventor: Marion Franklin Rudy (US)

Invention: Shock-absorbing cushion for shoes

Sector: Furniture, games

Company: Nike

Jogging is healthy exercise. But the impact of running on city streets and sidewalks can take a heavy toll on the joints and connective tissue of the human body.

On average, the feet of runners hit the ground a whopping 1 500 times per mile. And jogging releases forces more than four times a person's body weight. Other high-impact sports such as basketball can potentially shock the body with up to seven times its own mass.

So how about softening the blow? In 1979, Marion "Frank" Rudy patented small gas-filled membranes fitted into the soles of running shoes. They would become known as the Nike "Air" system.

For the invention, Rudy drew inspiration from his experience as an aerospace engineer. Working at American space agency NASA, Rudy had been introduced to a process known as "blow rubber moulding."

Rudy used this moulding process to create hollowed soles for athletic shoes. He then filled the hollowed cavities with highly dense gases, sealed in by rubber membranes. The result was a gas-filled, shock-absorbing cushion.

In 1979, Nike released the first running shoe featuring Air technology, the Tailwind. It became famous when British runner Steve Ovett won a gold medal at the Moscow Olympics just a year later.

Since then, the technology has enjoyed great commercial success. Between 1986 and 1993 alone, Nike sold more than $2 billion in Air-system shoes. Rival shoemakers introduced shock-absorbing pockets of their own. 

Frank Rudy supplied the patents to numerous follow-ups, including shock-absorbing insoles, gel padding and helium-based "Air" cushioning.