Why did NASA make air-cushioned trainers
It was originally made for Apollo. They were used to produce space helmets. While Tang and Teflon didn't come from NASA the Agency has developed many items we use in our everyday lives.
how do they help us today
Todays athlete has a wide variety of options to choose from,relies on the cushioning needed for a optimum. In the early early 1980s a process known as "blow rubber moulding" was used to produce space helmets.
http://www.nasa.gov/missions/shuttle/f_boots.html http://www.sportsdirect.com/nike-air-zoom-fly-2-mens-running-shoes-212445 http://www.complex.com/sneakers/2012/12/the-complete-history-of-cushioning-technology-in-sneakers http://www.nasa.gov/missions/science/f_apollo_11_spinoff.html http://www.independent.co.uk/news/science/50-years-50-giant-leaps-how-nasa-rocked-our-world-879377.html