In the early 1980's, Alvaro Z. Gallegos was running an average of seven miles a day. He suffered all the typical injuries associated with running—heel spurs, plantar fasciitis, knee trouble, hip pain, and back pain. And although he owned a shoe store at the time and had access to all types of running shoes, he was unable to find a shoe that eased his pain.
Realizing that the source of his pain was impact, Al reasoned that putting a “shock-absorber” in the heel of his shoe would reduce the force of impact. And as an added benefit, a spring would provide some form of energy return, to help him run faster and farther.