Newton Running Shoes.

Danny Abshire started working on Newton Running Shoes in the early 1990s, but he turned the corner after enlisting longtime Boulder real-estate developer and runner Jerry Lee as an investor in 2005.

The shoes use a patented system of hollow chambers and "actuator lugs" that act as levers and recycle energy from their impact on the ground into their next stride forward.

"We have an action and an equal and opposite reaction," said Abshire, noting that the colorful shoes take their name from Sir Isaac Newton. "It works off some fairly simple principles. We were astounded nobody had done it before."

Lee and Abshire launched the colorful shoes by selling them directly to athletes at Ironman expos last year, leading to a soft retail launch that quickly snowballed into about 100 retailers in the U.S. and international distribution. Lee said both he and Abshire wear Newton shoes while they run long-distance. "I'm the marathon guy and Danny is more the 50-, 100-mile guy," Lee said. $155 to $175 per pair retail. Made by Newton Running Co., Boulder, (877) 860-7695 or (303) 442-1113, www.newtonrunning.com. There is a retail locator on the website.

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