Make no bones about it, the concept of Nike Free is one of the most important innovations in the company’s history. It may not be as lauded as more highly visible technologies like Air Max or Flyknit, but it’s impacted everything the company has done the past 15 years from basketball to apparel.

“It was a paradigm shift for us and I really do think for the industry as well,” said Tobie Hatfield, director of the Nike Innovation Kitchen who concepted the original Nike Free in 2001. “I mean look at retail, there was never a natural motion silo before that. Nike Free basically started it.”

It may seem counterintuitive, but there are actual benefits to running with less cushioning if you’re a cyclical runner. The Nike Free was never meant to be a sneaker to cover long distances. It was built as a tool to awaken then intrinsic muscles in the foot and, in turn, strengthen the rest of the body. It’s a message that Hatfield has been preaching and educating about for the past 20 years.

“There’s a neuro-connection to the ground that we all have or don’t have depending on whether we’re filtering out that connection or not,” Hatfield said, adding that he believes every athlete in any sport should have a pair of Nike Frees in their bag. “Free helped us lessen that filter so we can turn these receptors back on. It’s so important to free the feet.”

The line has gone through several changes over the last decade--for better and for worse. Designers admit that recent iterations of the Nike Free have strayed from the line’s original concept of minimalism. Internal tests with runners revealed that weartesters couldn’t tell the difference between the 2017 Free RN and the Pegasus 34 in terms of which one was a natural running sneaker.

“Sometimes we kind of have to slap ourselves and get back and re-center ourselves,” Hatfield said. “I think that's what this 2019 model—the 5.0 and the 3.0, are doing—getting back to our roots of the Nike Free.”

The latest version of the Nike Free 5.0 is 26 percent more flexible and 2mm lower to the ground than its predecessor thanks to advancements in laser-siping. The upper on the 5.0 version is also a throwback to the original Nike Free with a single construction and synthetic suede reinforcements.

Scroll over the dots below as Hatfield breaks down all of the details on the latest updates to Nike Free.