Nike cofounder Bill Bowerman famously created the Nike Waffle Racer after pouring urethane into a heated waffle iron. The concept stemmed from track spikes, only without the spikes. Instead, the waffle mold left small, protruding squares to better grip surfaces. First marketed in 1973 as the Waffle Trainer, the shoes originally cost between $21.95 and $24.95. Later adaptations included the upgraded Nike Waffle Racer version and countless others. [The Waffle Trainer] was probably one of the first big Nike innovations, Highsnobiety footwear editor Chris Danforth told Business Insider. The resulting shoe was the Waffle Racer, but that resulting shoe pattern was also used on a few other subsequent Nike shoes.Six years after Bowerman's invention of the waffle sole, NASA engineer Frank Rudy pitched a new design concept to Nike. His sole technology included encapsulated air bubbles. The first shoe in 1979 was the Nike Air Tailwind, said Danforth. It had a hidden air bubble in the sole of the shoe. The air bubble stayed hidden until about 10 years later, in 1987 when they released the Air Max 1, which had the visible air. Nike's air technology has since been included in countless versions of Nike sneakers, including the infamous Air Jordans and Air Force 1 lines. The level of innovation that's gone into Nike Air — it probably has to be the most effective and best-marketed sneaker technology ever, added Danforth.While various sneakers today include mileage tracking, the Adidas Micropacer was the first of its kind. The sneaker had a built-in calculator that recorded and saved distances logged while running. The idea of a shoe with a computer in it? The Adidas Micropacer should be mentioned for sure, said Danforth. A rerelease of the original shoe is available today, though it is significantly more expensive. On Adidas' website, the newest Micropacer sells for $200.In the 1980s, Adidas unveiled sneakers with new and improved stabilization: Torsion technology. Danforth explained that the new stabilizing feature took form in a flexible bar in the mid-foot of the shoe. As the shoe bent, the bar provided support from forefoot to heel. Many of Adidas' sneakers today use the original Torsion stabilizing system, including some of the brand's most popular Adidas Boost versions.True to their name, Reebok PUMP shoes inflated to hug your foot shape. It would sort of lock your foot into the shoe, Danforth told Business Insider. It hasn't really stood the test of time, but definitely — in the timeline of innovation — the Reebok PUMP is worth mentioning. On Reebok's website today, several new versions of PUMP technology are sold. InstaPump Fury OG sneakers sell for $180, while a kids version sells for $50.Danforth told Business Insider that every main brand has different names and trademarks for cushioning, and Asics' claim to fame is Asics GEL technology. The running brand was the first to experiment with gel in order to provide a comfortable cushioning system for wearers. They actually have a story about how they dropped an egg from two stories up onto a gel pad and it didn't break, Danforth told Business Insider. That was their proof of concept for gel cushioning. Since the original launch of the innovative cushioning, Asics has created many sneaker variations using gel: GEL-Nimbus, GEL-Quantum, HyperGEL, and GEL-Lyte are just some of the versions available today.Danforth noted that Adidas Boost is another revolutionary cushioning technology and — due to its impact on fashion trends — has become one of Adidas' best-selling sneaker lines to date. [Adidas Boost] sort of reinforced this idea that performance shoes or running shoes can be comfortable, but also tied into this whole athleisure thing, where people are wearing running shoes to go grocery shopping, Danforth told Business Insider. One of the most expensive variations sells on Adidas' website for $250.Unveiled for the 2012 Olympic Games in London, Nike Flyknit made its mark as the first running sneaker to feature a knitted upper part of the shoe. Originally, it was just the American athletes training for the London Olympics who were wearing these shoes, and then they eventually made their way into the public domain, said Danforth. Nike Flyknit sort of, in a way, kickstarted this arms race for all other brands to create their own proprietary knitted textile. In the end, Adidas and Nike have taken the top two spots — although Nike did it first, they were a massive revolution for the whole industry. Other brands have subsequently released knitted sneakers, including Adidas Primeknit and Reebok Ultraknit.Danforth explained that while some of the most important innovations occurred in the 1970s and 1980s, recent advancements are developing every day. A big step for sustainability includes Adidas' recycled shoes. There's still super recent stuff that's going on, even as close as four, five years ago with Adidas Parley for the Oceans. [The company is] combing beaches around the world and collecting ocean plastic, then recycling to make fibers from the plastic and they have this ongoing collaboration where [sneakers] are manufactured with ocean plastic. As far as innovation goes, that's pretty cool.I think the biggest innovation within the past one to three years that people are talking about is Nike's auto-lacing shoes, Danforth said. Funnily enough, it started with Back to the Future 2 ... it started as a piece of film fiction and more recently Nike has built motors into shoes. Originally a recreation of Marty McFly's infamous self-lacing shoes, a pair of Nike auto-lacing sneakers was first unveiled at an auction with proceeds going to the Michael J. Fox Foundation in 2015. Following this success, a second generation retailed to the public for approximately $720. Now, Nike is marketing auto-lacing basketball sneakers for $350. Danforth explained that sneakers are controlled either by a button on the side or through an app on the owner's phone; the motor connects to cables, which tighten or loosen the shoes. Puma has also experimented with its own auto-lacing technology, called Puma Fit Intelligence.Danforth told Business Insider that Nike, New Balance, and other brands are also experimenting with 3D printing. Adidas, however, has partnered with a California company called Carbon in the past few years to create shoes with a printed, grid-like sole. The soles are made through a digital light synthesis process, and the current version — called Alphaedge 4D Shoes — is retailing for $300. TIME listed Adidas 4D technology as one of the best inventions of 2017. The franchise also collaborated with sustainable fashion designer Stella McCartney.