Continuing our week-long Reebok coverage, today we bring you the stories behind The Pump’s two iconic cushioning systems: ERS (Energy Return System) and Hexalite. In our latest exclusive, Reebok Pump creator Paul Litchfield reveals to Counter Kicks how these technologies were developed and how they work. Continue reading for an inside look at Reebok’s cushioning systems…
In the late 1980s, as the sneaker technology battle was heating up, Reebok needed to bring a performance-based cushioning to the marketplace to reassert its athletic equipment image. As a result, ERS was born.
Reebok debuted ERS, or Energy Return System, in 1987 to compete with Nike Air for cushioning preeminence. ERS was initially incorporated into shoes such as the Reebok ERS 1000 and ERS 2000 running models before making its way into the higher-profile Reebok Pump line via The Pump, Pump Twilight Zone, and Pump Omni Zone basketball shoes. Although it was gradually phased out of production upon the arrival of Reebok’s Hexalite cushioning, ERS did its part in holding the performance line for Reebok from 1987 to 1991.
Paul Litchfield, Vice President of Advanced Concepts at Reebok, on the development of ERS (Energy Return System): I started the Energy Return System really as one of my first projects at Reebok, just kind of working on new ideas. The intent originally was to create a platform of these independent tubes that, when you stepped on them, kind of squished together and as they squished together they kind of pressurized themselves because they were adjacent. Imagine these tubes all lined up underneath your foot with a certain spacing in between them, then when you stepped on them and as they squashed down, they pressed against each other and created their own spring effect. So, that’s where it started.
Because I was pretty new in the shoe business, my rudimentary models that I did weren’t ‘manufacturable.’ So we had to find ways to manufacture it. The Energy Return System ended up being a combination of this idea of these independent tubes with a balance of the manufacturing boundaries that are necessary in the shoe business. The Energy Return System did, I thought, a pretty adequate job at creating this cushioning effect.
“The honeycomb is one of the strongest yet lightest shapes found in nature. With modification, it was the theory behind the development of Reebok’s Hexalite technology. The Hexalite honeycomb design spreads shock over a larger area than EVA or polyurethane. As a result it combines cushioning and light weight for superb performance.” -Reebok
The successor to ERS, Reebok unveiled Hexalite cushioning in 1990 on an array of its models including the Court Victory tennis shoe, Pump Aerobic Lite, and Pump AXT and Pump SXT crosstraining footwear. The following year saw Hexalite incorporated into the Pump Running and Pump Walking shoes, as well as the Pump Omni Zone II and Pump Omni Lite basketball shoes.
According to Reebok, Hexalite is four times more durable than EVA foam and absorbs up to 23% more energy than an equal amount of EVA foam does. The honeycomb structure is reinforced by a tough urethane film and resists compression set (the tendency of cushioning to lose its ability to resume its original form after repeated compressions).
Hexalite continues on today in the form of Hexride, a cushioning system of cored-out hexagonal recesses in the midsole of the shoe. The air inside the hexagonal shapes is then sealed in with an impact-resistant polymer film. The result is a Hexalite-like impact protection on a broader, more unified platform.
Paul Litchfield on the development of Hexalite: A colleague of mine who worked with me was working on this notion of the honeycomb. The honeycomb is a great, lightweight structure. We worked with a company called Hexcel. They did the SR-71 spy plane, they did a lot of high-end government stuff on composites and lightweight materials. We worked with them on taking what is typically a rigid honeycomb structure and these guys made it with a material called thermoplastic urethane and this thermoplastic urethane basically was rubbery.
So what happened was, rather than collapsing and not returning to shape or collapsing and just being a one-time cushioning element, this honeycomb material became this package that provided cushioning and lightweight support. That’s where Hexalite came from. I still think Hexalite is really cool, and the way that it was made and how we got it created and incorporated into the shoes I thought, was very, very cool.