React

A history of cushioning excellence

Nike’s focus has always been on producing shoes with excellent cushioning. The brand’s founders, Bill Bowerman and Phil Knight, were both keen runners in their day, so they knew the importance of shoes that provide appropriate support. In the early days of the company, Bowerman realised how valuable foam was as a cushioning material, introducing it into the Nike Cortez and the Nike Waffle Racer. Thereafter, it remained an important part of their designs alongside Nike’s Air technology. Then, after more than four decades of innovation, a new kind of foam was invented that changed our perceptions of what shoe cushioning can do. This revolutionary material was called Nike React.

The development of foam

Throughout the 20th century, various foam technologies were developed, beginning in the 1920s when new techniques were used to work rubber into a structure filled with thousands of tiny air bubbles, giving it a soft, spongy feel. These methods evolved through the mid 1900s, eventually making their way into shoes. These materials were versatile and could be moulded into different configurations depending on the use. While some foams have lightweight, breathable properties that are perfect for use on uppers, others offer support and durability, making them better for midsoles. One such foam is EVA (ethylene vinyl acetate), and it is this material that Bowerman added to his designs in the early 70s.

An insurmountable challenge

Since then, new processes have been discovered to make materials, such as TPU (thermoplastic polyurethane) – a more durable foam that is also highly flexible. However, the main challenge for footwear scientists has always been to build a foam that has the full range of properties an athlete could want in a training shoe. This was true of the predecessor to Nike’s React foam, Lunarlon. Debuting in 2008, it proved to be a popular enhancement on previous EVA foam designs, providing good support and impact absorption alongside soft cushioning and bounce. However, despite being an upgrade on earlier foams, there was still room for improvement. Lunarlon had to be bolstered by a supportive layer which ultimately reduced its effectiveness by adding weight, reducing flexibility and limiting its ability to provide energy return – a term which refers to a shoe’s ability to reduce the amount of energy that is lost through its sole as the foot rolls through each step. The higher the energy return, the longer the wearer can go without expending too much energy, making it a useful trait in sports like basketball and running. If the need for this supportive layer could be removed, it would be possible to make a foam cushioning that was even lighter and more energy returning. 

As the 2010s came around, companies started to work more on energy return, but there were always problems balancing out the benefits of a foam sole – if your foam provided good cushioning, it lacked energy return, and if your foam was durable, it was also heavy. Athletes could never have all of the ideal attributes in one shoe, so they were always left having to make some sacrifice on performance. However, this was all about to change as Nike took on the challenge of creating a shoe that was lightweight and durable but which also had excellent energy return and top-quality cushioning. 

Breaking the mould

To make such an ambitious piece of equipment, Nike turned to the team in their Sports Research Lab. This talented group of scientists and engineers went to work, testing hundreds of combinations of materials and processing techniques until they found the perfect blend. As with Lunarlon, they brought together two different polymers, this time using a mixture of thermoplastic elastomers (TPE) and EVA to create a new synthetic rubber foam. After over 2000 hours of wear time and plenty of adaptations, they realised that they had found something special as the foam maintained its strength and softness, even after long hours of machine testing. For the first time, Nike had designed a cushioning system that brought together the most sought after characteristics: responsiveness, durability, softness and lightness. The brand named it “React” to reflect how quickly the foam returns to its original shape after the foot is lifted off it, which is what leads to great energy return.

Early endorsements

The first shoes to contain this remarkable new foam were both made for basketball, allowing players to use its high energy return to move quickly and jump more effectively while also receiving better impact protection. The React Hyperdunk 2017 Flyknit started things off. It was worn by San Francisco Golden State Warriors’ great Draymond Green throughout his team’s victorious 2017 NBA Finals campaign. In his role as a power forward, Green was incredibly versatile, making him the perfect player to showcase Nike’s equally adaptable new material. Another power forward, LA Clippers’ Blake Griffin, was chosen to wear the second React shoe, the Jordan Super.Fly 2017. Both players loved the shoes, with Griffin particularly happy with the freedom of movement he could achieve while also receiving cushioning and traction. This was the ideal reaction for Nike’s designers, who had made the shoe to facilitate better movement all over the court. Prior basketball shoes had often been aimed at different types of players working in different positions, but the React technology meant that these two could be worn by various kinds of players, supporting a range of body types and playing styles. 

React runners

Following the success of these initial designs, React was introduced to Nike’s running department, where further research and testing was undertaken to get the most out of its capabilities. The project was headed up by Director of Advanced Footwear at Nike Running, Ernest Kim, who wanted to create a shoe that would meet the needs of every kind of runner. Having seen the success of the React foam basketball trainers, he knew that his new shoe should contain React technology as well, but while the Hyperdunk and the Super.Fly had encased the foam, he wanted to free it to be the sole element under the runner’s foot. To mould it into the best shape and size for this, Nike’s researchers collected data on how athletes moved as they ran, as well as how and where their feet connected with the floor to understand where the supportive cushioning and traction was most needed. Using this information, they created pressure maps of the foot from which they constructed a matching React foam sole to provide the optimal support and cushioning in the most important locations. 

Staggering results

The first running shoe to contain this sole was the Epic React Flyknit. To find out just how good it was compared to Nike’s previous foams, Kim put it through its paces against Lunarlon-cushioned shoes. The results were astounding. Not only was React foam 11% softer and 13% more energy returning than its predecessor, it was also 30% lighter than comparative designs and far more responsive as well. As if that wasn’t enough, other studies showed that it was amazingly durable compared to other foams, with athletes able to get as much as 20% more use out of Nike React foam, making it their longest lasting. Some of the test runners loved it so much that it made them want to run more. Kim himself marvelled at how React foam improved on the brand’s previous materials in every aspect, not just one or two areas – an incredible achievement. These studies provided Nike with proof of React’s effectiveness, and they published an intriguing picture on their social media channels ahead of the Epic React Flyknit’s release. It featured a foot mould sat atop a layer of foam on top of a pillow with springs underneath, emphasising the shoe’s softness and bounce. Below the picture was a caption that read “The inspiration for a running innovation that feels like this (without actually looking like this)”. The groundbreaking Nike Epic React Flyknit was launched on 22nd February 2018.

With the first React foam runner, Nike had raised the bar for performance running shoes, setting a new standard for all others in the category. As always, the brand continued to innovate to see how far the foam could be pushed. In 2019, this led to the release of the Nike React Infinity Run, which was engineered specifically to decrease the incidence of running-related injuries. It employed a thick sole which contained 24% more React foam than the Epic React Flyknit 2 and was moulded into a rocker-like shape. This promoted easier movement of the foot and produced a slight forward tilt in the runner’s gait that propelled them along. It also aimed to limit pronation – the natural side-to-side rolling motion of the foot during movement, which is said to cause injury. Nike was keen to see just how effective the new design was, so Matt Nurse, Vice President of the Nike Sport Research Lab teamed up with Dr. Michael Ryan at the British Columbia Sports Medicine Research Foundation to compare the Infinity Run against another Nike running shoe which had been built to provide excellent motion control, the Nike Air Zoom Structure 22. 226 male and female runners undertook a 12-week schedule of training, at the end of which they ran a half marathon. Half wore the Infinity and the other half wore the Structure. The results came out in favour of the shoe with the React foam, whose injury rate was 52% lower than that of the Structure. This was a remarkable difference that showed just how good React foam is. 

Support for the sporting world

Naturally, Nike was keen to forge ahead with new React designs, and in the years following this study, the range was expanded to other sports like golf, skateboarding, football and tennis. It still remained a big part of its basketball and running divisions as well, being added to stalwarts of both sports, including the Jordan 1 and the Pegasus. Its durable, lightweight cushioning made it ideal for use in the line’s trail-running models, aiding runners as they transitioned between surface types. Nike’s famous gym training shoe, the Metcon, has benefited from React foam too, appearing on the React Metcon Turbo, where it adds to the shoe’s ability to balance responsive cushioning with stability and support. It has also been incorporated into some of Nike’s most popular sneakers, such as the Air Force 1 React and the Fontanka. It has even been combined with the famous Air cushioning system in the Nike Air Max 270 React. Designs like this highlight Nike’s desire to make comfortable shoes for everyday use as well as supportive performance footwear. On no shoe was this aim clearer than the React Element 87, which was designed by Sportswear Innovation Designer Daryl Matthews. Using data from real athletes, Matthews created a performance-driven shoe whose technical aspects also gave it a unique look that made it incredibly well-received on release. This was followed by a similar model called the React Element 55, which had several variations on the 87. These changes made the 55 more of a lifestyle design, but it was no less popular than the 87.

The beginning of a new era

Just a few short years after the first Nike React shoe was released, there have already been dozens of models containing this revolutionary new material. It came about through groundbreaking research and development that pushed the boundaries of what was possible with foam cushioning to produce something that set a new benchmark for performance shoes. With React amongst their suite of materials, Nike was able to offer training shoes which combined durability, energy return, softness and lightness for the very first time, with the added bonus of providing runners with the peace of mind that injuries would be much less likely. Beyond the sporting world, it has also supported those who have chosen React models as a fashion item by delivering a comfortable shoe that looks great too. This incredible story is just the beginning of React foam’s journey and it’s likely that Nike’s newest foam will be softening steps for a long time to come.