EVA – the material used to make the sole of over 90% of all cushioned sports shoes, has been around for getting on for 20 years now. There is no doubt that when it was launched, this material represented a quantum leap forward in footwear technology and whilst many advocates of barefoot running, blame the introduction of cushioned footwear and EVA in particular for what appears to be a change in the way people run, to a heel-strike gait, for many runners, cushioning under the foot allows them to run and makes tackling marathons possible.
This is not the place to debate whether or not cushioning is good. I am going to say that for many runners, it is desirable and I am one of them. On that basis, I was really intrigued to see what adidas had come up with when they announced, a few months ago, that they had a product that would revolutionise running.
That product is Boost – a propriatory mid-sole material that adidas have been developing for almost two years and which promises to be a massive improvement on EVA.
World, meet Boost
On Wednesday 13 February 2013 at 10:30am, Boost was launched in front of a group of journalists, writers, bloggers and others at an event in New York, USA. By 3pm I was running around Central Park in a pair. And I was very pleasantly surprised by what I found.
Boost mid-sole material
The first thing I noticed when I pulled on the Energy Boost shoes we had been given, was the material under my feet. Standing on the concrete floor in the conference centre where the presentation has taken place, the sole of the shoe felt springy and light, but not hugely different from EVA.
On the run, however, Boost really surprised me. It was much firmer than I expected and there was no loss of feeling or proprioception, which I thought there might be.
I think I felt that Boost would be a development of EVA – a softer, plusher material. But it is in fact, much firmer than many of the EVA-soled shoes I have run in recently. Certainly much firmer than Nike’s Lunarlon material. During my hour-long run with Stuart Miles from Pocket-Lint (a fine navigator of Central Park, it should be said!) I think I worked out why Boost is not a soft material by delving back into basic science at school.
The advantage that Boost offers, over EVA, is that it does not absorb force (or energy). Instead it rebounds and return energy from the footstrike. That is why it feels firm. At the presentation there were bins full of the little pearls of material that are fused together to make the mid-sole material and Stuart said that when he tried to compress the beads, they were resistant. So (and here is my basic and unverified scientific analysis) the force that the runner exerts on the mid-sole as his or her foot hits the ground, is returned as there is an equal and opposite reaction to the action of compression. Soft EVA simply absorbs energy. I likened the sensation of running in a shoes with an EVA mid-sole to riding a bike with suspension – it smoothes out the bumps, but at the same time absorbs the energy from pedaling, making the rider work harder. Boost is the equivalent of a stiff carbon frame and solid forks – possibly a rougher ride, but no loss of energy through absorbtion (in fact the opposite is true, so the analogy is not perfect).
The shoe that we were given is more then just the mid-sole material. It would be, in fact, a very interesting shoe even if it only had an EVA sole.
The upper is made of a fine mesh material that has very few seams and a nice snug, but not restrictive fit. adidas shoes tend to come up smaller than other brands anyway, but the pliable upper is very forgiving and also doesn’t threaten much in the way of blister-causing seams.
Overlayed onto the upper are some bands of what feels like PVC material that run from the sole up around the mid-foot and form the lacing eyelets. These seem to have the effect of pulling the mid-foot nice and snug, whilst leaving plenty of space in the toe-box. At the back of the shoe is an external heel-counter made of plastic, which gives the shoe a familiar feel for anyone used to running in adidas and holds the foot nicely in place. It is also interesting to note that the opening above the tongue is wider than usual then on the adidas shoes I wear – the AdiZero Adios and the Feather – and whilst this didn’t make any difference to me, I did wonder whether the pressure of the laces across the top of the foot might cause problems if the shoe is laced very tight.
Did I get a Boost?
Overall, I think that the adidas Boost is a very, very interesting development. I was really pleased with how firm the material felt and there was no doubt, even on the gentle run that I took with Stuart, that there is a noticable rebound to the material. I am interested to see how that feels on both a longer run and a shorter faster session.
I am always wary of promises that a development – whether that is in kit or footwear or technology like GPS – will change the way we run. But I do really think that Boost has the possibility to provide a little extra, a small advantage – a boost! – which, when it comes to trying to be the best runner you can be, will be welcome. I am already really looking forward to trying out the Adios AdiZero version later this year and, if the rumours I have heard are true, will be watching the elite adidas athletes who will be wearing that iconic racing flat with the new mid-sole material, tackle the London marathon in April. Who knows, maybe this will be the development which will boost them to achieve new levels of performance and bring the sub-2 hour marathon a step or two closer.