Color: Solar Blue/Carbon/Black
Intended use: Recovery runs, long distance. Use on all surfaces except trail.
Surfaces tested on: Road, synthetic track 21° C/70° F
Upper: Stretchable mesh, internal sleeve, plastic mid and rear-foot cage.
Midsole: Expanded TPU Infinergy foam made by BASF (Boost)
Outsole: Adiwear Carbon rubber.
Weight: 317 gms/11.18 Oz for a half pair of US10.5.
What a mighty difference two years can make. All these years, Adidas had a hard time trying to take a bite of the performance running footwear market; but the Boost launch last year suddenly changed all that. A singular cushioning platform has led to a reversal of fortunes for the German brand, leading to a tectonic shift in the running consumer’s perception – with a heavy tilt in its favour.
Brands market new technologies almost every second month, accompanied by boastful claims like being ‘game changing’ and ‘best ever’. But once in while comes something which actually lives up to the hype, with the potential to change the balance of power in the athletic footwear industry. The Boost is one such platform. So, what is the Boost, and why is it so good? We’ll give you a detailed background, much more than the standard press release text you might have read so far.
Numerous launch reports partly touch on the association between Adidas and BASF (the German chemical company) to bring Boost technology to life, but that is only half the story. For few years prior to the Boost launch, BASF had been working hard to create expanded TPU foam. In its un-expanded form, TPU (Thermoplastic Polyurethane) can be found in many everyday things. Places like the soft wheels of your aircraft carry-on bag, to grippy wheels of a skateboard and super bouncy crazy balls. No one had yet found a way to expand TPU to a foam structure – increasing its volume but making it lighter, and retaining its combined property of being soft and responsive at the same time. By 2009, Dr. Frank Prissok and Frank Braun, scientists from BASF had succeeded in creating the world’s first expanded TPU foam, and they named the novel material ‘Infinergy’. They knew it could be applied in a lot of potential areas; un-puncturable tyres, soft sport surfaces, vibration damping in automobiles and cargo protection in the logistics sector. And of course, shoes.
The base material of Infinergy foam is BASF ‘Ellastollan’ TPU, a polyurethane which has been in the chemical company’s portfolio for some time now. BASF does have an affinity towards footwear. In 2008, BASF introduced the ‘Pure’ shoe concept (nothing to do with Adidas, but a design oddly reminiscent of ‘Feet you wear’) which showcased the Elastollan in its unexpanded form. The year 2009 saw BASF bringing the Pure 1.1 concept shoe to design expos, and when Elastollan was successfully expanded to result in the particle foam Infinergy, Martin Vallo (Elastollan + footwear sales divison) went to Adidas. BASF and Adidas have a 25 year history of working together, so it seemed a perfect first-use opportunity for the Infinergy concept.
To cut a long story short, while the prototype foam was not ideal for footwear use, BASF and Adidas worked together to refine the formula, resulting in the final ‘Boost’ version. The volume of a typical Boost midsole contains around 2,500 individual oval beads, all fused together by an innovative steam molding process. This method melts the top layer of the bead, causing it to stick to the neighbouring particles without affecting its core structure. We’ve included a few useful infographics from the BASF and Adidas website which will help understand how Boost works.
And oh, the name. The ‘Boost’ name is a straight lift from the little known 2009 Adidas shoe, which featured a lattice-like, mechanical heel cushioning with a foam core. Google it, if you so wish.
The new foam debuted in last year’s Energy Boost, and general release happened on February 27th, 2013. Earlier this year was Boost’s first anniversary, and Adidas followed the original shoe up with its successor – the Adidas Energy Boost 2.0. The midsole and outsole unit is unchanged, carried over from last year’s model, and the upper features some tweaks while retaining the overall feel of the original Energy Boost.
Running in the Energy Boost 2 is a revelation of sorts. For years, footwear industry veterans have struggled to find the perfect balance between soft and responsive cushioning. Most of the time, results would lean in favor of one attribute, with the shoe feeling either too soft and outright firm. The unique cushioning property of Boost seems to have solved that conundrum.
Adidas throws around the much cliched term ‘Energy return’ a lot in its Boost marketing. While is it of any actual ‘energy return’ benefit to the runner still remains unsubstantiated, what stands true is its superior and long lasting responsiveness. So in glory of the moment, we’ll let this pass without bashing Adidas’ PR talk.
It feels noticeably soft at slow speeds, yet it is underscored by an overbearing springy sensation. Pick up pace, and the ride comes through as responsive without any ’sink-in’ delay. What’s also impressive is the smooth weight transfer and loading – the midsole of the Energy Boost 2 is a singular, near heel-to-toe unit of Infinergy foam. The consequence of which is a uniform and consistent cushioning feel from rear to front. The outsole also sits low and flat with a ‘lip’ extending beneath the heel, so that also helps in better first contact with the running surface.
Ground feel or feedback is slightly isolated, but then we guess that’s the job better done by the Adizero Adios Boost. There’s a line of coloured EVA (Ethylene Vinyl Acetate) foam just beneath the upper, and you might mistake it for a layer between the foot and Boost midsole. The coloured line is simply a rim surrounding the upper, and all that separates the bottom of the foot is a soft, contoured sockliner and a transparent film through which Boost is visible. There’s also a small circular cutout in the rear foot, just below the heel. This dials up the cushioning level in that area. The transparent film (under the sockliner) in the forefoot is thinner than in the back, allowing the front to feel more cushioning and flexibility. We haven’t seen this type of strobel execution before, so that’s something new in addition to the Boost technology.
The sockliner is a contoured, drop-in piece of foamy softness. The shape flares upwards beneath the arch, helping support it, and has a friction free top cloth. Lift the left insole, and there’s a MiCoach cavity, where there’s space to pop in the transmitter foot-pod.
In a first for any midsole foam, we observed zero compression line or creases on the wall even after multiple runs, and that points out the material’s resilience and high resistance to deformation. This means, as long as the outsole and upper stay put, the shoe should lose none of its cushioning properties – the idea itself sounds wonderfully remarkable. This also tosses out of the window the oft used recommendation of replacing your shoe every 400 miles. In that regard, the Adidas Energy Boost 2 seems to be holding up well, with no signs of wear on the outsole – yet.
A close-up of the midsole shows how individual Infinergy beads bond together; and when light is passed through, the midsole illuminates with a faint glow. This just shows the how expanded (low density) the TPU Infinergy foam is, and one of the reasons behind responsive cushioning. The brand and BASF claim the Boost to be extremely temperature resistant with little loss in its cushioning properties over temperature extremes, but we haven’t tested it in that aspect yet. From what we know of TPU, the Boost will certainly fare better than any other EVA foam available. We’ll post an update in case we have the opportunity to put the Boost to a weather extremity test.
Stability in the Energy Boost 2 comes from use of the plastic ’Torsion’ plate underneath the midsole, which sits low to the ground. The plate used in the Energy Boost is visible only in the mid foot, but it extends into a fork covering the sides of the forefoot, with a medial extension forming a stability levee under the rear-foot. The toe spring is quite high, and when combined with the Torsion ‘fingers’ underneath the forefoot, results in a smooth roll during toe-off’s. It does so by simulating a rocker motion while keeping weight distribution in a straight line.
The upper is very similar to last year’s Energy Boost, using what Adidas calls the ’Techfit’ construction. The upper fabric is a thick, spandex-like layer with plenty of stretch and printed details on its surface. The fit is tight, almost akin to a compression sock and there’s no open room at all. The toe box is also very low and pins the forefoot down to the sockliner, resulting in a heightened cushioned feel underneath. The fit is absolutely true to size (but need to half size up from Brooks or Nike due to conversion difference) with no extra room at all. Given the nature of the upper, runners would have to up-size half to one full size depending on their foot anatomy. Otherwise your forefoot or toes might rest uneasy.
The mid-foot is a different story though.
The 2013 Energy Boost featured mid-foot panels made of synthetic leather, but the 2014 Energy Boost 2 swaps those with a rigid plastic cage. The original Energy Boost already had a tight mid foot, and use of inflexible plastic on the 2014 model lends it all the subtlety of an under-bust corset. When worn with sports socks, pressure around the waist of the foot is borderline uncomfortable. What’s worse, this is not a break-in malady, but more a permanent one. The plastic panels don’t stretch out, and the feel stands in stark contrast to rest of the upper. It feels hard around the foot, and we certainly question the need for over constructing the Energy Boost 2 upper. The existing gusseted tongue set-up along with soft synthetic leather panels would have managed just fine.
Consequently, the Adidas Energy Boost 2 will come across as unusually tight unless worn with thin socks or without them. Barefoot running in the Energy Boost 2 can be done, though pressure from the plastic mid-foot panels might not agree with everyone. There is a strong sensation of something hard hugging the side of the foot. We do hope Adidas decides to tone down the next version of Energy Boost’s mid-foot.
The collar fit is a slight improvement over previous generation Energy Boost, backed by the change of material from an open structured air mesh to a fabric with greater density. It is also supported by the layer of fused plastic extending from the mid-foot cage; what worked against mid-foot fit works in favour of the collar. The molded plastic structure adds more than just aesthetic value in the rear-foot area, giving support and grip around the foot. Padding is comfortably compact, and gently swaddles the ankle area.
Reflectivity comes from the Adidas logo and array of dots on the heel, which illuminate when bathed in light. The execution is quite subtle. Unlike traditional reflective elements which are easily recognised by their shiny, silver surface, the Adidas logo looks like an ordinary layer. You are likely to mistake the Energy Boost 2 as a shoe with no night-time visibility, but as seen in the photograph above, that’s not the case.
The Boost platform has been marketed as a ‘game changer’ by Adidas, and for once, it is indeed so. A rarity where exaggerated marketing claims are becoming increasingly commonplace. But here the benefits are real and tangible.
There’s no taking away the fact the Boost foam just whops every other foam based cushioning in the market today, and should set-up sustained success for Adidas. The new technology magically delivers a perfect balance of softness and responsiveness, and is highly resistant to bottoming out – if that is not footwear utopia, what is. But they better watch out, because if this patent filing is anything to go by, brands like Nike could soon be snapping at their heels, and quite literally so.
The brand has high hopes for the Boost platform, with plans for 14 models by end of 2014, and a target of selling 15 million Boost featuring shoes by 2015. Considering that they sold 1.5 million pairs in 2013 alone with just three models (Energy Boost, Sonic and Adizero Boost), they should have little problem achieving their lofty ambitions.
The Germans have their magic potion. Endlich, like they say in Deutsch.
PS: Energy Boost 2.0 ESM is another version with a breathable stretch mesh, while the Energy Boost ATR has a water resistant upper and a gripper outsole. We had plans of reviewing the EB 2 ESM, but had to drop it due to time constraints.
(Note: Solereview paid full US retail price for the shoe reviewed)