Ted Westbrook is a regular contributor to Brains Report and a competitive high-mileage distance runner. He recently ran a marathon in under two hours and 40 minutes. So, he knows a thing or two about shoes. Here’s his review of the Adidas Ultra Boost Running Shoe.
Adidas has featured its latest-generation midsole material, a TPU foam developed by BASF that Adidas calls Boost, in its higher-end running shoes for about four years now. Boost is supposed to be soft and resilient—claims routinely made with each new recipe of the more standard EVA foams—but also provide superior “energy return.”
The idea here is that the foam bounces back more quickly than other types of foam so that less of the runner’s energy output is wasted by being absorbed into the midsole of the shoe. That type of waste is why shoes that feel very plush underfoot also tend to feel slow, and why running on a rain-softened grass field is more taxing for any given pace than running on a rubberized track. Boost is supposed to provide softness and cushioning without sacrificing efficiency.
How Much Does the Adidas Ultra Boost Cost?
With an MSRP of $180, the Adidas Ultra Boost Running Shoe is much more than I like to spend on training shoes. I’ve had consistently decent experiences with the neutral Nike trainers that I tend to find discounted to $80 or so (e.g., Pegasus 34 and Zoom Elite 9), so despite the hype and positive reports from runners, I hadn’t tried anything with Boost. But, having tried the new Nike midsole foams, ZoomX and React, the latter of which seems to have been aimed to pull back market share lost to Adidas, I got very curious about Boost. So, when I found a pair of Ultra Boost for $89, I went for it.
The Ultra Boost’s Construction
My size 9 weighed in at 10.7 oz, which is on the heavier side. The shoe has a distinctive and premium look to it, with a mostly knit upper made of Adidas’s Primeknit. That fabric is unusually stretchy and very soft. Helping to enclose the foot is a plastic cage with lace eyelets.
At the heel is an external plastic heel cup that is divided so that directly behind the Achilles area, it’s just Primeknit lined on the inside with a soft fabric. There’s no separate tongue, just a prominent peak of lined Primeknit in the front, and a similar peak of lined Primeknit in the back. Because of the stretchy knit construction, it’s necessary to grab both peaks to pull the shoe onto the foot.
The Sole of the Ultra Boost
The midsole material has a unique look, too, pointing up the Boost foam. It looks like what it is: a shaped wedge of thousands of individual expanded TPU pellets formed together. The midsole extends back a few millimeters past the heel and around the sides of the heel. It’s a wide swath of foam overall, even in the midfoot on both sides of the arch. Underneath is a full-length, full-width Continental rubber outsole with cutouts showing the Boost foam between round rubber lugs.
The Boost won’t contact the road (unlike the React foam in Nike’s Epic React, for instance) unless you’ve worn through the rubber or something really weird happens. It looks like an outsole that will provide good grip, maybe even for light trail work. Interestingly, at the outer corner of the heel, the outsole is sloped upward away from the ground. This is similar to the circa-2007 Nike Pegasus models, in which that slope was marketed as a stability feature.
My impression is that it has little to do with stability but may give the shoe added durability for runners, like me, who tend to land first on the outer edges of their heels when running slowly and/or downhill. This design should hold up better than a flat outsole that gets ground down on the outer rear edge with every heel strike.
The Amazing Feel of the Ultra Boost’s Upper
The upper is extremely comfortable on the foot. It gives everywhere you’d want it to give and feels very soft even where the Primeknit has no inner liner over the top of the forefoot. It’s softer than any Nike Flyknit I’ve worn and smooth enough that I might consider going sockless, which I would never do in Flyknit. This upper felt amazing.
Standing in the shoe, the cushioning of the Boost was noticeable, with the heel settling down into the foam. I’d put the softness between that of the semi-soft React and ultra-soft ZoomX. The plastic cage hit my foot in the right spot and the shoe seemed to fit true-to-size, slightly roomier than average, with a nice wide toe-box. Unlike the Nike Vaporfly 4% and its lofty and squishy ZoomX rearfoot, the Ultra Boost felt stable in walking mechanics. In fact, it gives the impression of being possibly the perfect walking shoe.
Although the 10mm heel-toe drop of the Ultra Boost is the same as that of the Nike Epic React, and their stack heights are almost identical (Ultra Boost at 27mm heel stack and Epic React at 28mm), the Ultra Boost feels like a flatter and lower shoe on the foot. This might be a function of the compressibility of the Boost material.
What Applications Is the Ultra Boost Best for?
At 10.7 oz, I don’t expect to wear the Ultra Boost for racing of any sort or for speed workouts. They seem best suited for recovery runs, long runs, and general mileage. This impression was borne out in my first run in the shoe, an 8-miler at a
Interestingly, it seemed to have less torsional rigidity (i.e., it would twist more easily) than the Epic React and Legend React. Despite that, the Ultra Boost has some hard-plastic inserts in the foam and the React shoes don’t. Ultra Boosts are not marketed as stability shoes for overpronators and are probably not well suited to those mechanics because of the softness and flexibility.
I do not know that the “energy return” qualities of the foam are all that palpable. They did not feel heavy at toe-off but also didn’t seem propulsive or snappy in the way that a Nike Vaporfly 4% does. The most noticeable sensation occurred during steep downhills, in which the foam seemed to bounce up in response to each foot strike. It wasn’t jarring, but also didn’t seem to translate to useable forward momentum.
A Comfortable – Yet Heavy – Long-Distance Training Shoe
The upper and fit continued to impress me on the run. They felt like slippers. These are the kind of shoes that will happily disappear on your feet during an easy run of any distance. The soft underfoot feel did not change when I picked up the pace for a 5:40 mile, and I didn’t sense that the foam was wasting a lot of rebound energy. That said, the weight of the shoes started to feel like pendulums at the ends of my legs after awhile at speed. This isn’t a shoe for confidence-building speed workouts, let alone races. But it provides a plush ride for the easier efforts that make up the vast majority of a training schedule.
Other runners have reported good durability with the Ultra Boost. I’ll also put that to the test. They’ll have to get 360 miles to meet my 25-cent-per-mile goal, which seems like a strong bet given the full rubber outsole coverage and heel slope.Buy the Adidas Performance Mens Ultra Boost Running Shoe on Amazon