Several months ago when adidas first started to market their new BOOST midsole material they made a big deal of touting the fact that the sole, which is composed of fused polyurethane beads, provides greater energy return than traditional EVA. The implication was that this energy return would provide a performance benefit to a runner by improving running economy (i.e., reducing the work needed to be done by our muscles to get from point A to point B).
I was very skeptical of this marketing approach since there was no physiological data available from actual runners to back up the claims based on mechanical testing. That data now appears to exist. In the June 2013 issue of Footwear Science is an abstract of a study titled “Running shoe cushioning properties can influence oxygen consumption.” The study was carried out by a team from the University of Calgary headed by Jay Worobets.
The study utilized a fairly simple methodology. Twelve runners ran both overground and on a treadmill in shoes with the Boost midsole and in identical shoes with a sole composed of more traditional EVA foam. While running, their oxygen consumption was monitored as a measure of running economy (increased oxygen consumption at a given pace = lower economy).
Results indicated that in both treadmill and overground running the subjects were slightly more economical in the shoes with the Boost midsole (differences were statistically significant). Here are the numbers:
|
O2 Consumption |
O2 Consumption |
|
|
|
|
EVA Shoe |
BOOST Shoe |
% Difference |
|
Treadmill |
44.7 ml/kg/min |
44.3 ml/kg/min |
0.9% |
|
Overground |
40.7 ml/kg/min |
40.3 ml/kg/min |
1.1% |
Though the differences were significant, the actual differences were quite small between the shoes on both running surfaces. Thus, BOOST improved economy by about 1%.
It’s important to keep in mind that the comparison here was between shoes that only differed in their midsole material, everything else was the same. There is no detail about which Boost shoe was used, what the midsole dimensions were, etc. So it’s very difficult to compare economy gained running in a Boost shoe to any other shoe on the market. As an example, previous research has shown that reducing shoe weight by about 3.5 oz (100g) results in an economy improvement of about 1%. So if the shoe used was the 9.3 oz Energy Boost, then it might not be any more economical than say the 5.7 oz adidas Gazelle. The benefit would be that you get the improved economy with additional cushioning in the Boost.
Having run in the adidas Energy Boost shoe myself a few times I also wonder if there is a certain thickness of midsole material required to provide any actual benefit. The Energy Boost has about 9-10mm more material under the heel than under the forefoot. As someone who doesn’t load my heels much when I run, the Boost did not feel all that different to me than a typical EVA shoe. But, if I forced a more pronounced heel strike I could really feel the bounciness that the Boost material provides (you can also feel it when walking in the shoes). My suspicion is that there is simply not enough Boost under the forefoot to provide a meaningful benefit. An Altra Torin or Hoka style Boost shoe would be an interesting thing to try!
So my take is that if you are a heel striker, Boost may provide a bit of an economy benefit for you in a very well cushioned shoe. If you are a midfoot or forefoot striker the benefit will likely not be as noticeable. Different shoes likely work better for different gaits.
As for myself, I actually didn’t enjoy running in the Energy Boost very much because there was too much heel for my taste, and it has a very pronounced heel flare – the sole extends well out from the margins of your heel on all sides. The upper is also too snug for my feet. Personally, I’d opt for a shoe like the adidas Hagio over the Boost for races of half marathon distance or less – lighter, firmer, and stiffer is my preference for speed. But over 26.2 miles I could see some value in a softer sole, and a 4-6mm drop Boost shoe might be something that would pique my interest a bit more as a distance shoe. Boost looks top be permeating the adidas line, so looks like we’ll have more to try out in the coming months!
About Peter Larson
Colour me skeptical, afterall there are many characterics in the shoes that can have an effect. The arch support, how comfy is the upper, the weight of shoe, the drop, etc.
From your comments – when I saw this material my first thought was hoping that they would license it and then it would show up in a pair of Hoka’s.
I imagine the added weight with the new midsole material will likely obviate any perceptible gains the Boost provides in efficiency compared to lighter weight shoes, at least for smaller runners and across shorter distances. Still, for people who just need all that cushioning, I guess it’s a decent option.
This reminds me of the Adidas Spring Blade… even if all the supposed claims about its “explosive energy” return properties are true and demonstrable and repeatable in non-laboratory settings, the added weight is sure to cut into whatever “efficiency advantages” it confers: IIRC, a size 9 Spring Blade is already about 3 ounces heavier than the equivalently sized Boost. Unless the Spring Blade improves runner O2 consumption economy by a whopping 2%, it’s probably better (or at least much cheaper and less of a fashion disaster) to go with the Gazelle.
Yes, my pair of Springblades in US10 weigh 13.7oz. It’s a very heavy shoe, so I totally agree.
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Ive used my pair for recovery runs and enjoy them. They are too heavy/bulky for racing. Personally, I think the adios which is coming on the market soon is the real test were waiting to see. One percent improvement and in a light shoe could be significant over 26.2 miles.
The question would be whether any removal of midsole material to make the shoes lighter compromises the beneficial effect of Boost.
Sent from my iPad
I certainly feel more relaxed when running in the Adistar Boost (support Boost). I do load my heels mid stance to engage my hams and glutes, and feel I can do so with nearly reckless abandon with the boost, where I would normally keep some tension in my calves instead in less cushioned shoes.
Intriguing research. I’ve put about 150 miles on my pair of Boost and haven’t noticed much difference either. I feel faster, though I will say that when it comes to improved energy return, I believe that distance runners have to keep a lot of other variables in mind (e.g. carb intake, adequate sleep, proper hydration). If one of these elements are highly off, I don’t believe a shoe even like the Boost can salvage a poor run.
Austin Bonds
Guest Advocate
Big Peach Running Company
Thank you for the post, Pete, very intriguing small study and great to hear your general comments as well! I was skeptical about the marketing of the compound before these first came out, but curiosity got the better of me, so I bought a pair as a replacement longer distance shoe and I’ve now completed several runs ranging from short distance to about 12K.
I find I can definitely feel a “boost” most when heel striking obviously, definitely not as much when striking mid-foot. I would also agree with others that this is too heavy for a race shoe (although not too bad). There are a bunch of features that I tend not to like in a shoe as well, such as the higher heel-toe drop, the snug upper and the heel flare.
Despite all that, I am finding I quite like the shoe, particularly the bouncy but still firmer nature I find from the Boost material. Thus I’ll be quite intrigued to see what other shoes they use it on!
I know they’re marketing the shoe this way, but I’ve just recently acquired a pair and it had nothing to do with potential performance gains (well, not directly anyway). I’m hoping that the shoe lessens impact, taxing the leg muscles/tendons less. This is somewhat related to oxygen consumption, but also just the fundamental laws of gravity and impact. I’m coming from a Kinvara, so it is a fairly radical change…but as a heavier runner I was wearing out Kinvara’s quickly and experiencing leg pain after they were well-broken in. I’m a little concerned about the change in heel drop, but we’ll see what my experience is. This doesn’t seem like a shoe that is geared toward serious performance runners; but more of one for the casual runner.
I know that a heavier shoe will actually tax some of the muscles more…but I get the feeling that impact is more of an issue for me than foot turnover.
This is a very interesting subject. I have yet to hear about a running shoe that can help you run more efficiently. These shoes sound like they can gain more mileage than other training shoes. I would like to test this pair of shoes out myself.
I always had problems with pain in my legs after running and tried everything including Brooks Ghost; Saucony eventually bought a cheap pair of Pegasus 29 which were so comfy and I didn’t get leg pain or black toes but everyone tells me they are poor so tried adidas boost and although I have broken a few PBs I do get a bit of ITB aggro with them and there does appear to be a definite advantage – as a person quite new to running but way past first flush of youth have found the boost excellent for shorter runs up to 10k but need the Pegasus for a half – any thoughts welcome
This shoe is pure marketing. It’s like putting an armchair looking saddle on a carbon bike for the 300 pound cyclists! If you are a heavy guy, work on your technique and weight first. You don’t need that 1% performance boost because you won’t be able to run fast anyway.
Excuse me for my negativity. I just want adidas to not sell snake oil to us…
I’m late here, but thought I would throw in my experience. I bought a pair of the first Adidas boost shoes and put 410 miles on them before the tread was done… Shame as the sole and uppers were still great, but I had zero traction at that point and had to buy a new pair.
I decided to give the Nike Flynit Lunar a try with all the great reviews. I liked my boost but can’t say I really noticed a huge difference, but when I switch over to the Nike that is when I did notice how great the boost sole was. 20 miles into the flyknit lunar I developed the worst shin splints I’ve ever had and my ankles & knees were sore as could be after each run… Once the shin splints subsided I went back to running and put another 30 miles on them and still wasn’t feeling comfortable in them and decided to buy another pair of Adidas boost shoes. After a few runs my knees and ankles were feeling fine again and my shin splints didn’t come back either. So that experience made me a believer in the boost sole.
Hi there,
it’s nice to see a bit of science to back up claims. However, may I point out that a 1% difference on a sample size of 12 is not statistically significant at all (unlike the statement you made).
Thus, from a scientific standpoint there is still zero evidence to back up the claims from Adidas.
Best,
Rob