Weight - 6.5oz size 10 (men's)
Heel to Toe Offset - 10mm
Midsole Material - ZoomX with full length carbon fiber plate
Category of Shoe - Long distance racing flat
|Excellent shaped toe box for a racing flat. Note the very minimal upper and non-existent heel counter. You can't argue the looks of these shoes.|
Upper and Fit
The first thing that jumps out at you is the design of the shoe. Nike does a very consistent job of making shoes that look fast and ones that are fashionably acceptable for casual wear (well, if you are into that sort of thing). The upper in general is minimal in deign and materials. It is a one piece upper made up of an engineered mesh, an almost non-existent heel counter, and a more traditional lacing system (hooray no fly wire!). The toe box is rather generous and the overall volume of the shoe is rather high, which came as a surprise for a shoe that is marketed as a racing flat. This higher volume isn't necessarily a bad thing, but does allow a wider range of feet to work with this shoe. For individuals like myself with narrow feet, you will have to really cinch down the laces. The unfortunate side effect is a bunching of the upper (see pictures below) and pressure on the top of the foot proximal (closer to the ankle). The heel hold is minimal, with a thin piece of material acting as a "heel counter-" if you have any extra mobility in the posterior foot you are forewarned. Overall, the foot is held in place, but I imagine that normal width to higher volume feet having fewer to no issues with the lacing. There really isn't any structure to this upper, just a paper thin engineered mesh holding the foot to the massive miracle ZoomX midsole. I still would recommend going true to size, because going down a half size will place your toes rather close to the front of the shoe. The tongue is not my favorite, as it is very thin and acts as a pressure point on top of the foot. Overall, the upper isn't anything special and I would argue that the Nike Streak 6 has a much more comfortable upper and hold.
This is the part you have been waiting for in this review, "what do Matt and I think about this new midsole and carbon fiber plate?" That's because the midsole with its ZoomX foam and full length embedded carbon fiber plate is what all the hype is about. To be honest, I'm not a fan. This shoe has some major flaws that I see as a potential issue for many runners (including elites). Let's first discuss the last or shape of the shoe. The heel has an exaggerated point with a marked curvature going straight back like a rudder on a boat. This heel flare paired with an extremely narrow midfoot, curved shape, very high stack height, and extreme toe spring makes for one unstable shoe. It would be like comparing a jeep to a corvette, where you have excellent cushioning but your center of gravity is way too high. Just standing in the shoe I can appreciate my midfoot sagging over the medial aspect of the shoe (and I have a very narrow foot). This sensation is amplified when running on anything other then a completely flat straight surface. The whole foot collapses inwards and results in the upper digging into the top of my foot. Unless you have perfect biomechanics (but honestly, what is the epitome of perfect biomechanics?), I don't see how this shoe could be comfortable in the long run. My concerns are compounded with the pain and overall discomfort in my forefoot. Speaking of the forefoot, this brings me to point number two of the midsole. The shoe has absolutely no flexibility. The VaporFly is a giant block of foam and is reminiscent of the earliest models from Hokka One One. Yes, the midsole is responsive along with the embedded carbon plate. But the problem is the forefoot is not allowed to flex normally at the metatarsals heads and locks your foot in a static position throughout the gait cycle. These forefoot issues are compounded with the aggressive toe spring, which locks your foot in dorsiflexion (i.e. more pressure is placed on the metatarsals during the gait cycle). Finally, the aggressive heel flare paired with a lack of any structure to the heel results in excessive motion in the posterior foot....an injury waiting to happen in those with extra mobility there. I'll let Matt Klein address all of these stability aspects in the Biomechanics section of this review.
The ZoomX is soft underfoot with a nice bounce. It reminds me of Hokka's RMAT midsole material or if the Adidas Adizero Boston was two times softer. All of this soft responsive foam is controlled with an embedded full length carbon plate. This plate does add a sense of propulsion, but as mentioned before, causes a lot of irritation once you've run for several miles. The ZoomX foam is responsive, but I don't feel it is anything revolutionary. I feel that honor goes to Adidas' Boost, despite other companies jumping on the bandwagon - Saucony's EVERUN, Brooks DNA AMP, Reebok's FloatRide, and now Nike's ZoomX and React foam.
Thoughts as a DPT: While I am impressed with the marketing campaign behind the Vaporfly 4% (that's basically what the sub 2 hour attempt from Nike was. A marketing ploy. Still an awesome thing to broadcast. Definitely enjoyed it), there are many biomechanical issues that I have. Like Dr. Kollias mentioned previously, there is little to no flexibility allowed in the forefoot for the metatarsals. This is a big problem, because extension of the MTP joints (metatarsophalangeal joints) is an essential component of the terminal stance or PROPULSION phase of gait. Loss of this is classic with individuals with hallux rigidis, as it is most commonly seen in the first toe (hallux). The inability to properly progress over the forefoot can cause hyperextension of the knees, calf issues, hip flexor tightness/compensation (early hip flexion to compensate for the inability to get into full hip extension). Nike has attempted to compensate for this with a great deal of toe spring, but that only goes so far. This is anecdotal, but I have had several running patients of mine present to me with a variety of lower extremity issues after running in these shoes. Cessation of running in these cleared up a great deal of their problems, but a few were able to compensate with extensive work on their ankle mobility into dorsiflexion. Ankle dorsiflexion and MTP extension are both very important for forward progression during the propulsive and end stage stance phases of gait. Take away one (MTP extension) and you need to make sure you have enough of the other. So we have been able to compensate somewhat for this, but it would be FAR better if there was some kind of flex groove at the MTP joints to allow for normal biomechanical movement at the forefoot. Limiting this is a great way to cause issues at the MTPs or higher up the chain. This is NOT to say that everyone will have problems. Only that some people might.
To address the second point Dr. Kollias raised, the rearfoot does have quite a bit of posterior heel flare. While there is an extensive heel bevel, it is centered, which is not where most people land IF they land at the rearfoot (posterior lateral landings are more normal). While it is biomechanically appropriate, aerodynamically having the bevel centered like that does make sense to decrease drag. Although I do not have any data so show that there is enough wind force that decreasing drag is necessary (I did not do the biomechanical tests for Nike on this shoe, so I do not know). So those with extensive rearfoot landings may feel a bit unstable or jarring landings in this shoe, which can be rectified by trying to land a little more anterior (but this does require changing your form. DO NOT make major form changes. These should occur very gradually and carefully to avoid shocking the body with anything too new. Like any new exercise, it should be incorporated slowly).
I would expect a normal amount of miles (400-500 miles is normal for me) in a shoe with this much midsole foam and the carbon fiber plate. I have been reading online that people are getting normal wear and not less than 100 miles that was initially reported. The strategically placed outsole rubber will help with wear in the traditional quicker wearing spots (lateral heel and forefoot). The ZoomX foam is new, so time will tell how durable it really is.
Rooms for Improvement
I think that Nike should get rid of the ridiculous heel flare and shorten the carbon plate so that it stops behind the metatarsal heads. I also think that lowering the overall stack height of the midsole will aid in increasing flexibility and making it an overall better long distance racing flat. Also, $250 dollars for a shoe? Really? (I know I fell for the hype, and here we are with this review. Then again, I am a shoe Geek.)
This review was probably much different then most other reviews published online. I feel that it is an interesting shoe, but there are many aspects that could be adjusted to make a more balanced shoe. The bizarre appearance adds an inherent instability to the shoe, which makes it a potential hazard for your biomechanics or will require an adjustment period. I think that for some people it will work amazing, while others will share my experience. But do not worry, there are plenty of other long distance racing flats available that in my opinion are superior in design and function. I know that people will argue that so many elites are winning with this shoe. Well yes that is a true point, but I would like to point out that the fastest marathon time was run in the Adidas Adios 2, and that the elites that have won in these shoes have faster times or equivalent times in other racing flats. That is all I have for this shoe. Thank you again for reading and send us your thoughts on the VaporFly 4%.
Thanks for reading!
Editor's Note: As always, the views presented on this website belong to Dr. Klein, Dr. Kollias or the selected few who contribute to these posts. This website should not and does not serve as a replacement for seeking medical care. If you are currently injured or concerned about an injury, please see your local running physical therapist. If you are in the Los Angeles area, Dr. Klein is currently taking clients for running evaluations.
Dr. Nathaniel Kollias DVM MPH
Doctor of Veterinary Medicine
Cornell University Lab Animal Resident
Dr. Matthew Klein PT DPT
Doctor of Physical Therapy
Kaiser SoCal Manual Therapy and Sport Fellow
Doctor of Physical Therapy
Kaiser SoCal Manual Therapy and Sport Fellow
***Disclaimer: These shoes were a personal purchase. We put at least 50-75 miles on trainers and 25 miles on racing flats prior to reviewing them. Currently Dr. Kollias has 30 miles on his pair in a variety of conditions. If you are a footwear rep looking for footwear reviews or consultations on development, we are currently looking to partner with companies to assist, discuss and promote footwear models. Partnership will not affect the honesty of our reviews.
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