Today I’d like to discuss Nike’s¹ interesting new (ish) line of racers, which include the Zoom Fly, Alphafly, and Vaporfly, among others. Running fan or not, you’re likely familiar with the basics of the controversial shoes: big heels and cushioning, air bags, and advanced carbon fiber plates, all wrapped in a gaudy, lightweight package. Similar to clap-skates in the 90’s and Speedo’s LZR swimsuit in 2012, the shoes have coincided with an influx of records both on the road and track, leading to the dubbing of the shoes as the ‘Cheaterflys,’ a monikor we imagine Nike’s marketing department are positively beaming over. Now, the readers of this website being the pure, capitalistically un-sullied adventure sports fans that they are, for us to discuss any Nike-related product –and to do so in a potentially glowing manner– is akin, perhaps, to something like Outside Magazine dedicating a section to reviewing the wonderfully rich taste of Nestle’s new line of rainforest-sourced chocolates. And yet, this being the future of running, and running (or at least walking) being the backbone of most adventure sports, the shoes and their technology cannot be ignored indefinitely.
History being cyclical, the running community has for 50 years flip-flopped between a love of minimalism and over-protection in shoe choice. These days –and like everything else in popular culture, it seems– the topic has become one of political fervency.
Nike, interestingly enough, has occupied both sides of the shoe spectrum: first with the wildly successful Nike Free line, which focused on mimicking, to various degrees, barefoot running, and in doing so strengthening the ligaments and tendons of the foot, and then, after witnessing Hoka’s skyrocketing sales figures, with their current line of towering, bulky racers.
We’ll leave the debate of which version of running is best –as well as the legality of said methods– to the message boards and professional governing bodies. It’s easy to get caught up in the mechanical doping conversation, after all. But honestly, as spicy a topic as elites potentially gaining unfair advantages is, it is unlikely to have any effect on spectators such as you or I.
Let’s instead have a discussion as to what the technology means, not for professional athletes, but for the rest of us average human beings: the aging, oft-injured population who trains not for world records or the potential of meaty contracts with sporting behemoths, but rather, simply for the love of the activity itself. Our main goal is to stay healthy in order to continue to enjoy this thing we love. So with that lens as our guide, how does Nike fit into this idea, and where does it differentiate itself (and excel) from those such as Hoka that came before it?
A quick background
Hoka’s max-cushion-yet-lightweight shoe design arose a decade ago as a result of a couple of former Soloman employees attempting to develop a shoe that would excel during downhill running, but the design soon spread to the roads. Older runners in particular were drawn to the shoes, which reduced fatigue and cushioned tired knees and ligaments. Yet the design –in particular the high heel or ‘stack’ height, drew the ire of competitive runners, who avoided it in favor of lower profile racers. It also didn’t help that the shoes were (and still are) anything but good-looking.
While living in Colorado Springs I sometimes crossed paths with some of the world’s top distance runners, as they used the track behind our apartment for their weekly interval sessions. One day I was talking with a former Olympian, and me being a massive fan of shoe technology, I asked him what he thought of the future of running shoes. Was Hoka onto something? He sneered at the idea and told me the shoes were to be avoided, as they were bound to injure anyone wearing them.
I’d love to hear his thoughts on Nike today, who of course decided to follow Hoka’s general idea, while improving upon the shoe in every way: lighter, stiffer, more aggressive, a carbon fiber plate to improve footstrike, and space-age ‘zoom x’ foam technology. The result was a shoe that stood nearly 40 mm off the ground, yet weighed in at just 7 ounces, while still delivering 10% more energy return than what was known as the world’s best running shoes at the time, the Adidas Boost series. The wide platform reportedly decreased muscular fatigue. Athletes could do more hard workouts, recover faster, and potentially even race faster, given they were ‘responders’ to the shoes. Marathon times plummeted, and eventually the 2 hr marathon – the last of what many had dubbed the ‘great 4’ of human achievement (sub 4 mile, Everest, Land on the moon) fell. I drove to Vienna in 2018 to watch Kipchoge break the 2 hour barrier, and the crowd around me (and subsequently, the newspapers reporting upon the accomplishment) seemed less focused on the achievement and more upon the hot pink, unreleased shoes Kipchoge and his racers were sporting– these would later be released as the ‘Alphaflys’.
I had my eyes on Nike’s new line for quite some time, but it was proving impossible to get my hands on any of the top tier shoes, at least without shelling out 250+ dollars. I was, however, able to find a pair of Zoom Flys at a local discount sporting goods store this spring, and after purchasing the only pair they had I rushed home to try them out. Zoom Flys are not terribly dissimilar from their more expensive counterparts. However, their carbon plate is supposedly a bit dumbed down, and the remarkably efficient Zoom X foam (otherwise referred to as pebax) present in the 4% has been replaced with React foam. According to Nike, React offers a substantial performance improvement over the the old Lunar foam (13% better energy return, to be exact) but after three pairs of Nike Reacts I should note I still find the Lunar to be superior performance-wise, although admittedly less durable. Still, I reckoned the Fly’s carbon plate alone was enough of a step up from my beat-up trainers that I could hopefully gain a bit of a feel for how the technology in the new Nikes works.
The Flys I purchased had the flyknit upper– this is a stretchy, skin-like material that offers little support, and given the already massive 33mm heel and 10mm drop, I had both the confidence and shakiness of a baby deer as I took my first steps. Right away the plate made itself known to me, thrusting me forward onto my toes in a pronounced manner. When not on my toes, however, I felt as if I would fall right off the back or side of the narrow, tapered heel, and my perpetually weak ankles voiced their concerns to me. And then I stepped out the door and began to jog, and guess what? The shoe still felt terrible. It felt slow; the cushion slushy at best; the support nonexistent. I doubted I could take a turn at any speed above a trot without rolling an ankle. Perhaps I’d been had. Maybe all the performance talk was simply marketing fluff. I thought about calling it quits, but what good would this do for an article? So after a 10 minute warm-up, I picked up the pace (expectations now tempered) and the most extraordinary thing happened, and the best way to describe the shoe’s transformation is to tell a story.
I’ve always loved sports cars, and as a kid I devoured magazines- Car & Driver, Sport Compact Car, Dupont Registry, and any other magazine the local Barnes and Noble might have in hand. I had two posters on my wall: the Ferrari 360 Modena (which I’ll admit has not aged well) and the delightfully absurd Lamborghini Countach. However, my Countach dreams took a hit when I read a reflection upon on it in Car and Driver. The car, the reviewer ventured, was best left as a poster on the wall. In real life the entry, via scissor door, is awkward for a normal-sized human, the air conditioning barely works, and the windows don’t roll down, meaning the cabin gets boiling in no time at all. Moreso, the foot-well is so cramped it doesn’t allow room for a shoe larger than 10.5. The list went on and on. Years later I drove one, and while all of this was in fact true, the journalist had left something important out. Above 30 miles per hour the car took on a life of its own. The steering tightened, the car began to feel agile, and everything came together in a wonderful harmony: the sounds of the road, the feel of the suspension, the shriek of the engine. Simply put, what the reviewer had failed to note was the fact that this car was not meant to be driven slowly.
So I ran at what I believed to be roughly 7:30 pace, and the shoe began to feel really good on my feet. Then my watch beeped at 800 meters and I was surprised to see I was running nearly 45 seconds quicker per mile than I had aimed for. And it just felt so effortless! The shoes were doing the work, it seemed, and I was just along for the ride. Without consciously focusing on it, my stride seemed to change to adapt to the shoe. I now had more of a back-kick and less knee lift than before, while my arm-swing also shifted, with a less-pronounced back-swing or ‘drive’. My arms stayed high and tucked into my chest in their motion- perhaps I needed less energy to propel myself forward than in the past, I surmised. There are already a few studies on efficiency changes with the shoes–and here I should iron out the first of the misconceptions of the shoes- Nike’s ‘4%’ dubbing does not refer to a time improvement, but rather to efficiency gain, and there is massive difference between the two– but none had covered the changes in arm carriage that would occur. I’d imagine this leads to far less oxygen expansion, especially for someone such as myself whose form normally consists of a nauseating amount of arm flailing and shoulder rolling.
Now we move on to the issue of energy return. I’ve dealt with problems on my left side for many years now: broken feet and toes, stress fractures, hamstring issues, even a hernia, and as a result I’ve begun to favor that side when running. I’ve gone so far as effecting a pronounced limp, dipping my left hip upon impact to lessen the forces on that side in a way not too dissimilar from the triathlete Lionel Sanders. I know I do this, but I couldn’t help it, at least until these shoes came into play. The massive cushioning and energy return meant that (and here I should make note of a second misconception: that energy return is not energy creation, but rather a bit less energy ‘lost’) for the first time in years, I was able to actually push my left foot into the ground with force and then drive off of it, rather than babying it for fear of bone pain. Immediately I was aware of a strength and efficiency I couldn’t remember feeling, at least not in the last 10 years. However, there was a downside to it: long neglected muscle groups immediately began to make themselves known to me, and the entire front or shin area of my left leg cramped.
I wasn’t going to let a seizing muscle stop this fantastic experience, so I kept running, and in doing so dropped the pace further. The shoes felt better and better the quicker I ran, and Strava had my next mile at 6:20. For nearly an additional hour, in a state of blissful, pain-free exuberance, I continued doing one mile loops, floating across the ground with an ease and practiced efficiency that was entirely foreign to me. Eventually I decided to call it a day before something went wrong. I was absolutely euphoric that night. Imagine running pain-free for the first time in 6 years, and being rewarded with a 10-mile PR to boot, but with the legs feeling as fresh as if I’d taken an off day!
I’ll admit I am at times prone to hyperbole, but I am also a cynic at heart. Prior to trying the shoes out, a part of me did suspect all the studies and hype were part of a fantastical, exaggerated effort by Nike (remember, this is the company that made people believe that Nike Shocks, possibly the hardest and least forgiving running shoes ever made, were squishy and even ‘bouncy.’) But what I experienced –and remember, this was with a cheap, watered-down version of the shoes– was nothing short of extraordinary.
It has been noted there are responders and non-responders to these shoes, and there is zero doubt I am a responder. To what % I improve from the shoe I am unsure, but here is what I will say: my heart rate in the Zoom Flys is the same while running 7:30 miles as it is at 8:05/mile pace in my usual daily trainers, the Lunartrainers, and that is truly extraordinary- although it may speak more to the extent my atrocious running economy limits me than anything else.
I reckon the people who will benefit the most from this technology are those in a similar position to me: iffy form, a history of injuries, and heavy. Studies have echoed this, showing a more pronounced benefit for ‘average joe’ runners as opposed to elites. However, to that point, I will caution that the Zoom fly is so stiff that at any pace slower than perhaps 7:30 per mile the plate will cease to perform its duty and the ride will become sloppy and unresponsive, so perhaps for slower runners the shoe would be best suited for tempo and speed days.
Nike claims its shoes are reducing injuries, and while there is evidence that stride changes from new stack heights may bring with them their own slew problems down the road –particularly Achilles issues, see Galen Rupp or Gwen Jorgenson and their Achilles surgeries– I’d reckon they aren’t too far off with this claim. My takeaway: ban them or don’t on the professional circuit, that’s none of my business. But please leave the technology for the rest of us; the aging, beaten-down hobby-joggers who just want to get out for a glorious, pain-free run from time to time.
¹Yes, we’re aware other brands are creating competitors with similar technology. As of now I have yet to see any come close to Nike in terms of performance, but more importantly, none are available in my market as of this writing. But if you’re avoiding Nike, by all means at least try out a competitor such as Hoka or Saucony.
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