Review: Nike ZoomX Vaporfly Next%

It’s not often that I change shoes, and this is to my knowledge the first time I have reviewed a pair of shoes. These shoes, however, have caused much controversy and I feel a desire to set the record straight as it were.

For a speed skater, I run a lot. Skaters are pretty divided on running with some really liking it as a form of training, and others really hating it. In most of the circles I’ve mixed, cycling remains the dominant form of cross training followed by resistance training with free weights. I’m one of the ones who likes to run – I ran for my high school and I also ran for my university in distances ranging from the 100m all the way to 800m. More recently, I’ve been doing ‘easy 10k’ workouts at aerobic threshold as part of my many self-experiments with training programs.

The first time I really paid attention to what shoes I was wearing was surprisingly late, when I started running at Melbourne University. I was advised to go to a shop called “Runner’s World” because it had a very wide selection of running spikes and while I was there, the shopkeeper noticed that I had very pronated ankles and started asking about what shoes I trained in. After about an hour of trying different shoes and running up and down the road outside, we determined that the Asics Gel Kayano best suited my ankle structure and gait. I still train in these shoes (I think they’re up to the 27th iteration of them which are helpfully called Gel Kayano 27).

Like many who pay cursory attention to the sporting world, I’ve been following with interest the many recent attempts to run the marathon distance of 42.195km in under 2 hours. This was finally achieved on the 12th of October 2019 by Eliud Kipchoge in an unofficial non-race world record attempt – the Ineos 159 Challenge. (Just as a funny little aside, I have the youtube video of the full record attempt running in another window while I’m writing this, and will try to conclude my writing before Kipchoge crosses the line.) The reason this wasn’t an officially recognised world record was mostly because it wasn’t a real race. Pace runners were cycled in and out, and they formed a protective ‘wind shield’ in front of Kipchoge while a pace car projected laser beams onto the ground to indicate the exact speed that they had to run, and coaches on bicycles rode alongside and occasionally handed energy gels to the runners as they ran. Nevertheless, this was an incredible athletic achievement and proof-of-concept. One can’t help but think that it is only a matter of time before the 2 hour mark is broken in open competition, especially considering that there are now two runners who have very similar marathon PBs – Eliud Kipchoge 2:01:39 and Kenenisa Bekele 2:01:41, both set at successive Berlin Marathons.

The reason I bring this up is because a big deal was made out of the shoes that have been worn by elite marathon runners in recent times. These shoes are an attempt by Nike to design the perfect shoe for distance running. A lot of rubbish has been written about the ideal design for a running shoe (minimalist shoes, I’m looking at you) based on notions about what our bodies are evolutionarily designed for. The truth of it is that our bodies are designed to walk and run on soft, uneven surfaces, so if we’re going to run a marathon on a road course, then the runner’s footwear needs to supply cushioning to compensate for the hardness of the road. In the context of something as specific as trying to run a marathon in what is essentially a straight line in under 2 hours, even that kind of analysis and interpretation breaks down. As our diversity of different kinds of sports shoes for different sports shows, the shoes should not be designed around what our bodies are evolved to do (because we never evolved to play basketball, or do power cleans) but as the most effective interfaces between our physiology and the demands of the sport. In fact, given that we already have very different shoes for specific things like Tennis and Weightlifting, it is perhaps surprising that it has taken this long to come up with a specific shoe for long distance running.

The ‘old school’ thinking was to make racing flats (as opposed to spikes) as light as possible. The next consideration was to make energy transmission from the foot to the ground as efficient as possible. This resulted in shoes which were light and thin, where the challenge was always to try to make the shoes stiff enough but still light. In parallel with racing shoes however, it was recognised that during training one had to wear different shoes. Firstly because racing flats were not designed to be durable, but also because the repeated impacts of running for hundreds of kilometres wears on the body and that shoes with more padding and structure were necessary to prevent injury. For a guy like me who doesn’t ever intend to race long distances but only does long runs for the purposes of cross training, these highly structured and padded training shoes are all I ever need – hence the Asics Gel Kayanos.

This is not the first time something like this has been attempted. The “Nike Free” series of shoes was originally any attempt to recreate the experience of running barefoot on soft grass (I’m not making this up – the Stanford track team at the time was doing very well, and one of the reasons was because they had a very low injury rate, and some of the reason for that was credited with a strategy of doing a lot of training barefoot on grass). The shoes didn’t end up being very successful for their intended purpose, but they did end up being very comfortable shoes to just lounge around in, and are currently my casual shoe of choice.

With this in mind, when an opportunity came up to get a pair of the latest ZoomX Vaporfly Next% shoes at a discount, I decided to give it a go and get a pair.

When trying them out at the shop, the first thing you notice is that the upper is very thin and light. It feels like someone varnished some tissue paper with pvc. There’s no padding except for a thin strip of what feels like neoprene just where the heel is. When you first stand up in the shoes, they feel… unstable. It was at this moment that I finally understood what Nike had done – these shoes are basically springs with a carefully-tuned directional element. The need for springyness is obvious – anyone who runs a lot knows that new shoes are a little faster than old shoes precisely because the new rubber is more springy. Your foot lands, your weight presses into the shoe, and a thick sole not only absorbs some of the shock, sparing your muscles, connective tissue, and joints, but also returns a little bit of energy which you can leverage when you push off. What these shoes do is try to maximise this energy return through a very thick and springy sole, and try to control the direction of that returned energy through the use of a carbon fibre plate and slightly unusually-shaped heel. Let’s have a look at the inside of the shoe:

(this is not my shoe)

The upper is as thin and light as possible, and I have a feeling that it will break before I can meaningfully wear through the sole. The sole is very thick and has a lot of give which makes these shoes an unusual experience to walk in. I feel sure that the difference in distance between the ground and the carbon fibre plate in the shoe is designed to ‘tune’ the energy return dynamics of the shoe. Ideally, you would land on the shoe, your bodyweight would press into it, the sole would compress, then the timing would be such that the release of this stored energy would coincide with your push off. In other words, the timing of the ‘echo’ of the force of the initial footstrike should coincide closely with the length of the ground contact time. There’s literally nothing in this shoe that serves a purpose other than propelling the wearer forward in a straight line – I wouldn’t want to have to turn a sharp corner in these, or kick a football.

But how are they to run in?

Lately I’ve been doing a lot of long ‘slow’ runs. An hour-long effort at lactate threshold 1, also known as aerobic threshold (this is the first intensity at which there is a sustained increase in blood lactate concentration above resting levels as a response to progressive increase in exercise intensity, as distinct from LT2 – anaerobic threshold which is the upper intensity limit at which the body maintains equilibrium between lactate production and lactate clearence – any sustained intensity above LT2 results in progessive accummulation of blood lactate concentration – the burning feeling in your legs). In layman’s terms, this is often referred to as “conversational” pace because an athlete should be able to comfortably maintain a conversation while at this intensity. For me, this is usually a little bit over 10km/h at a heart rate of 150bpm give or take depending on things like how well I’ve slept, how hydrated I am, and the ambient temperature. I do these runs around a park near my place which has a loop which is slightly over 2.5km which means that 4 laps gives me about 11km (and 8 laps is a half marathon plus epsilon). I cue up a few podcasts, pop my headphones in, and just run. When I’m feeling good, I will push it ever so slightly, and my laps do generally get a little faster as the run goes on, both because I’m more warmed up and also because the run is boring and I get a little excited when I sense that it is nearly over.

As soon as I went for a run with the new shoes, I was instantly faster for no extra effort.

I usually complete 10k in about 57-58 minutes. When I push it, it sometimes gets as fast as 53-54. These are not fast 10k times, nor are they supposed to be – I use them as an indication for my general fitness-health – if I’m sick or verging on overtraining, then these runs will reveal it, either by being very slow for the same perceived exertion, or with very inconsistent lap times. As soon as I went for a run with the Nike ZoomX Vaporfly Next% (what a mouthful) I was instantly faster for no extra effort. It was an unreal experience; I just started running, finding my rhythm, listening to my podcast, then I looked at my gps watch and it was showing 11.3km/h (it’s usually 10.3). As I got more and more used to the slightly unusual feeling of running in these shoes I got even faster, and importantly, a little smoother and able to run for less effort. Just yesterday I pushed it a little and snuck under 50 minutes for 10k for the first time in ages.

To be sure, you do have to make small adjustments to your running technique to make the most of these shoes, but there is absolutely no question that they are faster. When your foot strikes the ground it feels like you sink slightly into the ground and even slip forwards slightly and as you transfer your body weight forwards, you’re able to almost ‘dig’ your foot into the ground and then let the ground push you forwards as the hole you dug rebounds. Interestingly, the feeling of instability that you feel while walking in the shoes is not present while running.

There are downsides. For a person like myself with very pronated ankles, the load on the muscles which stabilise my ankles in my lower leg is significant. Running with my orthotic inserts helps, but I’m still not sure that this is something that I will ever completely adapt to. I already internally rotate from the hip slightly when I run to help compensate for my pronation, but this is something I haven’t had to deal with since switching to Asics Gel Kayanos. These shoes are designed for people with straight, neutral ankles. If you have very pronated ankles, you won’t be able to get the most out of them, and even if you can ‘correct’ your pronation with inserts, the upper of the shoe is thin and fragile and those inserts will likely reduce the life of the shoe.

So I would recommend these shoes with a few caveats. Obviously, they’re designed as racing shoes so they won’t last as long as a regular training shoe. They’re also not well-suited to people who have badly pronated ankles. They are definitely fast. In the future it would be really nice if Nike made a version of the shoe with more structure in the sole for arch support, and maybe a ‘training’ version of the shoe with a more robustly-built upper. For myself, I still do most of my running training in my Asics and only do the occasional run in the Nikes. That being said, I find myself wishing my Asics had the same amount of bounce and padding that the Nikes have – perhaps Asics will come up with their own version of this type of shoe.

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