Carbon Fiber Racing Shoe Battle

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Road racing shoes today are faster, more complicated and more expensive than ever. Nike created some controversy and a shoe company arms race in the running world with the Vaporfly 4% and now almost every shoe company has a comparable carbon racing shoe on the market. But what are the real differences between these shoes? We put some of the best to the test to get some hard data and real answers.

 

T-ToyBrown

Author: T-Roy Brown is a long time endurance athlete with a background in triathlon and NCAA Division 1 distance running. working with the multisport training program 2PEAK and running.COACH. T-Roy ran a 2:22:07 Marathon in 2019 and a 1:06:40 half marathon in 2020

 

 

Background

In 2017 innovation in marathon racing shoes created a huge leap in performance. Nike created the Vaporfly 4% claiming that this new shoe could increase running efficiency up to 4%. With this shoe and it´s two successors, the Nike Zoom X Vaporfly Next% and Nike Air Zoom Alphafly Next% suddenly personal bests and world records started to fall. After many of the best performances of all time were achieved in these shoes, people began to believe that Nike´s claim is likely more than just marketing.

Nike shoes made up 25 of the 36 Marathon major podium spots in 2018 and 31 in 2019. The clear differences in these shoes compared to the old school racers are the high stack height, a large amount of foam through the midsole and a carbon fiber plate running through the midsole.

This innovation and success sparked an arms race between shoe companies. Fast forward to today, and after World Athletics clarified what is allowed almost every brand has a carbon fiber shoe comparable to what Nike released in 2017.

Now that there are multiple options, which one should you get? to answer this question we took three of the most recent shoes on the market, the Nike Air Zoom Alphafly NEXT%, the Hoka One One Carbon X SPE, and the Brooks Hyperion Elite, and tested them with are partners at MedBase to get some hard data

Shoes Tested

Nike Air Zoom Alphafly Next%

Nike´s most recent road racing shoe and the newest version of the shoe that started the Carbon fiber marathon shoe trend is the Alphafly. Eliud Kipchoge famously wore a version of this shoe when he ran the fastest marathon of all time of 1:59:40 in the  INEOS 1:59 Challenge.

Specs

  • weight 210 grams
  • Heel to toe drop: 4mm (Forefoot: 35mm, Heel: 39mm)
  • Midsole material: Zoom x foam, Carbon Fiber plate and Airpods
  • Upper material Atomnit
Hoka One One Carbon X SPE

Hoka was the first real brand outside of Nike to release a carbon fiber marathon racing shoe with the Carbon X. The 50 mile world record was ran in this shoe by American ultra runner Jim Walmsley  along with many other impressive times. The Hoka One One Carbon X SPE is the most recent version of this shoe from 2020

Specs

  • Weight: 246 grams
  • Heel to toe drop: 5mm (Forefoot: 30mm, Heel: 35mm)
  • Midsole material: Carbon Fiber plate, top layer of softer PROFLY X foam and firmer bottom layer of foam
  • Upper material: Monomesh
Brooks Hyperion Elite

Another one of the first carbon fiber racing shoes released to compete with Nike. This shoe was able to claim some of the marathon major podium spots that were not occupied by the Nike shoe including a victory at the Boston Marathon in 2018 by Desiree Linden in the first prototype.

Specs

  • weight 195.6 grams
  • Heel to toe drop: 8mm (Forefoot: 14mm, Heel: 24mm)
  • Midsole material: DNA zero EVA foam, Carbon Fiber plate
Control Shoe/Daily Trainer – Nike Pegasus 37

We tested along with this shoe to have a comparison with something that is not a race shoe.

Specs

  • Weight 285 grams
  • Heel to toe drop: 10mm (Forefoot: 14mm, Heel: 24mm)

Test Procedure

We preformed our tests at Medbase Sports Medical Center Zürich on a HP Cosmos Quasar treadmill set at a 1% incline to most accurately mimic running outside. We measured Oxygen uptake with a Cortex Metalyzer 3B and heart rate with a polar heart rate monitor.

While collecting data we ran in the 4 different shoes listed above at three different speeds as follows:

  • 10 min Warm up at 4:30 min/km
  • 4×6 min at a pace 3:20 min/km;
  • Shoe change between sets about  1 min
  • Shoe order: Pegasus, Hoka; Brooks, Alphafly
  • 60 minute break
  • 10 min Warm up at 4:30 min/km
  • 4×6 min at a pace 3:10 min/km;
  • Shoe change between sets about  1 min
  • Shoe order: Alphafly, Brooks, Hoka, Pegasus
  • 60 minute break
  • 10 min Warm up at 4:30 min/km
  • 4×4 min at a pace 3:00 min/km;
  • Shoe change between sets about  1 min
  • Shoe order: Hoka; Alphafly; Pegasus; Brooks

I was the runner preforming these tests and 3:20, 3:10 and 3:00/km are approximately  marathon, half marathon and 10km paces for me currently. It is important to note that this test was preformed with only one test subject and there are the results will vary significantly with different runners.

Results

in the testing it was clear that the Alphfly preformed significantly better than the other shoes tested.

Oxygen Uptake

The oxygen required while running is directly correlated with a good aerobic performance while running. During the test we measured oxygen uptake throughout the duration of the running but for the data in charts and graphs below we only used the last 3:30 seconds for the 6 minute reps and the last 2 minutes for the 4 minute reps. The results were as follows:

M – is the mean amount of oxygen in liters per minute used in the last 3:30 for 3:20 and 3:10 pace and the last 2 minutes for the 3:00 pace. SD – is the standard deviation in oxygen uptake over the same period of time. % – is the percent variance in oxygen uptake compared to the Alphafly at the same speed
Graphical summary of all shoes across all speeds

You can see clearly that in our tests it took less oxygen to tun in the Alphafly at every pace. when I was running I could really feel the difference an the data shows it is in fact significant. The percentage variance changed slightly at different speeds but the Alphfly was consistently better.

what is really surprising is how much better the Alphafly preformed. the O2 uptake at 3:00 was comparable to that of the other shoes at 3:20 ad you can see in the chart below:

This is by far the most significant finding. It is also worth noting that while the Hoka was the worst shoe at 3:20/km, it was much closer to the Alphafly and significantly better than the brooks at faster speeds.

Heart Rate

We also collected heart rate data while preforming the test. The heart rate was influenced significantly by the order in which the shoes were tested. as a reminder at 3:00 the order was Hoka Alphafly Pegasus Brooks. at 3:10 the order was Alphafly Brooks Hoka Pegasus. and at 3:20 the order was Pegasus Hoka Brooks Alphafly.

The first shoe in the set was always the lowest heart rate and then it was higher for each of the next shoes tested with exception for the Alphafly at 3:20. If you look closely it does appear that the Alphafly may be a little better than the other shoes, but it is not as clear nor as good of a measurement as the oxygen uptake. Despite the raising heart rate as time went on oxygen uptake stayed more or less consistent as you can see in the final graph above.

Full results of the test written by or partners at medbase can be found here.

Conclusion and Summary

Test winner – Nike Air Zoom Alphafly NEXT%

As noted before the testing procedure has a major fault as it is just one runner and there are too many variables to take a 1:1 translation of these results to other runners. however, the results of the test are significant enough to say that wearing the Alphfly in comparison to these other racing flats will improve your performance.

The results showed that the Alphfly was at 10km pace (3:00/km) was comparable to the other shoes at marathon pace (3:20/km). You can not simply extrapolate this to the full race and say, “I will be 3 minute 20 seconds faster in a 10km” or “I will be 14 minutes faster in the marathon”. However there is a direct correlation with oxygen uptake and performance so you can say with confidence, “I will be faster road racing in the Alphafly”.

Now the Alphafly is the most expensive of all of the shoes tested but, depending on your goals, it may be worth it. It is certainly worth it for me and I will be doing my road racing in this shoe until something new happens.

2 replies on “Carbon Fiber Racing Shoe Battle”

This experiment has zero scientific value as you know which shoes you are running with, your test protocol is worthless and you were the only test subject.
I can easily setup a similar experiment and demonstrate that for example the Adidas James Harden Vol. 4 basketball shoe outperforms all running shoes as running efficiency is easily to influence by playing with cadence, stride length, vertical oscillation etc.
Also your heart rate values (and oxygen uptake) are completely useless: the last interval obviously records the highest heart rate, irrespective of the shoe.
For this to be a little bit credible you need more test persons, go through a sequence of intervals with one pair of shoes and repeat it several times and do the same with all the other shoes and make sure the test subject can’t see which shoe it’s wearing.
Nike has good marketing but their shoes are not magically fast.
Sam

Hi Sam

Thank you for taking your time and write us your feedback, as this helps us understand, how our community perceives our blog article. Let me comment on your statements, as I want to clarify some issues, including the goal of this little experiment of ours. With the innovation of these carbon fiber plate shoes, we wanted to create a little in-depth review, that is additionally more quantifiable, than just, “good, better or worse shoe”.

We agree that the scientific value of a case study does not lie in the significance of the results, but in the new ideas it generates in the field of exploratory research. In our case it gives runners something to think, debate and experiment about. If this article seems to be provocative, that’s good because it obviously is a debated issue.

Because the heart rate was clearly dependent on the length of the interval, we did not give this parameter much consideration. But as we have not seen a clear rise in the oxygen uptake during each interval, we concluded, that we can emphasize this value more, also as it is often referred to as proxy for running economy in literature.

As for our “so called” study design, we agree, that we should have done a lot differently (more subjects / RCT / several testings ect.) so we could have eliminated more disturbing factors and lead to results applicable to the general public. But in the protocol, we used, we tried to act as “unbiased” as possible (we all know it is impossible). So of course, we did not actively change our cadence, stride length or vertical oscillation just to make a point but you are right, if we were to “influence” this experiment, we could have done so (but to what purpose).

Let me clarify that proper research was not our goal. We will analyze, if we have to adjust our blog article accordingly, so people do not get confused about that. We don’t have to argue about the good marketing of nike and that training beats a fast shoe every time. Despite all that our observed data suggests, that there seems to be more potential in shoes, than we thought possible.

Best wishes,
Jan

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