LISTEN TO THE EPISODE HERE:
Associate Professor Dustin Joubert of Stephen F. Austin State University discusses his study comparing seven carbon-plated "Super Shoes", and how runners and triathletes should interpret and use the results. We also discuss more informal testing that Dr Joubert is doing on a regular basis in his lab, including shoes not included in the study.
In this Episode you'll learn about:
- What is a super shoe, what are the purported benefits, and the proposed mechanisms behind them?
- The Super Shoe study: protocol, shoes included, results and conclusions. Are the Nikes all-conquering?
- What does this mean for consumers? How should triathletes and runners go about selecting shoes for racing?
- Dr Joubert's informal testing, including the Adidas Adios Pro 2 and running in crocs!
- How do running economy benefits translate to performance benefits?
- What happens to the benefits from Super Shoes when running uphill or downhill?
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- My name is Dustin Joubert. I am an Associate Professor in the Department of Kinesiology and Health Science at the Stephen F. Austin State University Nacogdoches, Texas, United States. I have a PhD in Exercise Physiology, and I have been a runner all my life.
- I always had an interest in endurance performance, and more recently, I started looking into the running economy and these new shoes.
Why do the "super shoes" perform better than regular shoes?
- It has been interesting to look at the latest literature and access the terminology.
- The public calls them "super shoes", but that might mean different things.
- The primary characteristics of these shoes are still not well-addressed.
- They regularly present a higher stack foam (more compliant and resilient - they can store and return more energy). The shoes also have more cushions.
- The presence of a carbon plate increases the magnitude of bending stiffness, and it provides stability.
- The other factor is that the elite runners are wearing them as well.
What are the benefits and mechanisms behind these shoes?
- The 2018 Yokowama study on the Vaporfly shoes was the groundbreaking paper that presented the benefits of the Nike Vaporfly shoes. (the 4 % increase in performance)
- The reasons were that they were more compliant and resilient on the midzone foam. Thus, they can store and return more energy, decreasing the cost of running and improving the running economy.
- We can run at a faster speed with the same physiological stress. So, we have a performance improvement.
- That was the primary benefit presented in that 2018 study.
- Other papers addressed the impact of shoes. Some follow-up studies have confirmed the findings.
- The initial 2018 study had support from Nike. Thus people were reticent concerning the research. Nevertheless, the researchers were world-class, and there was no reason to doubt the quality of the paper.
- However, independent labs addressed that issue and confirmed the results. (improvements of 2-4 % in performance)
- The exact percentages vary slightly in the literature, but they present a consistent improvement.
- However, you notice that the focus was only the Nike Vaporfly shoes. Other companies have come to the market with a "super shoe", but the scientific community have not confirmed their benefits.
- This fact led us to do our study. We have performance benefits with this shoe. But we also have the other companies presenting alternatives. (and these shoes lack scientific validation)
- So, our goal was to understand if the market levelled after the affirmation of the Vaporfly shoes.
- I run on the Hoka Carbon X.
- I tested myself in the lab, and it did not give any benefits compared to regular shoes.
- When I purchased the Alphafly, I had an improvement of 4 %. So, it was an eye-opener.
- It tried to obtain as many shoes as possible to understand which ones were in the "super shoe" category.
Shoes considered in the study
- We did not have any funding from shoe companies. We got seven carbon plate "super shoes" and one traditional shoe.
- We tested the Hoka Rocket X, Endorphine Pro, Nike Alphafly, Asics Metaspeed Sky, Nike Vaporfly Next% 2, New Balance RC Elite, Brooks Elite 2.
- Our control shoe was a standard racing shoe. (Asics Hyperspeed)
Participant group of the study
- We wanted to test at 16 km/h (6 min/mile pace).
- It is the most common speed tested in the previous work. Therefore, we wanted to gather data at that velocity.
- As we are measuring running economy (aerobic view - oxygen consumption component), we need people to work aerobically at that intensity. (they are not at a level where anaerobic metabolism plays a role in the energy contribution)
- In conclusion, you need fit athletes that are relatively comfortable at those speeds.
- You need to maintain athletes below their lactate threshold. The qualification criteria were athletes could run under 17:30 for a 5 km distance.
- They were not the fastest runners, but competitive at least.
- We had a mix of collegiate runners and middle age marathon runners.
- We ended with 12 runners that met those criteria. We had limited funding, so we had a small range in terms of shoe size. Therefore, we could only evaluate male athletes.
- Moreover, our location is not in the city centre. So, recruiting people that meet those criteria was already a challenge.
- We did a five-minute set to measure the running economy.
- We put athletes running at an aerobic pace for five minutes to capture oxygen consumption, CO2 production and determine the energy expenditure. (through indirect calorimetric)
- It takes 2-3 minutes to achieve a steady-state. Therefore, we can capture the last couple of minutes of the set.
- As we had eight shoes, we did 8x5min reps with each subject.
- Every subject wore the shoes on the first visit. (in random order)
- We gave about five minutes to change the shoes and keep the protocol from taxing the body too much.
- We had athletes come a second time to take out the testing order of the shoes. (they tested them in the reverse order of how they proceeded on the first visit)
- Therefore, we could take the average of the two visits and compare the physiological parameters evaluated.
Results of the study
- The analysis focused on the benefits in terms of percentage compared to the control shoe. (did the shoes help compared to the control shoe?)
- We also evaluated if they had the same benefits as the Nike Vaporfly.
- We found a lot of variability between shoes regarding performance.
- We saw the Nike Alphahly and Vaporfly performing 3 % better than the regular shoes. (these have the same technologies. Therefore, these results were what we expected)
- The Asics Metaspeed Sky matched the performance of the Nike shoes.
- There was a middle ground. Some shoes performed better than the control shoe but worse than the Nike shoes. (Endorphine Pro and New Balance RC Elite with 1.5 % performance benefit)
- The shoes that did not give any performance benefits were the Hoka Rocket X and Brooks Elite 2.
Individual responses to different shoes
- The goal of these studies is to understand potential statistical performance differences and leave out any individual responses.
- We broke down athletes into the ones that have the highest and lowest responses to different shoes.
- The highest responders were the least economical athletes of the study. (they have more margin to improve)
- Maybe the Achilles and leg tendons are not as springy as the other athletes.
- Therefore, the shoes give them more benefit in that point.
- However, to do this type of analysis, you need a larger sample of data.
- People with slower cadence and more vertical oscillations benefit more from the shoes. However, as the sample was small, the evidence was not strong enough.
- I cannot say that there is a relationship between the run economy and the shoe benefit.
- People regularly state that everything is individual. And to some extent, that is true.
- To conclude that the top three shoes were beneficial, everyone needed to perform better.
- One of those three shoes was the best for every athlete.
- Some people had a 5 % improvement with the Alphaphly, while others might have only 1 %.
- It is on the magnitude of those differences that we see individuality.
Additional topics on the study and future research
- It is tough to keep up with the running shoe market. Academic research will never be a perfect solution to keep up to date.
- You can release a new shoe every 6-8 months.
- After this study, there were some updates on the shoes evaluated.
- There is a place for academic research when new shoes come to the market. Its use is to validate the claims and benefits of the upgrades.
- I have some interest in looking at individual responsiveness. However, those will take some studies only focused on that.
- Two articles have looked at the shoe effect on variable terrain performance. (after the release of the pre-print of this paper)
- Another article looked at the benefits of a new Nike prototype that brings benefits even with muscle damage.
- Therefore, I feel this is an area of research that will keep expanding. Covid slowed the release of studies, but I imagine there will be much research coming in the future.
Tips when selecting shoes
- In our conclusions, we state that people should be wary of buying shoes that lack validation. (against the top shoes on the market, or shoes that have scientific verification)
- There will be some shoes that will leave in disadvantage, compared to the top running shoes.
- It is trickier when the launch of a new shoe takes place. What should you do when looking at a brand-new product?
- However, I believe sports science facilities should promote more run economy testing. (there is a market for it)
- Endurance athletes that do metabolic testing might do run economy tests as well. (VO2 max and lactate tests)
- Economy tests use the same equipment as VO2max tests. Therefore, it makes sense for labs to do those tests.
- When you have a data sample of (n=1), it is the only one that matters. (n=1 means you are the subject of that study)
- If you can take the shoes to the lab and test, it gives you all the answers you need right there.
Running economy and performance
- You spend less energy and consume less oxygen to run at a specific speed by being more economical.
- However, the benefit is not from the energy saved. The improvement comes from running at the same physiological intensity faster.
- So, the question might be: if you are 3 % more economical, how much faster will you go?
- It is not a proportional relationship. However, at slower speeds, this might be the case.
- At faster speeds, you will be looking at a relation of 2/3. (elite marathon speed)
- A 3 % improvement in the running economy might lead to a 2 % increase in performance.
- Some calculators created by researchers allow for doing that modelling. (based on the pace you run)
Case study on the Adidas shoes
- The @labratrundown Instagram account is to provide objective data on shoes. Instagram is full of subjective data on running shoes.
- I tested the Adios Pro shoe on myself. You did not omit the shoe from our study. (intentionally)
- By the time we obtained all the shoes, we could not get that one. (sold out)
- I did not go well on that shoe. I am a good responder to the Alphaphly. (4.5 % benefit)
- I am regularly a responder with a 3.5 % benefit on the Vaporfly. And I was a percentage point lower on the Adios Pro.
- However, I cannot make broader conclusions from that.
- I wished we had it in our testing line-up.
- Without more data, we cannot say much more than that.
- It is substantial if a shoe gives me a 2-2.5 % increase in the run economy. I only have a better option on the table.
Running in crocs
- The work I did on the crocs was much more popular than on the Adios Pro.
- There is a runner that ran fast times on crocs. (sub 15 on the 5km, 1h06 on the half marathon)
- So, I tested myself on the crocs, and my economy was not good.
- It was 8 % worse than the Alphaphly. (4 % worse than the control shoe)
- My tip for someone running on crocs is to have thicker socks.
Nike Dragonfly shoes
- There is a follow-up study on the Yokohama study. They compared the Vaporfly shoe to a distance track spike shoe.
- That was before the launch of the dragonfly shoes.
- The heavier Vaporfly was even more economical than the light distance racing shoe.
- One thing they recommended from that paper was for track runners to consider running in the Vaporfly shoes.
- IAAF banned 25 mm or above stack height shoes. But NCAA, in the US, does not have any limitation on stack height.
- It seems many NCAA runners could benefit from the higher stack road running shoes.
- My testing sample was on the Alphafly to the Dragonfly. The Dragonfly was 2-3 % better than the control. (while Alphafly was 4 % better)
- The Dragonfly still helped me a lot, compared to other flat running shoes. However, the Alphafly is still the most economical shoe for me. (despite its weight)
- Even on shorter distances, I will run on that shoe.
- We tested at aerobic paces, but we do not know the benefits at faster speeds.
- We need to also consider the turns on the track or sprint to get to maximal speed. Are there some trade-offs in traction?
- We would need to perform more time trial data to get more information.
Testing spikes on the treadmill
- One of the treadmills we have is the Woodway treadmill.
- It has rubber slats on the belt. Therefore, they handle the spikes well.
- Of course, for traditional treadmills, that might be a problem.
Impact of the shoes when running on variable terrain
- One study had people run at a fixed speed (13 km/h), and they also showed the same economic benefits on flat terrain (3.8-4 %)
- The benefits lowered to 2.8-3 % when they tested uphill running. (5 % slope)
- And the same happened for downhill running.
- It is still an improvement. However, it is not as significant as running on flat terrain.
- While the running pace was low on the flats and the downhills, they could not increase the speed on the uphill sections. (remain below threshold)
- After reading this study, I was curious to see if the Alphafly would give me a penalty when running uphill. (because of the weight)
- When I tested myself on an uphill gradient, I saw similar data to what the study found.
- However, the gap between the Alphafly and the Vaporfly was smaller. Regularly, the Alphafly is better for me. However, when running uphill, that gap disappeared.
Additional comments on running shoes
- We are now looking to investigate the benefits of running shoes at slower speeds.
- Most of the studies paces range from 3-hour marathon time to faster speeds.
- So, we will evaluate shoe performance for slower velocities. (3h30-4h marathon pace)
Can you give three pieces of advice to runners or endurance athletes to improve their performance?
Consistency is crucial. In my running prime, I would focus more on strength. My body type would benefit from that. And maybe, I would not think as much. I have always been an academic and a student of my sport. Sometimes, when racing, you can overthink things. So, keep it simple and stupid.
Rapid fire questions
What is your favourite book, blog or resource?
What is an important habit that benefited athletically, professionally or personally?
I quit drinking alcohol a couple of years ago. And, for me, that had a significant impact on productivity in various areas.
Who is someone you have looked up to or who has inspired you?
I became a sports scientist because I met Arthur Lydiard. (the day before he passed away) He was doing a speaking tour in the US. And that changed my mind.
LINKS AND RESOURCES:
- Dustin's Instagram and Research Gate
- A Comparison of Running Economy Across Seven Carbon-Plated Racing Shoes - Joubert & Jones 2021
- A Case Study Comparison of Two Carbon-Plated Running Shoes on Running Economy and Running Mechanics - Joubert et al. 2021
- Metabolic cost of level, uphill, and downhill running in highly cushioned shoes with carbon-fiber plates - Whithing et al. 2021
- Nike Vaporfly 4% – can these shoes really make you run faster? with Wouter Hoogkamer | EP#179
- Extrapolating Metabolic Savings in Running: Implications for Performance Predictions - Kipp et al. 2019
- Excel spreadsheet: calculate race time savings based on economy improvements