The introduction of carbon-fiber-plate super shoes has revolutionized elite running. Since they were introduced in 2016 every world record from 5 k to the marathon has been broken. So how do super shoes with a carbon fiber plate impact performance, running form and the risk of injuries?
Carbon fiber plate super shoes increase running economy (measured by how much oxygen you use when you run) by up to 4%. This leads to race times that are about 2% faster than before the era of “super shoes”. (1)
What are carbon plate super-shoes and why are they fast?
Carbon plate super shoe construction
Super shoes have two key components that make them special – a stiff carbon plate and a very lightweight foam.
The foam creates a high level of energy return and its light weight reduces the energy cost of wearing the shoe (2), which is important as every 100g of shoe weight decreases running economy by 1%. (3,4) It is also hypothesized that the thick layers of foams in modern super shoes reduces muscle fatigue from vibrations. Finally the foam increases the stack height of shoes (typically to around 40mm), literally making runners legs “longer”.
The carbon plate provides structure, so the shoe, despite the cushy foam, is still a “stable platform” to run on. (5)
Why are carbon plate shoes so fast?
The stiff carbon plate reduces the upward bend (dorsiflexion) of toes, and the metatarsophalangeal (MTP) joints (located 2 cm behind your toes). This reduces energy usage at these joints which can then be used for forward motion.
Another performance relevant effect of the carbon fiber plate is that its stiffness and lack of bend shifts the ground reaction force forward (toward the toes). This creates a “longer lever arm” to apply force with, from the point of impact to the ankle. The stiffer plate increases the ankle joint moment.(6,7)
A speculative benefit of curved carbon fiber plates is the “teeter-totter” effect: as the center of pressure moves forward towards the end of a curved carbon fiber plate in the stance phase and the runner pushes off from the toe, the ground reaction force produces a force at the heel which helps lifting the heel at toe off.
The use of a stiff carbon plate also reduces the speed at which the gastrocnemius medialis (part of the calf) has to contract, potentially lowering the energy cost of running. (8)
During long distance runs the body naturally transfers work from lower parts of the body (ankle plantar flexor muscles) to larger upper muscle groups (knee extensor muscles) as it fatigues. This redistributed work load is less efficient as it uses larger muscle groups. Carbon plate shoes seem to delay this transition to later stages of the run, positively impacting running performance. (9)
The impact of carbon plate shoes on running form
Running in carbon plate shoes typically impacts running form in these ways:
- increases forward lean,
- increases stride length,
- decreased cadence
- increases vertical oscillation
- increases ground contact
- increases flight times
Apart from the carbon soles stiffness these changes are also a result of the foam soles high energy return and the increased “leg length” when running with shoes with a high foam stack. These changes are not conscious changes by the runner but a consequence of the shoes potentially higher energy return and the bodies reaction to it. (6,10)
Research also indicates that different runners react differently to super shoes, based on their physical characteristics, running form and speed.
To identify the impact of carbon plate super shoes on running form for yourself specifically consider an online running form analysis at movaia.com: Compare the analysis of a run with your everyday shoes with the analysis of a run with super shoes.
Durability of carbon-plate shoes
Carbon plate super-shoes have a few disadvantages. The most obvious one may be their high cost which is exacerbated by their shorter lifetime. That special, super-lightweight and energy-returning foam we talked about – it does not last very long.
Combined with a thin, lightweight outer sole this means carbon plate super shoes should be retired after 200 km or so – less than half of what you would get out of a more traditional running shoe.
Potential injuries in carbon plate shoes
Detraining of muscles and ligaments
With carbon plate shoes impacting running form and foot mechanics they make certain parts of your body – namely the metatarsophalangeal (MTP) joints and the ankle joint work less. These muscles and ligaments might weaken over time if you are doing a lot of mileage in these shoes. Weakening these muscles might ultimately negate any performance advantages “bought” with carbon plate shoes.
New types of injuries
A recent study also documents cases of navicular bone fractures (11) in elite runners using carbon-plate shoes. As less energy is stored in the muscles and ligaments of the ankle these forces are being diverted to the mid-sole were they are hypothesized to cause these injuries.
Furthermore the increased stack height from the substantial soles of super shoes can also lead to ankle sprains/ Like any new shoe also a super shoe can introduce new stresses to your body.
Carbon-plate super shoes should therefore be introduced gradually to give your body time to adjust to new movement patterns.
Any niggles or pain particularly over the navicular bone, anterior ankle or midfoot region should be taken seriously, as it may represent a more significant injury that requires further evaluation (12)
Overall carbon plate super shoes are probably best kept for race day and race specific workouts while doing most of your mileage in more traditional trainers to maintain strength in your ankles and foot.
Are carbon plate super shoes a good investment?
Research has shown that not everyone benefits from carbon plate shoes in the same way. Both among elite runners as well as amateur runners some improve their performance in these shoes while the performance of others actually deteriorates. (10).
Other studies show that the benefit of carbon plate shoes tends to increase with higher running speed and better running form. Runner specific physiological factors, such as foot morphology also play a role. (13) Hence there is risk associated with the investment in super shoes.
References
- Muniz-Pardos B, Sutehall S, Angeloudis K, Guppy FM, Bosch A, Pitsiladis Y. Recent Improvements in Marathon Run Times Are Likely Technological, Not Physiological. Sports Med. 2021 Mar;51(3):371-378. doi: 10.1007/s40279-020-01420-7. Epub 2021 Jan 13. PMID: 33442838; PMCID: PMC7805427 – https://pubmed.ncbi.nlm.nih.gov/33442838/
- Jay Worobets, John William Wannop, Elias Tomaras & Darren Stefanyshyn (2014) Softer and more resilient running shoe cushioning properties enhance running economy, Footwear Science, 6:3, 147-153, DOI: 10.1080/19424280.2014.918184),
- Hoogkamer, W., Kipp, S., Spiering, B.A. and Kram, R., 2016. Altered running economy directly translates to altered distance-running performance. Med Sci Sports Exerc, 48(11), pp.2175-80., https://pubmed.ncbi.nlm.nih.gov/27327023/
- Fuller JT, Thewlis D, Tsiros MD, et al, The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial, BMJ Open 2015;5:e008307, https://pubmed.ncbi.nlm.nih.gov/30102872/
- Carbon plate running shoes: Are they for me?, https://www.run4it.com/blogs/journal/carbon-plate-running-shoes-are-they-for-me
- Steffen Willwacher, Manuel König, Björn Braunstein, Jan-Peter Goldmann, Gert-Peter Brüggemann, The gearing function of running shoe longitudinal bending stiffness, Gait & Posture, Volume 40, Issue 3,2014, Pages 386-390, ISSN 0966-6362, https://doi.org/10.1016/j.gaitpost.2014.05.005
- Wessel van Veenen, Carbon fibre plates: the science behind the latest hype in running shoe technology, https://www.biomechanist.net/carbon-fibre-plates-the-science-behind-the-latest-hype-in-running-shoe-technology/
- Čigoja, Saša. (2021). Shoe Bending Stiffness and Muscle-Tendon Unit Function in Running, https://www.researchgate.net/publication/349115474_Shoe_Bending_Stiffness_and_Muscle-Tendon_Unit_Function_in_Running
- Sasa Cigoja, Jared R. Fletcher, Benno M. Nigg, Can changes in midsole bending stiffness of shoes affect the onset of joint work redistribution during a prolonged run?, Journal of Sport and Health Science, Vol. 11, Issue 3, 2022, 293-302, https://doi.org/10.1016/j.jshs.2020.12.007
- Chris Bramah, Carbon Fibre Running Trainers: Science behind the super shoes, (https://www.extramilehealth.com/post/carbon-fibre-running-trainers-science-behind-the-super-shoe)
- Knopp, M., Muñiz-Pardos, B., Wackerhage, H. et al. Variability in Running Economy of Kenyan World-Class and European Amateur Male Runners with Advanced Footwear Running Technology: Experimental and Meta-analysis Results. Sports Med (2023). https://doi.org/10.1007/s40279-023-01816-1)
- Tenforde, A., Hoenig, T., Saxena, A. et al. Bone Stress Injuries in Runners Using Carbon Fiber Plate Footwear. Sports Med (2023). https://doi.org/10.1007/s40279-023-01818-z
- Urushihata, Toshiya & Haba, Toshihiro & Nakagawa, Yuta & Kawamura, Daichi & Umezaki, Yasuyuki & Kumazawa, Ibuki. (2022). Original Article Effect of wearing carbon plate shoes on the running economy of pronated feet. 1. 40-49, https://www.researchgate.net/publication/362024791_Original_Article_Effect_of_wearing_carbon_plate_shoes_on_the_running_economy_of_pronated_feet