Carbon Fibre Footwear Myths + Facts
I recently recorded an Expert Edition with Simon Bartold and Paul Griffin around all things carbon fibre technology in shoes.
Ever since Eliud Kipchoge smashed the unthinkable two hour marathon mark in Vienna last October the running world has been buzzing with discussion around carbon fibre shoe technologies.
During the Episode Simon and Paul share around what carbon fibre technology means to elite runners and everyday runners.
The below summary as provided by Simon and Paul is useful in debunking common myths around the technology and also outlining what is known.
4 Carbon fibre shoe technology myths:
1. The introduction of carbon plates into running shoes is new.
This is not the case. In fact, this practice has been in place for at least 20 years (Influence of midsole bending stiffness on joint energy and jump height performance Stefanyshyn, D.J., Nigg, B.M. 2000 Medicine and Science in Sports and Exercise 32(2), pp. 471-476
2. The carbon fibre plate in shoes has a ‘spring effect’.
This is not correct, the plate does not act as a spring, but rather as a lever. (Hoogkamer, W., Kipp, S., & Kram, R. (2019). The Biomechanics of competitive male runners in three marathon racing shoes: A randomized crossover study. Sports Medicine, 49(1), 133–143.
3. All pates are the same.
This is not true, some plates are simple with a curve in one direction only, usually the sagittal plane (eg the Hoka Carbon X), whilst others (eg. Nike Air Zoom Next% AlphaFly) have complex geometry and are shaped like a spoon.
4. Everyone will run faster.
Everyone is different, and some runners will respond to the carbon plate, but others may not. Changes in spatiotemporal variables, metabolic cost, horizontal ground reaction forces, and subjective comfort arising from altering longitudinal bending stiffness (with a carbon plate) are running speed dependent. Therefore these shoe definitely have a focus on accomplished runners rather than novices. (Day and Hahn (2020). Optimal footwear longitudinal bending stiffness to improve running economy is speed dependent. Footwear Science, Volume 12, Issue 1.
4 Carbon fibre shoe technology facts:
1. Footwear mass, cushioning, and longitudinal bending stiffness (defined by carbon fibre plates) each affect the energetic cost of running.
2. Every runner is different and will respond differently.
In the case of Nike, the economic effect has been labelled as 4%. But in fact in most studies the measured effect is between 1.5 to 6%. Different runners respond differently. (Hoogkamer, W., Kipp, S., Frank, J. H., Farina, E. M., Luo, G., & Kram, R. (2018). A comparison of the energetic cost of running in marathon racing shoes. Sports Medicine, 48(4))
3. The geometry of the plate is important and may play a fundamental role in the performance of the shoe and its energetics.
A flat plate has been shown to increase positive work at the 1st MPJ whilst moderate to extreme curved plates decrease negative work, ie there was a decreased extension velocity which exceeded an increased flexion moment. (Farina et al. (2019) Creating footwear for performance running. Footwear Science 11;S1)
4. There is a point at which the stiffness of the plate may interfere with function.
Restriction of the natural metatarsophalangeal (MTP) flexion caused by stiffened shoes and the corresponding joint torque changes may reduce the benefit of shoe bending stiffness to running energetics. (Oh, K. Park, S., 2017, The bending stiffness of shoes is beneficial to running energetics if it does not disturb the natural MTP joint flexion. Journal of Biomechanics Volume 53, 28 February 2017, Pages 127-135
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Key contributions: Simon Bartold & Paul Griffin
Brad Beer (APAM)
APA Titled Sports & Exercise Physiotherapist (APAM)
B.Physio/ B. Ex. Sc
Founder POGO Physio
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