2024-04-13
Home SHOES'in'TECH Run like the wind… with carbon fiber in the midsole of your running shoes
SHOES'in'TECH

Run like the wind… with carbon fiber in the midsole of your running shoes

Your running shoes are a ball and chain. Meaning they might be comfortable, but slow you down compared to solutions that include a carbon fiber midsole. How so? Let's find out qualities and performance of this material created to improve running shoes.

Run like the wind… with carbon fiber in the midsole of your running shoes

True, for SpaceX’s Starship project, the one that is supposed to take tourists to the Moon and Mars (to put it layman’s terms), Elon Musk chose to build rockets out of stainless steel – it withstands extreme temperatures better, is less expensive, and is easier to assemble -abandoning the more traditional, though still avant-garde, carbon composites.

This does not make carbon fiber any less attractive for many other more ‘normal’ applications with a less Star Wars flavor.
On the contrary, it still figures as one of the best solutions to be used in running shoes to give it superpowers. Off with the countdown (it’s exhausting to give up the fascination with space) and let’s see why shoes equipped with carbon fiber midsoles bring benefits to runners.

What happens when we run

As we run, our feet discharge an amount of energy to the ground that is roughly equal to 3 times our body weight. A significant drain on resources. Depending on the terrain we move over, how fast and responsive we are, the amount of energy that is returned to us from contact with the ground changes. Think about how much more tiring it is to run on sand, which absorbs all our load, than on more elastic terrain. Even just asphalt, seemingly hostile, returns better thrust.

The purpose of the carbon fiber plates built into some footwear is precisely to capture as much energy as possible during the stance and flex phase of the foot and then return it in the form of thrust.

carbon fiber | shoestechnologies
Carbon fiber midsole

The advantages of carbon fiber in the feet

The main advantages of choosing models with carbon fiber midsoles are:

– Lightness
– Sturdiness, strength and durability
– Solid arch support
– Better performance, thanks to the superior responsiveness of the sole
– Prevention of many injuries

According to various estimates, carbon fiber midsole shoes can save about a couple of seconds per mile. For an amateur runner it might not be much, but in a professional race, a difference of a couple of minutes can be decisive for the final result. But I imagine that even the amateur does not disdain improving his or her performance.

What secret carbon fiber hides

It improves the pace, and consequently the economy of the race, by about 4 percent, which is reflected on the performance in an average time saving of about 2 percent: if you run 5 km it means scoring 20 seconds less on the stopwatch, but if you run a marathon it is a good 4,5 minutes stolen from Kronos.

carbon fiber | shoestechnologies
Hoka Rocket X 2

Tests conducted on athletes wearing the super-powered shoes showed that ground contact time, stride length, plantar flexion velocity and vertical swing of the center of gravity were significantly different from standard shoes.

In practice, the addition of carbon fiber plates to the midsole alters the dynamics of the foot and ankle joint with repercussions on calf dynamics-a combined action that reduces the energy cost of running by requiring less work and, therefore, less oxygen.

The carbon fiber plate increases the flexural rigidity of the shoe and shifts the runner’s center of pressure toward the forefoot rather than the heel resulting, therefore, in a more powerful thrust with less strain on the calf.

Finally, the rigid plate acts by constraining the metatarsophalangeal joint and prevents energy from being wasted with unnecessary flexion when pressing on the ground. Because less energy is wasted, more energy can be harnessed to achieve propulsive forces.

To summarize: the carbon fiber plate optimizes the musculoskeletal system, minimizes energy loss, and maximizes energy return.

Does it only work for running?

So far, we have focused only on running enthusiasts. A somewhat misleading approach, but helpful in better understanding the benefits of the technology. Carbon fiber midsoles are also great when applied to other sports or, even, to long, intensive walks. The energy return benefits everyone, even field hockey players, just to name a sport you wouldn’t think of.

carbon fiber | shoestechnologies
Anta Klay Thompson KT6

But will there also be some cons?

Of course, no one is perfect, and carbon ‘added’ shoes are not the panacea for all ills. They also lend themselves to some criticism.

In addition to usually being more expensive than regular running shoes, they also have less durability. For this reason, they are often intended only for high-speed training and racing.

It should also be kept in mind that not all models of shoes with carbon midsoles are allowed for every race or distance.

In some cases, because of their structure, the shoes can also cause injury rather than protect. The carbon plate, in fact, is a rigid material, so the shoe does not flex as well as it could, increasing the load on the foot, ankle and calf. Should the wearer experience any weakness in these areas, he or she could experience excessive strain and subsequent injury.

Who invented “carbon shoes”

Let’s close with a curiosity. Who was the first to think of putting a carbon plate into a shoe?

carbon fiber | shoestechnologies
Eliud Kipchoge during the Vienna Marathon in 2019

It is as always difficult to attribute authorship in these cases. By acclamation we tend to attribute the carbon shoe record to Nike, thanks to the feat of Eliud Kipchoge who ran the Vienna Marathon in 2019 breaking the 2-hour barrier. It was then that the Vaporfly, the model of shoe worn by Kipchoge, was made public, the result of Breaking2 research that aimed precisely at optimizing every aspect of a marathon runner to push himself beyond the limit.

But, in fact, shoes equipped with a carbon fiber plate in the midsole had existed since the early years of the new millennium, only they managed to ensure an improvement in running economy of only 1 percent, while the Vaporfly outperformed them by reaching 4 percent.

carbon fiber | shoestechnologies
Nike Vaporfly carbon fiber

And here is the curiosity: the researchers of the swoosh had the ingenious idea to raise the thickness of the sole using a special and very light foam (it was obviously important not to increase the weight of the model) thus going to create the space in which to place a curved carbon fiber plate, able to ensure a greater and more effective return of energy than traditional solutions.

Brilliant finding for brilliant shoes!

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