Runners are often looking for an “edge”—something that will help them run faster or longer with less effort.
Another avenue for performance improvements is through innovations in technology, namely by improving running shoes. The lighter the shoe, for instance, the less energy cost is associated with running at a given speed.
Carbon fiber running shoes are one of the latest innovations in training shoes. These shoes have a carbon fiber plate in the midsole of the running shoe and are boasted to improve running economy by at least 4%,
However, because these carbon fiber running shoes come with quite a hefty price tag, many runners are wondering if they’re worth the hype or should be reserved for the upper echelon of runners vying to break records.
In this guide, we will look at the science behind carbon fiber running shoes and whether they’re worth it.
In this guide, we will cover:
- What Are Carbon Fiber Running Shoes?
- History of Carbon Fiber Running Shoes
- Do Carbon Fiber Running Shoes Make You Faster?
- How Do Carbon Fiber Running Shoes Improve Running Economy?
Let’s get started!
What Are Carbon Fiber Running Shoes?
Carbon fiber running shoes refer to running shoes that have a thin carbon fiber plate embedded in the midsole of the running shoe.
The carbon fiber plate is surrounded by EVA foam, which is said to augment energy return.
History of Carbon Fiber Running Shoes
One of the key components of this experiment was crafting the fastest running shoes.
And, while the three runners designated for the project, due to the belief that they had the best shot of breaking the seemingly impossible barrier, toiled away with their training, Nike shoe designers got to work coming up with the most efficient running shoe.
On May 6th, 2017, in Monza, Italy, when Eliud Kipchoge nearly broke the 2:00 barrier for a full marathon, he was wearing prototypes of the now infamous Nike Vaporfly shoes.
What was special about these shoes? They had a thin carbon fiber plate in the midsole.
When Kipchoge eventually managed to run the incredible time of 1:59:40 in Vienna, Austria, on October 12, 2019, the Nike Vaporfly was released publicly for its worldwide debut.
Since then, nearly every major running shoe company has a carbon fiber running shoe (a shoe with a carbon fiber plate in the midsole) in its lineup.
Interestingly, though we tend to think of the Nike Breaking2 Project and the Nike Vaporfly as the genesis of carbon fiber running shoes, the concept of adding carbon fiber plates to the midsole of athletic shoes actually dates back to the early 2000s when research demonstrated that doing so increased the longitudinal bending stiffness of the shoe.
This made the shoe harder to bend, which resulted in a higher vertical jumping height.
Several years later, it was observed that up to a certain point, stiffer running shoes could also improve running economy, but this was long before the Breaking2 Project.
Do Carbon Fiber Running Shoes Make You Faster?
An article in Sports Medicine from January 2021 noted that at that time, every single women’s and men’s world record from 5 km to the marathon had been broken since the introduction of carbon fiber running shoes in 2016 by athletes wearing running shoes with carbon fiber plates.
Although this may not still be true a year and a half later, the authors argue that these incremental performance improvements are indeed a product of the technological advancement in running shoe technology—namely the carbon fiber plates—rather than due to actual physiological gains from changes in training methodology.
Carbon fiber plates in running shoes increase the elastic properties of the shoe, which reduces the energy cost of running.
For example, the Nike Vaporfly was found to increase running economy by more than 4%.
Even independent studies have confirmed that this rather seminal carbon fiber running shoe indeed improves running economy by 3-4.2% over standard track spikes, depending on the particular head-to-head shoe comparison.
For example, the Nike Vaporfly improved running economy by 4.2 % compared with the Adidas Adizero Adios 3, and still by 2.9% when matched in weight with the Adidas Adizero Adios 3.
Another study also demonstrated more than a 4% increase in running economy when wearing carbon fiber running shoes.
Practically, this improvement is said to correspond to at least a 2% improvement in performance time.
While this may not sound like much, it can actually be pretty significant.
Running Level has data for the average race finish times across all ages and genders for different distances. If we take those times and then apply a 2% improvement in finish time reflected by theoretically wearing carbon fiber running shoes, we see the following changes:
|Distance||Average Finish Time||Time Savings With 2% Improvement||Finish Time With a 2% Improvement|
How Do Carbon Fiber Running Shoes Improve Running Economy?
So, how exactly does adding a carbon fiber plate to running shoes improve running economy?
Running economy is essentially a measure of how efficiently you can run at a given submaximal pace.
In other words, how little your oxygen consumption needs to be to sustain your submaximal workload.
Studies have demonstrated that running in shoes with a carbon fiber plate alters running mechanics, thereby improving running economy.
For example, one study found that ground contact time, stride length, plantar flexion velocity, and center of mass vertical oscillation were significantly different when wearing carbon fiber running shoes compared to standard trainers.
It’s thought that adding carbon fiber plates to the midsole alters the metatarsophalangeal- and ankle-joint dynamics—particularly the dynamics of the plantar flexor muscles like the gastrocnemius and the soleus.
By changing the dynamics of your calves, the carbon fiber plates lower the energy cost of running by requiring less work and, thus, less oxygen while you run relative to running in regular running shoes.
Studies show that this is because the carbon fiber plate increases the running shoe’s 3-point bending stiffness and usually shifts the runner’s center of pressure towards the forefoot rather than the heel or midfoot.
Together, these altered biomechanics increase the lever (moment arm) of the foot from the ankle joint.
When the foot acts as a longer lever, you get a more powerful push-off while simultaneously requiring less of a stretch from the calf muscles (gastrocnemius and soleus).
When these muscles don’t have to generate force from a fully extended position—but rather are within more of their optimal range—they can generate more force because they’re in a biomechanically optimal position.
Moreover, the plantar flexor muscles are able to generate force much faster, which can give you more propulsive force.
Another way that adding the carbon fiber plate to the midsole improves running economy is because the stiff plate acts to limit the metatarsophalangeal (MTPJ) joint, primarily at the big toe.
This causes a reduction in “negative work,” meaning that it saves energy from being wasted by flexing unnecessarily when you press into the ground for the toe-off part of your stride.
Because less energy is getting wasted, more potential energy from the joint can be harnessed into propulsive forces.
The Nike Vaporfly wasn’t the first running shoe with a carbon fiber plate, but it was the first that was significantly more effective at improving running economy.
While the previous carbon fiber running shoes were able to improve running economy by about 1%, the Nike Vaporfly was found to improve running economy by 4%.
The innovations of Nike Vaporfly included the use of an extremely lightweight PEBAX foam for the midsole, which made it possible for Nike to significantly increase the stack height of the shoe without increasing the weight.
Note that stack height refers to how high the shoe is off the ground, so it’s essentially an indication of how much material is between your foot and the ground.
With a high stack height from the super thick midsole, Nike had room to add a curved carbon fiber plate rather than a flat one, which further increases the effectiveness of the plate by creating a see-saw effect from heel contact to toe-off.
Coupled with the energy return from the thicker foam, the see-saw effect of the curved carbon fiber plate makes the shoe even more effective at providing energy return.
In a nutshell, running shoes with carbon fiber plates reduce the mechanical energy needed to run, thus improving running economy and running performance.
The energy savings are due to three main effects of the carbon fiber plate:
- The carbon fiber plate optimizes the musculoskeletal system.
- The carbon fiber plate maximizes energy return in your stride.
- The carbon fiber plate minimizes the energy lost.
Ultimately, running in shoes with a carbon fiber plate does seem to improve running economy to some degree, depending on your speed and particular gait.
You also have to have sufficient calf strength to handle the longer effective lever arm induced by the carbon fiber plate. Otherwise, you won’t be able to capitalize on the benefits.
It’s also important to note that not all studies with carbon fiber shoes have necessarily demonstrated unequivocal improvements in running economy or performance.
One study found that running shoes with carbon fiber plates did not affect muscle activity in the soleus or calf, nor did these shoes improve running economy compared to traditional running shoes.
Another study comparing seven different carbon fiber running shoes from top running brands found that some of the shoes were not significantly better than traditional running shoes.
Only the Nike Alphafly and the Asics Metaspeed Sky were as effective at improving running economy as the Nike Vaporfly 2.
So, whether you drop the extra dough on carbon fiber running shoes is entirely up to you, but it may help you get the PR you’re chasing.
When buying running shoes, there are a number of important factors to consider to ensure you are choosing the best ones for you. Check out our running shoe guide to pick out your next perfect pair.