Let’s Talk About Shoes
When it comes to running gear, none is more important than your footwear. It is the most used and stressed over component. It carries us every mile. It can mean the difference between a good performance or injury-related drop at a race. So, it’s important to understand the most recent developments in shoe technology.
At the risk of oversimplifying, there are three types of running shoes in the market across all brands: Thermoplastic Polyurethane (TPU) foam shoes, Polyether Block Amide (PEBA) shoes, and PEBA with a carbon fiber plate known as Advanced Footwear Technology (AFT). Each shoe type provides different benefits.
TPU shoes tend to have more cushion to them and last for longer periods before requiring replacement (500 to 800 miles, depending on how well you take care of your shoes).
PEBA shoes are stiffer and lighter than TPU shoes, making them ideal for races. However, they lack the same cushioning as TPU shoes and break down faster, requiring more frequent replacement (Every 300 to 500 miles).
AFT shoes provide all the benefits of stiffer shoes, but with increased running economy potential as the carbon fiber plate enhances propulsion and energy return with each stride. In layman’s terms, the carbon fiber plate creates an extra spring in your step.
A study in 2024 performed at Beihang University, entitled Impact of Footwear Bending Stiffness on Lower-Limb Work Redistribution and Running Economy, found that footwear stiffness significantly improved running economy.
For the study, the scientists took 12 runners and studied their running kinetics wearing two different types of footwear with varying degrees of stiffness (PEBA type shoes and AFT type shoes). What they found was a decreased range of motion and angular velocity in the foot and ankle with AFT shoes, requiring less energy to propel into the next stride of the run.
In essence, AFT shoes, which are stiffer and provide the carbon fiber plate, significantly improves running economy through less energy cost per stride. However, there have been some questions of injury risk with frequent use of AFT shoes.
A study conducted in 2025 at the Anta Sports Science Laboratory in China, entitled Effects of Carbon-Fiber Plate Design on Foot Stress Injury, found that carbon fiber plate shoes increased stress on the plantar fascia and metatarsal in the foot. The study found the thicker the carbon fiber plate, the greater the stress on the foot.
Another study in 2025 conducted at Ningbo University, entitled The Effects of Different Carbon-Fiber Plate Shapes in Shoes on Lower Limb Biomechanics Following Running-Induced Fatigue, found that flat and curved carbon fiber plates increase activation and stress on the Tibialis Anterior (TA). With curved carbon fiber plate shoes, activation and stress was higher than normal on the TA pre-fatigue. On flat carbon fiber plate shoes, activation and stress on the TA was higher than normal on the TA post-fatigue. Both significantly reduces the joint movement of both the hip and knee and appears to rebound at different times on the TA.
So, with all that information at hand, how do we use it? Here is my simple, layman’s suggestion. Take it as you will:
Have a pair of TPU and PEBA shoes for training. Cycle through the TPU and PEBA shoes throughout the week. Use TPU shoes for your easy runs and PEBA shoes for speed workouts and your long runs.
Have a pair of AFT shoes. Use them once per week for a run that simulates your upcoming race. Then, use them on race day. Do not overuse because of the potential injury risk of frequent use.
Understanding your shoes, the material in them, and how to use that material to your benefit can enhance both your training and race performance.