Through the years, a few running shoe brands have attempted to make runners more efficient and faster with springs built in the heels or embedded in the forefoot of each shoe. Then lab-tested, maximally cushioned and carbon-plated supershoes burst on the scene and led to numerous race victories, world records, and personal best times.

Those shoes have changed the game—offering between 3 to 5 percent energy return improvement—but they’re also very expensive ($225-$300) and aren’t very durable, usually having a viable lifespan of 150 to 250 miles before their fragile midsole foams begin to break down or their energetic high-performance vibe tails off. There’s even a carbon-plated racing sandal coming out on the market soon.

But what if there as a carbon-plated solution that wasn’t part of a disposable pair of shoes that ultimately gets tossed aside when the performance materials begin to wear out?

Can interchangeable carbon-fiber insoles revolutionize running again by allowing runners to enhance the responsiveness of any pair of previously non-plated training shoes?

VKTRY Performance Insoles

VKTRY Performance Insoles ($150) are touted have a spring-loaded design that can help support explosive movements, fast sprints, high jumps, and quick cuts common to a variety of sports, including football, basketball, volleyball, and running. 

For the past month or so, I have been experimenting with VKTRY Performance Insoles in several pairs of road running shoes to try to find out. I received a pair of personalized aerospace-grade carbon-fiber insoles with a spring level based on my sport, gender, age and weight. I have simply pulled out the removable sockliner insoles of my shoes and inserted the VKTRY Performance Insoles. In each shoe trial, my initial run was only 2 miles to make sure the insoles weren’t causing any noticeable gait irregularities, but I later ran as many as 8 miles on subsequent runs.

Here are my initial insights and takeaways.

1. My first reaction is that, yes, VKTRY Performance Insoles seem to increase the responsiveness of many of my training shoes that don’t already have some kind of propulsion plate built into the mix. It’s added some snappiness to softer shoes and helped create a firmer flex pattern in others. So, far, I have found some of the best applications to be in my Mount to Coast R1, Saucony Ride 18, and Hoka Clifton 10 training shoes.  

2. The VKTRY insoles aren’t completely rigid, but instead they flex and recoil with the natural movements of my feet. To that point, the shoes I have put them in have not become completely rigid (like many carbon-plated racing shoes), but instead take on a semi-firm flex pattern that bend and load and unload under the pressure of my flexing foot.

3. I did a modified workout of 4 x 800-meter repeats on three different occasions in which I ran in the same pair of Hoka Clifton 10 shoes, alternating each rep with or without the insoles in the shoes. My goal was to average 3:30 for each interval and record my average heart rate for each one. It was a low-tech, unscientific study of one, but each time I did it, my heart rate was lower on the reps with the VKTRY insoles.

4. Because the size, shape, and interior volume of every shoe is different, the integration of VKTRY insoles is different with each shoe, too. Sometimes I found the insoles slid right into shoes and fit into a shoe perfectly, sometimes they seemed to have a slightly tight fit, while a few others (shoes with low interior volumes) it never really worked out.

5. The modified fit, feel, and ride of shoea with VKTRY insoles varied greatly. Some felt great and provided greater responsiveness at all paces. In some cases, the interior volume of a pair of shoes was compromised and created tight spots in the shoe, especially in medium- to low-volume shoes. 

6. So far I haven’t had any stability issues in any of the shoes I have tested with the VKTRY insoles, although I have felt better running in sub-maximal training shoes. (I have avoided putting the insoles in any shoe that already has any kind of propulsion plate, and I haven’t tried them in trail running shoes yet.)

7. The VKTRY insoles are topped with a soft layer of foam and a mesh fabric that helps disperse moisture, so I haven’t had any issues with a lack of breathability.

I will continue wear-testing these insoles in additional shoes this summer. You can read more about the science and development of the insoles at the VKTRY site and in this document.

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Senior editor Brian Metzler has wear-tested more than 2,500 running shoes and is the author of “Kicksology: The Hype, Science, Culture and Cool of Running Shoes” (2019) and “Trail Running Illustrated” (2019). He has raced just about every distance from 100 meters to 100 miles, but he’s most eager to share stories about his experiences pack burro racing in Colorado.