Nike React Infinity Run Is Stability Made Exciting

CONS:

• Heel cup too wide for some
• Pricey

So the shoe is soft yet responsive underfoot, which suits most types of on-road runs. Up top, a snug-fitting Flyknit Loft upper keeps your foot locked in place. “I loved the knit bootie construction,” said one tester. “It almost molded to my foot.” The material doesn’t stretch much, which is good for stability, although some wide-footed testers found it constricting. Minor gripes: Flyknit Loft breathes well but provides little cold- and wet-weather protection, and the ankle collar irritates bare skin—easy fix: wear crew socks. It’s worth it for the dynamic ride, and running on a hunk of bouncy React foam is good fun, too.

Soft, Stable Midsole

The shoe’s rocker-shaped React foam midsole has 24 percent more foam than its predecessor, the Epic React 2, and Nike minimized the material between you and the foam using a thin sockliner and no strobel board. So not only is there a lot of material beneath your foot—the men’s and women’s shoes have heel thicknesses of 33mm and 31mm, respectively, solidly in Hoka territory—but most of it is React foam. The midsole tested “very soft” in mechanical impact testing at the Runner’s World Shoe Lab, and it feels that way, as if there’s no bottom to the cushioning when you touch down.

Sometimes, the numbers betray a shoe’s actual behavior on a run. The Infinity Run scored average-to-low for energy return, consistent with other shoes with React foam midsoles like the Zoom Fly 3, yet it feels energetic. The midsole’s thick heel and rocker shape ease the strain as you roll through your stride, a process accelerated by the apparent “ramp” and high arch in the shoe’s midfoot.

Our testers generally loved the React foam midsole for its immediate shock absorption and progressive support. “I may not have felt like I put on the most springy shoes,” said one tester. “But the cushioning offers relief from the pounding of the pavement without the worry of turning your ankles.” Others described the cushioning as “firm but shock absorbing,” a testament to React’s ability to absorb impact forces while maintaining stability.

The Infinity Run isn’t explicitly a “stability shoe” in the classical sense, but it does have stability features that feel a bit more intuitive than the traditional approach. Eschewing a medial post, Nike went with a high arch and used a horseshoe-shaped guide rail on the rear of each shoe. The rails, like we’ve seen on shoes like the Brooks Adrenaline, are designed to help overpronators maintain a neutral foot orientation while not encumbering neutral runners. The flared-out forefoot foam adds to the planted feeling. “The wide base made this shoe feel very stable,” one tester said. “I felt like I could move quickly side to side and even do an agility workout in them because of how light and stable they are.”

Snug, Secure Upper

The shoe uses Nike’s new version of Flyknit, which is stronger and less stretchy than the previous iteration. Integrated into the one-piece upper, the tongue uses a stretchier knit to accommodate high insteps. “I really love that even though the collar and, especially, the tongue have stretch to them, they don’t weaken the integrity of the fit over the course of a run,” said one tester.

The toe box is reasonably wide, although it was too cramped for one of our testers with wide feet. The midfoot fit is a bit narrower. The heel cup is well-contoured to keep some runners’ heels planted, although others, myself included, felt it was too wide and allowed the rearfoot to slide about within the shoe.

Like old Flyknit, new Flyknit breathes well but doesn’t provide much protection from cold wind or rain. During winter testing, the Infinity Run did little to block the sub-freezing air, even when I wore thick wool socks. But the new material doesn’t seem to absorb as much water as old Flyknit, so that’s a plus.

More Rubber

Despite the shoe’s foam-first design, there’s a surprising amount of rubber on the sole, especially compared to the sparse placements on the Epic React Flyknit 2. I appreciated the generous forefoot rubber when pushing off at tempo speeds; there’s something about rubber that feels more direct than pushing off against foam. Our testers liked the shoe’s traction, although a couple noted that the outsole indentations held dirt and debris after outdoor runs ended.

Don’t Buy on Injury Protection

To sell you on the possibility that these shoes reduce injury, Nike commissioned a study: Start with 226 men and women and shod them in either the Infinity Run or the Air Zoom Structure 22, the brand’s long-running stability shoe that, until recently, would’ve been a go-to recommendation for an injured runner. After 12 weeks, Nike says, runners wearing the Infinity Run saw a 52-percent lower injury rate than those in the Structure 22.

Impressive, but context is important. First off, it’s a small sample, and we don’t know anything about the runners included. Secondly, 12 weeks is hardly enough time to evaluate how a shoe or type of shoe will affect you in the long term. Research indicates thatmaximal shoes make runners land harder and pronate more than traditional, neutral shoes, habits that could lead to injury down the line. Nike isn’t calling the Infinity Run maximal, but the shoe’s high stack height says otherwise.

Lastly, the comparison to the Structure 22 seems curious—it’s a shoe designed to alter the motion of your foot, so it would follow that changing to a stability shoe (and running in it exclusively) might lead to injury. As traditional stability shoes like the Structure 22 die out, the choice seems odd—why not test the new shoe against a more popular trainer like the Pegasus?

The Bottom Line

We’re skeptical of the research, but we’d be skeptical of any brand saying a shoe can prevent injuries. Shoe materials and advancements have improved footwear for decades, yet the injury rate hasn’t budged. Most of that is self-inflicted: We’re pretty good at hurting ourselves by overtraining, muscle imbalances, lack of strength, and myriad factors beyond our control. So forget about injury prevention and consider the React Infinity Run because outside of the marketing, it’s an energetic, exciting shoe.

What Our Testers Said

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Tester: Tracy M., tester since 2019
Gait: Overpronator | Footstrike: Midfoot

“I had reservations about the Nike React Infinity Run when I first tried it on—I’ve never worn a running shoe with that much cushioning before. But that ended up being my favourite feature. The extra cushioning provided a ton of stability. I have a pinched nerve in my lumbar spine that sometimes makes my left leg ache after running, but it seemed to ache a bit less after running in these shoes. Maybe that was the cushioning or maybe that was because they changed my posture or gait. I found myself leaning forward slightly and didn’t seem to pronate as much—whatever the reason, I’m not complaining. I didn’t do any races, just regular base runs, mostly on dirt trails. I didn’t really notice any increase in my speed but they were more comfortable that other shoes, so on days when I’d [intended to] go out for a quick 3 or 4 miles, I ended up an extra mile or so.”