Nike InfinityRN 4 Integrates ReactX Midsole Foam

Last updated on February 16th, 2024

InfinityRN 4 toebox/mudguard

The Nike ReactX InfinityRN 4 is a trainer that offers comfortable cushioning and stability, yet falls short on excitement. The newly designed ReactX midsole doesn't provide significant energy rebound and is best suited for relaxed or recovery runs. This latest iteration has undergone a complete transformation: it is slightly more pliable, offers enhanced comfort, and boasts improved durability, albeit with a slight increase in weight.

If you're a fan of the Infinity Run series, you'll be pleased with this updated version as it no longer features a heel clip, eliminating the noticeable arch. For those seeking an alternative to Nike's Pegasus and Structure series, the InfinityRN 4 presents itself as a viable choice.

If you're in search of a contemporary trainer with ample cushioning and a thrilling, lively feel, then the InifnityRN 4 is not the right fit for you.

In my assessment of the Infinity Run 3, I expressed the urgent necessity for a rejuvenation, as it showcased an identical midsole to its predecessors. Despite its commendable performance, the absence of novelty after three years becomes wearisome. Midsole technologies progress rapidly, rendering them obsolete in no time. That is why Nike revamps the midsoles of popular models such as the Pegasus and Vaporfly every two years.

InfinityRN 4 reactX foam

The initial releases of the Infinity Run were marketed as neutral trainers, but they gave off a stability trainer vibe because of the uncomfortable arch sensation. Upon putting them to the test, I found them more suitable as everyday sneakers for work rather than for running. Personally, I prefer trainers that offer a more cushioned and energetic experience. The Infinity Run, unfortunately, lacked that exciting factor and felt somewhat dull.

Infinity Run's fourth version receives the significant revamp I had been hoping for since last year. It showcases Nike's latest innovation, the never-before-seen ReactX midsole foam. Additionally, both the outsole and upper have undergone a complete redesign.

Nike does not categorize the InfinityRN 4 as a high-cushioned trainer, but it carries a similar price tag. Priced at $160 ($112 after discount for certain color options), it is in direct competition with other high-cushioned trainers such as the Nimbus, Glycerin, Triumph, and New Balance 1080.

The InfinityRN 4 now tips the scales at 11.2 oz (319 g), a full ounce (28 g) heavier than its predecessor. With each passing year, the shoe continues to gain weight. Additionally, the name has been altered to InfinityRN this year, replacing its former moniker - Infinity Run.

InfinityRN 4 heel/outsole

On my initial jog, I embarked on a 17-kilometer recovery route. The pace of my recovery felt ideally matched to the InfinityRN 4. The run had a slightly gentler feel compared to earlier editions, although it still possessed a touch of firmness that seemed somewhat incompatible with a fully cushioned trainer.

ReactX was a letdown for me as it seemed quite similar to the standard React foam: compact and lacking in energy rebound. In comparison to the Infinity Run 3, it did offer a higher level of comfort.

The appearance of the InfinityRN 4's upper brought to mind the Nike Free RN Flyknit 3.0, while its midsole evoked memories of the Under Armour Velociti Wind.

InfinityRN 4 upper

The InfinityRN 4's upper provides a tighter, more secure fit compared to its previous iteration, thanks to a more pliable Flyknit material that offers increased flexibility. Although it has a narrow fit, it remains true to its intended size. The upper molds to the shape of your feet, resulting in an overall heightened level of comfort. However, it does lend a more casual sneaker vibe.

The tongue of the shoe is cushioned and secured in place, remaining stable throughout runs. The foot is securely held in place, even without tying a runner's knot. The heel is supported by an internal counter, providing structure, and the ankles are surrounded by well-padded collar for exceptional comfort.

The upper's tendency to retain heat is my biggest dislike. Additionally, it absorbs a significant amount of perspiration, making it more suitable for cooler environments. Although there is a newly added water-resistant liner in the toe area, I haven't had the opportunity to evaluate its effectiveness in wet conditions.

InfinityRN 4 heel counter

The InfinityRN 4 brings back the heel pull tab that was absent in the Infinity Run 3, although reflective elements are still not included.

The InfinityRN 4 underwent a significant improvement that was of utmost importance: the alteration of the heel clip. In the previous version, the clip extended beneath the arch and resulted in an uncomfortable poking feeling. However, in the InfinityRN 4, they have completely eliminated the clip, making it exceptionally comfortable, particularly for individuals with flat feet.

The InfinityRN 4 falls short in comparison to other highly cushioned trainers when it comes to providing a comfortable ride and efficient energy return. Its sensation can be best described as lacking excitement. This trainer is simple and straightforward, designed solely for the purpose of helping you complete your daily mileage. During a 27 km run, I found it to be slow and outdated in terms of performance.

InfinityRN 4 waffle outsole

I reserve this shoe solely for my relaxed and recuperative runs. It is not designed for speed. Its weight is substantial, and its forefoot offers exceptional flexibility, unlike the MaxRoad 6 and GlideRide 3, which have a curved design to assist in accelerating when necessary.

The InfinityRN 4 caters better to those who strike their heels when running, rather than those who strike the forefoot or midfoot. This is because the shoe promotes heel striking by providing ample cushioning in the rearfoot, while offering significantly less cushioning in the forefoot.

The Nike website's product description for the InfinityRN 4 frequently emphasizes the terms "supportive" and "stability." The shoe features a midsole base that is moderately wide and includes raised edges, providing guidance to your feet during landings and enhancing stability. However, it does not quite fit the definition of a stability trainer. Instead, it has the feel of a neutral trainer.

The addition of a thick layer of waffle rubber across the entire outsole prevents any damage to the midsole foam, resulting in a slight increase in weight.

My pair of InfinityRN 4 shoes show minimal signs of wear on the outsole, and I believe their durability can match that of the Pegasus 40. The improved traction of these shoes is evident due to the raised lugs and the no longer completely flat outsole.

InfinityRN 4 laces

Following my initial experience, I wasn't particularly enthusiastic about engaging in another run with the InfinityRN 4. Despite its complete overhaul, the shoe fails to generate any sense of thrill. The revamped midsole fails to deliver adequate energy rebound and lacks a distinctive running experience. ReactX, the supposedly innovative foam, does not exude the qualities of a modern midsole material, and it would greatly benefit from being softer in composition.

InfinityRN 4 stands out as the superior installment in the series due to its exceptionally comfortable upper and arch support. However, it is disheartening that it has gained an additional ounce in weight. This extra weight gives the impression of a burdensome shoe during runs, as it lacks a noticeable rocker to enhance transitions and overall efficiency.

The InfinityRN 4 is a decent running shoe without any significant drawbacks. However, with a price tag of $160, I cannot suggest it when there are far superior, highly cushioned alternatives available, such as the Skechers MaxRoad 6. The MaxRoad 6 offers greater cushioning, a smoother experience, and significantly higher energy rebound.

The InfinityRN 4 can be seen as Nike's take on the Ultraboost Light, serving as a versatile sneaker suitable for both everyday wear and occasional runs. Similarities between the two include their knitted uppers, sturdy cushioning, and a higher price tag.

  • Price: $160 ($112 after discount for certain colors)
  • Style: DR2665-402 (Nike)
  • Color: Light Armory Blue / Star Blue / Court Blue / Black
  • Usage:
    • daily training
    • recovery runs
  • Constructions & Features:
    • new ReactX foam
    • revamped Flyknit upper and wider toe box
    • made with over 20% recycled content
    • high support / high cushioning / moderate responsiveness
    • water-repellent liner in the toe
    • waffle rubber outsole
    • adjustable and plush Flyknit tongue
    • soft foam collar
    • Weight: 353 g (Men's size 10)
    • heel drop: 9 mm
    • no longer features a heel clip
    • well-padded collar surrounded ankle
    • no reflective elements
InfinityRN 4 quarter/midsole