Nike ReactX Infinity Run 4: analysis, price, and impressions

The arrival of the new ReactX foam marked the most important change in this Nike daily trainer. Beneath a familiar appearance, the fourth iteration changed the midsole recipe to deliver a softer, bouncier ride than the previous generation, without straying from its approach as a shoe designed for easy running, logging miles, and prioritizing comfort over speed.

The result is a clearly mileage-oriented shoe, with a 9 mm drop, a wide forefoot base, and a very enveloping upper that aims to hold the foot securely. It is not designed for intervals, pace changes, or fast sessions; its natural territory is easy runs, the days when the goal is to add mileage without punishing the legs too much. That is where it fits best and where it makes the most sense.

What really changed in this version

The jump from React to ReactX is the most relevant technical headline. Nike presented this foam as an evolution with greater energy return and a smaller carbon footprint in the midsole. The brand spoke of a 13% increase in energy return versus React and a reduction of at least 43% in the carbon footprint of that component. In practice, the feel underfoot is softer and a bit livelier, although it does not reach the explosive response of the fastest premium foams.

That change did not come alone. The fourth release also felt roomier, especially in the base under the forefoot, and opted for a more robust build. The Flyknit-style upper is thicker, more closed, and more protective than a traditional mesh. That gives it a more luxurious presence and a very noticeable snug feel, but it also limits ventilation, something you notice on warm days or during long sessions under the sun.

The midsole remains the star, with a height of 39 mm at the heel and 30 mm at the forefoot according to the brand’s specs. That geometry creates a generous platform, designed to absorb impact and smooth the transition. It is not a super shoe and does not try to be one; its language is that of a comfortable road car, stable, somewhat heavy, and very planted, not that of a twitchy sports car.

Running feel: soft, stable, and not very nimble

The ride feels soft from the very first step. On the run, the foam feels plush, with a response that encourages easy paces and lets the miles pass without fighting the ground. The outsole rocker helps smooth the transition and gives a continuous rolling sensation, as if the shoe were pushing you forward without harshness.

That behavior has a clear tradeoff: weight. At 316 grams in the men’s lab-tested size, it sits on the heavy side of its category. That is not an outrageous figure for a heavily cushioned shoe, but it is enough to prevent it from feeling light on the stride. When pace rises, that burden becomes noticeable; the shoe asks for patience and performs much better at conversational pace than during demanding pace changes.

The overall feel is similar to a premium comfort shoe that aims to protect more than energize. For pronounced heel strikers, the model works especially well, because the drop and the shape of the whole setup make for a fairly natural transition. Midfoot strikers can use it too, although they may find livelier options if they want a more direct ground feel.

Fit, last shape, and sizing: the most delicate point

Fit is one of the areas that most affects the purchase decision. The hold is comfortable, but the last tends to run short. Both wear tests and technical analysis agree that it fits small and that, in many cases, going half a size up is advisable. The problem is not just length, but also a toe box with limited vertical volume, which can create pressure on the toes over longer runs.

The Flyknit upper helps lock down the midfoot with good firmness, and the collar and tongue padding provide a pleasant, almost homey, wrapped-foot feeling. However, that same thick structure limits airflow. The foot is very protected, yes, but also more enclosed. On a cool outing this may go unnoticed; in summer, not so much.

The interior geometry explains part of those sensations. The internal length measured in the lab was below the average of other comparable models, and the toe box height was low. That means it is not a particularly generous shoe in terms of volume. Anyone with a wide foot, long toes, or a preference for extra room at toe-off should pay close attention to this detail before deciding.

Cushioning and transition: lots of comfort, moderate response

Cushioning is the model’s main selling point. It is not aiming for a hollow soft feel, but for a comfortable ride with some elasticity. In independent testing, heel impact absorption was solid for a daily trainer and energy return landed at a good level, though far from the figures of Nike’s more radical foams. Simply put: it cushions well, rebounds enough, and does not aim to impress with explosiveness.

The difference from the previous generation lies in the softer midsole feel. The new compound feels kinder on repeated landings, with easier compression under load. That translates into less harshness when the legs are already tired and the body just wants to finish the run with dignity. For runs between 6 and 15 kilometers, that character makes a lot of sense.

The heel-to-toe transition is supported by the wide base. The forefoot, in particular, offers a generous platform that helps control lateral wobble. It is not a pure stability shoe, but it is a neutral shoe with a very calm ride. That is appreciated on regular surfaces and during aerobic base work, where the important thing is that the foot feels supported, not pushed around by gimmicks.

Grip, outsole, and durability: more durable than dazzling

The outsole is built to last. Nike has reinforced the rubber with a layout of small lugs and generous full-length rubber coverage. That strategy usually favors wear resistance, and it works well here. The shoe handles the miles nicely, both on the outer heel and in the repeated-load area of the forefoot.

The grip, however, sits in the decent but not outstanding range. On dry asphalt it performs without surprises; in wet conditions it offers reasonable security, though it does not provide the confidence of a outsole designed specifically for rain. It is one of those shoes that behaves reliably on most days, but does not win you over with traction when the ground gets tricky.

The durability of the upper also stands out. The thick fabric resists abrasion well, and the heel padding retains a good shape with use. That is the price of robustness: more protection and longer life, but less freshness and a bit more weight. In this model, Nike seems to have clearly chosen the path of durability and ongoing comfort over lightness at any cost.

Who this shoe makes sense for

It suits well anyone who wants a daily shoe for easy runs. Runners who go out at a comfortable pace, prioritize cushioning, and do not need a snappy response will find a reliable ally here. It can also work well for those returning to running cautiously and looking for a gentle, protective, and predictable feel underfoot.

Another logical profile is the medium-to-heavier runner looking for a stable base without entering the realm of corrective stability. The platform width, soft foam, and well-padded heel create a reasonable sense of control without turning the shoe into a rigid structure. For recovery runs or the days after a long run, it can make a lot of sense.

It is not the best option for anyone wanting lightness or pace. On faster sessions, the whole package feels less nimble than desirable. It is also not the most suitable for very hot climates, because the closed upper traps quite a bit of heat. If speed is the priority, there are lighter alternatives; if sustained comfort is the priority, this model moves up the list.

Comparison with other Nike training shoes

Within Nike’s lineup, this model occupies a very specific position. It does not compete with plated speed shoes or the brand’s more responsive models. Its role is closer to that of a comfortable cruiser with an extra layer of protection. Compared with other daily trainers, its identity rests on foam volume, enveloping support, and a more substantial than sporty aesthetic in the classic sense.

The difference with a Pegasus is clear: the Pegasus usually offers a more balanced feel between lightness and versatility, while this one leans more toward plush comfort. Compared with an Invincible, the Achilles’ heel of the Infinity is the weight and a less lively response. The comparison makes sense because both aim at comfort, but they do it from different places: one with more bounce, the other with more containment and a more grounded base.

Runners who value soft stability may prefer this option if they want a planted ride without marked corrections. At that point, the wide forefoot and the overall profile help make the experience feel more secure than fun. And for some runners, that is precisely what they want in a long-distance shoe: one that disappears from their mind while the miles go by.

Price, availability, and real value

Its launch price has hovered around 160–170 euros, a figure now common in well-cushioned training shoes. It is not a cheap buy, and that is exactly why it is worth looking closely at what it offers in return. Here, the value lies in comfort, durability, and the premium feel of the whole package, not in speed or extreme versatility.

The problem is that this price range puts it up against very serious rivals both inside and outside Nike. When a shoe gets close to that level, runners compare not only foam and weight, but also interior space, response, ventilation, and real-world versatility. In that league, the Infinity RN 4 wins on premium feel and loses some ground because of its mass and a fit that is not equally kind to everyone.

Its value depends heavily on how it will be used. If it is going to be a shoe for easy runs, leg recovery, and adding miles without overthinking it, the price makes sense. If the idea is to use it for everything, including moderate paces and livelier sessions, the outlay is less convincing, because there are more balanced options on the market.

What the lab says and what the runner feels

The numbers help organize the sensations. Cushioning is high but not extreme, energy return is good without being outstanding, flexibility sits in the middle range, and the weight puts it clearly above the average for its segment. That combination outlines a very recognizable shoe: comfortable, robust, full of personality, and not fond of haste.

On foot, that data translates into a fairly coherent experience. The soft foam reduces impact harshness, the upper holds securely, and the outsole behaves in a civilized manner. There are no big surprises, and that can be a virtue. Some shoes stand out because of one number; others, like this one, win you over through the sum of small details that you notice after several kilometers.

The less friendly side is also clearly defined: modest ventilation, slightly short sizing, high weight, and a response that does not invite acceleration. These are acceptable tradeoffs for anyone who values comfort above all else, but they are worth keeping in mind. In running, as in almost everything, the best product is not the one that boasts the most, but the one that best matches what the runner actually does.

A shoe with its own identity in a very competitive market

The fourth version of the model makes it clear that Nike was not aiming for an aesthetic or technical revolution, but rather a refinement of sensations within an already recognizable line. The switch to ReactX brings a more pleasant feel, the outsole gains durability, and the upper reinforces the sense of quality. All of that builds a long-distance shoe with a more mature than ambitious profile.

Its biggest virtue is also its biggest limitation: it specializes in comfort. That makes it very interesting for a specific segment of runners and less appealing to those who want one shoe for everything. It is a rotation shoe, not a Swiss Army knife. And in a market saturated with options, that definition matters more than any slogan.

The Nike ReactX Infinity Run 4 is best understood as a companion for easy miles rather than a performance tool. It has cushioning, a wide base, good durability, and a generous padded feel, but it is also heavy, fits a bit snugly, and ventilates poorly. That mix is not perfect, though it is quite coherent. On a day of easy running, where the asphalt feels like a conveyor belt and not a battlefield, that balance makes a lot of sense.

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