Adidas Adizero Prime X3 STRUNG review

We recommend the Adidas Adizero Prime X3 STRUNG for:

• Runners with plenty of room in the budget who want a shoe loaded with next-level foam and cutting-edge tech.
• Adidas fans looking for the brand’s top-tier innovation all wrapped into one model.
• Those chasing a maximalist shoe with sky-high shock absorption and energetic bounce.
• Loyalists of the Prime X who felt the second version lost its spark. Well, this one brings back a bit of v1's magic, but with a calmer, more stable ride.

We think the Prime X3 STRUNG falls short as a race-day option. We proved in the lab that most carbon-plated supershoes like the Adidas Adizero Adios Pro 4 or Hoka Cielo X1 2.0 offer similar shock absorption in a lighter, more race-ready build.

Additionally, we believe that even as a high-tech supertrainer, the price tag will be too high for most. With other options like the Saucony Endorphin Trainer or the New Balance FuelCell SuperComp Trainer v3 delivering similar performance at a much lower cost, the Prime X3 feels like a niche pick that only makes sense if price isn't a concern at all.

The previous generation was already ultra-cushioned with 148 SA, but Adidas raised the bar and made it even better. We tested it in the lab and found an astounding shock absorption of 160 SA in the heel, an incredible upgrade. 

Up front it’s less impressive at 125 SA, but still handles any long run with ease and it's fully ready to eat mile after mile.

With a monster-sized midsole built entirely from Lightstrike Pro (in 3 different formulations) we expected excellent energy return, and we weren’t wrong. 

We tested it under the ASTM F1976 standard and got 73.7% in the heel and 76.7% in the forefoot, both better than version 2. This result also places it among the top-tier supershoes on the market, offering a turbo-loaded ride that feels amazing at faster paces. However, if you were hoping for this shoe to shatter our lab record, it fell slightly short.

Adidas engraved the midsole with "50 mm" and we can't blame them, as that number was part of their marketing about the original Prime X being the “illegal supershoe.” But the brand has since shifted toward a premium-supertrainer role while keeping the same towering stack.

In our lab, we measured 48.1 mm, which comes remarkably close to Adidas' claim and ranks this model among the top maximalist shoes we've encountered after testing hundreds of them.

The forefoot is also massive at 35.1 mm, basically equivalent to the heel height of many daily trainers. Sounds wild, right?

It ensures that forefoot strikers won’t feel the ground at all, which can be either a dream or a drawback depending on your preferences.

Adidas claims a 7 mm drop, but that can't be based on World Athletics’ official measuring points. We measured 13.0 mm (almost double!) though there’s a trick behind it.

The PX3S features a dramatic rocker, and if you measure the forefoot stack slightly farther back from the official point, the drop becomes much more moderate. That's likely what Adidas did, and we’d also say it feels closer to an 8–10 mm drop—though that depends heavily on your footstrike.

The midsole of the Adidas Adizero Prime X3 STRUNG is a bit complicated, but we’ll make it easy for you.

It includes:

• A top layer of the new Lightstrike Pro made from A-TPU foam, first seen in the Adios Pro 4.
• A middle layer of the same ultra-bouncy A-TPU, sandwiched between a carbon plate and the Energy Rods 2.0.
• A small piece of (surprise!) softer Lightstrike Pro that sits just below the heel to soften every landing.
• A bottom layer of the older Lightstrike Pro crafted from TPEE, just like in the Adios Pro 3.

The full-length bottom layer isn't very soft at 19.5 HA, but that was expected. Basically, it adds durability and stability without killing the mega-bouncy ride that the Prime X is known for.

The top layer near the foot and the one between the stiffening elements came in at just 14.0 HA. And this ultra-soft foam is the reason why the ride feels noticeably smoother compared to its predecessor.

As for energy return, it’s just explosive, as we proved before. And the design? Totally one-of-a-kind. We confirmed here that Adidas is using the Prime X3 STRUNG as a flashy, tech-loaded showcase for their most cutting-edge innovations. Unfortunately for all of us, that comes with a whooping price tag too!

Adidas designers knew right away that building a shoe like the Prime X3 without a giant rocker was a not a good idea—its skyscraper-high stack and steel-like stiffness demand it. Therefore, you get a super-curved forefoot that helps push turnover forward.

Heel strikers also benefit from that signature rolling motion. We tested it during tempo efforts and noticed that the shoe now feels a touch more forgiving than before, with the rocker starting earlier and transitioning more gradually. In other words—it’s a superb set-and-forget shoe for marathon paces and long intervals, like switching on cruise control in a high-performance luxury sedan.

One of the biggest changes in the Prime X3 STRUNG compared to its predecessor is the switch to a single plate instead of two. Interestingly, we found that the plate has a hollowed-out center to help reduce weight.

Some were surprised to see the plate on top and the Energy Rods 2.0 underneath, but it makes sense—placing the plate above helps compress the foam more effectively and boosts energy return.

As we just mentioned, the PX3S uses full-length Energy Rods 2.0 like those found in the Adios Pro series. Positioned beneath the plate and the Lightstrike Pro puck, they add serious front-end stiffness to the ride.

With STRUNG uppers, the fit is always unpredictable, as Adidas keeps changing things and often pushes extremes with this tech. That’s why we were excited to test it using our unique gel mold method.

We discovered a roomy fit! It’s clearly better than previous generations for wide-footed runners, jumping from the PX2S’s 93.7 mm to an impressive 97.8 mm in our lab measurement.

The toebox narrows like in most shoes at 73.2 mm. While it’s not as spacious as the midfoot, it’s still roomy enough to handle 2-hour-plus long runs for the majority of runners.

Where the upper feels less generous is in toebox height at only 25.4 mm. We think that Adidas clearly aimed for a race-inspired fit to stay true to the Adizero name.

We’re not totally against it, as it offers a secure, locked-in feel with some benefits, but runners who dislike toe pressure might prefer earlier versions or simply another supertrainer.

The outsole of the Adidas Prime X3 STRUNG features two distinct rubber compounds. In the heel, there's a cream-colored section made of LIGHTTRAXXION rubber. The forefoot uses a small piece of Continental rubber in a teal tone, with two other zones made from LIGHTTRAXXION too.

Strategically placed cutouts expose the midsole foam to reduce weight, especially under the arch and between the rear and forefoot zones. And a small midfoot cavity reveals the Energy Rods 2.0 too.

With a carbon plate, full-length Energy Rods 2.0, and nearly 50 mm of foam, the Prime X3 STRUNG stands as the stiffest running shoe we've ever tested in the lab... at least until something even wilder shows up or Adidas releases version 4 in 2027. It clocked an insane 38.5N in our 30-degree bend test!

We were quite critical when discussing the weight of the Prime X2 STRUNG, which climbed to 10.8 oz or 305g from the (surprisingly) lightweight first generation. Version 2 felt undeniably bottom-heavy and lacked the nimble feel needed for quick transitions at faster paces.

Adidas managed to trim it slightly to 10.3 oz or 291g. While that’s a modest win and feels better than before, we still think the shoe feels overly bulky for its price.

The STRUNG upper is built with data-driven threads laid down by robotic precision, creating a lightweight and seamless fabric that adapts to foot movement while offering zoned support for added stability. It looks pretty super-cool and futuristic, but how does it breathe?

We found breathability to be solid, scoring 4/5, which makes the Prime X3 suitable year-round. That’s impressive given the upper initially looks less ventilated than it really is.

When we moved the STRUNG upper over our light, we clearly saw how Adidas engineered it with pinpoint precision, leaving small ventilation gaps throughout the design.

Under the microscope, this upper looks totally unique—nothing like the mesh or knit constructions we’ve tested before. 

Our close-up reveals a dense, interlaced web of threads, each placed with intention to improve structure, movement, or airflow.

As expected for an Adizero model, there are no plush foam pads or extra comfort elements in the upper. It still sticks to a performance-first, weight-saving design.

The adidas Adizero Prime X3 STRUNG is a neutral shoe that feels more stable than version 1, but slightly less than version 2 due to its softer midsole.

We found that the heel and midfoot provide minimal support because of the aggressive, narrow design. Up front, the broad forefoot promotes a secure toe-off, and it works very well for midfoot and forefoot strikers.

Can you use it if you have stability needs? We don’t recommend it. Even with its extreme stiffness, it has almost 50 mm of stack height and lacks proper support. A more sensible (and way cheaper) supertrainer for mild pronation would be something like the ASICS Superblast 2.

Our scale for torsional rigidity goes from 1 to 5, but with this shoe, we honestly wish we had a 6 or even a 7. The amount of built-in stiffness is ridiculous.

It sharply contrasts with the heel counter, which offers zero structure and scored just 1/5 in our lab test. That’s another big reason this shoe isn’t exactly built for stability, and it's the price to pay for having the amazing STRUNG upper.

Those landing in the front of the shoe will feel it impressively secure, as the forefoot is wide as a hippo doing yoga.

We measured a jaw-dropping 124.3 mm, an ultra-wide platform that gives forefoot strikers a stable and controlled ride.

However, the midfoot and heel are much narrower, with the latter measuring just 84.6 mm. That’s no surprise to us as Adizero shoes are always shaped this way, and for weight-saving reasons, a blocky, rectangular platform was never an option in the Prime X3 STRUNG.

The STRUNG upper is a masterpiece of engineering, and we absolutely love it. It’s lightweight, visually striking, breathable, and impressively durable.

Our Dremel test barely left a mark, so we gave the Prime X3 a perfect 5/5 score.

The heel padding performs well too, earning a solid 4/5 and giving us zero doubts about its long-term durability. After all, no one wants a $300 shoe with an upper that falls apart after a dozen runs.

The LIGHTTRAXXION compound on the Prime X3 didn’t perform as well as expected against the Dremel. We measured 1.9 mm of wear in our test, which makes us think the legendary durability seen in versions 1 and 2 is now history.

The outsole thickness comes in at just 1.8 mm, which isn’t exactly generous, but it makes perfect sense. This shoe belongs to the Adizero racing family and is already weighty, so a lean rubber layer was fully expected.

The insole is paper-thin too at only 2.7 mm, which was clearly intentional to maximize the feel of Lightstrike Pro foam underfoot. From our perspective, it’s a smart move by Adidas.

One of the best parts of using only premium foams and ditching EVA is how they handle cold temperatures. We discovered that after a 20-minute freezer nap, the Prime X3 lost just 11% of its softness.

The insole is fully removable, though keep in mind it’s very thin—so finding a replacement won’t be easy. You’d also lose the perforated design that helps improve airflow and overall ventilation.

Like all other STRUNG shoes, there are no reflective elements whatsoever.

The stretchy, knit-based tongue remains thin just like in previous Prime X models. We’re fine with that, but as with any tongue lacking a foam pad, be cautious when tightening the laces to avoid pressure points on the top of the foot.

We also discovered that the lacing system of the Adizero Prime X3 STRUNG features loop eyelets integrated into the STRUNG upper, strategically placed to apply tension where it matters most.

The laces thread through reinforced textile loops, replacing traditional punched holes or stitched eyelets for a more premium look and feel.

But unfortunately, Adidas delivered again simple-and-flat laces. With more brands moving to grip-enhancing, textured designs—like the ones in the Nike Alphafly 3—we can’t understand why Adidas doesn’t offer them, at least as a spare in the box like PUMA does now in certain supershoes. For a shoe priced at $300, we probably deserve that added detail.

The tongue of the Prime X STRUNG series tends to divide opinions. Some runners preferred the standard tongue from v1 (not the plasticky non-STRUNG one that was terrible to everyone) while others favored the sock-like design of version 2.

We found that Adidas stuck with the latter, offering a snug, sock-like fit once again. It eliminates tongue shifting, but the wraparound feel might be too invasive for some.

The price of the Prime X 3 STRUNG doesn’t divide opinions and we all agree it’s seriously expensive. It ranks among the priciest running shoes out there, and considering it’s likely not your best racing option, it’s hard to justify.

But if your wallet’s feeling generous and you seek the ultimate tech in running shoes, then why not?

Adidas has scrapped the iconic heel tab we loved in past versions, and we think this updated design lacks the same visual punch.