Saucony Endorphin Trainer review

We believe that the Endorphin Trainer can serve well to:

• Runners who disliked the Saucony Kinvara Pro’s lack of responsiveness.
• Forefoot or midfoot strikers needing a long-run shoe packed with a carbon plate and cutting-edge foam at a reasonable price.
• Saucony fans of the Endorphin line wanting a premium complement to their Endorphin Pro 4 or Endorphin Speed 4 for handling slow runs.

We believe that the Endorphin Trainer struggles a bit as a tempo shoe. Its ultra-firm PWRRUN layer that goes below the plate delivers low energy return and adds too much weight. We definitely think that the Nike Zoom Fly 6 or ASICS Superblast 2 offer a better running experience at faster paces.

Additionally, from our perspective, the narrow, snug-toe fit leaves little room for comfort during long runs for most runners. We think that anyone needing a more accommodating toebox will find the Adidas Adizero EVO SL or New Balance FuelCell SuperComp Trainer v3 to be superior alternatives.

The Endorphin Trainer hit the market as quick as possible to replace the underwhelming Kinvara Pro, and despite its slightly lower stack height, we feel it’s far more of a genuine supertrainer.

Some claim that for a shoe to qualify as a supertrainer, it must exceed 40 mm of stack height—but we think that’s becoming an arbitrary benchmark mainly tied to World Athletics’ racing limits.

In reality, the difference between 38.9 mm and, say, 40.3 mm is almost impossible to feel. We believe that a true supertrainer is more about being a performance-focused trainer packed with a high-rebound foam.

The forefoot also packs top-tier cushioning at 32.0 mm, making the Endorphin Trainer a super-solid choice for long runs.

With its new naming, it's clear that Saucony positions this shoe as the training companion to the Endorphin series, offering extra durability while keeping an ultra-responsive feel underfoot.

This shoe is listed with an 8 mm drop, but we measured 6.9 mm—slightly less, though it feels the same underfoot. It offers a solid geometry that works smoothly for all footstrikes, yet we believe it’s best for midfoot strikers.

Now we’re getting to the most fascinating part of the Endorphin Trainer. While the Kinvara Pro really underwhelmed with its energy return, Saucony aimed to flip the script here.

Like many supertrainers, this shoe features a dual-foam setup, with the premium one closer to the foot. We tested the TPEE-based incrediRUN foam and it shattered our lab record with an ultra-low 5.9 HA softness—an absolutely mind-blowing result.

During our runs, it felt remarkably different from anything else and bounced back with crazy energy!

However, the Endorphin Trainer doesn’t feel that soft when hitting the ground, and there’s a good reason. While most brands blend two foams with similar densities, Saucony went bold and mixed the softest foam we’ve ever tested in the lab with... one of the firmest!

That’s why, in our video, the shoe looks firm—pressing on the secondary layer shows almost no deformation. But underfoot, we experienced a different feel due to the much softer incrediRUN layer. We believe this setup won’t suit everyone, but it’s undeniably unique.

We found that the secondary layer hit 37.8 HA on our durometer, so we confirmed it's firm as concrete. And it's made from PWRRUN, so isn’t new for Saucony fans, but they modified the EVA foam to be ultra-dense here. In our view, maybe too much...

Like PEBA, TPEE basically keeps its softness even in cold temperatures. In the Endorphin Trainer, we measured a minor 3% change after 20 minutes in the freezer. That's a super-impressive result!

In true Saucony fashion, the insole stands out as something special compared to average offerings. We discovered it’s crafted from PWRRUN+ (TPU) foam, delivering an ultra-plush, bouncy feel thanks to its generous 7.2 mm thickness.

Those who love a late-stage rocker—meaning it doesn’t kick in early—will instantly appreciate the Endorphin Trainer, as we discovered it’s one of the most less curved midfoot designs among the supertrainers we tested.

This setup favours runners who dislike an overly-intrusive feel yet crave a highly-energised, snappy toe-off. And, as we said before, we think it's better suited for those who strike the ground with the midfoot or forefoot.

The Endorphin Trainer features a carbon plate, but we discovered it’s a different-than-usual design—covering only 3/4 of the shoe and leaving the heel unplated for softer landings. And despite being a partial-length plate, Saucony considers it part of the Speedroll Technology series.

The Endorphin Trainer midsole feels highly-polarising, and we found the toebox mirrors that bold character. Before taking measurements, we simply tried the shoes on to gain a first impression, instantly realising this wasn’t going to suit every feet out there.

Still, we believe numbers beat feelings, so we went ahead and measured. We crafted a 1:1 gel mould of the toebox using our ultra-precise method and discovered that at 92.3 mm, the widest part of the upper is definitely narrower than the average running shoe.

And for those with wide feet, things get even trickier as we move closer to the tip of the Endorphin Trainer.

In the big toe area, we measured 70.1 mm, which is undeniably a tapered, race-inspired design choice by Saucony.

On the other hand, we were surprised by the impressively high toebox height of the Endorphin Trainer at 28.9 mm.

There’s generous space for upward toe movement, making it a pleasant surprise for runners using this shoe for marathon-prep long runs.

With such a towering platform and a cloud-soft foam layer, we expected some instability. However, we discovered that the ultra-firm PWRRUN layer offsets this with extra support, making it a smart pick for runners with moderate stability needs.

Additionally, we were impressed by how the rigid carbon plate adds midfoot and forefoot stability, while the wide base provides a centred, secure ride.

Packing almost 40 mm of foam and a carbon plate, we knew this was destined to be a super-rigid shoe. However, since the plate stops short of the heel, we thought it might get a 4... but nope, it achieved a clear 5/5.

The heel counter is surprisingly flexible, scoring 2/5. This is quite unusual among supertrainers, though we believe Saucony clearly positions this shoe as less ideal for heel strikers—and this adds yet another subtle reason for that.

The Endorphin Trainer is massive—there’s simply no other way to describe it. When we unboxed the pair, we were genuinely amazed by its ultra-broad shape, making an average daily trainer look almost like a child’s shoe.

In the forefoot, we measured an impressive 121.7 mm width, which aligns more with a stability shoe. This super-wide platform plays a huge role in the grounded-and-secure feel we discovered while testing this model.

The heel is even more impressive when compared to the average shoe, measuring a remarkable 100.1 mm. It adds extra stability for heel strikers—especially important since the plate stops in the midfoot and the heel counter remains ultra-pliable.

Packing such a thick foam layer and a carbon plate running through the midfoot and forefoot, we knew this shoe wasn’t going to be flexible.

We tested it by bending the shoe 30 degrees with our custom machine, and 25.6N confirms it's stiff as a supershoe.

Here in the lab, the Endorphin Trainer kept getting more polarising with every single test—and weight followed the same trend. We discovered that at 10.05 oz or 285g, this is no lightweight supertrainer, leaving us underwhelmed.

It may not feel too heavy during slow or steady long runs, but when we tested it at faster paces, the bulky construction became unmistakably noticeable compared to many competitors on the market.

One of the first things that struck us visually about the Endorphin Trainer was the oversized ventilation holes that clearly signalled sky-high breathability.

To confirm this, we used our smoke machine and discovered that the Endorphin Trainer breathes incredibly well, almost outperforming every other shoe we’ve tested when it comes to battling overheating on hot long runs. It's another 5 out of 5 for this shoe.

We found that the thin mesh material used by Saucony contributes massively to this breathable feel, and when we moved the upper across a bright light, the airy structure became even more obvious to us.

Taking things further, we examined the shoe under our digital microscope, and it became clear that Saucony made a bold choice by skipping the common secondary layer under the mesh—boosting airflow compared to what we see in most running shoes.

Interestingly, we noticed the upper has a dual-personality design: the front half is thin and race-ready, while the rear section leans toward extra-comfort with generous padding for a plush-and-supportive feel.

We had some concerns about possible durability issues, as the shoe lacks a reinforcement layer below the upper, but after we tested it with our Dremel, the Endorphin Trainer impressed us with a respectable 3/5.

We got exactly the 3/5 score in the heel, although here it feels less impressive...

We were surprised to find that the Endorphin Trainer features only minimal orange rubber on the outsole, placed solely in the most wear-prone spots, leaving most of the surface exposed to a reinforced PWRRUN layer—raising clear concerns about long-term durability and wet traction here in the lab.

The orange rubber should offer pretty durable protection, and at 81.8 HC, it showcased average hardness. However, we strongly advise sticking to smooth, well-paved roads, as the exposed sections could face rapid wear and tear on rougher terrains.

To check if the orange rubber used by Saucony held well against wear and tear, we tested it with our Dremel for the third time in this review. After the tool finished, we found just 0.7 mm of damage, which is pleasantly impressive!

Those two pods of rubber feature 3.1 mm of thickness, which is quite a lot for a performance shoe designed for tempo workouts. We believe Saucony could use a thinner, 1.5 or 2.0 mm rubber instead, covering more outsole and boosting the shoe’s surface versatility.

We were happy to see that the reinforced EVA, despite being much softer than the rubber at 59 HC, delivered a good outcome with only 0.8 mm of damage against our Dremel.

However, it’s important to remember the real issue isn’t regular wear—but running on paths with sharp stones or debris, where ultra-durable works wonders while this EVA material can rip apart quickly.

The supertrainer market is boiling like lava with fierce competition among brands. The Endorphin Trainer is priced right alongside most rivals—neither discounted nor premium—and it feels exactly that way against the competition, landing squarely in the middle of the pack.

As seen in many of their other models, Saucony added three small, reflective circles to the back of the shoe for extra nighttime visibility.

One of the usual traits of supertrainers is you get some of the performance from a supershoe combined with the comfortable feel of a daily trainer. And the tongue definitely leans toward the latter category.

In fact, we discovered it feels almost identical to what we tested on the Saucony Ride 18, although this one is slightly thinner at 6.5 mm, yet still comfortable for long runs. We also found zero issues with the ultra-secure laces and the durable eyelet chain, which uses punched holes and includes an extra one for a runner's knot.

We found that Saucony added a partial gusset to the tongue, and it feels fantastic for a tempo-focused shoe—it’s non-intrusive, feather-light, and holds the tongue perfectly in place without any annoying shifts.

Saucony went with a sleek, minimal design, skipping a heel tab and using some TPU overlays to cover the stitching, giving the shoe a polished, premium finish.

The FormFit insole of the Endorphin Trainer looks ultra-cool, but if you want to remove it, there’s absolutely no problem doing so!