Saucony Endorphin Speed 4 review

We've concluded that the Endorphin Speed 4 is an outstanding pick for:

• Runners desiring a high-performance, all-around shoe that can even handle easy runs.
• Athletes looking for an interval shoe without a carbon plate.
• Fans of the Endorphin Speed series seeking a return to a firmer, more responsive ride from the softer v3.

While the Endorphin Speed saga aims to serve a broad audience, we believe there are better choices for certain runners.

For those who prefer a non-plated shoe, the ASICS Superblast might be a more suitable option. It's almost as light as the Endorphin Speed 4 but offers more foam for cushioning, lacks the nylon plate for a more traditional feel, and provides greater stability, albeit at a higher price point.

Moreover, we feel the ES4 may not be the ideal option for those who favour super-soft running shoes for speed training. The Nike Streakfly provides a plush experience at a more affordable price.

The moment we unboxed the Endorphin Speed 4 in our lab, the massive ventilation holes immediately grabbed our attention. They played a key role in the shoe scoring a perfect 5/5 in our smoke test.

Our initial impressions were confirmed when we held the upper against a powerful light. Indeed, it's among the most ventilated uppers we've encountered. However, for those planning to use it in colder climates, we recommend pairing it with thick socks for added warmth especially during easy runs.

Intrigued by the ventilation holes, we went in for a closer look with our lab's microscope.

The engineered mesh is finely tuned to maximize airflow in the toebox while maintaining a robust structure throughout the shoe.

Examining the entire upper, we noted Saucony's focus on creating a highly breathable shoe, not just in the toebox—which is common—but also with significant ventilation in the tongue and medial side, a rarity in running shoes.

Our initial foray into the durability of the Endorphin Speed 4 focused on the toebox—an area of concern due to its huge ventilation holes. And we're delighted to share that the shoe held up impressively in our Dremel test, securing a 3/5 rating. 

While this may seem like an average score, it's actually a commendable achievement for a well-ventilated mesh upper, demonstrating remarkable resilience. In fact, our testing revealed that even those prone to wearing holes in their shoes, whether at the big toe or pinky toe, can confidently opt for this model.

Another area that often shows early signs of wear is the heel padding—many runners find their Achilles rubbing against this spot, causing concern for durability. To evaluate the potential for damage here, we conducted another test, pulling out the Dremel and applying the same force as before. To our delight, the results were outstanding.

We were thrilled to award the ES4 a perfect 5/5, the highest possible score!

Riding high from two successful initial tests, we turned our attention to the outsole. We began by measuring its hardness, which came in at 77.0 HC on our durometer.

The Endorphin Speed 4 introduces a new outsole design that enhances traction while maintaining a considerable amount of exposed foam.

This is a bit softer than what we typically encounter. Our tests showed that this softer approach likely contributes to its strong grip across various terrains, such as asphalt, tracks, and even dirt roads.

Our main concern was the potential for early wear due to the slightly soft rubber. To address this, we decided to conduct one final test using the Dremel.

We were pleased with the outcome—after completing the test, we discovered a mere 0.8 mm indentation. This result is quite promising!

Finally, we examined the outsole thickness. Saucony maintained the exact 2.0-mm thickness from the Endorphin Speed 3. Although it might seem thin at first glance, remember that we're looking at a performance-oriented, lightweight running shoe.

In such models, minimizing weight is crucial, and a thicker outsole could mute the ride's responsiveness and add unnecessary bulk. From our standpoint, a 2.0-mm rubber outsole strikes a perfect balance for this shoe type, offering a nimble feel without sacrificing durability.

Indeed, the shoe feels incredibly light on the foot. Weighing in at just 8.4 oz (237g), it's almost like it vanishes when you're running. Yet, we noted a slight weight increase of 0.5 oz compared to its predecessor, even though the outsole thickness remains unchanged.

Let's uncover the reasons behind this weight gain!

The primary cause of the weight increase in the ES4 is its midsole. Using our calipers, we measured an impressive 36.2 mm in the heel area, making it the tallest Endorphin Speed model to date. This is a noticeable 2.1 mm increase from last year's model.

This design aligns with the current market trend of creating shoes with taller profiles for extra cushioning. Despite this increase, the Speed remains comfortably below the 40-mm mark. It's an excellent option for those who prefer a less towering shoe without compromising on long-run comfort.

The forefoot also sets a new record for the Endorphin Speed series at 27.5 mm.

We've observed that this feature makes it exceptionally versatile, ideal for effortlessly tackling both long runs and speed workouts—a hallmark of this all-around model.

The difference between the forefoot and the heel delivers an 8.7-mm drop, appealing to a broad spectrum of runners.

The Endorphin Speed series is celebrated for its wide appeal across runners with various footstrikes and paces. This popularity stems from its versatile design, not limited to a specific type of runner, but rather embracing a more universal approach. That's why the real 8.7-mm drop makes total sense to us.

Our caliper measured the insole at 5.1 mm, introducing an extra layer of plushness to the underfoot experience.

In the midsole, Saucony once again employed its Pebax-based, pellet-shaped PWRRUN PB foam, which has been a game-changer since its debut for its energy return and durability. Yet, there's a slight tweak in the formulation—the shoe now has a firmer feel, confirmed by our durometer reading at 22.3 HA.

The ride is neither too firm nor overly plush; it strikes a perfect balance. We consider this a positive shift from the previous version's softer feel, which some runners found too mushy, enhancing its responsiveness.

However, for those who prefer an ultra-soft midsole, the v3 might be the more suitable option.

As highlighted in our guide on running shoes and temperatures, Pebax foams like PWRRUN PB stand out for their exceptional performance in a variety of climates, making them a top choice for winter running.

To confirm this, we put the ES4 to the test by placing it in the freezer for 20 minutes. The result was impressive—the foam became only 5.6% firmer. 

The Endorphin Speed series has consistently incorporated a nylon plate for enhanced stability and a bouncier ride. The ES3 took this a notch higher with a winged plate design, a feature that continues in the ES4.

Coupled with a firmer midsole, it offers what we believe to be the most stable ride across all four versions.

Stability gets a major boost from smart design features like heightened midsole sidewalls, a revamped heel, and enhanced rigidity. These elements, coupled with the firmer midsole, play a crucial role in the shoe's impressive performance, guaranteeing a secure and stable run across all paces.

From the moment we unboxed and tested the shoe, we noticed it was more rigid than its predecessor. After some deliberation in the lab, we assigned it a 3/5 score for rigidity. This shift makes it lean more towards speed-focused runs rather than daily training, yet it still holds its ground as an all-around shoe.

The heel counter adopts a similar design to many other daily running shoes, featuring just enough rigidity to be noticeable but not overbearing. We found it both comfortable and secure for all distances, including long runs, with zero heel slippage.

Another key factor contributing to the shoe's enhanced stability and slight weight gain is its increased width.

It has expanded to 114.7 mm, which, while still modest, marks a noticeable change for forefoot strikers. However, despite this growth, the Endorphin Speed retains its agile feel.

The heel has also widened to 93.4 mm, nearly 4 mm more than the previous version, enhancing stability for heel strikers. Despite this, it continues to be a purely neutral running shoe and might not be the best speed training companion for those with stability needs. We suggest the Saucony Tempus instead.

Nylon-based plates, unlike their carbon-fiber counterparts, add minimal longitudinal stiffness to a shoe. Our 90-degree bend test yielded a 29.4N result, nearly identical to what we'd expect from a similarly-stacked shoe without a plate.

This makes it an great choice for daily running, offering a snappy-yet-comfortable experience without the intense rigidity often associated with carbon plates.

After another 20-minute session in the freezer, we assessed the stiffness. Just like with the softness, the performance was stellar, showing only a 3.2% increase in stiffness. This result is simply outstanding!

A significant—and delightful—upgrade in the fourth version of the Endorphin Speed is its upper.

It's now more spacious than ever, comfortably fitting runners with slightly wide feet. We measured its widest part at 101.7 mm, a change that enhances its inclusivity.

The upper's widest part enjoyed the overall increase in the shoe's width, but the toe cap area stayed at a comfortable average of 77.5 mm, which suits most feet just fine.

Saucony chose the semi-gusseted tongue again, an ideal feature for a lightweight shoe designed for fast paces that require a secure lockdown—and the ES4 delivers just that!

The tongue padding is kept to a minimal 2.0 mm, part of the effort to maintain a low weight.

Therefore, we advise caution when tightening the laces, particularly for longer runs, to prevent any lace bite.

In line with recent Saucony design trends, we didn't anticipate a heel tab, and indeed, there wasn't one to be found.

The insole is removable and features a very standard shape, allowing for easy insertion of third-party sockliners without any issues. Also, for runners with larger feet, opting for a thinner insole can also increase the shoe's overall internal volume.

We're always impressed when brands prioritize runner safety. Thus, discovering reflective elements on the Endorphin Speed 4 was a fantastic highlight, enhancing visibility and protection.