Saucony Endorphin Speed 4 Long Run Review: Comfortable Daily Trainer, Limited Upside at Fast Paces

Introduction

After roughly 58 miles, including a demanding 22-mile workout with 16 miles at marathon effort, the Saucony Endorphin Speed 4 has settled into a clear identity: a comfortable, easy-to-like daily trainer that does not quite deliver when you push it hard.

The standout session for this review was a Jack Daniels-style long run: a 4-mile warm-up, 8 miles at marathon pace, 1 mile at threshold, another 6 miles at marathon pace, and a final threshold mile. That is a serious test for any training shoe, and it revealed both the strengths and the limitations of the Speed 4.

Who This Shoe Is For

The Endorphin Speed 4 shines in a steady pace zone, roughly anywhere from 7:40 down to 6:30 per mile in this testing. During warm-up miles and comfortable long-run turnover, the shoe feels great: soft, smooth, and pleasant underfoot.

It also suits lighter runners or anyone who spends most of their training below that sub-6:30 threshold pace. At those efforts, the soft ride is a feature rather than a limitation, and the weight did not feel like a problem either.

Main Strengths

Comfort is the headline. Across two and a half hours of running, the shoe stayed comfortable for the bulk of the session, and it has racked up daily-trainer miles easily because of that easy, cushioned character.

There were some earlier comments suggesting the Speed 4 was a firmer, faster shoe than its predecessor, but this longer testing did not support that. This is a soft shoe, and it behaves like one. The ride is protective and relaxed, which is exactly what makes it enjoyable at steady paces.

It is also worth noting that the weight concern is overstated. The Boston 12 is actually heavier in the tester’s size, and the added mass was never the issue here. The issue is that a slightly heavier shoe should offer more pop than this one does.

Things to Consider Before Buying

The main limitation shows up past the 90-minute mark, especially in the forefoot. During the threshold attempts in the long run, the shoe developed a noticeable “bottoming out” feeling: reduced support and shock absorption from the forefoot foam, with more ground feel and less protection than earlier in the run.

When trying to drop into sub-6:20 pace, the shoe felt like it had a limiter on it. It simply lacked the aggression, bite, and forefoot response expected from an uptempo marathon training shoe. Compared with the Boston 12 and the Alphafly, both felt firmer and more supportive in the forefoot.

This is not necessarily universal. Lighter runners or those training at different pace ranges may not notice the same collapse in response. But for bigger or stronger runners chasing sub-3 marathon pace, the lack of structure becomes apparent.

Buying Advice

If your runs are mostly two hours or shorter and you are a lighter runner, the Endorphin Speed 4 should be a comfortable, rewarding pick as a daily trainer. It has earned its miles quickly in testing for exactly that reason.

If you regularly run hard workouts past the hour mark, or you are a bigger runner targeting sub-6:30 or sub-6:50 pace in marathon workouts, you will likely want a shoe with more bite and forefoot structure, such as the Boston 12 or a carbon-fiber plated racer.

On fueling during the test: one sachet of caffeinated Tailwind in tropical flavor, roughly 80 percent finished, was enough to feel well fueled without gels. For longer marathon sessions, mixing gels alongside a steady drink still makes sense to maximize sustainable calories.

Conclusion

The Saucony Endorphin Speed 4 is a comfortable daily trainer that earns its place in the rotation for steady miles and easy long runs. As a fast, uptempo marathon workout shoe, it falls short at harder efforts, particularly beyond the 90-minute mark for heavier runners. Buy it for the miles, not for the speed sessions.