The Saucony Endorphin Speed 4 is a nylon-plated lightweight trainer designed for tempo and long-run training. Its verified specifications — 36 mm heel stack, 28 mm forefoot stack, 8 mm drop, 215 g weight, PWRRUN PB midsole, nylon plate — place it in the tempo-trainer category at a listed Indian price of ₹14,999. This review evaluates the shoe against the published research on plated trainers and provides defensible use cases for the Indian runner.
The nylon plate distinguishes the Speed 4 from the carbon-plated Endorphin Pro 4 in two relevant ways. The plate is more compliant, producing a softer ride that tolerates longer training sessions. The plate is also more durable across high training mileage, which has implications for cost-per-kilometre that the carbon platform cannot match.
What the research says about plated trainers
A 2022 paper in the European Journal of Sport Science by Healey and colleagues examined nylon-plated versus carbon-plated shoes at submaximal paces. The study reported that nylon plates produce a similar direction of running-economy benefit at marathon and half-marathon paces, with a smaller magnitude than carbon plates but a flatter response curve across a wider pace range. The practical implication: a nylon-plated trainer is closer to "useful at most training paces" than a carbon-plated racing shoe.
A 2023 review in Sports Medicine extended this work and concluded that nylon-plated tempo trainers are an appropriate platform for higher weekly mileage, with less concern about the calf and Achilles loading patterns that have been linked to bone stress injuries in some case reports involving high training volumes in carbon-plated shoes. The defensible interpretation: the Endorphin Speed 4 is a training tool, not a race-only tool, and it can be used more frequently than its carbon-plated sibling.
The plate compliance question
Healey and colleagues also reported that nylon plates flex meaningfully through the midfoot under load, while carbon plates remain stiff. The flex contributes to the perceived softness of the Speed 4 versus the Pro 4. For Indian runners who train in heat and on uneven Indian road surfaces, the additional compliance is a defensible advantage; the published evidence does not support a stiffer plate as superior in all contexts.
Training use case 1: Weekly tempo and threshold sessions
The strongest use case is the weekly tempo. A typical Indian programme has one tempo session per week — 25 to 40 minutes at half-marathon to threshold pace — and the Endorphin Speed 4's 215 g weight, plate stiffness, and 36 mm stack are well-matched to the demands of this session.
Session structure
Examples: 4 x 8 minutes at half-marathon pace with two-minute jog recoveries; 30 minutes continuous at threshold; 6 x 1 km at 10K pace with 200 m jog recoveries. The Endorphin Speed 4 is worn for the entire session, including warm-up and cool-down. Use the STRIDD plan generator to structure the weekly plan and assign shoe categories to each session.
The defensible weekly frequency
One to two sessions per week. The 2023 Sports Medicine review concluded that nylon-plated trainers can be used at higher weekly frequencies than carbon-plated shoes without the loading concerns reported in carbon-plated case studies. Two tempo sessions per week is a defensible upper limit during the specific phase of marathon training, where one is at threshold pace and one is at marathon pace.
Training use case 2: Marathon-pace long runs
The second defensible use is the marathon-pace long run. The 36 mm stack provides cushion across 90 to 150 minutes of running, and the nylon plate sustains the rocker geometry across the duration without the foam compression that lighter shoes exhibit at the end of long sessions.
Session structure
For marathon training, one marathon-pace long run every two to three weeks during the specific phase. Length progresses from 12 km of marathon pace inside a 22 km run, up to 25 km of marathon pace inside a 32 km long run. The Endorphin Speed 4 is appropriate across the full progression, where the carbon-plated Pro 4 is typically reserved for the longest and most race-specific of these sessions.
Why the Speed 4 over the Pro 4 for most MP long runs
Cost per kilometre. The Endorphin Pro 4 is typically reserved for race day and a small number of tune-up sessions. The Speed 4 carries the bulk of the marathon-pace mileage during the specific phase. The cheaper running cost-per-kilometre of the Speed 4 is the defensible economic case, and the published evidence does not show the Pro 4 is meaningfully superior in training adaptation.
Training use case 3: The midweek progression run
A third use is the progression run — a session that starts at easy pace and finishes at marathon pace or faster. The Speed 4's geometry accommodates both ends of the pace range without the stiffness penalty a fully carbon-plated shoe imposes at easy paces.
Session structure
An 80-minute progression: 40 minutes easy, 20 minutes at marathon pace, 15 minutes at half-marathon pace, 5 minutes easy. Or a simpler version: 60 minutes with the last 20 minutes at marathon pace. Use the Speed 4 across the full session; the plate flex is a feature here, not a constraint.
The placement in a weekly programme
One progression run every two to three weeks during the specific phase. Pair it with one tempo and one long run for a defensible high-quality week. For runners chasing a half marathon goal, substitute marathon pace with goal half pace in the progression segments. The super-shoe comparison 2026 covers where the Speed 4 sits against other plated and non-plated trainers.
Training use case 4: Half marathon racing
The fourth use is the race itself. The Endorphin Speed 4 is a defensible half marathon racing option for runners not chasing a peak time, or for runners whose budget does not justify a separate carbon-plated racing shoe.
The economy comparison
The Healey 2022 study reports that nylon plates deliver approximately one to two per cent of running-economy benefit at race pace, against three to four per cent for carbon plates. For a 1:30 half marathon, the difference is roughly one to two minutes. Whether that gap justifies a second racing shoe is a runner-specific question that depends on race calendar, budget, and goal time. For the runner racing one or two half marathons a year, the Speed 4 is defensible as the single race-and-training shoe.
What the Speed 4 is not for
It is not for recovery runs at very easy paces, where the plate stiffness and weight provide no defensible benefit. It is not for off-road or trail use; the outsole geometry is calibrated for road. And it is not a single-shoe solution above 50 km per week; rotate it with a daily trainer to lengthen the usable life of both. For cheaper alternative platforms, see cheaper alternatives. For the broader catalogue, see STRIDD's Saucony catalogue and the main shoe archive. The comparison tool places the Speed 4 next to its direct rivals.