What Exactly Is a Super Trainer?

You know the shoes Ruth Chepngetich and Eilud Kipchoge wear, partially responsible for some of the fastest marathon times ever recorded? Those are called super shoes. They’re thick-soled, with ultralight, hyper-responsive foam midsoles embedded with carbon-fiber plates. Think of super trainers as the more easygoing but still light and responsive cousins of super shoes. We sliced one open at our gear lab in Colorado to find out what makes them go zoom.

Midsole Foam

At the heart of every super shoe and super trainer is a thick slab of high-tech foam that’s lighter, softer, and bouncier than any other midsole material to date. It’s created by a process called supercritical foaming that combines heat, pressure, and liquid gas to infuse bubbles into elastic polymers like PEBA, TPEE, and ATPU. The resulting midsoles deliver plush cushioning and trampoline-like ­rebound, but are squishy and unstable, requiring a balanced, ­powerful stride to optimize performance.

Super shoes have full stacks of these soft, bouncy foams. However, many super trainers, like the Puma Deviate Nitro 3 shown here, use a combination of foams—softer on top of firmer—to provide an energetic feel while delivering the kind of stride-supporting ride more suitable for a training shoe. The step-in feels soft underfoot, but when put through a heel-compression
test used to compare super shoes at the Outside Lab, the Deviate Nitro 3 super trainer was less squishy than all the racers we tested.

Traditional trainers use foams that are firmer and more supportive or are soft but not as bouncy—usually EVA or an EVA blend—delivering a more grounded, rolling ride.

Plate

All super shoes have a rigid, curved carbon-fiber plate embedded in the midsole. While many assume that this acts like a spring, research has shown that its role is to moderate the foam’s squish and channel its rebound, reducing energy loss and facilitating powerful push-offs.

Super trainers also typically have an embedded plate, but one with more flex. While rigid plates provide the most pop, they also dictate how the shoe rolls forward and can negatively alter the stride. A super trainer’s plate—like the one in the Deviate Nitro 3, made of a carbon-composite weave with a forked forefoot shape—­accommodates a wider range of paces and strides and is less prone to bouncing feet in unproductive directions when form deteriorates from fatigue.

Plates differ in flex, shape, and location within the foam. This ­affects how the foot rolls and interacts with the ground, and each feels different when combined with a runner’s unique stride.

Rocker

With the thick foam in many of today’s running shoes, the sole no longer flexes much at the ball of the foot. Instead, the foam’s height allows designers to cut away mass under the toe, creating a rocker shape. Rather than enabling the foot to flex as it moves through the stride, that shape allows the runner to roll off the toe while the foot remains in a neutral position. The rocker’s starting point, slope, and relationship to the plate all affect the shoe’s ride. In our measurements, the Deviate Nitro 3’s rocker started 8 percent later (closer to the toe) than the rocker on Puma’s Fast-R Nitro 2 racing super shoe, providing a stabler forefoot stance before rolling forward.

Outsole

A three-millimeter-thick rubber outsole covers more than 90 percent of the forefoot and all contact areas of the heel on the ­Deviate Nitro 3. This provides better grip and durability than the sole of a racer, which needs to be as light as possible and so has rubber only in small, optimized zones.

Upper

Super-shoe racers have minimal uppers with scant padding and strong, secure grip to hold the foot in place at speed. A super trainer’s upper is more plush and durable but still lightweight, thanks to strategically placed fabrics that stretch, breathe, or ­support as needed.

Featured Super Trainer

Puma Deviate Nitro 3 

Weight: 10.1 oz (men’s)
Stack Height: 39 mm (heel); 29 mm (forefoot)
Drop: 10 mm

Full Review

$160 at Puma  $160 at Running Warehouse