For its new natural-motion shoe, Baltimore-based Under Armour looked to an unlikely source. “We’ve taken inspiration from the poison dart frog,” said Dave Dombrow, senior creative director. “There are elements of grip that are taken from the frog [feet] that you can see on the bottom.” The outsole also is designed with perfing that removes weight and adds flexibility, while lug patterns mimic the bones of the foot. “It is very anatomical for that flex,” Dombrow said. The amphibious influence was aesthetic as well. “These are the exact colors and patterns of the poison dart frog,” Dombrow said. And using Under Armour’s proprietary Micro G EVA gives the shoe bounce. “It’s all about rebound, and getting that kind of response back in your foot.”
Minimus 10v2 Road
Boston-based New Balance started at the beginning to create the second generation road shoe for its barefoot-focused Minimus line. “We just threw the outsole out the window,” said senior product manager Bryan Gothie. The brand wanted a more minimal feel and a lighter construction that would still use high-abrasion Vibram rubber on heavy-wear areas of the sole. To cut back on weight and improve the fit, the team carved the EVA and Vibram Road Lite compound materials, which also added flexibility. The shoe uses Vibram Road Lite, a bouncy, lightweight rubber formulation, on the lateral forefoot, the midfoot and the big toe area — the areas an efficient runner will use to strike the ground. In the heel area the Vibram is inset into the heel lugs, while in the forefoot, it sits above the EVA to add durability to the sole. Gothie said, “We focused on the strike pattern unique to a more natural running gait. We have to design around that.”
Asics is putting a premium on biomechanics with FluidAxis, the firm’s new way of engineering the outsole to encourage natural pronation and supination for neutral runners. Simon Bartold, international research consultant for Osaka, Japan-based Asics, said the grooves in the shoes featuring FluidAxis are aligned not with the heel, like most running shoes, but with the subtalar joint, the one responsible for inversion and eversion of the foot. The off-center cleft starting in the heel runs at 42 degrees and lets the shoe compress to support the foot without needing additional features to guide the stride. “We understand the motions of pronation and supination are incredibly important to running,” Bartold said. “When you add features to resist those movements, they restrict normal motion and add weight to the shoe. By building a major area of [separation] that aligns with the subtalar joint, the shoe will deform along that axis and actually encourage those natural movements.”
Flexibility is the priority for Saucony’s newest minimal style, Virrata. The Lexington, Mass.-based brand, a division of Rockford, Mich.-based Wolverine World Wide Inc., has used the more-durable EVA+ material to make a one-piece midsole-outsole unit in other barefoot offerings like the Kinvara, but the Virrata’s exaggerated triangle lug design takes pliability to a higher level. “This is even more flexible in all directions, with torsional flexibility in the midfoot area to completely conform to the foot during the gait cycle,” said Pat O’Malley, SVP of global product. “We want the shoe to provide protection from man-made elements and impact. But at the same time, we’re trying to get the shoe out of the way of the runner so the body can work naturally.” Meanwhile, minimal application of carbon rubber in the heel and forefoot provide abrasion resistance and a platform for toe-off.