Advocates of barefoot running assert that it is more metabolically efficient than shod running. This idea makes sense because wearing shoes adds mass to the feet. However, previous studies that controlled for foot/shoe mass indicate that shoe or surface cushioning provides an energetic advantage over running barefoot. Further, running in lightweight shoes has about the same metabolic cost as running barefoot, suggesting that the positive effects of shoe cushioning may counteract the negative effects of added mass. We hypothesized that:​ 1) barefoot running would have the same metabolic cost as running with lightweight, cushioned running shoes and 2) the metabolic cost of barefoot running would be less on cushioned surfaces.

Eleven experienced barefoot runners ran at 3.35 m/s with a mid-foot strike pattern. Subjects ran barefoot (BF) and in lightweight cushioned running shoes (SH) (Nike Free 3.0;​ ~211 g /shoe) on a rigid treadmill. Subjects also ran barefoot on the same treadmill with 10 mm and 20 mm thick slabs of ethylene-vinyl acetate (EVA) foam affixed to the treadmill belt (Figure 1). The foam was identical to that used in the running shoes. Rates of oxygen consumption and carbon dioxide production quantified metabolic power. Our findings demonstrate that cushioning reduces the metabolic cost of running, and suggest that there may be an ideal amount of cushioning (e.g. < 20mm) beyond which metabolic benefits diminish.