Hollow-Structured Advanced Footwear Technology Improves Running Economy Through Enhanced Energy Storage and Return in Sub-3-Hour Non-Rearfoot Strike Marathon Runners.

This study investigated the effects of a hollow-structured advanced footwear technology (HAFT) compared with a normal advanced footwear technology (NAFT) on running economy (RE) and lower-limb biomechanics in habitual non-rearfoot strike (NRFS) runners. Sixteen male NRFS runners completed biomechanical and metabolic testing under both footwear conditions at a constant speed of 15 km/h. Compared with NAFT, the HAFT reduced energy cost by 2.9% after corrected for shoe mass (HAFT: 14.54 ± 1.00 W/kg; NAFT: 14.98 ± 1.09 W/kg; p = 0.001). Meanwhile, when running in the HAFT, which featured greater midsole compression (HAFT: 2.35 ± 0.08 cm; NAFT: 1.69 ± 0.08 cm; p < 0.001), higher energy storage (HAFT: 15.64 ± 1.45 J; NAFT: 11.03 ± 1.45 J; p < 0.001), and higher energy return (HAFT: 14.00 ± 1.30 J; NAFT: 9.87 ± 1.30 J; p < 0.001) than NAFT, runners exhibited increased leg stiffness (HAFT: 33.62 ± 6.03 kN/m; NAFT: 29.56 ± 5.54 kN/m; p = 0.001), and higher distal rearfoot positive work (HAFT: 0.86 ± 0.35 J/kg; NAFT: 0.41 ± 0.11 J/kg; p < 0.001). These improvements could be explained by a combination of direct mechanical effects (greater midsole energy storage and return), biomechanically mediated effects (changes in lower-limb energetics), and shoe-runner interaction effects, consistent with an NRFS-oriented hollow-structured plate-foam design.