Purpose: This study tests if running economy differs in minimal shoes versus standard running shoes with cushioned, elevated heels and arch supports, and in forefoot versus rearfoot strike gaits.Methods: We measured the cost of transport (mlO2/kg/m) in subjects who habitually run in minimal shoes or barefoot while they were running at 3.0 m/s on a treadmill during forefoot and rearfoot striking while wearing minimal and standard shoes, controlling for shoe mass and stride frequency. Force and kinematic data were collected when shod and barefoot to quantify differences in knee flexion, arch strain, plantarflexor force production, and Achilles tendon-triceps surae strain.Results: After controlling for stride frequency and shoe mass, runners were 2.41% more economical in the minimal shoe condition when forefoot striking and 3.32% more economical in the minimal shoe condition when rearfoot striking (p<0.05). In contrast, forefoot and rearfoot striking did not differ significantly in cost for either minimal or standard shoe running. Arch strain was not measured in shoes condition but was significantly greater during forefoot than rearfoot striking when barefoot. Plantarflexor force output was significantly higher in forefoot than rearfoot striking, and in barefoot than shod running. Achilles tendon-triceps surae strain and knee flexion were also lower in barefoot than standard shoe running.Conclusions: Minimally shod runners are modestly but significantly more economical than traditionally shod runners regardless of strike type, after controlling for shoe mass and stride frequency. The likely cause of this difference is more elastic energy storage and release in the lower extremity during minimal shoe running.(C)2012The American College of Sports Medicine
Effects of Footwear and Strike Type on Running Economy by Perl, Daniel P.; Daoud, Adam I.; Lieberman, Daniel E.