By Jordana Bieze Foster
Increasing running shoe bending stiffness helps improve running energetics up to the point at which it impairs metatarsophalangeal (MTP) joint flexion—a threshold that varies between individuals—according to research from the Republic of Korea.
Investigators from the Korea Advanced Institute of Science and Technology in Daejeon analyzed 19 individuals as they ran while wearing lightweight running shoes fitted with carbon-plate insoles of five different bending stiffnesses.
They found that increasing bending stiffness assisted with propulsion during running, reducing the metabolic cost of running by about 1%. However, at a certain level, the increased elasticity began to interfere with the natural flexion of the first MTP joint, reducing the contribution of ankle joint torque to push-off and counteracting the metabolic benefits. Within the study population, the threshold of bending stiffness for optimal energetics varied significantly from one runner to the next, suggesting running shoe design may need to be tuned to an individual runner’s needs.
The findings were epublished in January by the Journal of Biomechanics.
Oh K, Park S. The bending stiffness of shoes is beneficial to running energetics if it does not disturb the natural MTP joint flexion. J Biomech 2016 Jan 18. [Epub ahead of print]