The effect of the heel-to-toe drop of standard running shoes on lower limb biomechanics

Abstract

Running brings many health benefits, but can lead to injuries to the musculoskeletal system. Modern running shoes have been developed to improve running biomechanics, including the heel-to-toe-drop (HTD) which has been highlighted as a central feature in shoe design. The purpose of this study was to investigate impact force characteristics, joint kinematics and kinetics across three commonly-available HTDs, as well as between running with HTDs and barefoot. Fifteen recreational runners took part in this study. Full-body kinematics and ground reaction force (GRF) data were collected while the participants ran at a speed of 4 m/s in three different shoe conditions (4 mm, 8 mm, and 12 mm HTD) as well as barefoot. Comparisons between the four conditions were made for GRFs, joint kinematics and kinetics of the lower extremities. The results primarily showed that a 4 mm HTD led to increased vertical loading rate and maximum ankle moment and a decreased maximum knee moment compared to 8 mm and 12 mm HTD. In addition, differences in ankle and knee kinematics were seen between running in shoes and running barefoot. A lower HTD mainly altered the kinetics of the ankle and knee. Running with a low HTD did not lead to similar lower limb biomechanics as barefoot running. These findings are important because a deeper understanding of biomechanical responses may lead to more customized footwear, which could decrease the risk of running-related injuries.