The influence of prolonged running and footwear on lower extremity biomechanics

The effect of maximal isolated muscle and cardiovascular fatigue on lower extremity biomechanics during running has been investigated extensively. However, the majority of runners do not run to exhaustion regularly. Consequently, research and industry are interested in biomechanical changes over the course of a typical prolonged run and how footwear technology may affect them. This study investigated the influence of neutral and stability footwear worn during a 42-minute prolonged treadmill run on lower extremity biomechanics. Fourteen male rearfoot runners completed two prolonged running sessions where they ran for 21minutes on a force instrumented treadmill in a neutral shoe (baseline run). Participants then changed into another neutral shoe of the exact same construction but a different color or into a stability shoe and ran for a further 21minutes (intervention run). Three-dimensional kinematics and kinetics were measured at the beginning and end of each 21-minute running period. Main effects for time were observed at the hip, knee, and ankle during both the baseline and intervention runs. Particularly, increased knee flexion and rearfoot eversion observed during mid-stance may exhibit a strategy to reduce the effective mass and minimize joint loads applied to the foot and knee. No main effects for footwear condition were found in lower extremity biomechanics. However, individual responses to the neutral and stability shoe conditions were observed. Running shoe design should: (1) focus on both acute and prolonged changes in lower extremity biomechanics at the individual level, and (2) further investigate the use of materials/architecture that allow runners to stay within their initial (baseline) preferred motion path and/or provide greater support when preferred motion path changes throughout a prolonged run.