Background and Purpose. The growing popularity of running over the past twenty years has increased the likelihood of running-related injuries. These injuries are thought to be related, in part, to lower extremity structure and mechanics. If relationships between structure, mechanics and injury are established, we may be able to treat patients more effectively. Cavus and planus feet present with very different arch structures and may therefore lead to very different lower extremity mechanics and injury patterns. In order to better understand the relationship between foot structure, mechanics and injury, the purpose of this study was to determine if individuals with high-arched (HA) or low-arched (LA) feet exhibit specific mechanical abnormalities, and to determine if these foot types can be correlated to specific injury patterns.

Methods:​ Validity and reliability were initially established for a measurement of the medial longitudinal arch. Subjects were then screened using this arch measurement and categorized into HA and LA groups. Parameters of lower extremity kinematics and kinetics were compared between groups. Additionally, injuries were recorded and injury patterns were associated with arch structure.

Results:​ HA subjects were found to have increased lower extremity stiffness and vertical loading rate while LA subjects exhibited increased rearfoot eversion. eversion velocity and an increased rearfoot eversion to tibial internal rotation ratio. HA runners reported a significantly greater incidence of knee injuries, bony injuries and lateral injuries while LA subjects reported a significantly greater incidence of medial and foot and ankle injuries.

Conclusion:​ Based on these results, running-related injury patterns associated with differences in lower extremity mechanics exist between runners with HA and LA. These findings have implications for treatment and possible prevention of injury in runners.