Prediction of dynamic foot posture during running using the longitudinal arch angle

Background: A study was conducted to determine whether the longitudinal arch angle can be used to predict dynamic foot posture during running. Methods: Seventeen healthy, experienced runners participated in the study. The static longitudinal arch angle was determined from a digital image of the medial aspect of each subject's feet obtained in relaxed standing posture. For the dynamic phase, subjects were asked to walk across a 12-m walkway and then to run across a 25-m runway while the medial aspect of each foot was videotaped. The longitudinal arch angle was digitized from the video images at midstance in walking and at midsupport while running for five trials per extremity. Results: The longitudinal arch angle obtained in relaxed standing posture was highly predictive of dynamic foot posture at midstance in walking (r² = 0.854) and at midsupport while running (r² = 0.846). Conclusions: The static measurement of longitudinal arch angle is highly predictive of dynamic foot posture during walking and running. The longitudinal arch angle measured in relaxed standing posture significantly contributed to explaining more than 85% of the variance associated with the longitudinal arch angle position at midstance during walking and at midsupport while running. These results seem to validate use of the longitudinal arch angle as part of the foot and ankle physical examination.