Department of Exercise Science, University of Massachusetts-Amherst, 111 Totman Building, 30 Eastman Lane, Amherst, MA 01003-9258, USA.
OBJECTIVE: To investigate the influence of a custom foot orthotic intervention on the lower extremity dynamics in healthy runners. DESIGN: Three-dimensional kinematics and kinetics were collected on 15 female runners (>15 miles per week) while each performed the over-ground running trials in either a shoe only or a shoe+custom foot orthotic condition. Kinematic and kinetic variables were analyzed using Paired Sample t-tests. BACKGROUND: Custom foot orthotics are frequently prescribed treatment modality for the management of overuse running injuries. Although it is generally accepted that a custom foot orthotic intervention produces positive clinical outcomes, it remains unclear what influence this therapeutic modality has on the dynamics of the lower extremity. METHODS: Each subject performed five acceptable over-ground running trials (3.6 m s(-1) +/-5%) with and without the custom foot orthotic intervention in a running shoe. Selected maximum ankle and knee joint angles and moments were measured during the stance phase. RESULTS: While wearing the custom foot orthotic, subjects exhibited significantly decreased maximum values in rearfoot eversion angle, rearfoot eversion velocity and internal ankle inversion moment. CONCLUSIONS: In this sample of healthy female runners, the custom foot orthotic intervention led to significant decreases in maximum values for ankle dynamics in the frontal plane and in the sagittal plane of the knee joint. Relevance It remains unclear how a custom foot orthotic intervention influences lower extremity dynamics to produce positive clinical outcomes. Furthering our understanding of the dynamic influence will not only inform improved prescription and manufacturing practices but may provide insight into the mechanisms that cause overuse injuries.