Can Footwear Affect Achilles Tendon Loading?

OBJECTIVE: To investigate the effects of footwear on Achilles tendon tension by directly measuring Achilles tendon tension and dorsiflexion range of motion. DESIGN: A total of 48 matched pair tests were performed comparing the effects of shoe type (high-top vs low-top) for each shoelace configuration (tied vs untied). These were performed using the Achilles tendons of 4 human cadaver lower extremities that were instrumented with a customized load cell designed to measure tension. The lower extremity was inverted in a custom testing apparatus designed to inertially invoke dorsiflexion of the foot, putting the Achilles tendon in tension. SETTING: Research laboratory. PATIENTS: Left and right lower extremities of 2 human cadavers. INTERVENTIONS: None. Independent variables were shoe type and shoelace configuration. MAIN OUTCOME MEASURES: Achilles tendon tension and dorsiflexion range of motion. RESULTS: High-top shoes significantly reduced peak Achilles tendon tension by an average of 9.9% when compared with low-top shoes. Tied laces significantly reduced peak tension for low-top (3.7%) and high-top (12.8%) shoes when compared with untied laces. With tied laces, high-top shoes significantly reduced peak dorsiflexion angle by an average of 7.2% when compared with low-top shoes. Tied laces with high-top shoes significantly reduced peak dorsiflexion angle by an average of 4.7% when compared with untied laces. A P value of 0.05 was determined to be significant. CONCLUSIONS: This study offers valuable insight that footwear can affect Achilles tendon loading during dorsiflexion.