RESUMO
OBJECTIVES: This study examines the acute morphological changes (up to three days) in the normal, asymptomatic Achilles tendon (AT) in response to a single bout of exercise in relation to tendon dimensions and vascularity. DESIGN: Within-subject pre-post design. METHODS: Participants conducted a 7.7km pack march on a sealed road in a time of 1h 16min (approximately 6kmh-1). The longitudinal image of the sagittal diameter, transverse image of the area and vascularity at 20mm proximal to the superior aspect of the calcaneus and longitudinal image of the sagittal diameter at the insertion was measured the day before the pack march, immediately afterwards and then three days later. RESULTS: The tendon showed no significant change in sagittal diameter and cross-sectional area at 20mm proximal to the calcaneus and at the insertion immediately post-exercise. Tendon vascularity increased significantly in 91% of the left ATs and 87% of the right ATs in response to the pack march. Three days after the pack march an increase in sagittal diameter at the insertion and 20mm proximal to the calcaneus was observed and increased vascularity was still present in 22% of the ATs. CONCLUSIONS: This study highlighted the tendon's response to exercise and has shown that at three days post-exercise that the tendon had not recovered to pre-exercise levels with respect to tendon dimensions and vascularity.