Doppler Ultrasound Signal in Achilles Tendinopathy Reduces Immediately After Activity

Background: A relationship has been identified between vascularization on Doppler ultrasound (Doppler signal) and Achilles tendon pain. Doppler signal may increase minutes after prolonged activity, but the immediate effect is unknown. The aim of the study was to investigate the immediate effect of short term activity on Achilles tendon Doppler signal. Achilles tendinopathy patients (7 patients, 10 tendons) and asymptomatic controls (6 controls, 12 tendons) performed 2 activity tasks; a 2 minute continuous step task and one minute continuous calf raise task. Doppler signal was measured at rest and within a minute after each activity. The presence of Doppler signal was quantified using both semi quantitative (modified Ohberg scale; 0=no signal, 5 = > 90% of pathological area contains Doppler signal) and quantitative methods (pixel number). Doppler signal was present in 90% of symptomatic individuals and in none of the asymptomatic controls. The modified Ohberg scale and pixel number reduced significantly after both activity tasks and heart rate increased significantly (p < 0.05). Doppler signal in Achilles tendinopathy may decrease immediately after activities that load the calf muscle and increase heart rate, suggesting that this activity should be avoided prior to imaging to avoid false negative results.