Objectives The aim of the study was to identify the prevalence of degenerative change in the Achilles tendons of currently asymptomatic individuals and correlate it with their degree of physical activity.

Methods We recruited 126 healthy subjects, mean age 33.1, range 20 – 50 (78 males and 48 females). Their levels of physical activity were assessed by a questionnaire and scored using the Allied Dunbar Fitness Survey criteria, modified to exclude non-weight bearing activity. One investigator, who was blinded to the activity levels, ultrasound scanned all 252 tendons. Tendons were examined for evidence of hypoechoic regions, localised fusiform thickening, and the cross-sectional diameter of each was measured.

Results Overall 59% (149) of tendons had ultrasound evidence of hypoechoic regions. In 50 tendons (in 31 patients) there was a history of previous Achilles pain and 84% of these had hypoechoic regions. Thirty three percent of subjects in the lowest quartile of activity had evidence of hypoechoic regions compared to 72.6% in the most active quartile (Pearson Chi2 p < 0.01). Only 5.6% of all Achilles tendons had ultrasound evidence of localised fusiform thickening, with none in the inactive group compared to 6.4% in the very active group (Pearson Chi2 p =0.03).

Conclusions Degenerative changes, identified by ultrasound, are common in the Achilles tendon and are often asymptomatic. There is a direct relationship between these changes and levels of current and lifetime activity. The natural history of asymptomatic chronic Achilles tendinosis and their relationship to future pain or tendon pathology is unknown.