Differences Between Long Distance Road Runners and Treadmill Runners in Achilles Tendon Structure

Inclusion Criteria: * run regularly at least twice a week for half an hour, * over 80% of the training on a treadmill or road Exclusion Criteria: * pain or injury to Achilles tendon during the 6 months, preventing running for at least 3 days. * past Achilles tendon surgeries, * sprained ankle in the last six months, * lower limb and back pain while running * participants who report running with minimalist shoes.