[en] The purpose of this study was to determine the effectiveness of eccentric training models in treating various types of tendinitis and evaluate protection from re-injury when returning to causal activities, Isokinetic eccentric training was administered to 34 patients with chronic tendinitis (9 Achilles, 10 patellar and 15 epicondyllar) with a long duration of symptoms and failure of conventional treatment. Following training which consisted of 20 to 30 sessions of progressive increase of load and speed parameters, a significant reduction of pain indicated by the visual analog scale (average initial value > 6.5, final score less than or equal to 2.5). Seventy four percent of the patients were completely relieved or presented marked decrease in symptoms when returning to sport and occupational activities. and only 12% reported no change in their functional state. At the end of treatment. isokinetic assessment revealed no significant concentric or eccentric peak torque asymmetries between involved and non-involved sides. In comparison with pretreatment ultrasound observations which showed systematic hypoechoic lesions and thickness, 14/34 patients recovered homogeneous tendon structure and normalization of the diameter and 15 presented improvement in echostructure. Our treatment model proposing isokinetic eccentric exercises presents a very satisfactory short-term effect on three different localizations of chronic tendinitis.