All patients were instructed on how to perform the eccentric training by either of two physical therapists (TP or PJ). They were given practice instructions and a written manual on how to progress. A control on how the patients did their exercises was done by the physical therapist after 6 weeks. The patients were instructed to do their eccentric exercises 2 times daily, 7 days/week, for 12 weeks. During the 12-week training regimen, running activity was allowed if it could be performed with only mild discomfort and no pain.