Hamstring muscle strains are common in athletics, especially in the sprints and jumping events, and often cause extended absences from training and competition. At present, there are no studies systematically following acute hamstring strains over time with repetitive clinical examinations and correlating the findings with the actual time to return to sport. Magnetic Resonance Imaging (MRI) offers a means of non-invasively determining the location and extent of a hamstring strain. Since MRI investigations are both expensive and demand expert evaluation, simpler clinical assessment methods would be preferable. Such methods have, however, to be validated with parallel MRI-investigations. The aim of this study was to systematically follow the first six weeks after acute first-time hamstring strains in sprinters, with respect to injury situation, injury location and extent of the injury, recovery of strength, flexibility and function, as well as possible relationships between clinical and MRI findings and time to return to sport during a follow-up period of two years. This project was named the overall winner in the 2008 European Athletics Innovation Awards.