How many runners with new-onset Achilles tendinopathy develop persisting symptoms? A large prospective cohort study - Lagas, I. F.; Fokkema, T.; Bierma-Zeinstra, S. M. A.; Verhaar, J. A. N.; van Middelkoop, M.; de Vos, R.-J. (Scandinavian Journal of Medicine & Science in Sports, 2020)