Iberoamerican Cochrane Centre, IIB Sant Pau, Barcelona; CIBER of Epidemiology and Public Health, Barcelona, Spain; ITRT, Quiron-Teknon Hospital, Barcelona, Spain; Sport Catalan Council, Generalitat de Catalunya, Barcelona, Spain; Medical Services, Barcelona Football Club, Barcelona, Spain; High Performance Centre, Health Consortium of Terrassa, Barcelona, Spain; Vithas Montserrat Hospital, Catalunya National Institute of Physical Education, Lleida, Spain; CIBER of Epidemiology and Public Health, Barcelona, Spain. Clinical Epidemiology and Public Health Department, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Barcelona, Spain.