1. MA Risberg, PT, PhD, is Associate Professor and Chairman, Norwegian Research Center for Active Rehabilitation (NAR), Orthopedic Center, Ullevaal University Hospital; Norwegian Sport Medicine Clinic (NMI); and Norwegian School of Sport Sciences, Oslo, Norway
2. I Holm, PT, PhD, is Professor, Rikshospitalet Medical Center, University of Oslo, Oslo, Norway
3. G Myklebust, PT, PhD, is Associate Professor, Norwegian Sport Medicine Clinic (NIMI) and Norwegian School of Sport Sciences, Oslo, Norway
4. L Engebretsen, MD, PhD, is Professor and Chairman, Division of Neuroscience and Musculoskeletal Medicine, Ullevaal University Hospital, and Faculty of Medicine, University of Oslo