MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby DE22 3DT, UK. Department of Surgery and Anaesthetics, Royal Derby Hospital, Derby DE22 3NE, UK. Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX1 2LU, UK. Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK. Research and Development, Abbott Nutrition, 18004 Granada, Spain. Research and Development, Abbott Nutrition, Columbus, OH 43219, USA.