1. From the University of Turku, Departments of Medicine (M.J., J.S.A.V.) and Clinical Physiology (O.T.R.), Turku, Finland; Department of Health and Functional Ability (G.A), National Public Health Institute, Helsinki, Helsinki, Finland; Department of Health and Functional Capacity (J.M.), National Public Health Institute, Turku, Turku, Finland; Department of Clinical Physiology (M.K.), University of Tampere, Tampere, Finland; Department of Pediatrics (L.T.), Vaasa Central Hospital, Vaasa, Finland;...