1. Division of Interdisciplinary Research and Practice, School of Health and Social Care, University of Essex, Colchester CO4 3SQ, UK
2. Department of Gerontology, Africa Centre for Epidemiology, Accra North P.O. Box AN 16284, Ghana
3. College of Sport, Health and Engineering, Victoria University, Melbourne, VIC 8001, Australia
4. Department of Applied Clinical and Educational Sciences, Indiana State University, 401 North Seventh Street, Terre Haute, IN 47809, USA
5. Department of Public Health, California State University, 5151 State University Drive, ST 305, Los Angeles, CA 90032, USA