1. Department of Human Biology, UCT/MRC Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa;
2. South African Medical Research Council, Cape Town, South Africa;
3. Endocrine Unit, Department of Medicine, University of Cape Town, Cape Town, South Africa;
4. Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System and University of Washington, Seattle, Washington;
5. Department of Medicine, Umeå University, Umeå, Sweden;
6. Endocrinology Unit, Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, Scotland.