1. UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
2. South African Medical Research Council, Cape Town, South Africa.
3. Wits/MRC Developmental Pathways for Health Research Unit, Department of Paediatrics, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa.
4. Endocrine Unit, Department of Medicine, University of Cape Town, Cape Town, South Africa.
5. Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.