1. University of Cape Town/Medical Research Council Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town 7701, South Africa
2. Department of Human Biology, University of Cape Town, Cape Town 7701, South Africa
3. Biostatistics Unit, Cape Town 7505, South Africa
4. Department of Statistics, University of Western Cape, Cape Town 7535, South Africa
5. South African Medical Research Council, Cape Town 7505, South Africa
6. Diabetes and Endocrine Unit, Department of Medicine, University of Cape Town, Cape Town 7701, South Africa