An Exercise Intervention to Unravel the Mechanisms Underlying Insulin Resistance in a Cohort of Black South African Women: Protocol for a Randomized Controlled Trial and Baseline Characteristics of Participants

Julia H Goedecke; Amy E Mendham; Louise Clamp; Pamela A Nono Nankam; Melony C Fortuin-de Smidt; Lindokuhle Phiri; Lisa K Micklesfield; Dheshnie Keswell; Nicholas J Woudberg; Sandrine Lecour; Ali Alhamud; Mamadou Kaba; Faith M Lutomia; Paul J van Jaarsveld; Anniza de Villiers; Steven E Kahn; Elin Chorell; Jon Hauksson; Tommy Olsson

doi:10.2196/resprot.9098

An Exercise Intervention to Unravel the Mechanisms Underlying Insulin Resistance in a Cohort of Black South African Women: Protocol for a Randomized Controlled Trial and Baseline Characteristics of Participants

JMIR Res Protoc. 2018 Apr 18;7(4):e75. doi: 10.2196/resprot.9098.

Authors

Julia H Goedecke^{1

2}, Amy E Mendham^{1

2}, Louise Clamp², Pamela A Nono Nankam², Melony C Fortuin-de Smidt², Lindokuhle Phiri², Lisa K Micklesfield^{2

3}, Dheshnie Keswell², Nicholas J Woudberg⁴, Sandrine Lecour⁴, Ali Alhamud⁵, Mamadou Kaba⁶, Faith M Lutomia⁶, Paul J van Jaarsveld^{1

7}, Anniza de Villiers¹, Steven E Kahn⁸, Elin Chorell⁹, Jon Hauksson¹⁰, Tommy Olsson⁹

Affiliations

¹ Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa.
² Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
³ South African Medical Research Council / University of the Witwatersrand Developmental Pathways for Health Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Gauteng, South Africa.
⁴ Hatter Institute for Cardiovascular Research in Africa, Department of Medicine, University of Cape Town, Cape Town, South Africa.
⁵ Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa.
⁶ Division of Medical Microbiology, Department of Pathology, University of Cape Town, Cape Town, South Africa.
⁷ Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
⁸ Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, WA, United States.
⁹ Department of Public Health and Clinical Medicine, Umeå University, Umea, Sweden.
¹⁰ Department of Radiation Sciences, Umeå University, Umeå, Sweden.

Abstract

Background: The pathogenesis of type 2 diabetes (T2D) in black African women is complex and differs from that in their white counterparts. However, earlier studies have been cross-sectional and provide little insight into the causal pathways. Exercise training is consistently used as a model to examine the mechanisms underlying insulin resistance and risk for T2D.

Objective: The objective of the study was to examine the mechanisms underlying the changes in insulin sensitivity and secretion in response to a 12-week exercise intervention in obese black South African (SA) women.

Methods: A total of 45 obese (body mass index, BMI: 30-40 kg/m²) black SA women were randomized into a control (n=22) or experimental (exercise; n=23) group. The exercise group completed 12 weeks of supervised combined aerobic and resistance training (40-60 min, 4 days/week), while the control group maintained their typical physical activity patterns, and both groups were requested not to change their dietary patterns. Before and following the 12-week intervention period, insulin sensitivity and secretion (frequently sampled intravenous glucose tolerance test) and its primary and secondary determinants were measured. Dietary intake, sleep quality and quantity, physical activity, and sedentary behaviors were measured every 4 weeks.

Results: The final sample included 20 exercise and 15 control participants. Baseline sociodemographics, cardiorespiratory fitness, anthropometry, cardiometabolic risk factors, physical activity, and diet did not differ between the groups (P>.05).

Conclusions: The study describes a research protocol for an exercise intervention to understand the mechanisms underlying insulin sensitivity and secretion in obese black SA women and aims to identify causal pathways underlying the high prevalence of insulin resistance and risk for T2D in black SA women, targeting specific areas for therapeutic intervention.

Trial registration: Pan African Clinical Trial Registry PACTR201711002789113; http://www.pactr.org/ATMWeb/ appmanager/atm/atmregistry?_nfpb=true&_pageLabel=portals_app_atmregistry_portal_page_13 (Archived by WebCite at http://www.webcitation.org/6xLEFqKr0).

Keywords: adipose tissue; body fat distribution; cardiorespiratory fitness; diabetes mellitus, type 2; diet records; ectopic fat; energy metabolism; exercise; fatty acids; fatty liver; gastrointestinal microbiome; inflammation; insulin resistance; lipids; metabolomics; mitochondria; skeletal muscle.

©Julia H Goedecke, Amy E Mendham, Louise Clamp, Pamela A Nono Nankam, Melony C Fortuin-de Smidt, Lindokuhle Phiri, Lisa K Micklesfield, Dheshnie Keswell, Nicholas J Woudberg, Sandrine Lecour, Ali Alhamud, Mamadou Kaba, Faith M Lutomia, Paul J van Jaarsveld, Anniza de Villiers, Steven E Kahn, Elin Chorell, Jon Hauksson, Tommy Olsson. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 18.04.2018.

Abstract

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