The South Pacific Islands Resist Diabetes With Intense Training (SPIRIT) Study : impact of progressive resistance training and aerobic training on glycaemic control in Māori and Pacific Islands people with type 2 diabetes and grade III obesity : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Exercise and Sport Science, Institute of Food, Nutrition, and Human Health, College of Sciences, Massey University at Wellington, New Zealand

Abstract

The purpose of the South Pacific Islands Resist diabetes with Intense Training (SPIRIT) study was to evaluate and compare the effectiveness of two conventional training modalities for improving glycosylated haemoglobin (HbA1c) and related physiological and psychological outcomes in Polynesian adults diagnosed with type 2 diabetes and visceral obesity. Twenty-six adults of self-identified Māori or Pacific Islands descent (20 women, 6 men; 47 ± 8 years; 116.3 ± 27.5 kg; waist circumference 124.0 ± 17.8 cm) were randomised to progressive resistance training (PRT) or aerobic training (AER), 3x/week, for 16 weeks. Nine subjects per exercise group (n = 18) completed the study and were included in per protocol analyses. Within-group ANOVAs revealed that HbA1c remained elevated in PRT and AER after 16 weeks of training (10.7 ± 2.1 to 10.6 ± 2.4%, P > 0.05; 8.9 ± 1.9 to 8.8 ± 2.1%, P > 0.05, respectively). AER resulted in significant reductions in systolic (P = 0.006) and diastolic blood pressure (P = 0.02), an increase in skeletal muscle GLUT4 (P = 0.02), capillary density (P = 0.05), and power output (watts) (P < 0.001), while PRT resulted in a significant increase in upper (P = 0.001) and lower body strength (P < 0.001) and a reduction in hip circumference (P = 0.05). Eight (5 AER, 3 PRT) of 18 subjects completed ≥ 75% of available training sessions. Post-hoc analysis on these eight patients revealed a significant reduction in waist circumference (P < 0.001). Despite low attendance, many SF-36 QOL domains scores and the Physical Component Summary scores significantly improved in both groups (P ≤ 0.002). The findings of this doctoral research project suggest that improvement of metabolic outcomes may be delayed or overwhelmed by a combination of low attendance and class III morbid obesity (BMI ≥ 40 kg/m2). The improvements observed in QOL and muscle outcomes suggest that psychological and myocellular changes may precede changes in systemic metabolic outcomes. Additional research is required to investigate these hypotheses and overcome barriers to exercise adoption in Māori and Pacific Islands people with morbid obesity and type 2 diabetes.