Abstract
High‐intensity intermittent training (HIIT) has been shown to reduce the risk of chronic conditions including the development of type 2 diabetes mellitus (T2DM). Independently, a low vitamin D status has also been linked to the prevalence of T2DM. The aim of this study was to investigate if there was a synergistic metabolic effect of HIIT and vitamin D supplementation on glycemic control. A total of 20 male and female participants (age, 34 ± 9 year; BMI, 31.4 ± 2.8 kg·m−2) completed 6 weeks HIIT, and were randomized to ingest 100 μg·day‐1 of vitamin D3 or placebo. Response to an oral glucose tolerance test (OGTT) was determined at baseline and at 72 h postintervention. Glucose tolerance was improved as a result of the HIIT intervention, shown through a reduction in glucose and insulin concentrations during the OGTT, accompanied by a decrease in glucose (829 ± 110 to 786 ± 139 mmol·h−1·L−1; P = 0.043) and insulin (8101 ± 4755–7024 ± 4489 mU·h−1·L−1; P = 0.049) area under the curve (AUC). Supplementation increased 25‐hydroxyvitamin D3 concentration by 120% to a sufficiency status (P < 0.001). However, the consumption of vitamin D3 seemed to attenuate the glucose response during an OGTT. Triglyceride content was lowered following the intervention (P = 0.025). There was no effect of the intervention on insulin sensitivity (IS) indices: ISIM atsuda and HOMA‐IR. Our findings demonstrate that HIIT improves glucose tolerance in nondiabetic overweight and obese adults; however vitamin D3 supplementation did not proffer any additional positive effects on the measured indices of metabolic health.
Highlights
Obesity and lack of regular exercise are reported to be the leading causes of chronic diseases (Booth et al 2012) and global mortality (WHO, 2010), with exercise playing a major role in the prevention of type 2 diabetes mellitus (T2DM) (Pan et al 1997; Boule et al 2001; Knowler et al 2002)
Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society
Both waist and hip circumference were reduced (P = 0.019; P = 0.002, respectively) as a result of the High-intensity intermittent training (HIIT) program; this was accompanied by a decline in the systolic blood pressure by 6 mmHg after the 6 weeks (P = 0.004); there was no influence of vitamin D supplementation on these outcomes (Table 1)
Summary
Obesity and lack of regular exercise are reported to be the leading causes of chronic diseases (Booth et al 2012) and global mortality (WHO, 2010), with exercise playing a major role in the prevention of type 2 diabetes mellitus (T2DM) (Pan et al 1997; Boule et al 2001; Knowler et al 2002). The initial pathophysiological events in the development of T2DM are insulin resistance, glucose intolerance, and chronic hyperglycemia (Kahn 2003), suggesting interventions should address these underpinning metabolic syndromes. In addition to the low exercise status in the UK (BHF, 2015), another contributor in the etiology of chronic diseases, such as T2DM, multiple sclerosis, and cardiovascular disease, is vitamin D deficiency (Holick 2004). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.
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