A Comparison of the Effects of Aerobic and Intense Exercise on the Type 2 Diabetes Mellitus Risk Marker Adipokines, Adiponectin and Retinol Binding Protein-4

With a more sedentary population comes growing rates of obesity and increased type 2 diabetes mellitus (T2DM) risk. Exercise generally induces positive changes in traditional T2DM risk markers such as lipids, glucose tolerance, and insulin sensitivity; however alterations in concentrations of many circulating cytokines and their respective receptors are also becoming apparent. These cytokines may be early-response health risk factors otherwise overlooked in traditional T2DM risk marker analysis. Plasma levels of two adipocyte-originating cytokines, adiponectin and retinol binding protein 4 (RBP-4), alter following exercise. Adiponectin has anti-inflammatory, anti-atherosclerotic, and anti-insulin resistance roles and its secretion increases with physical activity, whilst elevated RBP-4 leads to increased insulin resistance, and secretion decreases with increasing physical activity; thus these plasma adipokine levels alter favourably following exercise. Although current data are limited, they do suggest that the more intense the exercise, the greater the positive effect on plasma RBP-4 levels, whilst lower intensity aerobic exercise may positively improve adiponectin concentrations. Therefore short-duration, high intensity training may provide a time-efficient alternative to the recommended 150？min moderate aerobic exercise per week in providing positive changes in RBP-4 and other traditional T2DM risk markers and due to increased compliance give greater health benefits over the longer term. 1. Introduction An increase in sedentary lifestyle has led to a rise in obesity, with over 60% of UK adults and 30% of UK children being overweight. Obesity gives rise to the increased prevalence of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD), two of the leading causes of mortality and morbidity [1, 2]. In the UK there are 3.5 million diagnosed diabetes sufferers, and prevalence is projected to increase to 5 million by 2025; this needs to be addressed to reduce mortality and morbidity rates and minimise the economic costs of T2DM and related diseases [3]. A sedentary lifestyle has been shown to disrupt biochemical processes including the preservation of specific insulin-sensitive glucose transporters (GLUT4), which help maintain constant plasma-glucose levels [4], and the regulation of anti-inflammatory mediators [5]. The disruption of these processes can be observed by measuring specific T2DM risk factors, such as mass index (BMI), lipid profile, body fat index (BFI), glucose tolerance and insulin sensitivity tests, and plasma inflammatory