Type 2 diabetes has reached epidemic proportions worldwide and is associated with increased risk of cardiovascular diseases and premature mortality. Diet and physical activity (PA)-based lifestyle interventions have been shown to prevent progression to type 2 diabetes in patients at high risk. Regular PA substantially reduces the risk of type 2 diabetes and a high level of PA is associated with a substantial reduction in type 2 diabetes risk. In addition, there is strong evidence suggesting a steep inverse relationship between both PA and cardiorespiratory fitness (CRF) and mortality in patients with type 2 diabetes. Of particular concern is the dramatic, steep increase in mortality among patients with low CRF. An important point is that obese individuals who are at least moderately fit have a lower mortality risk than those who are normal weight but unfit. A large body of evidence demonstrates that exercise improves glycaemic control in type 2 diabetes; the greatest improvements are achieved with combined aerobic and resistance training. A primary goal of public health strategies is to promote PA and move patients out of the least fit, highrisk cohort by increasing PA among the least active. Any plan to deal with the global epidemic of type 2 diabetes must give major attention to low PA and how this can be reversed in the general population.
KeywordsFitness, mortality, physical activity, exercise, type 2 diabetes 1 In 2012, type 2 diabetes imposed direct and indirect costs of an estimated $245 billion in the US.2 It is estimated that low levels of physical activity (PA) causes 7 % of the global burden of disease from type 2 diabetes, and that inactivity causes more deaths than smoking.
3In addition to type 2 diabetes, low PA has been demonstrated to contribute to obesity, coronary heart disease (CHD)/myocardial infarction (MI), stroke, hypertension (HTN), dyslipidaemia, osteoporosis and cancer (colon, breast and bowel). 4,5 As a result, sedentary lifestyles are one of the most significant public health problems of the 21st century. Low PA was directly responsible for 3 % of disability adjusted life-years in the UK in 2002.6 Furthermore, it has been estimated that low cardiorespiratory fitness (CRF) was the cause of approximately 16 % of deaths in the Aerobics Center Longitudinal Study, which was more than the combined number of deaths due to smoking, obesity and diabetes in this population.7 Despite the known risks of low PA, there have been substantial declines in PA over the past decades. Over the last 50 years in the US, it has been estimated that daily occupation-related PA has decreased by more than 100 calories, 8 and household management PA has fallen by well over this amount.9 In addition to the effects of PA on morbidity and mortality, there are clear economic reasons to improve PA: a US cohort study (8,000 health plan members and national population percentage estimates derived from the National Health Interview Survey) found that low PA, overweight and obesity were associated with 23 % of ...