Effects of Exercise on Prevention and Treatment of Cardiometabolic Risk

Obviously, exercise exerts many different effects at a molecular level, rendering it very difficult to attribute the final effects on disease prevention or treatment to one effect, including HDL-C.

Several prospective cohort trials have shown a reduction in the risk of type 2 diabetes in individuals participating in physical activity of moderate intensity compared with being sedentary (Wing 2010; Uusitupa et al. 2009). This difference was also found in people who walked regularly (typically >2.5 h of brisk walking) (reviewed by Jeon et al. 2007).

Regular aerobic exercise is widely considered an important tool for primary and secondary cardiovascular prevention since it is thought to reduce the risk of fatal and nonfatal events in the general population (Chapman et al. 2011; Heran et al. 2011). Although the volume of moderate-intensity physical activity able to provide a reduction in cardiovascular mortality was initially considered to range from 2.5 to 5 h/week, similar results appear to be obtainable with 1–1.5 h/week of vigorous-intensity or a combination of vigorousand moderate-intensity exercises (Wen et al. 2011; Sattelmair et al. 2011). However, a systematic review of exercisebased rehabilitation found a decrease in total and cardiovascular mortality but no difference in the number of new myocardial infarctions (Heran et al. 2011). Further, the Look AHEAD Trial which had, as a goal, to achieve and maintain a weight loss of at least 7 % by both reducing caloric intake and increasing physical activity in type 2 diabetic patients found no reduction in cardiovascular events in a 10-year follow-up (Wing et al. 2013). Similar negative results were obtained by the Finnish Diabetes Prevention Study after a 10-year lifestyle intervention (diet + exercise) in middle-aged, overweight people with impaired glucose tolerance (Uusitupa et al. 2009). To interpret these discrepant results, one has to consider differences in patient disease (type 2 diabetes versus established coronary artery disease) versus the general population, follow-up time and patient intervention type(s) (Sattelmair et al. 2011; Wen et al. 2011; Heran et al. 2011; Uusitupa et al. 2009).

Exercise improved the components of the metabolic syndrome in affected patients (Pattyn et al. 2013). In patients with established type 2 diabetes mellitus included in the Look AHEAD Trial, increased physical activity had beneficial effects on glycaemic control and cardiovascular risk factors, including HDL-C and TAGs (Wing 2010). However, in other studies, aerobic and/or resistance training was shown to improve glycaemic control, but did not change HDL-C or TAGs in adults with type 2 diabetes (Sigal et al. 2007). There were major differences in the number of patients and follow-up time between studies that should be considered when interpreting these different results (Wing 2010; Sigal et al. 2007). Furthermore, one study included a hypo-caloric diet together with exercise (Wing 2010), whereas the other only included exercise (Sigal et al. 2007). In summary, there appears to be a consensus that regular aerobic exercise raises HDL-C in a way closely related to plasma TAG reduction. Regular aerobic exercise may prevent type 2 diabetes and CVD, probably with more intensity in primary than in secondary prevention. In particular, aerobic exercise does not seem to prevent CVD in patients with established type 2 diabetes. The role of exercise-induced

changes in HDL in these outcomes is largely unknown.

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