Role of exercise training on cardiovascular disease in persons who have type 2 diabetes and hypertension

Type 2 diabetes and cardiovascular health

Type 2 diabetes is associated with dysfunction and failure of various organs, especially the heart and peripheral blood vessels. The molecular basis for type 2 diabetes is poorly understood but insulin resistance and β-cell dysfunction are well-documented [1], [2]. Environmental influences and genetic factors [3], [4], and in particular, the increasing prevalence of obesity [5] and a sedentary lifestyle [6] are likely contributors to the increasing prevalence of type 2 diabetes.

Two other

The coexistence of type 2 diabetes and hypertension

Hypertension is associated with diabetes, largely independent of age and obesity [22], although abdominal visceral obesity is an especially strong risk factor for the development of both conditions [23]. Hypertension is part of the metabolic syndrome [24], with a prevalence as high as 60% in patients who have type 2 diabetes [25]. According to The Seventh Report Of The Joint National Committee On Prevention, Detection, Evaluation, and Treatment Of High Blood Pressure [26], diabetes is a

Exercise training for diabetes and hypertension

The American College of Sports Medicine Position Stand on “Exercise and Type 2 Diabetes” [25] says, “physical activity, including appropriate endurance and resistance training, is a major therapeutic modality for type 2 diabetes.” The American Diabetes Association Clinical Practice Recommendations 2002 [32] says “the possible benefits of exercise in type 2 diabetes are substantial.” Data from the National Health Interview Survey [33] demonstrated that among a diverse spectrum of adults who had

Left ventricular diastolic dysfunction: a precursor to heart failure

Heart failure is a frequent consequence of type 2 diabetes, independent of coronary artery disease [49], [50]. The most common feature of the diabetic heart is abnormal early left ventricular diastolic filling which suggests reduced compliance or prolonged relaxation [51]. Several mechanisms for diabetic cardiomyopathy have been proposed, including small and microvascular disease, autonomic dysfunction, metabolic derangements, and interstitial fibrosis [50]. Hypertension also is associated with

Exercise and left ventricular diastolic dysfunction

The age-related decline in early diastolic filling is less pronounced in healthy, older persons who have a long history of endurance exercise compared with their sedentary peers [74], [75]. Moderate-intensity aerobic and resistance exercise for 10 weeks improved LVDD in men who had mild hypertension [76]. In healthy normotensive men, 60 to 82 years of age and 24 to 32 years of age [77], aerobic training for 6 months increased early diastolic filling at rest and during acute exercise by 14%,

Impairment of endothelial vasodilator function

Impaired endothelium-dependent vasodilator function in the micro- and macrocirculation, which is mediated primarily by nitric oxide, is well-established in type 2 diabetes [81], [82], [83], [84], [85], [86], [87]. An attenuation of leg blood flow secondary to impaired endothelium-dependent vasodilation was demonstrated in patients who had type 2 diabetes [88]. This mechanism may be of importance in determining the leg ischemic threshold in diabetic individuals who have peripheral arterial

Exercise and endothelial vasodilator function

Exercise increases blood flow to active muscles; the elevated shear stress on the vessel walls could be a mechanism for the increased production of endothelium-derived nitric oxide that leads to smooth muscle relaxation and vasodilation [94]. In a rat model of noninsulin-dependent diabetes [95], 16 weeks of running, but not food restriction or a sedentary condition, improved endothelial vasodilator function in the aorta—presumably because of an increase in nitric oxide—as suggested by increased

Increased arterial stiffness

With aging and hypertension, the arteries stiffen from progressive degeneration of the arterial media, increased collagen and calcium content, and large artery dilation and hypertrophy [106]. Aortic stiffening is a stronger predictor of cardiovascular events and recently was shown to be an independent predictor of fatal stroke in patients who had essential hypertension [107]. The process of artery stiffening is accelerated by diabetes [28], [108] and insulin resistance [109]. The

Exercise and arterial stiffness

It was suggested that growth factors that are released during repeated bouts of exercise may mediate stiffness or that increases in heart rate and blood pressure during exercise condition artery walls [112]. In rats that ran on exercise wheels for 16 weeks, aortic cross-sectional compliance was higher than in sedentary animals; this indicated favorable structural adaptations to exercise [113], [114]. In the Baltimore Longitudinal Study of Aging [115], higher maximal oxygen uptake was associated

Systemic inflammation: does it underlie the development of diabetes and hypertension?

In The Women's Health Study [118], elevated C-reactive protein and interleukin-6 levels predicted the development of type 2 diabetes. This association was independent of BMI, family history of diabetes, smoking, exercise, alcohol use, and hormone replacement therapy. The Atherosclerosis Risk in Communities Study [119] reported that inflammation markers and endothelial dysfunction predicted the development of diabetes and obesity. In the Monitoring of Trends and Determinants in Cardiovascular

Exercise and inflammation

In the Cardiovascular Health Study [124], higher self-reported physical activity was associated with lower concentrations of several inflammation markers, independent of gender, cardiovascular disease, age, race, smoking, BMI, diabetes, and hypertension. In recent data from the National Health and Nutrition Examination Survey III [125], regular participants in jogging and aerobic dancing were less likely to have elevated cardiovascular markers, independent of age, race, sex, BMI, smoking, and

Exercise and lipoproteins

Patients who have type 2 diabetes have a dyslipidemia that is characterized by increases in atherogenic small, dense, low-density lipoprotein (LDL) subfractions and serum triglycerides and decreases in high-density lipoprotein (HDL)-2 cholesterol [131]. After a 4-week program of exercise training and reduced calorie diet in patients who had type 2 diabetes, reductions in body weight and improvements in glycemic control were associated with reductions in serum cholesterol and apolipoprotein B

The role of body composition and fat distribution

The increasing prevalence of type 2 diabetes is correlated highly with the prevalence of obesity [134]. Based on data from Behavioral Risk Factor Surveillance System [135], the prevalence of obesity (BMI ≥30) 19.8% in 2000 and was 20.9% in 2001 (an increase of 5.6%), whereas the prevalence of diabetes increased to 7.9% from 7.3% (an increase of 8.2%). The prevalence of BMI of 40 or higher in 2001 was 2.3%. Overweight and obesity were associated significantly with diabetes, high blood pressure,

Exercise and body composition

The exercise training–induced improvements in glycemic control can occur independent of changes in total body weight. Because few studies report body mass in terms of lean and fat mass, or visceral fat, it is uncertain if glycemic changes are independent of reductions in fat mass or increases in lean tissue. Studies in persons who did not have diabetes showed that increased fitness and activity may reduce abdominal fat [137], [142], [143]; limited data suggest a preferential loss of abdominal

Guidelines for exercise training

Generally, exercise is considered to be a standard of care for glycemic control and blood pressure reduction. Based on scientific evidence and expert opinion, exercise guidelines have been published by the American College of Sports Medicine for type 2 diabetes [25] and for hypertension [147]. Guidelines from the American Diabetes Association can be found in their Handbook of Exercise in Diabetes [148]. The key recommendations that are applicable to patients without significant health

Exercise precautions

The risk-benefit of exercise is highly favorable for most patients who have diabetes and hypertension; however, some precautions are warranted (Table 1). Moderate or severe hypertension (systolic blood pressure ≥160 mm Hg or diastolic blood pressure ≥100 mm Hg) should be controlled to lower levels before starting an exercise program [165]. An exercise stress test should be performed to rule out ischemia, complex arrhythmias, and symptoms. Although contraindications to exercise based on glycemic

Summary

Exercise training is an essential component in the medical management of patients who have type 2 diabetes and hypertension. Regular exercise improves the cardiovascular health of individuals who have these conditions through multiple mechanisms (Fig. 1). These mechanisms include improvements in endothelial vasodilator function, left ventricular diastolic function, arterial stiffness, systematic inflammation, and reducing left ventricular mass. Exercise training also reduces total and abdominal