Hypertension is the most common risk factor for heart disease, stroke, and renal disease and has been identified as a leading cause of mortality. In a recent meta-analysis of 13 prospective cohort studies, high-level recreational physical activity was associated with decreased risk of developing hypertension when subjects were compared to a reference group with low-level physical activity (RR 0.81). In another meta-analysis that included 30 studies involving patients with existing hypertension, aerobic endurance training was shown to reduce blood pressure by 6.9/4.9 mm Hg.
Type 2 diabetes is a worldwide problem with significant health, social, and economic implications. Diabetes results from a complex interplay of environmental and genetic components. There is strong evidence that such modifiable risk factors as obesity and physical inactivity are the main nongenetic determinants of the disease. Current diabetes treatments can help control hyperglycemia and slightly reduce diabetic complications, but cannot eliminate all the adverse consequences and have had limited success at reducing macrovascular complications. Since current methods for treating diabetes remain inadequate, prevention of the disease is preferable.
Stroke is the third leading cause of death in Canada, where 5.5% of all deaths are due to cerebrovascular diseases. Physically inactive people have a significantly elevated stroke risk (RR 1.60). In a systematic review, high levels of physical activity were associated with a 31% risk reduction. The reduced risk of stroke is seen in both men and women, and it appears that this benefit may be present for both ischemic and hemor-rhagic stroke.
Cancer is now the leading cause of death among Canadians, accounting for 29.9% of all deaths (more than MI and stroke combined). Population studies from the 1980s have identified an increased risk of developing cancer among physically inactive people.[4,20] In the NHANES I survey, physical inactivity was associated with a relative risk of 1.8 for men and 1.3 for women compared with their physically active counterparts. Multiple studies provide compelling evidence that high physical fitness levels are associated with a reduced risk of developing and dying from cancer. A recent meta-analysis confirmed that fitness is inversely related to cancer mortality: individuals with high cardiorespiratory fitness levels had a 45% reduced risk of total cancer mortality (RR 0.55) when compared with their unfit peers, independent of adiposity.
Depression is associated with poorer adherence to medical treatments and reduced health-related quality of life, as well as increased disability and health care utilization. Furthermore, depression is independently associated with increased cardiovascular morbidity and mortality, and is commonly seen in patients with CHD.