Physical Activity and Cardiovascular Disease Prevention: A Causal Relationship?
Based on studies linking regular physical activity to reduction in cardiovascular disease (CVD), the 2008 Physical Activity Guidelines Advisory Committee report included recommendations for 75 minutes per week of vigorous or 150 minutes per week of moderate intensity exercise.1
“Suggesting fitness and exercise—when it is deemed safe for each individual patient by his/her physician—is an important part of maintaining health. Exercise, as advocated by the American Heart Association, should be part of a comprehensive strategy to prevent CV and non-CVD,” Ravi Shah, MD, from the cardiovascular division and Harvard Medical Faculty physician at Beth Israel Deaconess Medical Center in Boston, Massachusetts, told Cardiology Advisor. “Every patient should check with his/her provider about the safety of exercise before embarking on an exercise regimen.”
In a recently published paper, Thijs M.H. Eijsvogels, PhD, from the department of physiology at Radboud University Medical Center in Nijmegen, the Netherlands and colleagues sought to summarize the evidence for CV risk reductions with exercise.
Despite a lack of classically designed clinical trials, research points to a causal relationship between physical activity and primary prevention of CVD. The authors offered several explanations for the estimated 59% reduction in CVD,1 including improved insulin sensitivity and glucose metabolism, body weight reduction, reduced triglycerides, and lowered blood pressure.1
The dose-response relationship between exercise and mortality is highlighted by the relatively large risk reductions in transitioning from an inactive state to a mild or moderately active state. In addition, even standing for 2 or more hours per day was associated with a 10% reduction of all-cause mortality compared with those who stood less (hazard ratio [HR]: 0.90; 95% confidence interval [CI]: 0.85-0.95).1
For patients who do not meet the recommended volume of exercise, benefit may still be achieved with moderate to vigorous exercise. For instance, running 68% of the recommended volume was associated with a lower all-cause mortality (HR: 0.70; 95% CI: 0.58-0.85) and CVD mortality (HR: 0.45; 95% CI: 0.31-0.66).1
In terms of intensity, high-intensity interval training was associated with improvements in cardiorespiratory fitness. However, the dose-response curve tended to flatten after 11 MET-h/week of vigorous exercise. The authors wrote, “These findings indicate that increasing volumes of moderate-intensity exercise are associated with further improvements in CVD health, whereas for vigorous intensity, lower volumes are associated with maximal risk reduction.”