Small amounts of physical activity are associated with a significant decreased risk of cardiovascular disease (CVD) even in individuals with an inactive lifestyle, according to research published in the Journal of the American College of Cardiology.
Regular physical activity and exercise training have been shown to improve CV health and decrease CVD and CV mortality. In this meta-analysis, researchers examined the benefits of exercise volume and intensity with CV risk. They found that the association between physical activity and CVD is curvilinear, which indicates that even a slight change from an inactive lifestyle to a mild or moderately active lifestyle can significantly reduce the risk of CVD, while further increasing exercise volumes will produce a smaller risk reduction.
Specifically, high-intensity interval training (≥6.0 metabolic equivalent of task [METs]) leads to greater improvements in cardiorespiratory fitness when compared with moderate intensity activities (3.0-5.9 METs of energy expenditure). MET score uses exercise intensity (a multiple of the resting metabolic rate) from the Compendium for Physical Activities multiplied by an assessment of frequency (sessions per week) and duration (hours per week) to calculate the exercise volume in MET-h/week.
The maximal risk reduction for CVD mortality was placed at 41 MET-hr/week, which is 3.5 to 4 times greater than the recommended volume and equals 547 minutes per week of moderate-intensity exercise at 4.5 METs or 289 minutes per week of vigorous-intensity exercise at 8.5 METs. Risk of CVD mortality was reduced by 45% in individuals who performed exercise at this volume (hazard ratio [HR]: 0.55; 95% confidence interval [CI]: 0.46-0.66) compared with inactive controls. Beyond 11 MET-hr per week, there was no observed further CVD risk reduction in vigorous-intensity exercise.
Patients with established CVD can also reduce the risk of recurrent CVD events with physical activity. Guidelines from the American College of Cardiology and American Heart Association recommend 30 to 60 minutes of moderate-intensity activity per day for healthy adults. In addition, a meta-analysis of 504 studies suggests that adding resistance exercise to aerobic exercise produces improvements in muscle strength and body fat compared with aerobic exercise alone.
“Adding strength training to aerobic programs tends to produce larger increases in cardiopulmonary fitness and improvements in quality of life (QOL) in patients with CVD,” the authors wrote. “Increased QOL may occur because the increase in exercise capacity and strength increase self-confidence and independence after a CVD event.”
In patients who experienced myocardial infarction, exercise-based rehabilitation demonstrated a lower risk of all-cause mortality (odds ratio [OR]: 0.74; 95% CI: 0.58-0.95), CVD mortality (OR: 0.61; 95% CI: 0.40-0.91), cardiac mortality (OR: 0.64; 95% CI: 0.46-0.88), and reinfarction (OR: 0.54; 95% CI: 0.38-0.76). Similar results were seen in patients with coronary heart disease (all-cause and CVD mortality reductions; relative risk [RR]: 0.87; 95% CI: 0.75-0.99 and RR: 0.75; 95% CI: 0.63-0.87, respectively).
While exercise and training programs appear to benefit most people, researchers did acknowledge the possibility of individuals with genetic predispositions for CVD who should not exercise excessively. These individuals may have desmosomal proteins associated with right ventricular cardiomyopathy presented in earlier in life and showed signs of more severe disease than individuals with similar genetic mutations but whose lifestyles are less physically active.
“The available evidence should prompt clinicians to strongly recommend low and moderate exercise training for the majority of our patients,” the authors concluded. “Equally important are the initiatives to promote population health at large through physical activity across the life span, as it modulates behavior from childhood into adult life.”
Eijsvogels T, Molossi S, Lee D, Emery M, Thompson P. Exercise at the Extremes: The Amount of Exercise to Reduce Cardiovascular Events. J Am Coll Cardiol. 2016; 67(3):316-329. doi: 10.1016/j.jacc.2015.11.034.