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The Call for a Physical Activity Vital Sign in Clinical Practice

elderly couple to the marathon in the park

According to the Bureau of Labor Statistics, the most common shared occupational health risk is sedentary behavior. Physical inactivity increases the relative risk of coronary artery disease, stroke, hypertension, and osteoporosis by 45%, 60%, 30%, and 59%, respectively. Epidemiologic data suggest that physical inactivity is associated with an increased risk of 25 chronic diseases. Because approximately 90% of American adults do not meet current physical activity guidelines, deaths attributable to physical inactivity may soon exceed those attributed to cigarette smoking. For these reasons, physical inactivity is increasingly recognized as a major public health problem.

Increasing physical activity is reflected in improved cardiorespiratory fitness, expressed as metabolic equivalents (METs; 1 MET = 3.5 mL O2/kg/min), which in turn correlates with a reduced risk of cardiovascular disease. In persons with and without heart disease, each 1-MET increase in cardiorespiratory fitness is associated with an approximately 15% reduction in mortality. In addition, individuals with low cardiorespiratory fitness have higher annual healthcare costs, higher rates of surgical complications, and are 2 to 3 times more likely to die prematurely than their comparably fitter counterparts. Collectively, these data and other recent reports suggest that the primary beneficiaries of regular exercise seem to be those constituting the bottom 20% of the cardiorespiratory fitness/physical activity continuum, and that even simple walking metrics can provide independent and additive prognostic information.

Although the American Heart Association recently emphasized that physical inactivity represents a leading cause of death worldwide, the beneficial effects of regular exercise are generally underestimated by many clinicians. Consequently, the burden of physical inactivity continues to grow as physical activity is suboptimally addressed in most clinical encounters. These represent missed opportunities to counsel patients and use proven behavioral interventions, including pedometers, accelerometers, smart-phone apps, and heart rate monitors. Accordingly, habitual physical activity, the key determinant of cardiorespiratory fitness, should be considered a “vital sign.”


The Case for a Physical Activity Vital Sign

Vital signs (eg, blood pressure, heart rate, tobacco use) are metrics that reflect key parameters underlying health and disease. Their ubiquity in clinical practice is driven by several factors. First, vital signs inform clinicians about the likelihood of future disease and the presence and severity of acute and chronic illness. Second, they provide temporal trends that may signify occult, subclinical disease or the favorable impact of lifestyle and/or pharmacologic intervention. Finally, they represent discrete quantitative measurements that can be used to educate and engage patients in the therapeutic process. In this role, vital signs are most effective when they can be linked to health outcomes that have direct meaning to both patient and provider.

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-Robert E. Sallis, MD, Aaron L. Baggish, MD, Barry A. Franklin, PhD, James R. Whitehead, BS

This article originally appeared in the September 2016 issue of The American Journal of Medicine.

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