AHA Emphasizes Importance of Cardiorespiratory Fitness

January 09, 2013

MUNCIE, Indiana – The American Heart Association (AHA) has published a new policy statement emphasizing the importance of cardiorespiratory fitness in the US population, noting that cardiorespiratory fitness is as strong a predictor of adverse clinical outcomes as traditional risk factors and other exercise test variables, including ST-segment depression and hemodynamic responses [1].

"Certainly, we encourage all physicians and public-health professionals to be advocating that people need to increase their physical-activity levels and would get tremendous benefit from doing so," chair of the AHA policy statement, Dr Leonard Kaminsky (Ball State University, Muncie, IN), told heartwire . "One of the points we make in our paper, though, is that the actual risk factor of low cardiorespiratory fitness, which is a very potent risk factor, is one that is underutilized out there."

You don't have to be a marathon runner or an elite-level runner to get the protective benefits of fitness.

In the statement, published January 7, 2013 in Circulation, the AHA writing committee is encouraging clinicians to assess cardiorespiratory fitness with the hope that researchers can gather more information on aerobic fitness and its related variables to identify individuals who might be at risk for adverse clinical outcomes, such as cardiovascular disease. In almost every chronic disease and risk factor, it seems, there is clearly an impact of cardiorespiratory fitness that is favorable, noted Kaminsky.

"Individuals with any condition, whether it be diabetes, hypertension, or obesity, if they increase their cardiorespiratory fitness levels, their overall risk profile is better than it is in individuals with low cardiorespiratory fitness levels but a more favorable aspect of that other condition," he told heartwire . "It seems to be a more potent variable in that sense."

Creation of a National Registry

The AHA is also advocating the creation of a national registry that includes data on cardiorespiratory fitness that would also allow researchers to track aerobic fitness over long periods of time, just as is being done with other variables such as cholesterol, blood pressure, physical-activity levels, and body weight, among others. Importantly, it would also provide more information on normative aerobic fitness levels in subsets of the population.

Speaking with heartwire , Kaminsky said one of the goals of the national registry is to increase awareness about the importance of cardiorespiratory fitness. Many of the assessments are performed in exercise centers and research settings, but not as frequently in clinical practice. While information is available in pockets of the country, including data from the Aerobics Center Longitudinal Study (ACLS), the hope is more information would allow researchers to determine normative cardiorespiratory fitness levels, via direct measurements of VO2, in groups stratified by age, sex, and body composition in large samples representative of the US population.

The registry would also help define normative values of aerobic fitness across strata of physical-activity levels. As Kaminsky noted, physical activity is simply a behavior, and while both are inversely associated with the risk of cardiovascular disease, there are factors that contribute to aerobic fitness than other physical-activity levels, including age and genetics. In addition, cardiorespiratory fitness is a more clinically meaningful measure than self-reported physical-activity levels, which are prone to considerable error.

"One of the intended consequences of being more active, however, is to increase your fitness level," said Kaminsky. "You don't have to be a marathon runner or an elite-level runner to get the protective benefits of fitness. It's really more about people who have been inactive, the sedentary individuals. If they could just become more active and increase their cardiorespiratory fitness to more average levels they would get tremendous benefit."