Key Concepts about Physical Activity versus Cardiovascular Fitness

Physical Activity versus Cardiovascular Fitness

Physical activity is not the same as cardiovascular fitness. Physical activity is defined as any bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above a basal level. In contrast, cardiovascular fitness is a distinct health characteristic, defined as “a set of attributes that people have or achieve that relates to the ability to perform physical activity”.¹ Cardiorespiratory fitness is one aspect of physical fitness, which is multidimensional and also includes muscular strength and endurance, body composition, and flexibility. The relative importance of any one of these fitness attributes depends on the health outcome of interest.

The associations between fitness and health are usually stronger than associations for reported physical activity and health. Investigations of the Aerobics Center Longitudinal Study cohort showed low cardiorespiratory fitness resulted in a 3-fold increase in risk of mortality for men and a 5-fold increase in risk of mortality for women,² whereas the risk of mortality associated with reported physical inactivity was considerably less.  Relative risk (RR) was 1.70 for men and 0.95 for women.³