A new analysis of the longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) study, published online June 1, 2010 in Hypertension, shows that both physical fitness and physical activity are inversely associated with the development of hypertension over a period of 20 years [1]. But importantly, the researchers illustrate that activity was significantly associated with nonhypertensive blood-pressure readings only when fitness levels were the highest.

The study is one of the few to jointly measure fitness and activity, and distinguishing between the two is important, they explain, because physical activity is a behavior, whereas aerobic fitness is a physiologic measure.

"We know that activity is the principal behavioral determinant of fitness, and we know that being more physically active can improve one's fitness. But the activity needs to be moderate to vigorous to adequately improve fitness to see the greater health benefits," lead author Dr Mercedes R Carnethon (Feinberg School of Medicine, Chicago, IL) told heartwire . While she concedes that this may not be rocket science, she says: "We are showing this, for the first time, with objective data, and it's good that this is consistent with what we know."

People should adopt good habits early on.

Also, the measurements were taken in young adulthood "and showed that even at a time when most young people are not that worried about their heart-disease risk factors and hypertension, it's important to adopt a physically active lifestyle," Carnethon says. Activity and fitness matter because activity behaviors tend to track over time, and this work shows that activity and fitness count in relation to the long-term development of heart disease. "So people should adopt good habits early on," she observes.

Hypertension Could Be Avoided if People Improved Their Fitness

Carnethon et al tested whether fitness and activity were independently associated with the 20-year incidence of hypertension in 4618 men and women aged 18 to 30 initially, who were participating in the CARDIA study.

At baseline, fitness was estimated based on the duration of a symptom-limited graded exercise treadmill test, and physical activity was self-reported.