Cardiovascular diseases (CVDs) account for a large proportion of deaths in people over the age of 45 years, according to background information from the authors. "Numerous risk factors for CVD, including hypertension, diabetes, and hypercholesterolemia (high cholesterol), are suspected to be influenced by fitness, and these factors may mediate the association between low fitness and mortality [death]," the authors write.
Mercedes R. Carnethon, Ph.D., from Northwestern University's Feinberg School of Medicine, Chicago, and colleagues investigated whether low fitness, estimated by short duration on an exercise treadmill test, was associated with the development of CVD risk factors and whether improving fitness was associated with risk reduction.
The participants, men and women 18 to 30 years of age, were enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. The CARDIA study recruited 5,115 participants from four geographic areas (Birmingham, Ala., Chicago, Minneapolis, and Oakland, Calif.). Participants who completed the treadmill examination at baseline were followed up from 1985 - 1986 to 2000 - 2001. A subset of participants (n=2,478) repeated the exercise test in 1992 - 1993.
"After adjustment for age, race, sex, smoking, and family history of diabetes, hypertension or premature myocardial infarction [heart attack], participants with low fitness (less than 20th percentile) were 3- to 6- fold more likely to develop diabetes, hypertension, and the metabolic syndrome than participants with high fitness (at or above 60th percentile)," the authors write. "Improved fitness over 7 years was associated with a reduced risk of developing diabetes and the metabolic syndrome, but the s
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