The most striking indication of the health burden of poor fitness in the U.S. population is the strong association among poor fitness, obesity and cardiovascular risk factors that is already present in adolescents and young adults, according to a study by Northwestern University researchers.
"Findings from the study have very obvious implications for the nation's obesity epidemic," said Mercedes Carnethon, lead author on the study, published in the Dec. 21 issue of the Journal of the American Medical Association.
Carnethon is assistant professor of preventive medicine at Northwestern University Feinberg School of Medicine.
This is the first large-scale study to quantify "fitness" as opposed to physical activity physical activity is a behavior while fitness is a physiological trait.
Obesity and poor physical fitness are often related, although thin persons are not necessarily physically fit just because they are thin, Carnethon said.
Carnethon and co-researchers studied 3,100 adolescents (ages 12 to 19) and 2,200 adults (ages 20 to 49) from the cross-sectional nationally representative National Health and Nutrition Examination Survey 1999 to 2002 with no cardiovascular disease who underwent exercise treadmill testing to achieve at least 75 to 90 percent of their age-predicted maximum heart rate.
Results of the study showed that an estimated 7.5 million adolescents (34 percent) and 8.5 million adults (15 percent) have poor fitness. Prevalence of poor fitness was higher in adult females (16 percent) than males (12 percent). Non-Hispanic blacks and Mexican-Americans were less fit than non-Hispance whites.
In all age-sex groups, the greater the body mass index and waist circumference, the lower the level of fitness. In addition, total
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