Decline in Cardiorespiratory Fitness Speeds Up After 45

Study suggests progression also depends on smoking status, weight and exercise levels

MONDAY, Oct. 26 (HealthDay News) -- Aging does not necessarily spell a linear decline in cardiorespiratory fitness, with lifestyle factors playing an important role, according to a study in the Oct. 26 issue of the Archives of Internal Medicine.

Andrew S. Jackson, of the University of Houston, and colleagues conducted a study of 3,429 women and 16,889 men aged 20 to 96 years who underwent between two and 33 health examinations from 1974 to 2006 as part of the Aerobics Center Longitudinal Study, looking at lifestyle variables such as body mass index, smoking behavior and aerobic exercise levels, as well as cardiorespiratory fitness measured by a maximal Balke treadmill exercise test.

The decline in cardiorespiratory fitness as the study cohort aged was not linear, the researchers found, with current smokers, for example, having lower cardiorespiratory fitness, and increased body mass associated with a decline in cardiorespiratory fitness. However, those who self-reported physical activity had better cardiorespiratory fitness.

"These Aerobics Center Longitudinal Study results confirmed that lifestyle was related to cardiorespiratory fitness independent of aging. With lifestyle statistically controlled, the nonlinear decline in cardiorespiratory fitness with aging remained," the authors write. "Maintaining a low body mass index, being physically active, and not smoking are associated with higher cardiorespiratory fitness across the adult life span."

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