Fitness Levels Decline With Age

(October 27, 2009) - As if you didn't already know this, it gets tougher and tougher to stay in shape as you get older. Men and women become gradually less fit with age, with declines accelerating after age 45, according to a report in the Archives of Internal Medicine, one of the JAMA/Archives journals. However, maintaining a healthy body mass index (BMI), not smoking and being physically active are associated with higher fitness levels throughout adult life. (Read about "Body Mass Index" "Quit Smoking" "Getting Started on Fitness")

"The U.S. population is aging and is becoming more obese (Read about "Obesity") and sedentary," the authors write as background information in the article. "It is well documented that the cardiorespiratory fitness of men and women declines with age and that body composition and habitual physical activity are related to cardiorespiratory fitness." Low fitness levels increase the risk of diseases and interfere with older adults' ability to function independently.

Researchers studied 3,429 women and 16,889 men age 20 to 96 who participated in the Aerobics Center Longitudinal Study (ACLS) between 1974 and 2006. During the study, participants completed between two and 33 health examinations that included counseling about diet, exercise and other lifestyle factors along with a treadmill exercise to assess fitness.

Statistical models showed that while fitness levels declined continuously over time, the decrease was not linear or steady - cardiorespiratory fitness declined more rapidly after age 45. The decline for men was greater than that for women.