Elderly people who bustle around the house, spend much time on their feet, climb stairs, and hold down jobs might be buying themselves precious years of life.
In a new study, researchers used a precise measure of calorie burning to assess activity. A total of 302 people, ages 70 to 82, completed questionnaires regarding their daily activities. All the volunteers got around without help, and none lived in an assisted-care facility or had been diagnosed with a life-threatening illness.
Each volunteer was given water containing a harmless, easily traced isotope of oxygen. By measuring this isotope in the carbon dioxide in each participant's urine, the researchers calculated how many calories that person burned during a 2-week period in which they went about their normal activities, says study coauthor Todd M. Manini, a physiologist at the National Institute on Aging in Bethesda, Md.