Every Little Bit of Activity -- Even the Kind You Barely Notice -- May Count
Sound too good to be true? That's the finding from the National Institute on Aging's Todd Manini, PhD, and colleagues.
"Simply expending energy through any activity may influence survival in older adults," they write in The Journal of the American Medical Association's July 12 issue.
Does their theory hold water? Perhaps, says a journal editorial. Manini's finding on longevity motion is "provocative and if documented by future research would have major implications for physical activity recommendations," the editorialists write.
Manini's team studied 302 healthy adults in Pittsburgh and Memphis who were 70 to 82 years old. When the study started, participants said they had no problem climbing at least 10 stairs, walking 0.4 kilometers, or performing basic daily chores.
Researchers first checked how much carbon dioxide each participant typically exhaled.
Greater activity means greater carbon dioxide production, the researchers reasoned. Think of a sprinter panting hard after a race, compared to the calm, even breathing of a spectator watching the race.
To measure carbon dioxide production, participants drank a glass of water with "labeled" hydrogen and oxygen. Over the next four hours, the researchers checked participants' urine and blood samples to determine carbon dioxide production and total energy expenditure (amount of calories burned per day).
Participants took the carbon dioxide test twice, two weeks apart.
Calories Burned, Death Rate
The researchers then calculated how many calories each of the participants burned per day. Every calorie counted, whether it was burned in formal exercise or in digestion, household chores, or simply fidgeting.
Participants also rated their own health and reported their physical activities, whether mild (such as walking) or vigorous (jogging, for instance).
After that, their only obligation was taking two yearly phone calls -- over an average of six years -- from the researchers.
Those phone calls had a simple purpose: See which participants were still alive. Year after year, most participants picked up the phone when the researchers called. But 55 participants -- about 18% of the entire group -- died during the follow-up period.