August 2011: Even if you can’t squeeze in the recommended 30 minutes a day of exercise, a new study from Taiwan suggests that a little activity is still better than none at all. Just 15 minutes a day of exercise, or 90 minutes a week, was associated with a 14% lower mortality rate and an extra 3 years of projected life expectancy, compared to no exercise at all. Researchers quizzed 416,000 adults on their exercise habits and calculated their projected life expectancy, then followed participants for about 8 years. Both women and men benefited from as little as 15 minutes of daily exercise, and each extra 15 minutes of daily activity was associated with an additional 4% lower risk of death. An editorial accompanying the findings said the study “may convince many individuals that they are able to incorporate physical activity into their busy lives. – The Lancet”

Tufts Health and Nutrition Letter, January 2012

People at higher genetic risk for Alzheimer’s disease may be able to offset that propensity by exercising, according to a new observational study at Washington University in St. Louis. Researchers used PET scans to image the brains of 163 participants, ages 45-88, who tested normal on a test for cognitive decline. They identified 52 as carriers of APOE epsilon-4, a genetic risk factor for Alzheimer’s. Among sedentary APOE epsilon-4 carriers, the scans showed greater buildup of amyloid plaques in the brain associated with the development of Alzheimer’s. But the carriers who were physically active, meeting the American Heart Association guidelines for regular exercise, showed no more buildup of amyloid plaques than found in the brains of non-carriers. Although the study wasn’t designed to prove cause and effect, the scientists noted that the genetic risk “makes beneficial lifestyle factors, such as exercise, preferentially important.” – Archives of Neurology