Improvement in Aerobic Fitness Selectively Boosts Neurocognitive Function

WESTPORT, Jul 29 (Reuters Health) - Small increases in aerobic fitness selectively improve frontally mediated executive control processes, according to study results published in the July 29th issue of Nature.

The abilities to plan, coordinate, schedule, and selectively attend to information in the environment typically show the largest declines with normal aging, Dr. Arthur F. Kramer, of the University of Illinois at Urbana-Champaign, told Reuters Health. He and colleagues theorized that improvements in cardiorespiratory fitness would lead to improvements in executive control processes.

They randomly assigned 124 sedentary adults, 60 to 75 years of age, to 6 months of aerobic walking or anaerobic stretching and toning. According to a university press release, subjects assigned to walking started with 15 minutes, 3 days a week, and gradually increased to between 45 and 60 minutes, 3 days a week. Subjects assigned to stretching met for 1 hour on 3 days a week.

At the end of the exercise program, the researchers found that subjects in the aerobic group, but not those in the anaerobic group, had improved on tests of their ability to switch between tasks, ignore task-irrelevant stimuli, and stop an action in response to a signal. In addition, subjects in the aerobic group showed significant improvement in oxygen consumption compared with those in the anaerobic group.

In an interview with Reuters Health, Dr. Kramer said that a "reasonable explanation" for the results is that improved oxygenation of tissue translates into improved brain blood flow, specifically to the frontal and prefrontal areas of the brain associated with executive control processes.

Dr. Kramer and colleagues note in the paper that the "...beneficial effect of aerobic conditioning was selective: it did not affect performance on other measures in the same tasks that were not tied to frontally mediated executive functions."

Nature 1999;400:418-419.