The authors believe their findings emphasize the importance of a more active lifestyle "in protecting motor function from the adverse neurobiological effects of aging."
The study, published online in Neurology, found that the most physically active participants did not experience a reduction in their movement abilities, even when magnetic resonance imaging (MRI) demonstrated they had high levels of age-related brain damage.
"These results underscore the importance of efforts to encourage a more active lifestyle in older people to prevent movement problems, which is a major public health challenge," says study author Debra A. Fleischman, of Rush University Medical Center in Chicago, IL.
White matter hyperintensities are small areas of brain damage frequently found in the brains of older people and have been associated with impaired motor functioning such as difficulties with walking.
Research has suggested that physical activity could alter the impact of this brain damage on motor functioning in old age, and it is this hypothesis that the study authors wished to test.
Previous studies in both humans and animals have suggested that the benefit of physical activity on brain health in aging could be due, at least partially, to enhanced blood flow, the production of new blood vessels and improved maintenance of the circulatory system in the brain.
For the study, 167 participants with an average age of 80 were asked to wear movement monitors to track their exercise and nonexercise activity over the course of up to 11 days. Each participant's movement abilities were also tested, and MRI scans were utilized to assess the volume of white matter hyperintensities in their brains.
The 10% of participants who were most active were found to be more physically active than participants at the 50th percentile of activity levels to the equivalent of walking for an additional 1.5 hours a day at around 4 km/h.
Detrimental effect of brain damage more pronounced among least active participants
For the most active 10% of participants, greater volumes of white matter hyperintensities did not appear to affect the scores of their movement tests. However, among participants at the 50th percentile of activity levels, greater amounts of this brain damage were associated with significantly lower scores in the movement tests.
The average score obtained in the movement tests was 1.04. Among participants at the 50th percentile of activity levels, the researchers found that scores ranged from 1.16 for people with the least amount of brain damage to 0.9 for people with the highest amount of brain damage.
Participants with even lower levels of physical activity appeared to be even more affected by white matter hyperintensities. These results remained the same after potentially confounding factors such as body mass index and vascular disease were taken into account by the researchers.
Fleischman believes their findings may indicate that exercise can make neural networks more resilient. "Physical activity may create a 'reserve' that protects motor abilities against the effects of age-related brain damage," she suggests.
Although these findings are limited by the use of cross-sectional measures, further scans are being collected from the participants, allowing the researchers to report on long-term changes to motor functioning, levels of brain damage and physical activity in the future.
In an accompanying editorial, Dr. Richard Camicioli and Joe Verghese state that the mechanisms for the protective effect of activity on the negative effects of white matter hyperintensities are unclear.
"To determine whether physical activity is causally related to improved mobility would require a randomized study," they conclude. "Given the high prevalence of WMH [white matter hyperintensities] even in middle-aged individuals, interventions that seek to stabilize or improve gait should be performed."
Recently, Medical News Today reported on a study claiming that a spouse is more likely to increase their exercise levels if their partner does.