Use it or lose it: Stopping exercise decreases brain blood flow
In their study paper, the researchers discuss how evidence shows endurance exercise training improves cerebrovascular health and has positive effects on the hippocampus, but what happens to these benefits if exercise ceases is somewhat unclear. Lead author J. Carson Smith, associate professor of kinesiology at UMD said it was already known that the hippocampus is important for learning and memory.
He explained that studies of mice and rats have shown exercise increases growth of new blood vessels and brain cells. Also, research shows that in older people, exercise can protect the hippocampus from shrinking. He notes:
“So, it is significant that people who stopped exercising for only 10 days showed a decrease in blood flow to brain regions that are important for maintaining cognitive health.”
Using magnetic resonance imaging (MRI) brain scans, the team measured brain blood flow in healthy, physically fit older adults aged from 50-89 years (average 61) before and after a 10-day period during which they stopped all exercise.
The results showed significant reductions in resting brain blood flow in eight brain regions - including the right and left hippocampus. The other regions included parts of the “default mode network” - a brain structure that is known to deteriorate quickly in people with Alzheimer’s disease.
However, the researchers found no significant change in cognitive function - measured using verbal fluency tests - in the participants from before to after they stopped exercising.
The participants who volunteered for the study were all “master athletes” whom the researchers describe as “a unique population and should not be considered equivalent to older adults who engage in regular moderate to vigorous intensity leisure-time physical activity.”
With an average continuous endurance training history of around 29 years, the volunteers regularly took part in national and regional events. Just before taking part in the study, they were running an average of 59 kilometers a week and training on 5 days a week.