In the Journals
You can lose cardiovascular endurance after stopping exercising for a few weeks, but what impact does extended time off have on your brain? A small study published August 2016 in Frontiers in Aging Neuroscience examined cerebral blood flow in physically fit older adults ages 50 to 80 years before and after a 10-day period during which they stopped all exercise. The participants, half of whom were men, were all defined as master athletes who had participated in endurance exercise for at least 15 years. Their routines included at least four hours of high-intensity endurance training per week.
Using MRI brain imaging techniques, researchers found that after the athletes stopped exercising, blood flow decreased 20% to 30% in eight brain regions, including the left and right hippocampus. The hippocampus is responsible for learning and memory and is one of the first brain regions to shrink in people with Alzheimer's disease.
However, the researchers were quick to point out that they found no evidence of cognitive decline over the 10-day period—just that brain blood flow was reduced. They also did not assess the role of exercise intensity or determine whether the drop in brain blood flow could occur sooner than 10 days. Previous studies have shown that exercise can increase the growth of new brain blood vessels and brain cells. This study supports the message that exercise can contribute to brain health, but consistency also is key.