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Nice study that explains why sitting for long periods is so unhealthy - it reduces blood flow to the brain (cerebral blood flow) . The results from a study conducted in the United Kingdom (UK) found that prolonged, uninterrupted sitting (4 hours in the study) in healthy office workers reduced cerebral blood flow. However this was offset when frequent, short-duration walking breaks were taken - about 2 minutes of walking every 30 minutes. However, taking a 8 minute walking break every 2 hours did not have the same positive effect - even though that was the same amount of walking over the 4 hour period.

Maintaining good blood flow to the brain is a great reason to stretch your legs and walk a few minutes whenever possible, preferably at least every 30 minutes - whether at work or at home. From Medical Xpress:

Sitting for long hours found to reduce blood flow to the brain

A team of researchers with Liverpool John Moores University in the U.K. has found evidence of reduced blood flow to the brain in people who sit for long periods of time. In their paper published in the Journal of Applied Physiology, the group outlines the experiments they carried out with volunteers and what they found.  ...continue reading "Sitting For Long Periods and Reduced Blood Flow To the Brain"

What happens to your brain when you stop exercising? The results of this Univ. of Maryland study should be a wake up call for those who are not quite convinced of exercise's health benefits to the brain. The researchers examined cerebral blood flow in athletes (ages 50-80 years, who were recruited from running clubs) before and after a 10-day period during which they stopped all exercise. Using MRI brain imaging techniques, they found a significant decrease in blood flow to several brain regions important for cognitive health, including the hippocampus, after they stopped their exercise routines.

As the researchers pointed out: "...the take home message is simple -- if you do stop exercising for 10 days, just as you will quickly lose your cardiovascular fitness, you will also experience a decrease in blood brain flow." The only good news was that there were no differences on cognitive measures both before and after stopping exercise for 10 days. From Science Daily:

Use it or lose it: Stopping exercise decreases brain blood flow

We all know that we can quickly lose cardiovascular endurance if we stop exercising for a few weeks, but what impact does the cessation of exercise have on our brains? New research led by University of Maryland School of Public Health researchers examined cerebral blood flow in healthy, physically fit older adults (ages 50-80 years) before and after a 10-day period during which they stopped all exercise. Using MRI brain imaging techniques, they found a significant decrease in blood flow to several brain regions, including the hippocampus, after they stopped their exercise routines.

"We know that the hippocampus plays an important role in learning and memory and is one of the first brain regions to shrink in people with Alzheimer's disease," says Dr. J. Carson Smith, associate professor of kinesiology and lead author of the study, which is published in Frontiers in Aging Neuroscience in August 2016. "In rodents, the hippocampus responds to exercise training by increasing the growth of new blood vessels and new neurons, and in older people, exercise can help protect the hippocampus from shrinking. So, it is significant that people who stopped exercising for only 10 days showed a decrease in brain blood flow in brain regions that are important for maintaining brain health."

The study participants were all "master athletes," defined as people between the ages of 50 and 80 (average age was 61) who have at least 15 years history of participating in endurance exercise and who have recently competed in an endurance event. Their exercise regimens must have entailed at least four hours of high intensity endurance training each week. On average, they were running 36 miles (59 km) each week or the equivalent of a 10K run a day! Not surprisingly, this group had a V02 max (maximum volume of oxygen) above 90% for their age. This is a measure of the maximal rate of oxygen consumption of an individual and reflects their aerobic physical fitness.

Dr. Smith and colleagues measured the velocity of blood flow in brain with an MRI scan while they were still following their regular training routine (at peak fitness) and again after 10 days of no exercise. They found that resting cerebral blood flow significantly decreased in eight brain regions, including the areas of the left and right hippocampus and several regions known to be part of the brain's "default mode network" -- a neural network known to deteriorate quickly with a diagnosis of Alzheimer's disease. This information adds to the growing scientific understanding of the impact of physical activity on cognitive health.

New research showed that eight days after a concussion, the concussed athletes (football players) looked and felt like they had recovered (clinical recovery), but MRIs showed that there were still neurophysiological abnormalities (significant blood flow decrease) in their brains. They did not look at if and when the blood flow returned to normal, but that research also needs to be done.

It is very disturbing to look at both this research and also the finding that the off-season is not enough for high school football players to recover from the repeated hits (not concussions, but sub-concussive hits) that they receive during the football season (Nov. 24, 2015 post). Do student football players really know and understand the dangers to their brains from the repeated hits and also concussions that occur in football? From Medical Xpress:

Reduced blood flow seen in brain after clinical recovery of acute concussion

Some athletes who experience sports-related concussions have reduced blood flow in parts of their brains even after clinical recovery, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA). The results suggest a role for MRI in determining when to allow concussed athletes to return to competition.

Decisions to clear concussed athletes to return to action are typically based on symptoms and cognitive and neurological test results. However, there is increasing evidence that brain abnormalities persist beyond the point of clinical recovery after injury. To find out more, researchers from the Medical College of Wisconsin in Milwaukee studied concussed football players with arterial spin labeling, an advanced MRI method that detects blood flow in the brain.

Dr. Wang and colleagues studied 18 concussed players and 19 non-concussed players. They obtained MRI of the concussed players within 24 hours of the injury and a follow-up MRI eight days after the injury and compared results with those of the non-concussed players. Clinical assessments were obtained for both groups at each time point, as well as at the baseline before the football season.

The concussed players demonstrated significant impairment on clinical assessment at 24 hours post-injury, but returned to baseline levels at eight days. In contrast to clinical manifestation, the concussed players demonstrated a significant blood flow decrease at eight days relative to 24 hours post-injury, while the non-concussed players had no change in cerebral blood flow between the two time points.

"In eight days, the concussed athletes showed clinical recovery," Dr. Wang said. "However, MRI showed that even those in clinical recovery still had neurophysiological abnormalities. Neurons under such a state of physiologic stress function abnormally and may become more susceptible to second injury." "For years, we've relied on what athletes are telling us," Dr. McCrea said. "We need something more objective, and this technology may provide a greater measurement of recovery."