By Amanda Gardner
TUESDAY, Dec.1 (HealthDay News) -- A strong cardiovascular system in young adulthood may boost brainpower, making for better school grades and more overall success later in life, new research suggests.
Given that most doctors and laypeople know (or should know) the benefits of exercise and its impact on healthy bodies, the authors of a new study, appearing in this week's online issue of the Proceedings of the National Academy of Sciences, are hoping the findings can influence public policy.
Doctors "have known the principal idea for 3,000 years: A healthy mind lives in an healthy body," said study senior author H. Georg Kuhn, professor for regenerative neuroscience at the Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg in Sweden. "We are aiming at politicians and educators who decide on academic curricula and budgets and how sport fits into the picture of academic success."
The study also found that genetics played a lesser role in explaining the mind-body link than did environment.
"This gets back to empowerment. You can't determine that exercise or eating well isn't going to help you because of your genetic background," said Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City and a spokeswoman for the American Heart Association. "This is showing you that, regardless of genes, what you choose to do and how you choose to live can make a difference."
The relationship between physical activity and cognitive function has been studied before, but usually in older adults (in relation to dementia) and in children.
And studies that focused on young adults, as these authors did, have tended to be smaller.
"Young adulthood is the time span in which important behavioral habits and cognitive functions are shaped," explained Kuhn. "It is the period when academic performance has the biggest impact on the future life."
This is also a time when the central nervous system is still developing, he noted.
The study was an extremely large one, involving 1.2 million Swedish men born between 1950 and 1976.
More than 250,000 of the men were sibling pairs and more than 3,000 were twins, of which 1,432 were identical twins.
The researchers took information from the time the men were conscripted into the military (age 18), which is compulsory in Sweden. This information was then correlated with information on the men's prior academic performance, how many siblings they had and what socioeconomic class they came from.
Better cardiovascular fitness was associated with higher intelligence, although muscle strength was not, the researchers found.
"The emphasis at gyms is for strength over aerobic capacity but aerobic fitness is where we need to pay our focus," said Dr. Jonathan H. Whiteson, co-director of the Joan and Joel Smilow Cardiopulmonary Rehabilitation and Prevention Center at NYU Langone Medical Center in New York City.
The twins portion of the analysis showed that environmental factors accounted for more than 80 percent of the equation, and genetics for less than 15 percent.
Any number of factors could explain why better cardiovascular fitness through exercising impacts brain function, including improved blood flow to the brain, diminished anxiety, enhanced mood and less fatigue, Whiteson said.
"We've known that aerobic exercise has been associated with improved cognitive performance. We've known that from studies dating back from the '70s," he said. "They picked the area of young men which may not have had a lot of research. This confirms what we've already known about younger and older individuals."
There's more on cardiovascular fitness at the American Sports Medicine Institute.
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