A recent study has shown that teenage boys who are fit and healthy turn out to be smarter and successful adults.
The study, conducted by Nancy Pedersen of the University of Southern California and colleagues in Sweden, showed that better cardiovascular health among teenage boys correlates to higher scores on a range of intelligence tests - and more education and income later in life.
"During early adolescence and adulthood, the central nervous system displays considerable plasticity. Yet, the effect of exercise on cognition remains poorly understood," Pedersen said.
Pedersen, lead author Maria Aberg of the University of Gothenburg and their colleagues looked at data for all 1.2 million Swedish men born between 1950 and 1976 who enlisted for mandatory military service at the age of 18.
In every measure of cognitive functioning they analyzed - from verbal ability to logical performance to geometric perception to mechanical skills - average test scores increased according to aerobic fitness.
However, scores on intelligence tests did not increase along with muscle strength, the researchers found.
"Positive associations with intelligence scores were restricted to cardiovascular fitness, not muscular strength, supporting the notion that aerobic exercise improved cognition through the circulatory system influencing brain plasticity," Pedersen said.
The results of the study also showed the importance of getting healthier between the ages of 15 and 18 while the brain is still changing.
Boys who improved their cardiovascular health between ages 15 to 18 exhibited significantly greater intelligence scores than those who became less healthy over the same time period.
Over a longer term, boys who were most fit at the age of 18 were more likely to go to college than their less fit counterparts.
The study appears in the current issue of PNAS Early Edition.