A flurry of recent articles demonstrates the beneficial relationship between exercise and brainpower. What exercise does for muscles, it seems, it also does for the brain, according to the new research. And the fitter the brain, the better it works.
The basic explanation, known since the 1930s, goes something like this. Aerobic exercise helps the heart pump more blood to the brain and body; more blood means more oxygen, which leads to better-nourished brain cells and better cognition (Carmichael, 2007). But the underlying relationships remained a complex mystery. Where does it all start? In the brain? Muscles? Or maybe somewhere else?
With advances in biochemistry, brain-screening technologies, physiology and neuroscience, scientists have been able to do some disentangling. What is interesting, and new in the research, is that the trigger appears to be aerobic exercise. The exercise-cognition relationship starts in the muscles. Exercise does more to improve thinking than thinking does (Reynolds, 2012b), meaning that you will do far more to get your brain in shape if you go for a run or swim than if you just play sudoku or other mental-training games.
The enzymes responsible for spurring the reaction enter into the bloodstream every time a muscle is flexed and then travel to the brain. Once there, they spark the production of several chemicals (e.g., brain-derived neurotrophic factor, BDNF) and cause the growth of new neurons in the hippocampus, an area that controls learning and memory. With regular exercise, the body builds up BDNF levels and the brain´s nerve cells start to branch out, join together, and communicate with each other in new ways. In other words, regular exercise improves the physiology necessary for learning. Brains low on BDNF aren´t as sharp or quick (Carmichael, 2007).
The exercise-induced processes creating BDNF and growth of new neurons operate at every age. It is well known that neurons die as we age. Yet, it seems that, in the elderly, exercise increases the size of the brain´s frontal lobes, the area responsible for executive functioning and fueling higher thought patterns. Walking or cycling regularly for six months to a year has been shown to improve memory and problem solving skills by 15-20% and to increase the size of the hippocampus (which appears to be particularly sensitive to BDNF) by 2%. This is an effect equivalent to reversing brain aging by 1-2 years (Kramer, cited in Gray, 2012). But, like most everything in life, maintenance is key. Whereas new neurons and connections between them last for years, their functioning will decline within a month of inactivity (Carmichael, 2007).
The effects of exercise could be even greater for brains that are still developing. Research suggests that there is a relationship between exercise and differential volumes of specific brain regions involved in cognitive functions and that these differences may persist throughout one’s lifespan (see Chaddock, et al., 2011). Lower-fit children have smaller bilateral hippocampal volumes – and thus poorer relational memory task performance and recognition – than higher-fit children. The difference in the size of the hippocampus can be as much as 12% between fit and unfit kids. Much the same seems to happen with the the dorsal straitum, an important structure for executive control.
Higher-fit kids think more efficiently and are better multi-taskers. In research led by Arthur Kramer, director of the Beckman Institute for Advanced Science and Technology at the University of Illinois (cited in Gray, 2012), fitter children were better at crossing the street when distracted by music or holding a conversation on a hands-free mobile phone than less-fit kids. He found that, whereas fit children could cross a road in a virtual reality simulation with ease when distracted, less-fit children tended to walk at the same speed as fitter children but misjudged the speed and distance of the computer generated vehicles. In the simulation, these differences were important: the less-fit kids often ended up with the screen going red, meaning that they had been hit by oncoming traffic.
Exercise helps the brain develop well. It also primes the body and brain to withstand the effects of aging. To reap its fullest benefits, start exercising early and make exercise a lifelong habit.
Carmichael, Mary (2007). “Stronger, Faster, Smarter.” The Daily Beast. Online at: www.thedailybeast.com/newsweek/2007/03/25/stronger-faster-smarter.print.html
Chaddock, Laura, Matthew B. Pontifex, Charles H. Hillman, and Arthur Kramer (2001). “A Review of the Relation of Aerobic Fitness and Physical Activity to Brain Structure and Function in Children.” Journal of the International Neuropsychological Society 17:1-11. Online at: http://www.ncbi.nlm.nih.gov/pubmed/22040896
Gray, Richard (2012). “Regular Exercise Can Improve Memory and Learning.” The Daily Telegraph. 19 February. Online at: http://www.telegraph.co.uk/health/healthnews/9090981/Regular-exercise-can-improve-memory-and-learning.html
Reynolds, Gretchen (2012a). “How Working the Muscles May Boost Brainpower.” New York Times 9 May. Online at: http://well.blogs.nytimes.com
Reynolds, Gretchen (2012b). “How Exercise Could Lead to a Better Brain.” New York Times 18 April. Online at: http://well.blogs.nytimes.com