Improving brain function While sport and exercise have long been linked to improved mental health, only recently have researchers realized that the mental effects of exercise are far more profound and complex than they once thought.
Aerobic exercise helps the heart pump more blood to the brain, increasing the flow of oxygen and nourishment to brain cells. At the same time, as muscles work, they send chemical signals to the brain that trigger the production of brain-derived neurotrophic factor (BDNF). With regular exercise, the body builds up BDNF and the brain’s nerve cells start to branch out, join together and communicate with each other in new ways. This is the fundamental physiological process underlying all learning — every added connection between brain cells signifies a new fact or skill that has been learned and saved for future use. BDNF makes this learning process possible. Consequently, brains with more BDNF have a greater capacity for knowledge, while brains that are low in BDNF have difficulty absorbing new information.
BDNF levels remain fairly constant in adulthood but, as people begin to age, their individual neurons slowly start to die off. Scientists used to think this loss was permanent, but animal studies over the last decade have shown that the replacement of nerve cells can be triggered quite easily by exercise. A study published in March 2007 in the Proceedings of the US National Academy of Sciences, extended this finding to humans for the first time, showing that it is possible to grow new nerve cells in the brain through exercise. After placing participants on a three-month aerobic exercise program, researchers found that all the subjects appeared to grow new neurons in the brain, with those who experienced the greatest cardiovascular fitness gains showing the most nerve cell growth.
Other experiments have shown that this growth is concentrated in the brain’s hippo campus, in the area that controls learning and memory, as well as the frontal lobes where executive functioning — higher-order thought such as decision-making, multitasking, and planning — resides.
Exercise has been found to restore the hippo campus to “a healthier, younger state” and to cause the frontal lobes of the brain to increase in size. In numerous studies of men and women in their 60s and 70s, brisk walking and other aerobic workouts have yielded improvements in executive functioning. Subjects have fared better on psychological tests, answering questions more accurately and quickly. According to one study, “It’s not just a matter of slowing down the aging process. It’s a matter of reversing it.”Early studies also suggest that people who exercise at least a few times a week tend to develop Alzheimer’s less often, and later in life, than their more sedentary counterparts.
As far as scientists know, new neurons cannot grow in other parts of the brain, but these regions benefit from exercise in other ways. Blood volume, like brain volume, increases with exercise. As a result, active adults have less inflammation in the brain. They also have fewer small, barely perceptible cardiovascular strokes that can impair cognition without the person even knowing. Dopamine , serotonin, and nor epinephrine levels in the brain are also all elevated after exercise, creating greater focus and calm and reducing impulsivity . The effects of physical exertion on the brain are even more potent when it comes to children, because their brains are still developing. Until about the age of 20, children and youth don’t have fully developed frontal lobes, so they engage other parts of the brain to perform necessary functions, including those involved in learning. In a study of third- and fifth-grade physical education students, exercise accelerated not just executive functioning, but a broad variety of skills ranging from math to logic to reading.
Based on this research, many educators are now advocating for strengthened physical education in public schools, arguing that longer physical education classes can help to ensure students’ success in other subjects. This is consistent with a number of studies conducted over the past half century that show that significant periods of daily physical activity in school do not impair academic achievement and, in fact, can improve it. Questions remain about why some forms of exercise affect the brain far more than others. Most researchers have focused on aerobic exercise. The few studies that have examined stretching, toning and weightlifting have found little or no effect on cognition.
Researchers also don’t have a clear idea of how much exercise is too much. Caution is recommended with children, because they are generally not developmentally ready to engage in extended periods of high-intensity exercise. ( For more information on exercise guidelines for children and youth.
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