The benefits of physical activity in preventing chronic health conditions and as a therapeutic approach for people diagnosed with them are well recognized. There is a plethora of medical and scientific evidence documenting how regular physical activity can help prevent and/or treat hypertension, type 2 diabetes, abnormal blood lipids, coronary artery disease, stroke, osteoporosis, arthritis, certain cancers and other conditions. The strength of this evidence has resulted in the American College of Sports Medicine and U.S. Department of Health and Human Services recommending that all Americans undertake a minimum of 150 minutes per week of moderate-intensity aerobic exercise and that children and adolescents participate in 60 minutes or more of daily physical activity. Unfortunately, most Americans do not achieve these recommended minimum levels.
Frequently, people who are physically active will comment that the reason they exercise is because “it feels so good when I’m finished,” and while the comment is often made with a bit of sarcasm, it actually may be quite insightful. A growing body of research has begun to demonstrate a number of positive effects of physical activity on brain function, both in youth and adults of all ages. The brain is an amazing organ, consisting of more than 100 billion nerve cells or neurons that communicate with the assistance of hundreds of different chemicals. The neurons have specialized extensions referred to as “dendrites” and “axons.” Dendrites serve as the receiving branch of the nerve cell, whereas axons handle outgoing messages to the next neuron. Dendrites and axons do not touch each other but, instead, communicate through a small chemical gap called a “synaptic junction.” It is at this junction that the electrical message from the axon is chemically converted and taken across the gap by a neurotransmitter to the receiving dendrite where it is reconverted to an electrical signal.
Communication within the brain and across the various synaptic junctions is regulated by a variety of different chemicals or neurotransmitters. A few of the more common neurochemicals that affect brain function, along with some of their basic roles, are:
- glutamate: stimulates activity
- gamma-aminobutyric acid: attenuates or slows down activity
- serotonin: influences mood, impulsivity, anger, aggressiveness
- norepinephrine: influences attention, perception, motivation, arousal
- dopamine: influences voluntary movement, cognition, working memory and learning, ability to experience pleasure and pain
- brain-derived neurotrophic factor: improves the function of neurons and encourages their growth and enhances communication and learning
- insulin-like growth factor 1: within the brain, insulin-like growth factor 1 plays a role in neurogenesis (cell growth) and learning.
The positive effects of regular exercise on these and other neurochemicals and their associated impact on overall brain function are numerous and just beginning to be understood. Exercise has been shown to stimulate the growth of cerebral blood vessels, enhance communication across synapses, boost mood and act as a natural antidepressant, augment memory and learning and increase brain density. The latter is true in white matter, which contains the nerve fibers that run throughout the brain. In essence, exercise primes the brain to enhance learning and memory and helps people age somewhat gracefully with better maintenance of cognitive function.
Research also has demonstrated that exercise and physical fitness are associated with enhanced learning and academic performance in school aged youth. This effect appears to extend to older populations and even individuals with medical conditions, such as multiple sclerosis (MS), where highly fit patients with MS have demonstrated better performance on cognitive function tests than patients with MS who are less fit.
Although our complete understanding regarding the effect of exercise on cognitive function is still in its infancy, the data are compelling and provide one more important reason to not skip daily physical activity. Regular exercise is critical to everyone’s health, physical function and cognitive well-being.