Exercise and the Brain: It Will Make You Want to Work Out

A plethora of scientific evidence clearly
depicts how regular aerobic exercise and resistance training can help to prevent and/or manage hypertension, coronary heart disease, stroke, type 2 diabetes,
osteoporosis, arthritis, stress, colon cancer, abnormal cholesterol levels and depression (Kravitz 2007). More recently, research on the favorable effects of exercise and brain function has been emerging.

The goal of this article is to highlight some of the known effects of exercise on brain cognition in children and adults. Cognition refers to thinking, reasoning, remembering, imagining or learning.

Sibley and Etnier (2003) conclude in their research review that a significant positive relationship exists between physical activity and cognitive function in children aged 4–18 years. These investigators note that physical activity improves young people’s perceptual skills, intelligence quotient, verbal and mathematical test scores, developmental level and academic readiness. Hillman, Erickson and Kramer (2008) propose that findings on brain function in youth clearly indicate that exercise early in life can be of great importance for improving cognitive health during childhood and that the benefit of physical exercise on brain function may extend throughout the adult lifespan.

Hillman and colleagues (2008) go on to state that many physical activity requirements in schools have been reduced or eliminated in order to focus on academic performance, and yet no evidence exists that the removal of exercise has positively influenced academic achievement. In fact, Field, Diego and Sanders (2001) have shown that high-school seniors who do more exercise and sports participation (7 or more hours per week) have higher grade averages, use drugs less frequently and have better relationships with their parents than those who do little exercise and sports participation (< 2 hours) a week.

Van Praag (2008) suggests that aerobic exercise in childhood might increase the resilience of the brain later in life, resulting in what is called cognitive reserve (less age-related degeneration of brain tissue). Although the mechanism of this cognitive reserve is unclear at this time, Hillman and colleagues hypothesize that it might be attributed to enhanced cortical development (i.e., development of the cerebral cortex, which is involved with higher-
order tasks, such as information processing and language), leading to lasting changes in brain function and structure.

Hillman and colleagues highlight that there is very little research on cognitive function and exercise in young adults. The authors note, moreover, that most studies that involve this demographic do so merely to better describe and explain changes in brain health occurring in older populations. However, van Praag asserts that exercise does improve cognition in young and older adults. Yaffe and colleagues (2001) measured cognitive function in 5,925 elderly women (≥ 65 years of age) over a 6–8 year period. The study results showed that the more physically active females in the study had the least cognitive decline. Physical activity was assessed by self-reported walking blocks (one block estimated at about 170 yards) and energy expenditure in time spent doing recreational activities. In an invited review by Kramer, Erickson and Colcombe (2006), several studies indicate a significant, and often considerable, relationship between physical activity and increased cognitive function in adulthood. These authors suggest that physical activity may impart a neuroprotective effect on the brain, boosting brain health and cognitive functioning.

Kramer, Erickson and Colcombe explain that the largest positive effects observed from exercise on cognition are in areas of the brain referred to as executive central command. The components of brain executive central command include working memory, planning, scheduling, multitasking and dealing with ambiguity (e.g., such as doubt and uncertainty). The authors emphasize that these components are often areas of substantial decline with aging.

The majority of research on exercise and brain function has used cardiovascular exercise as the intervention, and this is considered the most significant form of exercise for improved brain function (Hillman, Erickson & Kramer 2008). However, Kramer, Erickson and Colcombe propose that programs combining aerobic exercise, resistance training and flexibility are quite effective for improving cognitive function, although the underlying mechanisms are speculative at this time. The authors hypothesize that the unique differences among flexibility, strength training and cardiovascular exercise may encourage a broad range of neural and chemical adaptations in the brain.

Most of the research aimed at understanding how exercise affects brain function has been done on animal models. Many of the observed changes in the brain involve neurogenesis (new nerve cell generation), neurotransmitters (chemical substances that transmit nerve impulses across a synapse—the tiny communication gap between the neurons in the brain) and vascular (new blood vessel) adaptations (van Praag 2009). An increase in neurogenesis has been demonstrated to improve cognition. Van Praag states that exercise is the strongest neurogenic stimulus (as observed in animal model studies) and that the robust effect of exercise on neurogenesis is maintained throughout life in animals that are continuously exercising. Much of this neurogenesis occurs in the hippocampus of the brain, an important area for learning and memory (van Praag). In fact, Hillman and colleagues state that hippocampus cell proliferation is the most consistently observed effect from exercise and can occur at all stages of life.

Early brain and exercise research indicated that exercise produced an increase in some brain neurotransmitters, potentially inducing a “runner’s high” in endurance exercisers (Hillman, Erickson & Kramer 2008). Now exercise has been found to increase other neurotransmitters and appears to increase the synapse communication capacity in the brain. What’s more, aerobic exercise induces the formation of new blood vessels in the brain during childhood and adulthood, improving brain circulation (for oxygen and nutrient delivery), function and health.

The recent research impressively shows that being physically active has multiple positive effects on brain function over the course of a lifetime. At this time, literally nothing is known about which exercise design (mode, intensity, duration and frequency) best improves brain health. However, besides the many other health benefits of exercise, fitness professionals can use new “buzz” phrases to enthusiastically promote physical activity to clients and students: cardiovascular and resistance exercise, as well as flexibility training, are “neuroprotective” to the mind and increase a person’s “executive central command” ability to think critically and resolve life’s many challenges. Doesn’t that make you want to work out? n