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Exerise and the Brain: It Will Make you Want to Work Out
Len Kravitz, Ph.D.

A plethora of scientific evidence exists that clearly depicts how regular aerobic exercise and resistance training can help to prevent and/or manage hypertension, coronary heart disease, stroke, type II 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 is 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.

Exercise and Brain Health in Children
Sibey and Etnier (2003) concluded in their research review that a significant positive relationship exists between physical activity and cognitive function in children aged 4-18 years. They noted that physical activity improves a youth's perceptual skills, intelligence quotient, achievement, verbal tests, mathematic tests, developmental level and academic readiness. Hillman and colleagues (2008) propose the findings with brain function in youth clearly indicate that exercise early in a person's life can be of great magnitude for the improvement of cognitive health during childhood and this may extend throughout one's adult lifespan. The authors continue that many physical activity requirements in schools have been reduced or eliminated to increase a student's academic performance and yet no evidence exists that the removal of exercise has positively influenced academic achievement. In fact, Field, Diego and Sanders (2001) showed that high school seniors who did more exercise and sports participation (7 or more hours per week) had higher grade averages, used drugs less frequently, and had better parental relationships than those who did little exercise and sports participation (<2 hours) a week. van Prag (2008) suggests that aerobic exercise in childhood might increase the resilience of the brain later in life, resulting in what is called cognitive reserve (the mind's resilience to brain neurological damage). Although unclear at this time, Hillman et al. hypothesize the mechanism of this cognitive reserve may be attributed to enhanced cortical (i.e., the cerebral cortex which is involved with higher order processing such as information processing and language) development, promoting lasting changes in brain function and structure.

Exercise and Brain Health in Adults
Hillman and colleagues (2008) highlight that there is very little research on the cognitive function and exercise with young adults. The authors note that most of the research involving young adults does so merely to better describe and explain the changes in brain health occurring in older populations. However, van Prag (2008) asserts that exercise does improve cognition in young and older adults. Yaffe and colleagues (2001) studied 5,925 elderly women (&Mac179; 65 years of age) over a 6-8 year range of time in which they measured cognitive function. Their 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 (1 block estimated at about 170 yards) and energy expenditure in time spent doing recreational activities. In an invited review, Kramer, Erickson and Colcombe (2006) summarize that several studies suggest a significant, and often times considerable, relationship between physical activity and increased cognitive function in adulthood. These authors suggest that physical activity may impart a neuroprotective effect in the brain, boosting brain health and cognitive functioning.

What Cognitive Process Seem to be Optimally Affected by Exercise?
Kramer, Erickson and Colcombe (2006) explain that the largest positive effects observed from exercise on cognition are in areas referred to as 'executive central command'. The researchers continue that 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.

What Type of Exercise Programs is Best To Improve Cognitive Function?
It should be noted that the majority of the exercise and brain function research has been done using cardiovascular exercise as the intervention, and it is considered the most significant form of exercise for improved brain function (Hillman, Erickson, Kramer, 2008). However, Kramer, Erickson and Colcombe (2006) propose that programs combining aerobic exercise, resistance training and flexibility are quite effective for cognitive function improvement, although the underlying mechanisms why are speculative at this time. The authors hypothesize that the unique differences in flexibility, strength training and cardiovascular exercise may encourage a broad range of neural and chemical adaptations in the brain.

What are the Mechanisms that Mediate the Effects of Exercise on Brain Health?
Most of the research in understanding the mechanisms of how exercise affects brain function has been done with animal models. Much of observed changes in the brain involve neurogenesis (new nerve cell generation), neurotransmitters (chemical substances that transmits 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 continues that exercise is the strongest neurogenic stimulus (as observed in animal model studies). As well, the robust effect of exercise on neurogenesis is maintained through life in animals that are continuously exercising. Much of this neurogenesis occurs in the hippocampus of the brain, which is an important area for leaning and memory (van Praag). In fact, Hillman and colleagues (2008) state that this 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 resulted in an increase in some brain neurotransmitters that induced a 'runners high' effect with some endurance exercisers (Hillman, Erickson and Kramer, 2008). Presently, other neurotransmitters have been shown to be increased from exercise and appear to increase the synapse communication capacity in the brain. Lastly, 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.

Exercise and Brain Health Conclusions
The recent research impressively shows that being physical activity has multiple positive effects on brain function over the course of a lifetime. At this time, however, literally nothing is known as to what exercise design (mode, intensity, duration, and frequency) best improves brain health. However, a new 'buzz' phrase to enthusiastically promote with clients and students (besides the many other health benefits of exercise) is that cardiovascular exercise, resistance exercise and flexibility are 'neuroprotective' to the mind and increase a person's 'executive central command' ability to critically think and resolve life's many challenges. Doesn't that make you want to workout?

Side Bar 1. 10 'Fascinating' Facts about the Brain
Here are some interesting bits of information about the brain.
1) The average brain, which weighs about 3 lbs, has approximately 100 billion neurons.
2) There are about 100,000 blood vessels in the brain.
3) You continue to make new neurons throughout life as long as you use your brain in mental activities.
4) The brain uses about 20% of the total oxygen of the body at rest.
5) Excessive stress can alter brain cells, structure and function.
6) You can't tickle yourself because the brain can distinguish between unexpected touch and your own touch.
7) While awake, your brain generates between 10 and 23 watts of power-or enough energy to power a light bulb.
8) Every time you blink, the brain 'kicks in' to keeps things illuminated so the world doesn't go dark during the blink (which we do about 20,000 times a day).
9) The average number of thoughts that you experience each day is about 70,000.
10) That brain is 75% water.
Source: Nursing Central Assistant (Retrieved 10-31-09)

@Bio:Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, Albuquerque, where he won the Outstanding Teacher of the Year award. Len was recently honored with the 2009 Canadian Fitness Professional Specialty Presenter of the Year award and chosen as the American Council on Exercise 2006 Fitness Educator of the Year. He has also received the prestigious Can-Fit-Pro Lifetime Achievement Award.

Field, T., Diego, M., and Sanders, C.E. (2001). Exercise is positively related to adolescents' relationships and academics. Adolescence, 36(141), 105-110.

Hillman, C.H., Erickson, K.I, and Kramer, A. F. (2008). Be smart, exercise your heart: exercise effects on brain and cognition. Nature Reviews Neuroscience, 9(1), 58-65.

Kramer, A.F., Erickson, K.I., and Colcombe, J. (2006). Exercise, cognition, and the aging brain. Journal of Applied Physiology, 101, 1237-1242.

Kravitz, L. (2007). The 25 most significant health benefits of physical activity and exercise. IDEA Fitness Journal, 4(9), 54-63.

Sibley B.A. and Etnier J.L. (2003). The relationship between physical activity and cognition in children: a meta- analysis. Pediatric Exercise Science, 15:243-256.

van Prag, H. (2009). Exercise and the brain: something to chew on. Trends in Neuroscience, 32(5), 283-290.

Yaffe, K., Barnes, D., Nevitt, M., Lui, L.Y., and Covinsky, K. (2001). A prospective study of physical activity and cognitive decline in elderly women: women who walk. Archives of Internal Medicine, 161(14), 1703-1708.