Exercise

Definition

Exercise is physical activity that is undertaken in order to improve one's health. Physicians, physical therapists, and researchers have found that exercise plays an important role in the maintenance of brain, nerve, and muscle function in the human body. New research suggests that exercise may delay mental deterioration with age and disease, and perhaps even promote neurogenesis (nerve cell growth).

Description

Health care professionals recommend regular exercise because it increases energy, contributes to overall health, improves sleep, increases life expectancy, and enhances lifestyle. In terms of specific medical disorders, exercise has been shown to prevent or delay the onset of coronary artery disease, bone loss and osteoporosis, some types of cancer, and stroke.

Generally, exercise is categorized into the following four types:

• Aerobic exercise focuses on strengthening the heart, lungs, and circulatory system. Its major goal is to increase the heart rate and breathing rate. Examples of aerobic exercise include jogging, bicycling, swimming, and racket sports.
• Strength training focuses on strengthening muscles and joints. It also improves balance and increases metabolism. Weightlifting is the most common form of strength training.
• Balance exercises are used to improve stability. They stimulate the vestibular system, which includes muscles, joints, sensory organs, the inner ear, and the brain.
• Stretching exercises improve flexibility, which helps prevent injury during other forms of exercises and may decrease chronic pain. Stretching exercises include yoga, tai chi, and basic stretches.

All four types of exercises have been found to be important to maintaining brain, nerve, and muscle health.

Exercise and the brain

Exercise is particularly beneficial to the health of the brain. It has long been known that exercise causes the endocrine system to release serotonin and dopamine, hormones in the brain that produce feelings of euphoria and peacefulness. These hormones often allow people who exercise to think more clearly and perform mental tasks more easily. Exercise has also been successfully used as a treatment for depression, used in lieu of prescription antidepressants.

A 2003 study on mice suggests that new brain cells can grow as a result of exercise. This neurogenesis, previously thought not to occur in adult mammals, is concentrated in the hippocampus, the part of the brain responsible for learning and spatial memory. In addition, the study found that the mice subjected to an exercise regimen had stronger synapses than the mice that were sedentary. Other research shows that nerve growth factors, called neurotropins, are stimulated by exercise. Finally, exercise increases blood flow to the brain, as well as collateral circulation, enhancing mental function and nerve cell stimulation.

Exercise and aging

Aging naturally affects a variety of processes in the human body. Exercise has many positive benefits that prevent or slow the age-related deterioration of brain, nerve, and muscle functions.

In 2001, a study reported by the Mayo Clinic showed that regular exercise in older people slowed rates of mental deterioration, including Alzheimer's disease and dementia. On tests of mental acuity, older people who exercised regularly performed just as well as younger people who did not exercise. Another study found that regular walking greatly slowed rates of mental decline in older women.

Between the ages of 30 and 90, natural aging processes result in the loss of 15–25% of the brain tissue. In particular, losses are significant in the parts of the brain consisting of gray matter, which is associated with learning and memory. The February 2003 issue of Journal of Gerontology: Medical Sciences reported that this natural degradation of gray matter in older people was significantly decreased in people who exercised regularly compared to those who did not exercise. In the study, fitness levels were determined by treadmill-walking tests and tissue degradation was measured using magnetic resonance imaging (MRI).

Balance is often affected as people age. Balance depends on input from the eyes, ears, and other sensory organs, all of which are affected by age. In addition, muscle strength and tone are required for balance. The natural aging process includes contraction of muscle tissue, and sedentary lifestyles only exacerbate the weakening of muscles. Joints supported by strong muscles are more stable than joints that are supported by weak muscles. Strength training, in particular, has the potential to counteract loss of muscle strength.

Physical therapy and the brain, nerves, and muscles

Therapeutic exercises have been designed to enhance a variety of aspects of physical fitness in patients suffering from diseases and dysfunctions. Goals of physical therapy include improving circulation, coordination, balance, and respiratory capacity. Exercises may be geared toward mobilizing joints and releasing contracted muscles and tendons.

Patients suffering from neurological disorders can be treated with a variety of physical therapies. For example, motor neuron damage or partial peripheral nerve damage may respond to a specific type of physical therapy called proprioceptive neuromuscular facilitation (PNF). PNF focuses on exercises that build muscle strength by applying resistance to muscle contraction. Patients who have experienced cerebrovascular accidents may undergo PNF combined with training for muscle strength, balance, and coordination. Multiple sclerosis is treated with PNF along with physical fitness training. Physical therapies for Parkinson disease focus on general physical fitness training, along with stretching exercises.

Resources

BOOKS

Putnam, Stephen C. Nature's Ritalin for the Marathon Mind. Hinesburg, VT: Upper Access Book Publishers, 2001.

Ratey, John. A User's Guide to the Brain: Perception, Attention, and the Four Theaters of the Brain. Vancouver, WA: Vintage Books, 2002.

OTHER

Effects on Neurologic Diseases and Mental Decline. Health and Age. (March 18, 2004). <http://www.healthandage.com/Home/gm=0!gc=2!gid6=2908>.

Frankenfield, Gay. "Exercise May Improve Learning and Memory." WebMD January 4, 2004 (March 18, 2004). <http://my.webmd.com/content/article/17/1676_50120.htm?lastselectedguid={5FE84E90-BC77-4056-A91C-9531713CA348>.

Lawrence, Star. "Train Your Brain with Exercise." WebMD July 28, 2003 (March 18, 2004). <http://my.webmd.com/content/article/67/79909.htm?lastselectedguid={5FE84E90-BC77-4056-A91C-9531713CA348>.

Warner, Jennifer. "Exercise Saves Brain Cells." WebMD January 29, 2003 (March 18, 2004). <http://my.webmd.com/content/article/60/66925.htm?lastselectedguid={5FE84E90-BC77-4056-A91C-9531713CA348>.

ORGANIZATIONS

Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. Division of Nutrition and Physical Activity, 4770 Buford Highway, NE, Atlanta, GA 30341-3724. (888) CDC-4NRG ((888) 232-4674). <http://www.cdc.gov>.

The President's Council on Physical Fitness and Sports. Department W, 200 Independence Ave., SW, Room 738-H, Washington, DC 20004. (202) 690-9000; Fax: (202) 690-5211. <http://fitness.gov/index.html>.

Juli M. Berwald