Exercise

Definition

Exercise is physical activity that is planned, structured, and repetitive for the purpose of conditioning any part of the body. Exercise is utilized to improve health, maintain fitness and is important as a means of physical rehabilitation.

Purpose

Exercise is useful in preventing or treating coronary heart disease, osteoporosis, weakness, diabetes, obesity, and depression. Range of motion is one aspect of exercise important for increasing or maintaining joint function. Strengthening exercises provide appropriate resistance to the muscles to increase endurance and strength. Cardiac rehabilitation exercises are developed and individualized to improve the cardiovascular system for prevention and rehabilitation of cardiac disorders and diseases. A well-balanced exercise program can improve general health, build endurance, and delay many of the effects of aging. The benefits of exercise not only improve physical health, but also enhance emotional well-being.

A study released in 2003 reported that exercise combined with behavioral therapy may even help manage the symptoms experienced by Gulf War veterans. Specifically, exercise helped improve symptoms related to fatigue, distress, cognitive problems and mental health functioning. In the same year, the American Heart Association released a statement saying that exercise was beneficial even for patients awaiting heart transplants. Another study showed that women who participated in strenuous physical activity over a number of years could reduce their risk for breast cancer. Finally, research showed that men and women age 40 to 50 who exercised moderately for 60 to 90 minutes a day were less likely to catch a cold than those who sat around.

Precautions

Before beginning any exercise program, an evaluation by a physician is recommended to rule out any potential health risks. Once health and fitness are determined, and any or all physical restrictions identified, an individual's exercise program should be under the supervision of a health care professional. This is particularly true when exercise is used as a form of rehabilitation. If symptoms of dizziness, nausea, excessive shortness of breath, or chest pain are present during any exercise program, an individual should stop the activity and inform a physician about these symptoms before resuming activity. Exercise equipment must be checked to determine if it can bear the weight of people of all sizes and shapes.

Description

Range of motion exercise

Range of motion exercise refers to activity aimed at improving movement of a specific joint. This motion is influenced by several structures: configuration of bone surfaces within the joint, joint capsule, ligaments, and muscles and tendons acting on the joint. There are three types of range of motion exercises: passive, active, and active assists. Passive range of motion is movement applied to a joint solely by another person or persons or a passive motion machine. When passive range of motion is applied, the joint of an individual receiving exercise is completely relaxed while the outside force moves the body part, such as a leg or arm, throughout the available range. Injury, surgery, or immobilization of a joint may affect the normal joint range of motion. Active range of motion is movement of a joint provided entirely by the individual performing the exercise. In this case, there is no outside force aiding in the movement. Active assist range of motion is described as a joint receiving partial assistance from an outside force. This range of motion may result from the majority of motion applied by an exerciser or by the person or persons assisting the individual. It also may be a half-and-half effort on the joint from each source.

Strengthening exercise

Strengthening exercise increases muscle strength and mass, bone strength, and the body's metabolism. It can help attain and maintain proper weight and improve body image and self-esteem. A certain level of muscle strength is needed to do daily activities, such as walking, running and climbing stairs. Strengthening exercises increase this muscle strength by putting more strain on a muscle than it is normally accustomed to receiving. This increased load stimulates the growth of proteins inside each muscle cell that allow the muscle as a whole to contract. There is evidence indicating that strength training may be better than aerobic exercise alone for improving self-esteem and body image. Weight training allows one immediate feedback, through observation of progress in muscle growth and improved muscle tone. Strengthening exercise can take the form of isometric, isotonic and isokinetic strengthening.

ISOMETRIC EXERCISE

During isometric exercises, muscles contract. However, there is no motion in the affected joints. The muscle fibers maintain a constant length throughout the entire contraction. The exercises are usually performed against an immovable surface or object such as pressing one's hand against a wall. The muscles of the arm are contracting but the wall is not reacting or moving as a result of the physical effort. Isometric training is effective for developing total strength of a particular muscle or group of muscles. It often is used for rehabilitation since the exact area of muscle weakness can be isolated and strengthening can be administered at the proper joint angle. This kind of training can provide a relatively quick and convenient method for overloading and strengthening muscles without any special equipment and with little chance of injury.

ISOTONIC EXERCISE

Isotonic exercise differs from isometric exercise in that there is movement of a joint during the muscle contraction. A classic example of an isotonic exercise is weight training with dumbbells and barbells. As the weight is lifted throughout the range of motion, the muscle shortens and lengthens. Calisthenics are also an example of isotonic exercise. These would include chin-ups, push-ups, and sit-ups, all of which use body weight as the resistance force.

ISOKINETIC EXERCISE

Isokinetic exercise utilizes machines that control the speed of contraction within the range of motion. Isokinetic exercise attempts to combine the best features of both isometrics and weight training. It provides muscular overload at a constant preset speed while a muscle mobilizes its force through the full range of motion. For example, an isokinetic stationary bicycle set at 90 revolutions per minute means that despite how hard and fast the exerciser works, the isokinetic properties of the bicycle will allow the exerciser to pedal only as fast as 90 revolutions per minute. Machines known as Cybex and Biodex provide isokinetic results; they generally are used by physical therapists.

Cardiac rehabilitation

Exercise can be very helpful in prevention and rehabilitation of cardiac disorders and disease. With an individually designed exercise program set at a level considered safe for the individual, people with symptoms of heart failure can substantially improve their fitness levels. The greatest benefit occurs as muscles improve the efficiency of their oxygen use, which reduces the need for the heart to pump as much blood. While such exercise doesn't appear to improve the condition of the heart itself, the increased fitness level reduces the total workload of the heart. The related increase in endurance also should translate into a generally more active lifestyle. Endurance or aerobic routines, such as running, brisk walking, cycling, or swimming, increase the strength and efficiency of the muscles of the heart.

Preparation

A physical examination by a physician is important to determine if strenuous exercise is appropriate or detrimental for an individual. Prior to the exercise program, proper stretching is important to prevent the possibility of soft tissue injury resulting from tight muscles, tendons, ligaments, and other joint-related structures.

Aftercare

Proper cool down after exercise is important in reducing the occurrence of painful muscle spasms. It has been documented that proper cool down also may decrease frequency and intensity of muscle stiffness the day following any exercise program.

Risks

Improper warm up can lead to muscle strains. Overexertion without enough time between exercise sessions to recuperate also can lead to muscle strains, resulting in inactivity due to pain. Stress fractures also are a possibility if activities are strenuous over long periods of time without proper rest. Although exercise is safe for the majority of children and adults, there is still a need for further studies to identify potential risks.

Normal results

Significant health benefits are obtained by including a moderate amount of physical exercise in the form of an exercise prescription. This is much like a drug prescription in that it also helps enhance the health of those who take it in the proper dosage. Physical activity plays a positive role in preventing disease and improving overall health status. People of all ages, both male and female, benefit from regular physical activity. Regular exercise also provides significant psychological benefits and improves quality of life. Studies released in 2003 showed the actual activity in the brain promoted by regular aerobic exercise. It appears that exercise also improves problem solving and other brain-related abilities.

Abnormal results

There is a possibility of exercise burnout if an exercise program is not varied and adequate rest periods are not taken between exercise sessions. Muscle, joint, and cardiac disorders have been noted among people who exercise. However, they often have had preexisting or underlying illnesses.

Key Terms

Aerobic

Exercise training that is geared to provide a sufficient cardiovascular overload to stimulate increases in cardiac output.

Calisthenics

Exercise involving free movement without the aid of equipment.

Endurance

The time limit of a person's ability to maintain either a specific force or power involving muscular contractions.

Osteoporosis

A disorder characterized by loss of calcium in the bone, leading to thinning of the bones. It occurs frequently in postmenopausal women.

For Your Information

Resources

Books

• Bookhout, Mark R., and Grenman, Philip. Principles of Exercise Prescription. Woburn, MA: Butterworth-Heinemann, 2001.
• Harr, Eric. The Portable Personal Trainer. New York: Broadway Books, 2001.
• McArdle, William D., Frank I. Katch, and Victor L. Katch. Exercise Physiology: Energy, Nutrition, and Human Performance, 5th ed. Philadelphia: Lippincott, 2001.
• Redding, Morgan. Physical Fitness : Concepts and Applications. Dubuque, IA: Kendall/Hunt Publishing, 2001.
• Roberts, Matt. 90-Day Fitness Plan. Littleton, CO: DK Publishers, 2001.

• Brun, J. F., M. Dumortier, C. Fedou, and J. Mercier. "Exercise Hypoglycemia in Nondiabetic Subjects." Diabetes and Metabolism 27 (2001): 92-106.
• "Cognitive Behavioral Therapy Plus Exercise May Alleviate Symptoms." Mental Health Weekly Digest (March 31, 2003): 3.
• Evans, E. M., R. E. Van Pelt, E. F. Binder, D. B. Williams, A. A. Ehsani, and W. M. Kohrt. "Effects of HRT and Exercise Training on Insulin Action, Glucose Tolerance, and Body Composition in Older women." Journal of Applied Physiology 90 (2001): 2033-2040.
• "Exercise May Help Patients." Heart Disease Weekly (March 30, 2003): 44.
• Killian, K. J. "Is Exercise Tolerance Limited by the Heart or the Lungs?" Clinical Investigations in Medicine 24 (2001): 110-117.
• Resnick, B. "Testing a model of exercise behavior in older adults." Research in Nursing and Health 24 no.2. 83-92. (2001)
• "Stay Active to Stay Cold-Free: A Recent Study Found that You can Ward Off the Sniffle with a Little Exercise." Natural Health (March 2003): 30.
• "Strenuous Physical Activity Throughout Life can Decrease Risk ." Cancer Weekly (March 18, 2003): 32.
• "Study is First to Confirm Link Between Exercise and Changes in Brain." Obesity, Fitness and Wellness Week (February 22, 2003): 13.

• American College of Sports Medicine. 401 W. Michigan Street, Indianapolis, IN 46202-3233. (317) 637-9200. Fax: (317) 634-7817. http://www.acsm.org/. mkeckhaver@acsm.org.
• American Medical Association. 515 N. State Street, Chicago, IL 60610. (312) 464-5000. http://www.ama-assn.org/.
• American Physical Therapy Association. 1111 North Fairfax Street Alexandria, VA 22314. (703) 684-2782. http://www.apta.org.
• National Athletic Trainers' Association. 2952 Stemmons Freeway, Dallas, TX 75247-6916. (800) 879-6282 or (214) 637-6282. Fax: (214) 637-2206. http://www.nata.org/.

• American Diabetes Association. http://www.diabetes.org/exercise.
• American Heart Association. http://www.americanheart.org.
• American Orthopaedic Society for Sports Medicine. http://www.sportsmed.org.
• American Society of Exercise Physiologists. http://www.css.edu/asep.

Source: Gale Encyclopedia of Medicine, Published December, 2002 by the Gale Group

The Essay Authors are L. Fleming Fallon, Jr., MD, DrPH, Teresa G. Odle.

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