Crowds regularly descend upon community exercise facilities following our end-of-year holidays. Perhaps New Year's resolutions to become more active are the driving force. Perhaps an awareness of increasing weight is another factor. Regardless of the motivation, the numbers of participants in regular exercise of whatever type steadily decline over the first weeks of each New Year. Exercise requires squeezing time from schedules already stressed by demands of family, work, and civic and religious endeavors. Exercise shifts from commitment to a passing fancy.

Against this backdrop of failed good intentions, the benefits of exercise need more careful consideration. Extensive scientific literature indicates the following benefits of exercise have sound documentation: weight control, reduction in cardiovascular disease, and cancer prevention. Exercise also improves immune function, bone density, and slows dementia in older persons. In all age groups, exercise is an important tool in dealing with depression.

Food Intake and Exercise

While reduction in food intake is critical to achieving and maintaining a normal weight, exercise can play an important, complementary role. Male office workers consume an average of 2500 kilocalories per day (A kilocalorie, abbreviated kcal hereafter, is a precise measure of energy, representing the amount of heat necessary to raise the temperature of a liter of water by 1 degree Centigrade). Middle-aged homemakers consume an estimated 2100 kcal daily. This figure will increase to 2300 kcal for a female factory worker. The number of calories consumed by various weight-bearing exercises such as walking and jogging depend upon body weight, steadily increasing as weight increases. A male walking at a moderate pace will consume 2-5 kcal per minute. A program of moderate calisthenics such as step-aerobics raises the figure to 5-7.5 kcal per minute. Jogging increases the energy expenditure to 7.5-10 kcal per minute. A regular program of brisk walking would consume up to 2000 kcal in a week, in addition to providing an interval of relaxation in varied environments.

How Exercise Benefits You

Cardiac Disease & Stroke

Many studies attest to the reduction of illness and improved mortality among regular exercisers. For example, in an eight-year follow-up of a large population of adult men and women, researchers from the Cooper Institute found that mortality ranged from 64 per 100,000 person years in the least fit or physically active group of men to 18.6 per 100,000 person years in the most fit group. For women, the range was 39.5 to 8.5 for the same levels of fitness.

Numerous studies attest to the benefits of exercise in reducing the incidence of cardiac disease and stroke. Some of the benefit comes from reductions of such cardiac risk factors as blood fats, glucose, and blood pressure. Other benefits come from improved efficiency and strength of heart muscle and dilating of arteries, making blood flow easier. Exercise plays a vital role in the recovery and rehabilitation of persons who have suffered heart attacks and stroke. Physical fitness permits the heart and circulation to respond safely to sudden demands for increased work, as is needed when changing a tire or escaping from danger.

Cancer

Regular exercise decreases the incidence of several cancers. The best evidence also supports a reduction in risk for colon and breast cancer. Other studies suggest that exercise may reduce the likelihood of prostate cancer. Why this happens is unclear. One explanation holds that fat-soluble, environmental chemicals cause many cancers. Body fat absorbs these environmental chemicals and retains them, which may cause cancer. Exercise decreases body fat and the associated build-up of these chemicals within the body.

Immunity

A number of recent studies have evaluated the effect of exercise on elderly subjects whose immune systems typically become less active. A two-year program of moderate exercise in a group of women aged 62-86 years produced a substantial benefit in the immune system. Another study showed that exercise training in a group of elderly people prevented or reversed an age-related decline in an important class of infection fighting cells. Regular exercise thus could reduce the chance of illness related to infection in older people. An better immune response may also protect against the development of cancer.

Mental Function

A natural consequence of aging is a slowing of mental function or cognitive function. Exercise has several benefits for older sufferers of cognitive impairment and dementia. Regular exercise improves mental and physical function, reduces the risk of falls, and leads to positive behaviors. In addition to slowing the rate of cognitive decline, exercise may protect against or delay the onset of dementia.

Bone Loss

Weight-bearing exercises also will stimulate the buildup of bone. Bone loss due to age or hormonal influences (osteoporosis) is slowed or prevented. Back pain decreases, and hip and vertebral fractures are reduced. In addition to this protective role, regular exercise can reverse some of the effects of osteoporosis that is already underway.

Depression

Many reports deal with the benefits of exercise in depression, either as a single therapy or combined with medication and psychotherapy. In a recent laboratory study of moderately depressed men, aged 20-45, a program of regular, moderately intense exercise consistently reduced depressive symptoms. Milder levels of exercise had little effect. Regular exercisers suffer less depression, possibly due to the known effect of exercise in elevating the body's production of natural, mood-elevating chemicals (endorphins).

Overall Health

Regular exercise clearly protects and improves our health. Exercise can restore function lost to illness or injury. An exercise program can be as simple as regular walking or as complex as participating in a strenuous, supervised program of step-aerobics or swimming. For an exercise program to succeed, it must be convenient and enjoyable. For an adult with no health problems, walking is a good way to begin. An inexpensive pedometer allows tracking of distance and calorie consumption.

Where Can You Start?

Before undertaking more sustained and strenuous exercise, a medical check-up is advisable. This will detect any potential problems or needed limitations. An experienced trainer at a gym can outline a safe, reasonable schedule of regular exercise that is tailored to the individual. Healthful exercise may be found in a wide variety of activities including cycling, square and ballroom dancing, and gardening. Exercise can become the most relaxing interval of the day. Exercise should not be subject to sprees of over-indulgence. This can lead to injury or exhaustion. Regular engagement in pleasurable, moderate physical activity is as vital as a healthful diet and adequate rest. Exercise belongs in everyone's year-round schedule. The cost of exercise may or may not be covered by insurance.

For Further Information You May Consult the Following:

• Katch and McArdle, Nutrition, weight control and exercise, Second Edition, Lea and Febiger Philadelphia 1983.
• Drela N et al, Moderate exercise may attenuate some aspects of immunosenescence. BMC Geriatr 2004; 4:8-12
• Mooren, F et al Exercise-induced apoptosis of lymphocytes depends on training. MED Sci Sports Exerc 2004; 36:1476-1483.
• Neksawan et al, Effect of dietary fat intake and exercise on inflammatory mediators of immune system in sedentary women and men. J Am Coll Nutr 2004; 23:331-340.
• Bauman A, Updating the evidence that physical activity is good for health. J Sci Med Sports 2004; April 7 (1-Suppl) 6-19.
• Roberts C and Barnard R, Effects of exercise and diet on chronic disease. J Appl Physiol 2005; 98:3-30.
• Bauman A, Updating the evidence that physical activity is good for health. J Sci Med Sport 2004; April 7(1-Suppl) 6-19.
• Heyn, P et al. Effects of exercise training on elderly with cognitive impairment and dementia. Arch Phys Med Rehab 2004; 85:1694-1704.
• Dunn, A et al. Exercise treatment for depression: Efficacy and dose-response. Am J Prev Med 2005; 28:1-8.
• Blair et al, Physical fitness and all-cause mortality, a prospective study of healthy men and women. JAMA 1989; 262:2395-2401