Exercise.

« broad, and most studies suggest a positive relationship between physical fitness and mental achievement. The relationship between regular aerobic exercise and cardiovascular health and longevity is well established.

Regular exercise leads to a reduction in the risk ofcoronary heart disease, in which fatty deposits (plaque) form in blood vessels supplying the muscular wall of the heart, compromising oxygen delivery to the heartmuscle.

In addition, with regular exercise the efficiency of the heart during exercise is increased. Many people exercise to lose weight.

A calorie is a unit that measures the energy content of foods and the energy expenditure by the body.

When the daily calorieintake from food is the same as calories expended from exercise, weight remains the same.

The number of calories burned during exercise varies greatly with the typeof physical activity, but the key to successful weight reduction is to exercise regularly, without increasing food intake proportionally.

For example, walking one hour perday may utilize only 300 calories of energy per day, a small fraction of an individual's daily caloric intake.

But over a period of time, if food consumption issimultaneously reduced or remains the same, significant weight loss will result.

One sound approach to reducing calories is to eat healthier foods that contain more fiberand less fat, and therefore fewer calories.

This type of diet has also been proven healthier for the heart and blood vessels. One area of controversy has been how much exercise is enough to improve general health, reduce the risk of heart disease, and increase longevity.

Meaningful studieson this topic are very difficult to perform because they require large populations of subjects and many years of data collection, and because poor health sometimesresults in limitations to physical activity.

Despite these difficulties, it is clear that regular exercise, along with a generally healthy lifestyle, is beneficial.

People who havesedentary lifestyles make up half the population of industrialized societies, and this group has the most to gain by exercising.

One recent U.S.

National Institutes ofHealth (NIH) panel suggested that as little as 30 minutes every day of purposeful, moderately strenuous physical activity—for example, rapid walking or lawnmowing—is sufficient to lower the risk of heart disease.

There is no conclusive evidence to prove that an especially rigorous exercise routine, such as running manymiles per day, as opposed to walking or jogging daily, will add years to a person's life. VI GETTING IN SHAPE Physical fitness is often defined in terms of four measurements: cardiovascular-respiratory function, body composition (the proportion of lean body mass in comparisonto fat), flexibility, and muscular endurance and strength.

Exercise is characterized in terms of four variables as well: frequency, intensity, duration, and mode.

Inplanning an exercise program, it is important to take into account one's personal fitness objectives and the exercise regimen that will best meet those objectives.

Ageand existing health conditions should also be considered.

Individuals over the age of 40 or who suffer from serious health problems or physical limitations should firstconsult a physician for recommendations about the best exercise program to adopt. A Fitness Goals If overall fitness or prevention of heart disease is a primary goal, 20 to 30 minutes of moderate-intensity, daily aerobic exercise—such as walking, jogging, swimming, ordance aerobics—should be considered.

In general, begin with shorter exercise sessions and gradually work up to 20 to 30 minutes.

In addition to reducing risk of heartdisease, such an aerobic-exercise program will also help in weight reduction and altering body composition, and in enhancing flexibility. If improving muscle strength is the primary consideration, regular, high-intensity workouts with weights are more appropriate.

Studies have shown that even olderpeople can benefit greatly from a weight-lifting workout.

In particular, bone density, often a concern in the elderly, is increased, muscle atrophy (decrease) isprevented, and general strength and coordination are improved by this type of exercise.

A structured, supervised weight program after consultation with a physician isrecommended. Stretching exercises, including yoga, will enhance flexibility.

In planning an exercise program, be sure to include stretching exercises and warm-up and cooldown periodsto prevent muscle pulls and other injuries. B Exercise Intensity If an aerobic program is adopted, in addition to duration (at least 20 to 30 minutes) and frequency (daily or several times a week), intensity of the exercise should alsobe considered.

The intensity of the aerobic exercise can be determined by evaluating the heart rate attained during exercise.

The maximum heart rate (beats perminute) for an individual is approximately 220 minus age.

To improve aerobic capacity (VO 2 maximum), exercise should be performed at an intensity that produces a heart rate of at least 70 percent of this maximum.

For a 20-year-old, for example, the maximum heart rate is 220 - 20, or 200.

The heart rate should rise to at least140 (70 percent of 200).

You can determine your heart rate by placing two fingers over the radial artery in the wrist or the carotid artery of the neck.

By keeping anoccasional record of heart rate responses to a standard exercise (for example, jogging at a rate of 1 mile per ten minutes), it is possible to track your fitness progress;over a period of several weeks, the same exercise will produce a lower heart rate.

Similarly, the intensity of exercise (such as the speed of jogging) required to producea given rise in heart rate will increase. The most important aspect of getting in shape is to make exercise an integral part of one's lifestyle.

Exercising to stay as physically fit and healthy as possible should bea lifelong commitment, and is especially important to people who perform little physical work in their day-to-day lives. Contributed By:Adam K.

MyersMicrosoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation.

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