What is Fitness and How much physical activity do adults need?

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During the past two decades, exercising to stay fit has come to be associated with running, cycling, and other aerobic activities, which have been given the most emphasis because they enhance cardio respiratory endurance the aspect of fitness that provides the most impressive health benefits. Aerobic exercise will continue to be the cornerstone of fitness programs. Yet many people in long- term aerobic programs may lose muscle mass and flexibility, particularly in their upper bodies.

Physical fitness, as experts in the field have long stressed, actually has the following components.

Cardiorespiratory endurance

Cardiorespiratory endurance is reflected in the sustained ability of the heart and blood vessels to carry oxygen to your body’s cells.

Muscular fitness

Muscular fitness consists of both strength and endurance. Muscular strength is the force a muscle produces in one effort a lift, a jump, a heave as when you swing a mallet to ring a carnival bell. Muscular endurance refers to the ability to perform repeated muscular contractions in quick succession, as in doing 20 push-ups or sir- ups in a minute. Although muscular endurance requires strength, it is not a single all-out effort.


Flexibility refers to the ability of your joints to move freely and without discomfort through their full range of motion. This varies from person to person and from joint to joint. Good flexibility is thought to protect the muscles against pulls and tears, since short tight muscles may be more likely to be overstretched.

Body composition

Body composition generally refers to how much of your weight is lean mass (muscle and bone) and how much is fat.

A well-rounded program

Each of these components can be measurably improved with appropriate types of exercise. The American College of Sports Medicine, in its exercise guidelines for healthy adults, recommends a well-rounded program that includes strength training along with aerobics. The emphasis isn’t on lifting heavy weights but on resistance training of moderate intensity at least twice a week, in workouts that can take as little as 15 minutes per session. For a sedentary person, strength training and aerobic exercise together will help improve body composition by increasing muscle mass and reducing fat tissue.

While flexibility is not as important to health as cardiorespiratory endurance or muscular fitness, a regular program of stretching can help prevent injuries to muscles, tendons, and ligaments (the connective tissue that binds muscles together or muscles to joints). For sedentary people, stretching also simply provides relief from muscle tension and stiffness.

Variety is a key

Exercise and fitness were once synonymous with exhaustive workouts, running marathons, or “going for the burn.” But no longer. Being active is the key to becoming and staying fit and you can achieve this through a variety of pursuits. Jogging and aerobics classes, once the premier exercise activities, continue to attract participants. But as the nation and its fitness habits mature, people have been shifting to all manner of activities, from fitness walking to ballroom dancing. Two classic low-impact activities, swimming and cycling, continue to gain in popularity. At the same time, others have chosen newer types of sports and recreations, from mountain biking to inline skating to spinning classes. No single exercise adequately builds all aspects of fitness equally well. Research also concluded that most people like to continue with activities that are available and pleasing.

How much exercise is enough?

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Numerous studies have shown that exercise helps lower the risk of many major diseases as well as premature death. And studies also suggest that any improvement in physical fitness is beneficial that it isn’t necessary to become an athlete to improve your odds of staying healthy longer.

For years the primary exercise goal of the American College of Sports Medicine (ACSM) has been fairly strenuous: at least 20 minutes of vigorous aerobic exercise (such as running or cycling) at least three times a week in order to strengthens the cardiovascular system. ACSM is the most influential group in this field, and it helps shape the government’s official advice. But it’s estimated that only 16 percent of Americans meet this strenuous goal, so ACSM modified it in 1998. The goal post was lowered to help get people moving. And several other goals, regarding strength training and stretching, were added.

Here are the latest guidelines from ACSM:

Lower-intensity exercise is good for you

It can lower the risk of heart disease, hypertension, osteoporosis, diabetes, colon cancer, and obesity. The benefits of moderate activity were shown in two studies published in the Journal of the American Medical Association. Inactive people can become fitter and healthier by starting with such low-level activity and they’re more likely to stick to it and then eventually increase the intensity. Three out of four Americans are totally or mostly sedentary, and for them the greatest health boost comes simply from getting up and becoming active.

Start by adding a few minutes of increased activity to your day, and work up to 30 minutes most, preferably all, days of the week. All you have to do are the normal things, like walking and taking the stairs, but just more often, a little longer, and/or a little faster.

Short bouts of activity count

During a day, brief exercise sessions have an additive benefit. That is, three 10-minute periods of exertion can be almost as beneficial as one 30-minute session.

So does more intense exercise

For additional cardiovascular benefits and to boost HDL (“good”) cholesterol significantly, however, more intense workouts (such as brisk walking, cycling, or running) lasting at least 20 minutes at least three times a week are necessary. Cardiovascular benefits increase with the length and intensity of your workouts. The optimal intensity will depend on your age and physical condition.

Two or three sessions per week should be the minimum. Start with light weights or low settings on weight machines. One set of 8 to 15 repetitions of each exercise can improve muscle strength and endurance nearly as much as the traditional three sets, at least for beginners.

Add stretching

A stretching routine to build flexibility should be done for 10 to 20 minutes at least two or three times a week.

The bottom line is simple: some exercise is good, and more is better than some.

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