Fit for health

Content provided by the Faculty of the Harvard Medical School

Fit for health

Everyone agrees it’s good to be physically fit, but exactly what should you strive for?

2006 is the 50th anniversary of the President’s Council on Physical Fitness and Sports, an effort launched by President Dwight D. Eisenhower after he learned that more than half of America’s young people were unable to pass even rudimentary fitness tests. Half a century later, the message is the same for people of all ages: Fit is good. But what exactly is “fitness,” and how do you know if you’re fit?

It depends partly on what the fitness is for. For example, each sport has specific training regimens designed to enable players to safely meet that sport’s demands. But most of us are concerned about health-related physical fitness — the qualities that can help us stay independent and increase our resistance to disease, injury, and pain.

You can’t do anything about some of the things that determine your level of physical fitness — your genes and your age. Happily, the rest is much more under your control. Regardless of where or when you start, you can improve your fitness level by becoming more active. And that means more than just “exercise.” Experts distinguish cardiorespiratory fitness, muscle strength and endurance, flexibility, and balance. Here’s a guide to these elements of fitness — why they’re important for healthy aging, how you can assess where you stand now, and which activities are research-proven.

Cardiorespiratory fitness

Cardiorespiratory (also called aerobic or cardiovascular) fitness is a measure of how well your respiratory and circulatory systems supply oxygen and fuel to the muscles under various types of demand — in other words, exercise capacity. Cardiorespiratory fitness is what allows you to rush for a bus, visit friends in walk-up apartments, or walk uphill without struggling. As we get older, it tends to decrease by about 1% each year.

Low cardiorespiratory fitness is a strong predictor of premature death — as significant as smoking, high blood pressure, obesity, and diabetes. Moreover, poor cardiorespiratory fitness exacerbates the effects of other risk factors. For example, a study found that low cardiovascular fitness raises the risk that a woman with normal blood pressure will develop hypertension in the next five years.

Professional testing. The most accurate test of aerobic fitness is called the VO₂ max. Performed in an exercise or cardiac stress test lab under close medical supervision, it measures the amount or volume (V) of oxygen (O₂) that you use when you exercise as hard as you can. You ride on an exercise bike or walk or run on a treadmill, increasing speed and difficulty until you reach maximum intensity (that is, until exhaustion). During the test, the air you exhale is analyzed to calculate your VO₂ max. Less intense measures of aerobic fitness, called submaximal tests, may be done in a doctor’s office or at a gym.

How to test yourself. Try the Cooper 12-minute fitness test. Go to a track and see how far you get in 12 minutes, walking or running or both. Then rate yourself as follows: Poor to fair for less than 0.5 mile; good for 0.5–1.0 mile; very good for 1.0–1.5 miles; and excellent if you make it more than 1.5 miles.

Though not as precise as the VO₂ max, the Cooper test can provide a good indication of physical fitness, says Dr. Harvey B. Simon, associate professor of medicine at Harvard Medical School and author of The No Sweat Exercise Plan (see “Selected resources”). Its main limitation is that it doesn’t give an accurate picture if you have orthopedic problems.

How to improve cardiorespiratory fitness. Do any exercise that raises your heart rate and makes you breathe faster — brisk walking, swimming, cycling, or aerobics, for example. Aerobics purists used to say that exercisers had to work out at 70%–80% of their maximum heart rate in order to get cardiorespiratory benefits. But according to Dr. Simon, evidence suggests that more moderate exercise is sufficient to improve both cardiovascular risk factors and overall health.

A good rule of thumb is that if you can talk easily while exercising, you need to work harder. Conversely, if you can’t carry on a conversation at all, back off a bit. Aim for 30 minutes or more on most days; it’s fine to reach that total by way of 10- to 15-minute periods.

Muscle strength and endurance

In an interview that appeared in the New York Times magazine in April 2006, former Secretary of State Madeleine Albright, age 69, revealed that she works out three times a week and can leg press 400 pounds. That’s an impressive achievement at any age and one that exemplifies another aspect of physical fitness: muscle strength, or how forcefully a muscle can contract against resistance. Equally important is endurance — the muscle’s ability to keep working without becoming fatigued.

Our muscles tend to get smaller and weaker with age, but we can counter these effects through resistance training. It will pay off in the ability to walk up stairs or hills, lift a suitcase or grocery bag, finish a gardening task without getting too sore or tired, and get up easily from a chair or the toilet. It has other proven health benefits. For example, strengthening neck and shoulder muscles can relieve chronic neck pain; quadriceps strengthening eases knee pain; abdominal strengthening can ease or prevent lower back pain; and an overall strengthening program can help reduce the symptoms of fibromyalgia.

Strength training also lowers body fat, boosts metabolism, and reduces the risk of obesity, diabetes, high blood pressure, and elevated cholesterol. It can be an aid to rehabilitation after a heart attack or stroke and is often recommended for people with heart failure. Finally, working the muscles strengthens the bones they’re attached to, helping maintain bone density and reducing the risk for osteoporosis.

Professional testing. To evaluate muscle strength and endurance precisely, you need equipment that supplies exact amounts of resistance. If your medical condition allows, a physical therapist or a trainer at a health club can do it with resistance machines. A physician can also assess the strength of certain muscles by seeing how forcefully you can push against hands-on resistance.

How to test yourself. You can use the weight of your own body for resistance to estimate your muscle strength and endurance. For the arms, count how many modified push-ups you can do without stopping (see illustration A). Lie face down on the floor. Keeping your knees in contact with the floor, push yourself up to full arm’s length, then lower yourself to the floor. Compare your result with Table 1.

For the abdominal muscles, count how many curl-ups you can do continuously for one minute (see illustration B). Lie on your back with knees bent and feet on the floor. Cross your arms over your chest, fingers touching the front of your shoulders. Bring your elbows to your knees, then return to the starting position. Compare your total with Table 2.

For the leg muscles, stand 8–12 inches in front of a sturdy chair, with your feet apart and your arms out in front of you. Without stopping, count how many times you can squat down until your buttocks barely touch the chair (see illustration C). Compare the number with Table 3.

Testing strength and endurance

How to improve muscle strength and endurance. Strength training, or resistance exercise, involves lifting or pushing against weight supplied by your own body or by a weight machine, free weights, or elastic resistance bands. The National Institute on Aging and the Centers for Disease Control and Prevention describe various strengthening exercises (see “Selected resources”).

You can also work with a physical therapist or personal trainer to design a program suited to your personal needs. If you have any heart or orthopedic problems or if you’ve been ill, talk to your physician before starting.

Flexibility

Flexibility is a measure of the range of motion of your joints as well as the elasticity of the muscles, tendons, and ligaments surrounding the joints.

With age, muscles and elastic tissues stiffen and shorten, causing poor posture and leaving you prone to injury. For example, inflexible ankles can impair balance, increasing the risk of sprains and falls. If you stay flexible, you’ll be better able to avoid injuries, reach high cabinets, bend to tie your shoes, and generally sit and move more comfortably.

Professional testing. The best-known official assessment, called the YMCA sit-and-reach test, evaluates flexibility in your lower back and hamstring muscles. You can do it yourself with a yardstick. Warm up for 5–10 minutes with some gentle stretching exercises. Place the yardstick flat on the floor with the high-numbered end touching a wall. Facing the wall, sit on the floor with your legs straight out and your heels about a foot apart. Line your heels up with the 15-inch mark (the yardstick should be between your legs, with the zero end aimed toward your body). Without bouncing, slowly stretch forward with your arms straight and one hand over the other. Touch the yardstick as far from your body as possible, and note the number of inches. Repeat twice and compare your best reading with YMCA standards in Table 4.

Other ways to test yourself. You can approximate the sit-and-reach test by standing with legs straight and bending forward to reach the floor. If it’s easy and comfortable, you have good lower back and hamstring flexibility. If you can’t do it, or it hurts to try, you need work in this area. The sit-and-reach test measures general flexibility, but each joint has its own level of flexibility. To learn more, try some challenges. Reach your right hand over your right shoulder, and extend your left hand up behind your back toward the right hand. Can you make your fingertips touch? Can you point and flex your feet fully? Tip your head to the side until it is halfway to your shoulder? Do a complete arm circle?

Improving flexibility. Stretching exercises and activities such as yoga can improve flexibility, reduce stress and back pain, and improve posture, gait, mood, and energy. It’s also important to stretch after strength training and aerobic exercises, which can stiffen muscles. To learn how to stretch, sign up for a yoga class, consult a book on exercise and fitness (see “Selected resources”), or ask a trainer for suggestions.

Balance

Keeping your balance while walking, going down stairs, or bending over is a complex feat. It depends on your inner ear, which detects the orientation of the head in relation to the rest of the body and the body in relation to the ground. The brain, eyes, and muscles use that information to prevent you from falling. Your brain also has special receptors that tell you if your joints are in a safe position.

With age, balance can diminish, increasing the chance of a dangerous fall. If your balance is poor, you may not feel confident using a stepstool, walking on uneven ground, or in some cases even venturing outside independently.

Professional testing. A clinician can do in-office balance tests such as asking you to walk slowly or with a wide gait, or timing how long you can stand on one foot. In the laboratory, balance can be assessed with an investigational procedure called dynamic posturography, which analyzes your balance system as you try to remain upright on a small shifting platform (you’re harnessed so you can’t actually fall). The test may not be covered by insurance.

Testing yourself. Stand erect in your bare feet. Lift one foot behind you until your shin is parallel to the ground. Note how long you can hold it there. Repeat on the other side. Then compare your best result with Table 5.

How to improve balance. When you practice balancing on one foot, gradually reduce the amount of support you use to keep your balance: Hold onto your support with just one hand; once you’re secure doing that, try using just your fingertips; finally, let go entirely. While waiting in line or brushing your teeth, stand on one foot. Try to sit down and get up without using your hands (this requires strength as well as balance). If you can, walk at your own pace on irregular surfaces (such as trails or cobblestone paths) that require you to adjust to uneven pressure on different parts of your feet.

Tai chi, a traditional Chinese martial arts exercise performed in a slow, relaxed manner, has been shown to improve balance and prevent falls. Playing golf can also help improve balance in older people.

As you work on various elements of physical fitness, record your initial test scores, and repeat the tests every few months. You may be amazed at your progress.

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Last updated:	August 22, 2006