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In This Report

•	Highlights
•	Introduction
•	Recommended Exercise Method...
•	Exercise's Effects on the H...
•	Exercise's Effects on Diabe...
•	Exercise's Effects on Bones...
•	Exercise's Effects on the L...
•	Exercise's Effects on Weigh...
•	Exercise's Effects on Other...
•	Complications
•	Motivation
•	Resources
•	References

Related Reports

•	Coronary Artery Disease and...
•	Heart Attack and Acute Coro...
•	Congestive Heart Failure...
•	High Blood Pressure
•	Cholesterol, Other Lipids, ...
•	Stress
•	Smoking
•	Heart-Healthy Diet
•	Stroke
•	Weight Control and Diet

Encyclopedia

•	Exercise and age
•	Losing weight with exercise...
•	Exercise and weight loss...

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Exercise

Highlights

Exercise is Good for You

According to the National Institute on Aging, the combination of a sedentary lifestyle and unhealthy diet contributes to more deaths in the United States than anything except smoking.

It’s Never Too Late to Start 

A report published in the February 2006 Journal of Aging and Health found that an exercise program that combines walking and weight lifting can have a big impact on senior fitness. The average age of the study participants was 83.5. After exercising twice a week for four months, the volunteers significantly increased their body strength, balance, and flexibility.

Need motivation? Get a dog

A study in the February 2006 American Journal of Preventive Medicine found that dog owners do almost twice as much walking as those who don’t have a four-legged friend. Regular walking is a good way to stay in shape.

Exercise and Illness

• Exercise helps kids ward off future neck pain. A study published in the February 2006 British Journal of Sports Medicine found that women who had the greatest endurance strength as teenagers had a lower risk of neck tension than those with lower teenager endurance strength. Men who were more flexible as teenager had a lower risk of neck tension than those who were less flexible in their younger years.
• Walking improves the health of people with diabetes, and lowers their medical expenses. A report in Diabetes Care found that people who exercised for 38 minutes per day lowered their blood pressure, cholesterol and AIC levels, and heart disease risk, even if they didn’t lose weight. The increase in activity equaled about 2,200 extra steps a day.

Introduction

Everyone's goal for a long and healthy life should include a healthy diet, regular exercise, and maintaining normal weight. The combination of inactivity and eating the wrong foods is the second most common underlying cause of death in the United States (smoking is the first). Although most evidence on the benefits of exercise focus on heart protection, studies now are reporting that fitness has a stronger benefit on mortality rates than even some heart risk factors. (The more fit the individual, the lower the risk.)

Some research is suggesting that our genes were designed for exercise. In other words, during prehistoric times, if a person couldn't move quickly and wasn't strong, he or she died. Those who were fit survived to reproduce and pass on these "fitter" genes. Some researchers believe that with the current sedentary culture, these genes have become maladaptive and their effects produce a number of bad effects, which can lead to many chronic illnesses.

The goals of exercise are the following:

• Improve oxygen delivery and metabolic processes
• Build strength and endurance
• Decrease body fat
• Improve movement in joints and muscles
• Improve sense of well being

No one is too young or too old to exercise. The United States Surgeon General recommends at least 30 minutes of moderate exercise, such as brisk walking, nearly every day. However, strenuous exercise has risks that people should discuss with a physician. You should always check with your doctor before starting a new exercise program, especially if you have any of the following risk factors:

• History of smoking
• Obesity
• Family history of a long-term disease
• A symptom you haven’t told your doctor about
• Chest pain
• Shortness of breath
• Heart palpitations
• Blood clots
• Infections
• Fever
• Unexplained weight loss
• Foot or ankle sores that won’t heal
• Joint swelling
• Pain or trouble walking after a fall
• Eye injury or eye surgery
• Hernia
• Hip surgery

Fifty percent of all people who begin a vigorous training regime drop out within a year, so the key to reaching and maintaining physical fitness is to find activities that are exciting, challenging, and satisfying.

Recommended Exercise Methods

A few simple rules are helpful as you develop your own routine.

• Don't eat for 2 hours before vigorous exercise.
• Drink plenty of fluids before, during, and after a workout.
• Adjust activity according to the weather and reduce it when fatigued or ill.
• When exercising, listen to the body's warning symptoms, and consult a doctor if exercise causes chest pain, irregular heartbeat, undue fatigue, nausea, unexpected breathlessness, or light-headedness.

Heart Rate Goal

Heart rate is the standard guide for determining aerobic exercise intensity. It can be determined by counting one's own pulse or with the use of a heart rate monitor. To feel your own pulse, press the first two fingers of one hand gently down on the inside of the wrist or under the jaw on the right or left side of the front of the neck. You should feel a faint pounding as blood passes through the artery. Each pounding is a beat.

Click the icon to see how to take a radial pulse

Click the icon to see how to take a carotid pulse.

There are different types of heart rates.

Resting heart rate. The average resting heart rate for a person at rest is 60–80 beats per minute. It is usually lower for people who are physically fit, and often rises as you get older. You can determine your resting heart rate by counting how many times your heart beats in one minute. The best time to do this is in the morning after a good night’s sleep before you get out of bed.

Maximum heart rate. To determine your own maximum heart rate per minute subtract your age from 220. For example, if you are 45, you would calculate your maximum heart rate as follows: 220-45= 175.

Target heart rate. Your target rate is 50 to 75% of your maximum heart rate. You should measure your pulse off and on while your exercise to make sure you stay within this range. After about 6 months of regular exercise, you may be able to increase your target heart rate to 85% (but only if you can comfortably do so).

Certain heart medications may lower your maximum and target heart rates. Always check with your doctor before starting an exercise program.

Note: Swimmers should use a heart rate target of 75% of the maximum and then subtract 12 beats per minute. The reason for this is that swimming will not raise the heart rate quite as much as other sports because of the so-called "diving reflex," which causes the heart to slow down automatically when the body is immersed in water.

VO2 Max. Serious exercisers may use a VO2 max calculation, which measures the amount of oxygen consumed during intensive, all-out exercise. The most accurate testing method uses computers, but anyone can estimate V02 without instrumentation (with an accuracy of about 95%):

• After running at top pace for 15 minutes, round off the distance run to the nearest 25 meters.
• Divide that number by 15.
• Subtract 133.
• Multiply the total by 0.172, then add 33.3.

Olympic and professional athletes train for VO2 max levels above 80. But for the average person interested in fitness, a VO2 max equaling between 50 and 80 is considered an excellent score for overall fitness.

Click the icon to see an image on exercise and heart rate.

Warm-Up and Cool-Down

Warming up and cooling down are important parts of every exercise routine. They help the body make the transition from rest to activity and back again, and can help prevent soreness or injury, especially in older people.

• Warm-up exercises should be practiced for 5 to 10 minutes at the beginning of an exercise session. Older people need a longer period to warm up their muscles. Low-level aerobic exercise such as brisk walking, swinging the arms, or jogging in place, is the best approach.
• To cool down, you should walk slowly until the heart rate is 10 to 15 beats above your resting heart rate. Stopping too suddenly can sharply reduce blood pressure, and is a danger for older people. It may also cause muscle cramping.

• Stretching may be appropriate for the cooling down period, but it must be done carefully for warming up because it can injure cold muscles. (There is no clear evidence, however, that stretching reduces muscle injuries.)

Warming up before exercise and cooling down after is just as important as the exercise itself. By properly warming up the muscles and joints with low-level aerobic movement for 5 to 10 minutes, one may avoid injury and build endurance over time. Cooling down after exercise by walking slowly, then stretching muscles, may also prevent strains and blood pressure fluctuation.

For most people, exercise may be divided into three general categories:

• Aerobic or endurance
• Strength or resistance
• Flexibility

A balanced program should include all three. (Speed training is also a major category, but is generally practiced only by competitive athletes.)

Aerobic (Endurance) Training

Benefits of Aerobic Exercise. Regular aerobic exercise provides the following benefits:

• Builds endurance
• Keeps the heart pumping at a steady and elevated rate for an extended period
• Boosts HDL ( "good") cholesterol levels
• Helps control blood pressure
• Strengthens the bones in the spine
• Helps maintain normal weight
• Improves one's sense of well being

Types of Aerobic Exercise. Aerobic exercise is usually categorized as high or low impact. Examples of each include the following:

• Low- to moderate-impact exercises: Walking, swimming, stair climbing, step classes, rowing, and cross-country skiing. Nearly anyone in reasonable health can engage in some low- to moderate-impact exercise. Brisk walking burns as many calories as jogging for the same distance and poses less risk for injury to muscle and bone.
• High-impact exercises: Running, dance exercise, tennis, racquetball, squash. High-impact exercises should be performed no more than every other day and less for those who are overweight, elderly, out of condition, or have an injury or other medical problem that would preclude high-impact.

Click the icon to see an image of aerobic exercise.

Aerobic Regimens. As little as one hour a week of aerobic exercises is helpful, but 3 to 4 hours per week are best. Some research indicates that simply walking briskly for 3 or more hours a week reduces the risk for coronary heart disease by 65%. In general, the following guidelines are useful for most individuals:

• For most healthy young adults, the best approach is a mix of low- and higher-impact exercise. Two weekly workouts will maintain fitness, but three to five sessions a week are better.
• People who are out of shape or elderly should start aerobic training gradually. For example, they may start with five to 10 minutes of low-impact aerobic activity every other day and build toward a goal of 30 minutes per day, three to seven times a week. (For heart protection, frequency of exercises may be more important than duration.)
• Swimming is an ideal exercise for many elderly and certain people with physical limitations, including pregnant women, individuals with muscle, joint, or bone problems, and those who suffer from exercise-induced asthma.
• People who seek to lose weight should aim for six to seven low-impact workouts a week.

One way of gauging the optimal intensity of exercise is to aim for a "talking pace," which is enough to work up a sweat and still be able to converse with a friend without gasping for breath. As fitness increases, the "talking pace" will become faster and faster.

Shoes. All that's really necessary for a workout is a good pair of shoes that are made well and fit well. They should be broken in, but not worn down. They should support the ankle and provide cushioning for impact sports such as running or aerobic dancing. Airing out the shoes and feet after exercising reduces chances for skin conditions such as athlete's foot.

Clothing. Comfort and safety are the key words for workout clothing. For outdoor nighttime exercise, a reflective vest and light-colored clothing must be worn. Bikers, roller bladers, and equestrians should always wear safety devices such as helmets, wrist guards, and knee and elbow pads. Goggles are mandatory for indoor racquet sports. For vigorous athletic activities such as football, ankle braces may be more effective in preventing ankle injuries than tape.

Aerobic-Exercise Equipment. Home aerobic exercise machines can be adapted to any fitness level and can be used day or night. Before investing in and bringing home any exercise machine, however, it is wise to first test it at a gym. In addition, initial supervised training when using these machines can reduce the risk of injury that might occur with self instruction.

Very inexpensive exercise machines tend to be flimsy and hard to adjust, but many sturdy machines are available at moderate prices. The higher-end models may utilize computers to record calories burned, speed, and mileage. While their readouts may provide motivation and gauge the intensity of a workout, however, they are not always accurate.

The following are a few observations on specific equipment:

• A good floor mat is important to provide cushioning for all home exercises.
• A simple jump rope improves aerobic endurance for people who are able to perform high-impact exercise. Jumping rope should be done on a floor mat plus a surface that has some give to avoid joint injury.
• For burning calories, the treadmill has been ranked best, followed by stair climbers, the rowing machine, cross-country ski machine, and stationary bicycle. (Elliptical trainers, however, may be even better than treadmills for increasing heart rate, calorie expenditure, and oxygen consumption.)
• Stationary bikes condition leg muscles and are fairly economical and easy to use safely. The pedals should turn smoothly, the seat height should adjust easily, and the bike's computer should be able to adjust intensity.
• Stair machines also condition leg muscles. They offer very intense, low-impact workouts and may be as effective as running with less chance of injury.
• Rowing and cross-country ski machines exercise both the upper and lower body.

Strength or Resistance Training

Benefits of Strength Exercise. While aerobic exercise increases endurance and helps the heart, it does not build upper body strength or tone muscles. Strength-training exercises provide the following benefits:

• Build muscle strength while burning fat
• Help maintain bone density
• Improve digestion

It is also associated with a lower risk for heart disease, possibly because it lowers LDL (the so-called "bad") cholesterol levels.

Click the icon to see an image of cholesterol.

Strength exercise is beneficial for everyone, even people in their 90s. It is the only form of exercise that can slow and even reverse the decline in muscle mass, bone density, and strength that occurs with aging. Please note: People at risk for cardiovascular disease should not perform strength exercises without checking with a doctor.

Types of Muscle Contractions. There are three types of muscle contractions involved in strength training:

• Isometric contractions do not change the length of the muscle. An example is pushing against a wall.
• Concentric contractions shorten muscles. An example is the "up" phase of a bicep curl.
• Eccentric contractions lengthen muscles. An example is the "down" phase as weights are lowered.

Click the icon to see an image of isometric exercise.

Strength-Training Regimens. Strength training involves intense and short-duration activities. For beginners, adding 10 to 20 minutes of modest strength training two to three times a week may be appropriate. The following are some guidelines for starting a strength regimen:

• The sequence of a strength training session should begin with training large muscles and multiple joints at higher intensity and end with small muscle and single joint exercises at lower intensities.
• Both concentric (shortening) and eccentric (lengthening) muscle actions should be performed. Emphasizing eccentric contractions (the movements that lengthen muscles) is of increasing interest. This approach involves slowing and increasing the duration of these "down" movements. It appears to significantly increase blood flow, and some evidence suggests it may achieve stronger muscles more quickly and improve cardiovascular function compared to a standard movements. It may be particularly beneficial for older people and some people with chronic health problems. Eccentric training increases the risk for muscle soreness and injury, however, and this approach is still controversial.
• Strength training involves moving specific muscles in the same pattern against a resisting force (such as a weight) for a preset number of times. This is called a repetition. Students should first choose a weight that is about half of what would require a maximum effort in one repetition. In other words, if it would take maximum effort to do a single repetition with a 10-pound dumbbell, than the person would start with a five-pound dumbbell. In the beginning, most people can start with one set of 8 to 15 repetitions per muscle group with low weights. As individuals are able to perform one or two repetitions over their routine, weights can be increased by 2 - 10%.
• Breathe slowly and rhythmically. Exhale as the movement begins. Inhale when returning to the starting point.
• The first half of each repetition typically lasts 2 to 3 seconds. The return to the original position lasts 4 seconds.
• An alternative technique called "super slow" training stretches out one repetition to a 14-second count. This method places far more stress on the muscle group, so fewer repetitions are needed. A full week of recovery is required before repeating this workout. The goal is to initiate changes in the muscles so that the body continues to burn calories after the exercise. Some people report dramatic results from this approach, but scientific verification of these anecdotes is not available. It is very tedious, in any case, and people have a hard time sticking with it. People with high blood pressure should not use this approach.
• Joints should be moved rhythmically through their full range of motion during a repetition and not locked up.
• For maximum benefit, one should allow 48 hours between workouts for full muscle recovery.

Click the icon to see the proper way to breathe during exercise.

Strength-Training Equipment. Unlike aerobic exercise, strength training almost always requires some equipment. Strength-training equipment does not, however, have to cost anything.

• Any heavy object that can be held in the hand, such as a plastic bottle filled with sand or water, can serve as a weight.
• Dumbbells (1 to 10 pounds) and resistance bands are inexpensive, portable, and effective.
• Wearable weights help strengthen and tone the upper body.
• Ankle weights strengthen and tone muscles in the lower body. Wearable ankle weights should not be worn during high-impact aerobics or jumping.
• Handgrips strengthen arms and are good for relieving tension.
• A pull-up bar can be mounted in a doorway for chin-ups and pull-ups.

More elaborate and expensive home equipment for working body muscles is also available, costing from $100 to over $1,000. No one should purchase or use strength-training equipment without instruction from a professional.

Flexibility Training (Stretching)

Benefits of Flexibility Training. Flexibility training uses stretching exercises. Many stretching exercises are particularly beneficial for the back. In general, flexibility training provides the following benefits:

• Prevents cramps, stiffness, and injuries
• Improves joint and muscle movement (range of motion)

Certain flexibility practices such as yoga and tai chi, also involve meditation and breathing techniques that reduce stress. Such practices appear to have many health and mental benefits and may be very suitable and highly beneficial for many older people and patients with certain chronic diseases.

Click the icon to see an image of flexibility exercise.

Flexibility Training Regiments. Doctors recommend performing stretching exercises for 10 to 12 minutes at least three times a week. The following are some general guidelines:

• When stretching, exhale and extend the muscles to the point of tension, not pain, and hold for 20 to 60 seconds. (Beginners may need to start with a 5- to 10-second stretch.)
• Breath evenly and constantly while holding the stretch.
• Inhale when returning to a relaxed position. (Holding your breath defeats the purpose; it causes muscle contraction and raises blood pressure.)
• It is important when doing stretches that involve the back to relax the spine, to keep the lower back flush with the mat, and to work only the muscles required for changing position, often only the abdomen.

Exercise's Effects on the Heart

Inactivity is one of the four major risk factors for coronary artery disease. However, exercise helps improve heart health in people with many forms of heart disease and can even reverse some risk factors, such as some of the effects of smoking.

Like all muscles, the heart becomes stronger and larger as a result of exercise so it can pump more blood through the body with every beat and sustain its maximum level with less strain. The resting heart rate of those who exercise is also slower because less effort is needed to pump blood.

People who exercise the most often and vigorously have the lowest risk for heart disease, but any exercise is beneficial. Studies consistently find that light to moderate exercise is even beneficial in people with existing heart disease. However, anyone with coronary artery disease should seek medical advice before beginning a workout program.

The heart is a large muscular organ that pumps blood throughout the body. Valves inside the heart open and close. This controls how much blood enters or leaves the heart.

Effects of Exercise on Heart Disease & Cholesterol

Exercise has a number of effects that benefit the heart and circulation, including improving cholesterol and lipid levels, reducing inflammation in the arteries, assisting weight loss programs, and helping to keep blood vessels flexible and open. Studies continue to show that physical activity and avoiding high-fat foods are the two most successful means of reaching and maintaining heart healthy levels of fitness and weight.

The American Heart Association recommends that individuals perform moderate-intense exercise for 30 minutes on most days of the week. This recommendation supports similar exercise guidelines issued by the Centers for Disease Control and Prevention and the American College of Sports Medicine.

Coronary Artery Disease. People who maintain an active lifestyle have a 45% lower risk of developing heart disease than do sedentary people. Experts have been attempting to define how much exercise is needed to produce heart benefits. In 2002, a well-conducted study on overweight adults confirmed previous research that reported beneficial changes in cholesterol and lipid levels, including lower LDL levels (bad cholesterol), even when people performed low amounts of moderate or high intensity exercise such as walking or jogging 12 miles a week. However, more intense exercise is required to significantly change cholesterol levels, notably increasing HDL (good cholesterol). An example of such a program would be jogging about 20 miles a week. Such benefits in the study occurred even with very modest weight loss, suggesting that overweight people who have trouble losing pounds can still achieve considerable heart benefits by exercising.

Some studies suggest that for the greatest heart protection, it is not the duration of a single exercise session that counts but the total daily amount of energy expended. Therefore, the best way to exercise may be in multiple short bouts of intense exercise, which can be particularly helpful for older people.

Resistance (weight) training has also been associated with heart protection. It may offer a complementary benefit to aerobics by reducing LDL levels. Exercises that train and strengthen the chest muscles may prove to be very important for patients with angina.

Effects of Exercise on Blood Pressure. Regular exercise helps keep arteries elastic, even in older people, which in turn ensures blood flow and normal blood pressure. Sedentary people have a 35% greater risk of developing hypertension than athletes do.

Click the icon to see the risks associated with untreated hypertension.

It should be noted that high-intensity exercise may not lower blood pressure as effectively as moderate-intensity exercise. In one study, moderate exercise (jogging two miles a day) controlled hypertension so well that more than half the patients who had been taking drugs for high blood pressure were able to discontinue their medication.

However, a small study published in 2005 suggests that moderate exercise does not have a significant impact on systolic blood pressure (the top number) in older adults. While those who exercised did have notable drops in both the top and lower (diastolic) blood pressure levels, the only statistically significant change was the decrease in the lower number.

Experts recommend at least 30 minutes of exercise on most -- if not all days. Studies have indicated that yoga and tai chi, an ancient Chinese exercise involving slow, relaxing movements, may lower blood pressure almost as well as moderate-intensity aerobic exercises.

Click the icon to see an image of someone practicing yoga.

Anyone with existing hypertension should discuss an exercise program with their doctor. Before starting to exercise, people with moderate to severe hypertension should lower their pressure and be able to control it with medications. They should avoid caffeinated beverages, which increase heart rate, the workload of the heart, and blood pressure during physical activity. Everyone, and especially people with high blood pressure, should breath as normally as possible through each exercise. Holding the breath increases blood pressure.

Effects of Exercise on Heart Failure. Traditionally, heart failure patients have been discouraged from exercising. Now, exercise performed under medical supervision is proving to be helpful for select patients with stable heart failure.

• Studies continue to report benefits from exercise training. In one study, heart failure patients as old as 91 years old increased their oxygen consumption significantly after six months of supervised treadmill and stationary bicycle exercises.
• Progressive resistance training may be particularly useful for heart failure patients since it strengthens muscles, which commonly deteriorate in this disorder. Even simply performing daily handgrip exercises can improve blood flow through the arteries.

Experts warn, however, that exercise is not appropriate for all heart failure patients.

Effects of Exercise on Stroke  

All stroke survivors should have a pre-exercise evaluation done by their doctor before starting an exercise program.

The effects of exercise on stroke are less established than on heart disease, but most studies are positive on its benefits. The following are some examples:

• According to one major analysis, men cut their risk for stroke in half if their exercise program was roughly equivalent to about an hour of brisk daily walking five days a week. In the same study, exercise that involved recreation was more protective against stroke than exercise routines consisting simply of walking or climbing.
• A 2000 study of women also found substantial protection from brisk walking or striding (rather than casual walking).

Exercise Programs for High-Risk Individuals

Anyone with heart disease or risk factors for developing heart disease or stroke should seek medical advice before beginning a workout program. Patients with heart disease can nearly always exercise safely as long as they work out under medical supervision. Still, it is often difficult for a doctor to predict health problems that might arise as the result of an exercise program. At-risk individuals should be very aware of any symptoms warning of harmful complications while they exercise.

Some experts believe that anyone over 40 years old, whether or not they are at risk for heart disease, should have a complete physical examination before starting or intensifying an exercise program. Some doctors use a questionnaire for people over 40 to help determine whether they require such an examination:

• Has any doctor previously recommended medically supervised activity because of a heart condition?
• Is chest pain brought on by physical activity?
• Has chest pain occurred during the previous month?
• Does the person faint or fall over from dizziness?
• Is bone or joint pain intensified by exercise?
• Has medication been prescribed for hypertension or heart problems?
• Is the person aware of or has a doctor suggested any physical reason for not exercising without medical supervision?

Those who answer "yes" to any of the following questions should have a complete medical examination before developing an exercise program.

Stress Test. A stress test helps determine the risk for a heart event from exercise. Anyone with a heart problem or history of heart disease should have a stress test before embarking on an exercise program. Experts currently also recommend this test before a vigorous exercise program for older persons who are sedentary, even in the absence of known or suspected cardiovascular disease. It is expensive, however, and some experts believe that it may not be necessary for many older people with no evident health problems or risk factors. They recommend instead a carefully monitored program, starting out with low-intensity exercises and gradually building up.

Click the icon to see an image of a coronary artery spasm.

Click the icon to see an image of stable angina.

Exercise's Effects on Diabetes

Moderate aerobic exercise can lower your risk for type 2 diabetes. An important study found that adults who worked out 2 and 1/2 hours a week cut their risk by 58%.

Exercise has positive benefits for those who have diabetes. It can lower blood sugar, improve insulin sensitivity, and strengthen the heart. Strength training, which increases muscle and reduces fat, may be particularly helpful for people with diabetes, but evidence is needed to confirm this. One study reported that yoga helped patients with type 2 diabetes reduce their need for oral medications.

In 2005, researchers reporting in the journal Diabetes Care documented how much walking inactive people with type 2 diabetes would need to do to improve their health. They found that people who walked a minimum of three miles every day were in better health and had lower medical expenses after two years. Those who remained sedentary for that time period had a decline in health and higher healthcare costs. Those who worked out for 38 minutes per day lowered their blood pressure, cholesterol and AIC levels, and heart disease risk, even if they didn't lose weight. The increase in activity equaled about 2,200 extra steps a day.

An earlier study found that healthy lifestyle changes may work better than the prescription medication metformin (Glucophage) when it comes to preventing metabolic syndrome, which is a combination of risk factors including abdominal obesity, insulin resistance, high triglycerides, and hypertension.

Some Precautions for People With Diabetes Who Exercise

The following are precautions for all people with diabetes, whether type 1 or 2:

• Because people with diabetes are at higher than average risk for heart disease, they should always check with their physicians before undertaking vigorous exercise. For best and fastest results, frequent high-intensity (not high-impact) exercises are best for people who are cleared by their physicians. For people who have been sedentary or have other medical problems, lower-intensity exercises are recommended using regimens designed with physicians.
• Strenuous strength training or high-impact exercise is not recommended for people with uncontrolled diabetes. Such exercised exercises can strain weakened blood vessels in the eyes of patients with retinopathy. High-impact exercise may also injure blood vessels in the feet.

Patients who are taking medications that lower blood glucose, particularly insulin, should take special precautions before embarking on a workout program.

• Glucose levels swing dramatically during exercise, people with diabetes should monitor their levels carefully before, during, and after workouts.
• Patients should probably avoid exercise if glucose levels are above 300 mg/dL or under 100 mg/dL.
• To avoid hypoglycemia, diabetics should inject insulin in sites away from the muscles they use the most during exercise.
• They should also drink plenty of fluids. Before exercising, they should also avoid alcohol, which increases the risk of hypoglycemia.
• Insulin-dependent athletes may need to decrease insulin doses or take in more carbohydrates prior to exercise but may need to take an extra dose of insulin after exercise. Stress hormones released during exercise may increase blood glucose levels, in non-diabetics insulin is released to control this. A person with diabetes must regularly test their blood sugar and take any medications as instructed by their doctor.

A person with diabetes must regularly check their blood sugar (glucose) level.

Exercise's Effects on Bones and Muscles

Exercise is critical for strong muscles and bones. Muscle strength declines as people age, but studies report that when people exercise they are stronger and leaner than others in their age group.

Exercise helps kids lower their risk of chronic pain in the future. Research has shown that it helps them prevent back and neck pain. The more flexible men are as teenagers, the lower their risk of neck tension in the future, according to a  study published in the February 2006 British Journal of Sports Medicine. The same report found that women who had the greatest endurance strength as teenagers had a lower risk of tension neck than those with lower teenager endurance strength. However, men with the greatest endurance strength had higher rates of knee injuries later on.

Joints are complex structures. They are designed to bear weight and move the body. Above the knee is the femur (thigh bone). Below the knee is the tibia (shin bone) and fibula. The kneecap is also called the patella. It rides on top of the lower portion of the femur and the top portion of the tibia. The muscles and ligaments connect these bones and the space between them is cushioned by fluid-filled capsules (synovia) and cartilage. When you exercise, the muscles pull on the bones, strengthening them. The range of motion of a joint represents how far it can be flexed (bent) and extended (stretched).

Effects of Exercise on Osteoarthritis

Joints require motion to stay healthy. Long periods of inactivity cause the arthritic joint to stiffen and the adjoining tissue to atrophy. A moderate exercise program that includes low-impact aerobics and power and strength training has benefits for osteoarthritic patients, even if exercise does not slow down the disease progression. Many patients who embark on an exercise program report less disability and pain and are better able to perform daily chores and remain independent than their inactive peers. Older patients and those with medical problems should always check with their doctor before embarking on an exercise program.

Click the icon to see an image of osteoporosis.

The following are useful exercises for osteoarthritis patients:

• Strengthening exercises builds muscle strength. Some experts encourage patients to emphasize strengthening leg muscles as a first treatment step, even before using pain relievers. They fear that patients who rely on pain killing drugs may overuse knees, which do not have muscle tissue sufficiently strong enough to protect the joints from further damage. Strengthening the thigh muscles is certainly protective who have not developed osteoarthritis.
• Range-of-motion exercises increase the amount of movement in a joint and muscle. The best examples are yoga and tai chi, which focus on flexibility, balance, and proper breathing. In one 2001 study, older adults who practiced the gentle movement, breathing, and meditation exercises of tai chi for 10 weeks reported less pain than their peers who did not learn the technique.
• Low-impact aerobic workouts help stabilize and support the joint. Cycling and walking are beneficial, and swimming or exercising in water is highly recommended for people with arthritis. (Arthritic patients should avoid high-impact sports, such as jogging, tennis, and racquetball.)
• Some researchers are now focusing on "power" training, which involves improving the muscle's ability to move more rapidly against resisting forces, such as gravity. (For example, such training helps people to stand up or climb stairs more quickly.) Muscle power declines more rapidly than muscle strength and may be particularly important in older people.

Exercises Effect on Fractures and Falls

Exercise is very important for slowing the progression of osteoporosis and extremely important for reducing the risk for falling, which causes fractures. Falls are one of the leading causes of death in people over age 65. Exercise helps build balance and flexibilty, which reduces the risk of falling.

Specific exercises may be especially helpful for reducing the risk for fracture:

• Weight-bearing exercise are very beneficial for bones in people of all ages, even older people. This approach applies tension to muscle and bone, and the body responds to this stress by increasing bone density, in young adults by as much as 2 - 8% a year. Careful weight training can also be very beneficial for elderly people, particularly women. In addition to improving bone density, weight-bearing exercise reduces the risk for fractures by improving muscle strength and balance, thus helping to prevent falls.
• Regular brisk long walks improve bone density and mobility. In one 2002 study, for example, older women reduced their risk of hip fracture by over 40% by working out for just four hours a week.
• Exercises specifically targeted to strengthen the back can be beneficial in improving posture and may even reduce kyphosis (hunchback) in people with osteoporosis.
• Low-impact exercises that improve balance and strength, particularly yoga and tai chi, have been found to decrease the risk of falling. In one study tai chi reduced the risk by almost half.

Click the icon to see an image of the bone-building exercise.

Note on Female Athlete Triad. Some young female athletes who exercise very intensely and are subject to intense pressure to remain thin are at risk for the so-called female athlete triad, which includes osteoporosis.

Effect of Exercise on Back Pain

People who do not exercise regularly face an increased risk for low back pain, especially during times when they suddenly embark on stressful unaccustomed activity, such as shoveling, digging, or moving heavy items. Although no definitive studies have been done to prove the relationship between lack of exercise and low back pain, sedentary living is probably a primary nonmedical culprit contributing to this condition. Lack of exercise leads to the following conditions that may threaten the back:

• Muscle inflexibility can restrict the back's ability to move, rotate, and bend.
• Weak stomach muscles can increase the strain on the back and can cause an abnormal tilt of the pelvis.
• Weak back muscles may increase the load on the spine and the risk for disc compression.
• Obesity puts more weight on the spine and increases pressure on the vertebrae and discs. Studies report only a weak association between obesity and low back pain, however.

Benefits for Chronic Back Pain. People in with sudden and severe back pain should not exercise. Exercise plays a very beneficial role in chronic back pain, however. In one study, for example, patients with back pain lasting for an average of 18 months were assigned eight one-hour exercise sessions over four weeks. They showed greater improvement in nearly every area, including reduced pain and increased capacity, compared to patients who did not exercise.

Exercise should be considered as part of a broader program to return to normal home, work, and social activities. In this way, the positive benefits of exercise not only affect strength and flexibility but they also alter and improve the patients' attitudes toward their disability and pain.

Repetition is the key to increasing flexibility, building endurance, and strengthening the specific muscles needed to support and neutralize the spine. Some exercise programs used for prevention or treatment of chronic low back pain include the following:

• Low-impact Aerobic Exercises. Low-impact aerobic exercises, such as swimming, bicycling, and walking, can strengthen muscles in the abdomen and back without over-straining the back. Programs that use strengthening exercises while swimming may be a particularly beneficial approach for many patients with back pain. In one study, for example, pregnant women who engaged in a water gymnastics program had less back pain and were able to continue working longer.
• Lumbar Extension Strength Training. Exercises called lumbar extension strength training are proving to be effective. Generally, these exercises attempt to strengthen the abdomen, improve lower back mobility, strength, and endurance, and enhance flexibility in the hip and hamstring muscles and tendons at the back of the thigh.
• Yoga, tai chi, chi kung. These exercises combine low-impact physical movements and meditation. They are based on principles of disciplining the mind to achieve a physical and mental balance and can be very helpful in preventing recurrences of low back pain. In one study, pilates, an exercise practice that uses yoga principles, was helpful in a woman with progressive and disabling severe low back pain from early scoliosis. This approach deserves further research.
• Flexibility Exercises. Whether flexibility exercises alone offer any significant benefit is uncertain. One study suggested that any benefits derived from flexibility exercises are lost unless the exercise regimens are sustained.
• Retraining Deep Muscles. Studies are finding a link between low back pain and impaired motor control of deep muscles of the back and trunk. According to these studies, contraction exercises specifically designed to retrain these muscles may be effective for patients with both acute and chronic pain.

It is important for any person who has low back pain to have an exercise program guided by professionals who understand the limitations and special needs of back pain and who can address individual health conditions. One study indicated that patients who planned their own exercise did worse than those in physical therapy or doctor-directed programs.

Hazardous Effects on the Back. Improper or excessive exercise can also cause back pain.

Exercise's Effects on the Lungs

Patients with chronic lung problems have difficulty exercising. Shortness of breath is a major limitation in most patients, but in about a third, muscle fatigue is an even greater problem. Although exercise does not improve lung function, training helps many patients with chronic lung disease by strengthening their limb muscles, thus improving endurance and reducing breathlessness.

Effects on Respiratory Infections (Colds and The Flu)

In people who already have colds, exercise has no effect on the illness' severity or duration of the infection. High-intensity or endurance exercises, however, appear to suppress the immune system while they are being performed. Some highly trained athletes, for instance, report being susceptible to colds after strenuous events. People should avoid strenuous physical activity when they have high fevers or widespread viral illnesses. Very low-fat diets appear to worse thie effect.

Effects of Exercise on Asthma

Long-term exercise may help control asthma and reduce hospitalization. One 2000 study found that aerobic exercise improves breathing capacity and function in-patients with mild asthma. People who enjoy running should probably choose an indoor track to avoid pollutants. Swimming is particularly excellent for people with asthma. Yoga practice, which uses both stretching, breathing, chest expansion, and meditation techniques may have specific benefits that include stress reduction as well as airway opening. One study reported that two thirds of patients who practiced yoga regularly were able to reduce or eliminate their asthma medications.

Exercise-Induced Asthma. About 40% to 90% of asthma cases are exercise-induced asthma (EIA), in which exercise triggers coughing, wheezing, or shortness of breath. It occurs most often in children and young adults and during intense exercise in cold dry air. EIA is triggered only by exercise. Unlike allergic asthma, there is no long-term increase in airway activity. People who only have EIA do not require long-term maintenance therapy. The warm-up and cool-down periods, which are important for any exercise regimen, may help reduce EIA events. A study of military recruits found that exercise-induced asthma attacks did not hinder their ability to perform or train, suggesting that EIA is not a reason to exclude people from physically demanding occupations.

Exercise-induced asthma is distinct from allergic asthma in that it does not produce long-term increase in airway activity. People who only experience asthma when they exercise may be able to control their symptoms with preventive measures such as warm-up and cool-down exercises.

Effects of Exercise on Emphysema

Walking is the best exercise for people with emphysema. Patients should try to walk three to four times daily for five to 15 minutes each time. Devices that assist ventilation may reduce breathlessness that occurs during exercise. Inspiratory muscle training involves exercises and devices that make inhaling more difficult in order to strengthen breathing muscles. In a 2001 study, patients who took part in a training group improved their breathing, walking capacity, and quality of life. Yoga or martial arts exercises, such as tai chi, that emphasize breathing techniques and balanced movements may be particularly beneficial for these patients.

Exercise's Effects on Weight

Exercising helps people reduce their weight, maintain weight loss, and fight obesity. Research has shown that women who regularly exercise but do not change their diet can lose significantly more weight than less active women.

Thirty minutes of moderate-intensity exercise may be adequate to maintain cardiovascular health, but it might not prevent weight gain. Recommendations published in 2003 and 2004 suggest that 45 to 60 minutes per day is necessary to prevent weight gain. Children may need more activity.

Losing significant weight requires both exercise and calorie restriction. In addition, if a person exercises but doesn't diet any actual pounds lost may be minimal because dense and heavier muscle mass replaces fat. Nonetheless, regardless of weight loss, a fit body will look more toned and be healthier.

People who exercise are more apt to stay on a diet plan. Exercise improves psychological well being and replaces sedentary habits that usually lead to snacking. Exercise may even act as a mild appetite suppressant.

Exercising without dieting still adds health benefits. One study found that overweight but fit people have half the death rate of overweight, unfit people. Research suggests that people who have trained for a long time develop more efficient mechanisms for burning fat and are able to stay leaner.

Lifting weights builds muscle, which burns calories more efficiently than other body tissues.

The following are some suggestions and observations on exercise and weight loss:

• The treadmill burns the most calories of standard aerobic machines. It may be particularly effective when used in short multiple bouts during the day. Exercise sessions as short as 10 minutes in duration that are done frequently (about four times a day) may be the most successful program for obese people.
• The more strenuous the exercise, the longer the metabolism continues to burn calories before returning to its resting level. This state of elevated metabolism can last for as little as a few minutes after light exercise to as long as several hours after prolonged or heavy exercise.
• Resistance, or strength, training is excellent for replacing fat with muscles. It should be performed two or three times a week.
• Fidgeting may be very helpful in keeping pounds off. Regular exercise is certainly the best course, but for people who must sit for hours at work, frequently shifting positions while sitting may have some benefit.
• It is important to realize that as people slim down, their initial level of physical activity becomes easier and they burn fewer calories per mile of walking or jogging. The rate of weight loss slows down, sometimes discouragingly so, after an initial dramatic head start using diet and exercise combinations. People should be aware of this phenomenon and keep adding to their daily exercise regimen.
• As people age, they also need to exercise more to keep off the same amount of weight.
• Changes in fat and muscle distribution may differ between men and women as they exercise. Men tend to lose abdominal fat (which lowers their risk for heart disease faster than reducing general body fat). Exercise, however, does not appear to have the same effect on weight distribution in women. A study of women who underwent aerobic and strength training resulted in fat loss in their arms and trunk, but no gain in muscle tissue.

Because obesity is one of the risk factors for heart disease, anyone who is overweight must discuss their exercise program with a physician before starting.

Exercise's Effects on Other Conditions

Physical activity makes you healthier. It lowers your risk for  cardiovascular disease and reduces bone loss. Physical activity also helps the body use calories more efficiently, which helps you eliminate body fat and lose weight. It also helps you maintain weight loss by increasing your metabolism and reducing your appetite.

Effect of Exercise on Cancer

A number of studies have indicated that regular exercise may reduce the risk of breast, prostate, and colon cancer. Exercise not only lowers a woman's chance of getting breast cancer, it can help those who have received chemotherapy for the disease fight off fatigue. 

A 2004 study showed that prostate cancer cells have a 27% reduction in growth when exposed to exercise serum (blood serum taken from patients who exercise) compared to control serum, suggesting that exercise changes blood chemicals to be less hospitable to cancer cells.

Physical activity has been said to lower a man's risk of colon cancer, but data linking exercise to a lower risk in woman has been inconsistent. A 2006 study published in the International Journal of Cancer concluded that exercise may not reduce a woman's risk of colon cancer. Previous studies, including the Nurses Health Study and the American Cancer Society's Cancer Prevention Study II, found that exercise reduced a woman's risk of colon cancer by 30-40%. The prospective cohort study involved nearly 32,000 mostly postmenopausal women who were participating in a breast cancer trial. The women were given questionnaires and asked to rank their exercise habits according to light, moderate, and heavy activity. The study author says the conflicting result may be due to a misclassification of certain activities.

Effects on the Gastrointestinal Tract

Endurance athletes often report stomach problems, such as bloating, diarrhea, and gas, even at rest. Experts suggest that moderate regular exercise, might reduce the risk for some intestinal disorders, including ulcers, irritable bowel syndrome, indigestion, and diverticulosis. Older people who exercise moderately may have a lower risk for severe gastrointestinal bleeding.

Effects on Kidney Disease

Patients with end-stage kidney disease who exercise four to five times per week have better survival rates than those who are less active, researchers involved in the Dialysis Morbidity and Mortality Wave 2 study report. However, the majority of study participants said that severe physical limitations that prevented them from exercising that often.

Effects on Neurologic Diseases and Mental Decline

Studies have shown that regular exercise, particularly walking, helps reduce one's risk for memory loss. A 2005 study found that older men who walked less than a mile daily had a 71% higher risk of dementia than those who walked more than two miles a day. An earlier study found that walking regularly protects women from mental decline. To date, there are no clear theories for the apparent benefit, although a preliminary study in mice suggests that physical activity changes the way brain-damaging proteins are metabolized in the brain, thus slowing the development of Alzheimer's disease. (Stretching and weight training appear to have no such effects.)

Aerobic exercise has been linked with improved reaction time, perception, and math skills in people of all ages.

People with existing neurologic diseases, such as multiple sclerosis, Parkinson’s disease, and Alzheimer’s disease, should be encouraged to exercise. Specialized exercise programs that improve mobility are particularly valuable for Parkinson's patients. Patients with neurological disorders who exercise experience less spasticity as well as reduction in, and even reversal of, muscle atrophy. In addition, the psychological benefits of exercise are extremely important in managing these disorders. Exercise machines, aquatic exercises, and walking are particularly useful.

Effects on Emotional Disorders

Some research has suggested that exercise may have antidepressant effects. Although there is little strong evidence that exercise can help manage depression, a number of studies have suggested benefits. Research findings include:

• Just 30 minutes of brisk exercise three times a week was as effective as medication in relieving the symptoms and reducing relapse in many patients with mild to moderate depression.
• Over half of older women with depression that did not respond to medication improved with 10 weeks of exercise. (About a third of women who did not exercise also improved during that time.)
• Studies on elderly, depressed patients report modest benefits from exercise, even in those who do not response to antidepressants. (Simply participating in a group activity may help improve mood.)
• Teenagers who were active in sports have a greater sense of well being than their sedentary peers; the more vigorously they exercised, the better their emotional health.
• A 2003 study found that physical inactivity is strongly linked to depression in children 8 to 12 years of age.

Specific exercises may be particularly beneficial:

Aerobics. Either brief periods of intense training or prolonged aerobic workouts can raise chemicals in the brain, such as endorphins, adrenaline, serotonin, and dopamine, that produce the so-called runner's high. Weight loss and increased muscle tone can boost self-esteem.

Yoga. Yoga practice, which involves rhythmic stretching movements and breathing have been found to positively affect mood and may have clinical potential as a technique for improving and stabilizing mood. A study comparing yoga to aerobic exercise found that men have significantly lower levels of tension, fatigue, and anger after yoga than after swimming. (Yoga and swimming tended to produce equal benefits in women.)

Click the icon to see an image of the benefits of yoga.

Effect of Exercise on Pregnancy

Moderate exercise in healthy pregnant women does not increase the risk for miscarriage, preterm labor, or rupture of the membrane. Not exercising increases the risk for complications, including low-birth weight babies. Exercising increases the fetal heart rate, which in turn protects the baby.

Healthy women with normal pregnancies should exercise at least three times a week, being careful to warm up, cool down, and drink plenty of liquids. Many prenatal calisthenics programs are available.

The following are specific exercises that may benefit the pregnant woman:

• Swimming and water aerobics may be the best option for most pregnant women. Swimming has special benefits for those with fluid buildup. Water exercises involve no impact, overheating is unlikely, and swimming face down promotes optimum blood flow to the uterus.
• Performing yoga exercises under the guidance of informed instructors can be very helpful.
• Walking is also beneficial.

To strengthen pelvic muscles, women should perform Kegel exercises at least six times a day. This involves contracting the muscles around the vagina and urethra for three seconds 12 to 15 times in a row.

Experts generally recommend the following precautions for pregnant women who exercise:

• Fit women who have exercised regularly before pregnancy may work out intensely as long as the physician approves and no discomfort occurs.
• As a rule, for previously sedentary low-risk expectant mothers, the pulse rate should not exceed 70 - 75% of the maximum heart rate or more than 150 beats per minute. (In one study, such women exercised to 150 to 156 beats per minute three times a week without any harmful effects, but any woman should check with their physician before embarking on such a program.)
• According to one study, vigorous exercise may improve the chances for a timely delivery. All pregnant women, however, should avoid high-impact, jerky, and jarring exercises, such as aerobic dancing, which can weaken the pelvic floor muscles that support the uterus.
• During exercise, women should monitor their temperature to avoid overheating, a side effect that can damage the fetus. (Pregnant women should not use hot tubs or steam baths, which can cause fetal damage and miscarriage.)

Note: Strenuous exercise may affect the flavor of breast milk for a short time afterward. Nursing mothers who engage in such activity might want to wait about an hour after exercising before they feed their infant.

Complications

Exercise may lead to injury if not done properly. Always exercise with care.

Injuries from High-Impact Exercise

Competitive running or high-impact aerobics pose a high risk for a number of injuries in the bones and muscle. The effect of high-impact exercise on the back is not entirely clear. Some research suggests that over time, it may increase the risk for degenerative disc disease. A survey of people who played tennis, however, found no increased risk for low back pain or sciatica.

High-impact exercise can also cause dizziness, ringing in the ear, motion sickness, or loss of high-frequency hearing.

Some research further suggests that in people unused to exercise, intense activity increases production of harmful particles in the body called free radicals. These unstable oxygen particles  injure muscle tissue. Muscle pain in this case does not occur until 24 to 48 hours after exercise.

Some people have a higher than average risk for injury:

• About half of people at any age who participate in competitive running or high-impact aerobics experience minor injuries at least once a year. Young, intensely competitive athletes may be at risk for permanent injury. Studies are mixed over whether intensive high-impact sports in younger people cause long-term degenerative joint disease.
• As more older people start exercising, there has also been a risk for injuries. Between 1990 and 1996, injuries from active sports increased by 54% in people age 65 and older.
• Women are far more likely than men to suffer knee injuries.
• Urinary incontinence affects many female athletes who engage in high-impact exercise.
• Tennis players are at high risk for injuries from repetitive force on the shoulder joint.

Preventing High-Impact Injuries. The following may be helpful for preventing injury:

• Wear shock-absorbing footwear with weight-dampening inserts.
• Combine weight lifting with jumping exercises. This may prevent injury by strengthening hamstrings and improving coordination.
• Vary training and alternate easy and harder workouts.
• Be careful to warm up, cool down, and stretch. Flexibility is the key to preventing many muscle strains.
• Take days off now and then. The risk of injury increases when athletes train more than five times a week.

Because of the association between high-impact exercises and oxidation, some experts suggest that eating foods rich in antioxidants, such as vitamins A, C, and E. Such foods include many fresh fruits and vegetables.

Treating Minor Injuries. Most mild or moderate injuries respond well to a simple, four-step treatment: rest, ice, compression, and elevation (RICE). This regimen works well for both spot injuries and chronic problems. Ice packs, which reduce inflammation and pain, can help acute injuries and can be useful for the first few hours after a chronically injured area is exercised. How much or how long to compress the injury is unclear. Evidence suggests that early movement is helpful, although taping or bracing in people with a recurrent ankle sprain is known to be protective. It may not be helpful in those without a previous ankle injury.

Minor injuries like sprains may be treated at home if broken bones are not suspected. The acronym RICE can help you remember how to treat minor injuries: "R" stands for rest, "I" is for ice, "C" is for compression, and "E" is for elevation. Pain and swelling should decrease within 48 hours. Gentle movement may help, but pressure should not be put on a sprained joint until pain is completely gone. This can take up to a few weeks.

Heat, ultrasound, whirlpool, and massage may speed healing if applied a day or two after the initial injury or for warm-up before another workout session.

Female Athlete Triad

Some young female athletes who exercise very intensely and are subject to intense pressure to remain thin are at risk for the so-called female athlete triad. This triad of symptoms includes menstrual dysfunction, eating disorders, and osteoporosis. Eating disorders among young female athletes is estimated at 15 - 62%. Women at higher risk include ballet dangers, gymnasts, and divers. Continued intense exercise causes a stress response in which estrogen (the primary female hormone) declines. Estrogen loss then can lead to infertility and osteoporosis. Iron depletion and anemia may also be a problem in women who exercise frequently, even at moderate intensity. A doctor should be consulted for any of these concerns.

Improper Mechanics and Its Effect on the Back and Shoulders

Incorrect movements can literally cause mechanical problems in the muscles. They are usually the result of improper exercise instruction and inattention. A single jerky golf swing or incorrect use of exercise equipment (especially free weights, nautilus, and rowing machines) can cause serious back injuries.

Between 30 - 70% of cyclists experience low back pain. Pain may be improved by adjusting the angle of the bicycle seat.

Dehydration

Everyone should drink lots of fluid during intense exercise. Thirst is often a poor indicator of dehydration in people who exercise, particularly older people. During a tough workout in a hot environment, the body can lose two liters of fluid per hour through sweat. Anyone who exercises intensively should take the following precautions:

• Drink 6 to 8 ounces of fluid about 15 minutes before a workout, and then pause regularly during exercise for more.
• Water is the best choice for replenishing body fluids. Glucose-sodium-potassium solutions, the so-called "sports drinks," that promise instant energy are apparently no better than water at improving endurance during prolonged intense running.
• Caffeinated beverages like coffee and soft drinks give short bursts of energy but can actually reduce fluid. Caffeine before a workout has been shown to temporarily raises blood pressure and reduces blood flow to inactive limbs.

Contrary to popular belief, drinking fluids will not cause cramps. Adequate hydration, in fact, helps prevent the painful involuntary muscle spasms that sometimes occur during exercise.

Hyperthermia (Overheating)

Overheating, or hyperthermia, can be a problem with strenuous exercise or when working out in hot weather. Overheating can cause mild to life-threatening conditions. Heat exhaustion, a moderate form of hyperthermia, is characterized by the following symptoms:

• Lightheadedness, nausea, headache, hyperventilation, fatigue, and loss of concentration.
• A high temperature (above 103° F), possibly accompanied by complaints of chills and clammy skin.

Individuals should rest in a cool, dry place, drink plenty of fluids, and bring down their body temperature with ice packs pressed against the skin.

Heatstroke. Heatstroke is the most dangerous complication of hyperthermia. The victim may suddenly cease sweating, after which symptoms such as altered consciousness, seizures, and even coma, may quickly follow. Heat stroke is a medical emergency and requires immediate cooling of the victim in an ice-water bath or with ice packs. One study suggests that risk for serious complications from exercising in high temperatures may persist as late as the following day, even if the weather has cooled down.

Click the icon to see an image of the dangers of heatstroke.

Frostbite and Hypothermia

Precautions also need to be taken in cold weather. When exercising in winter, dress in layers, including gloves and socks, which create insulated air pockets that trap heat. In cold weather, wear shoes with less ventilation than those worn in the summer. Fingers, toes, ears, and nose are most susceptible to frostbite. From stinging or aching, frostbite progresses to numbness. Fingers and toes may become white. Soaking the extremities in warm water can help, but only once there is no risk of refreezing, since a second bout of frostbite after thawing can accelerate tissue damage. Hypothermia can be life threatening and can occur even after prolonged exposure to temperatures that are above freezing. The condition is characterized by extreme fatigue, mental confusion, apathy, and a lack of coordination. The victim should be warmed as soon as possible with blankets, body heat, and warm fluids.

Motivation

Motivation, or a lack thereof, is one reason may people stop exercising. Here are some tips for avoiding burn out:

• Think of exercise as a menu rather than a diet. Choose a number of different physical activities that are personally enjoyable such as sports, dancing, or biking. Although experts say you should get 30 minutes of aerobic exercises at least five times a week, those times can be divided into shorter periods -- such as 10 minute sessions. In addition, people can achieve health benefits from other exercise programs, including weight training, yoga, or tai chi.
• Stick to a prepared schedule and record progress.
• Develop an interest or hobby that requires physical activity.
• Adopt simple routines such as climbing the stairs instead of taking the elevator, walking instead of driving to the local newsstand, or canoeing instead of zooming along in a powerboat.
• Try cross training (regularly switching from one type of exercise to another). Studies suggest it is more beneficial than focusing only on one form of exercise.
• Exercise with friends.
• Join a gym or take classes. Many affordable programs are available.
• For those who can afford them, personal trainers can be very helpful and are available in many gyms and exercise clubs. Personal trainers without any connection to a well-reputed gym or fitness club should be certified by a major fitness organization, such as the Aerobics and Fitness Association of America (AFAA) or the American Council on Exercise.
• Exercise videos may also be helpful, but people should be sure they are suited to individual age and health needs and bear the seal of the AFAA.
• Consider getting a dog. A study in the February 2006 American Journal of Preventive Medicine found that dog owners in Canada walk almost twice as much as those who don’t own a dog. Regular walking is a good way to improve health.

Differences in Motivation Between Men and Women. Motivation factors may differ by gender and women appear to have a harder time. In one study weight loss was the greatest motivator to exercise for women and muscle tone was the primary motivator for men. Unfortunately, cosmetic effects may take a long time to become apparent, discouraging people from continuing even though their health is improving.

Motivating Children and Adolescents

Obesity among children and adolescents has now become epidemic in the United States. Experts say that children should be vigorously active for at least 20 to 60 minutes 3  to 5 days a week. Parents and schools must be imaginative and rigorous in encouraging children to exercise.

Role of Parents.  Parents must make conscious efforts to limit sedentary activities and to encourage physical ones for their children. This includes monitoring the time children spend on the computer, watching TV, or playing video games and suggesting different forms of entertainment. Even children who aren't interested in joining a Little League team may enjoy a round of catch with their parents, walking in the park, or swimming in a local lake.

Role of Schools. Early school physical education programs can make a significant difference and the earlier these routines are learned, the more likely they will be carried forth into a healthy adulthood. Schools should emphasize team cooperation or individual improvement and self-mastery. Studies have shown that people tend to give up more quickly and feel less competent if their perceptions of success are based only in comparison to their peers.

People mature at different rates, and there seems to be a genetic component to coordination, strength, speed, and one's response to resistance exercise. Nonetheless, everyone should strive to be as fit as they possibly can, given their strengths and limitations.

Resources

• http://fitness.gov/ -- The President's Council on Physical Fitness and Sports
• http://www.ncppa.org/ --National Coalition for Promoting Physical Activity
• http://www.acefitness.org --American Council on Exercise
• http://www.arthritis.org --The Arthritis Foundation offers tips on exercising with arthritis
• http://www.justmove.org/ -- Just Move (American Heart Association)

References

Abbott, RD, White, LR, G. Ross, W, et al. Walking and Dementia in Physically Capable Elderly Men. JAMA. 2004;292:1447-1453

Calton BA, Lacey JV Jr, Schatzkin A, Schairer C, Colbert LH, Albanes D, Leitzmann MF. Physical activity and the risk of colon cancer among women: A prospective cohort study (United States). Int J Cancer. 2006 Feb 17; [Epub ahead of print] 

Di Loreto C, Fanelli C, Lucidi P, et al. Make your diabetic patients walk: long-term impact of different amounts of physical activity on type 2 diabetes. Diabetes Care. 2005 Jun;28(6):1295-302.

The National Institute on Aging. Exercise: Getting Fit for Life. Available at: http://www.niapublications.org/agepages/exercise.asp.   Accessed on March 3, 2006.

The American Heart Association. What is a Safe Rate While Exercising? Available at: http://www.americanheart.org/presenter.jhtml?identifier=3034847. Accessed on March 3, 2006.

Mikkelsson LO, Nupponen H, Kaprio J, Kautiainen H, Mikkelsson M, Kujala UM. Adolescent flexibility, endurance strength, and physical activity as predictors of adult tension neck, low back pain, and knee injury: A 25 year follow up study. Br J Sports Med. 2006 Feb;40(2):107-13.

Brown SG, Rhodes RE. Relationships among dog ownership and leisure-time walking in Western canadian adults. Am J Prev Med. 2006 Feb;30(2):131-6.

Simons R, Andel R. The effects of resistance training and walking on functional fitness in advanced old age. J Aging Health. 2006 Feb;18(1):91-105.

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