1. Define exercise.

Exercise is physical activity that is planned and structured for the sole purpose of improving, maintaining, or expressing a particular type(s) of physical fitness (1). Exercise differs from the term physical activity in that physical activity consists of activities performed for purposes other than the specific development of physical fitness. It should be noted, however, that regular physical activity can improve physical fitness.

Exercise includes two broad categories of activity-aerobic and anaerobic exercise. Aerobic exercise includes long duration activities such as running, bicycling, and swimming that extract energy more slowly from biochemical reactions that require oxygen. Anaerobic exercise, on the other hand, includes activities such as sprinting and weight lifting, which utilize biochemical reactions, that provide high levels of energy in the absence of oxygen.

2. Define fitness.

Fitness is a set of attributes that relate to one's state of well-being that provides optimal performance for a given exercise or physical activity (1). There are many components to fitness and they include muscular strength, power and endurance, as well as cardiorespiratory endurance, flexibility, balance and agility.
3. Does an improvement in level of fitness improve health outlook?

Numerous studies have demonstrated that behavioral changes, including improving one's level of physical fitness, delay all causes of mortality and extend life (2). In a study involving Harvard alumni over an 11- to 15-year period of time it was shown that men, regardless of their age, who were initially sedentary but adopted a more moderate to vigorous lifestyle of regular exercise activity had a 51% lower risk of dying than men that remained sedentary. This study also revealed that becoming more physically active on a regular basis was of equal benefit in terms of heart mortality risk reduction as quitting cigarette smoking, reducing body weight, or controlling blood pressure.

The evidence continues to be overwhelming that even mild to moderate regular exercise, for both men and women, promotes good health, improves quality of life, and can significantly increase life expectancy. These results are achieved not only through a substantial reduction in the risk of dying from heart disease, but also from cancer and other degenerative diseases.

4. How does exercise affect lipid profiles?

Regular exercise improves lipid metabolism in men and higher-volume aerobic exercise programs also increase high-density lipoprotein cholesterol (HDL-C) levels in both pre- and postmenopausal women (3). Studies of resistance training found no increases in HDL-C. Levels of low-density lipoprotein-cholesterol, total cholesterol, and body fat were reduced.

5. What should an adequate medical evaluation of a healthy person include before an exercise prescription is given?

Before any healthy individual over the age of 35 starts an endurance and strength-training program, they should see their health care provider for a complete evaluation, which should include a physical exam, lab work and possibly an exercise stress test. The lab work should include at the very least a fasting lipid profile (total cholesterol, LDL, HDL, and triglycerides), a metabolic panel to evaluate electrolyte status along with liver and kidney health, and a complete blood count.

6. How much aerobic exercise is necessary to achieve cardiovascular benefits?

The American College of Sports Medicine (ACSM) recommends that aerobic endurance exercise should be performed 3 to 5 days per week, for 20 to 60 minutes continuously at 55% to 90% of maximum heart rate (4). They point out, however, that very sedentary individuals may have to exercise at the low end of the intensity range for a longer duration than do physically active individuals.

The Centers for Disease Control and Prevention (CDC) recommends that, at a minimum, adults engage in moderate-intensity physical activity in which they expend approximately 200 kcal/day (about 30 minutes a day). These activities can be outside of a formal exercise program and can also be intermittent. Mild-to-moderate exercise is far better than none, but vigorous exercise is best of all.

7. How important are warm-ups and cool-downs?

Proper warm-ups and cool-downs are an essential part of a well-designed exercise program to assure maximum performance and minimize injuries. A warm-up of 5 to 10 minutes of low-intensity calisthenic-type exercise, such as slow or brisk walking or light cycling, is ideal. A cool-down period of about the same duration will provide a gradual recovery from the endurance phase of both aerobic and anaerobic exercise activities.

8. Are flexibility exercises important?

Flexibility diminishes with age but there is no evidence this is part of the aging process. Loss of flexibility is more likely due to diminished physical activity. Flexibility training can be improved at any age through static stretching and range-of-motion exercises that promote elasticity of the soft tissues. Flexibility training should always be performed at the end of an exercise program when all the tissues are warm, for at least 2 to 3 days per week for about 10-15 minutes (5).

9. How does exercise affect aging?

Exercise is undoubtedly the best "medication" healthcare providers can prescribe for their patients. Increased fitness resulting from a regular exercise program can dramatically reduce the effects of aging that lead to functional declines and poor health.

A recent study of men in their 50s at the University of Texas Southwestern Medical Center at Dallas showed that just 6 months of aerobic exercise training in which the frequency, duration and intensity were gradually increased, resulted in returning them back to the level of fitness they had at age 20 (6). This was confirmed by measuring the subject's aerobic power-the heart and lungs' ability to supply oxygen to their working muscles, and their cardiovascular performance. The conclusion of the researchers is that "no matter what your age, it's your current fitness level, not you're past fitness level, that really dictates how fit you are."

10. Why is it important for individuals to include resistance strength training in the exercise program?

Until recently, resistance training was felt to be appropriate only for young, healthy, male athletes. This mindset has led many to overlook the enormous benefits of resistance training for younger women, older men and women and even children. There is a rapid decline in the muscle strength of sedentary individuals starting at about age 50 (7). We now know that this decline can be totally prevented and even reversed by simply incorporating resistance exercise training into an individual's lifestyle. Some studies have actually shown that with just two months of strength training people can literally reverse two decades of muscle loss (8).

Improvement in the strength of elderly people also has important implications for their health and the quality of their lives. For one thing, their balance and coordination is improved and their chances of falling is greatly reduced-falls are a major source of injury, fractures and debilitation leading to death for the elderly. Strength training has also been found to help maintain and even increase bone density in both women and men of all ages, further reducing their risks for fractures.

11. What are "free weights?" Do they have any advantage over resistance machines?

Exercise with free weighs involves dumbbells and barbells rather than the resistance machines seen in most commercial and home gyms. Athletes and strength coaches believe that free weights offer advantages that resistance machines do not provide. The athlete must completely control the weight being lifted while maintaining balance. This requires the recruitment of a greater number of motor units-not only in the muscles being trained, but also in stabilizing muscles. Many experts believe that this form of resistance training results in greater muscle growth as well as increased strength over what one can achieve with resistance machines. A good strength-training regimen incorporates both free weights and resistance machines into an individual's exercise program.

12. Does our ability to adapt to training decrease with age?

Recent studies in which older subjects were encouraged to train at higher intensities have demonstrated that individuals have a considerable ability to increase their endurance capacity and strength with proper training at any age (9). Exercise training can minimize or even reverse the syndrome of frailty, which is so prevalent among the most elderly.

13. What is the best way to determine what an individual should weigh?

Currently, the body mass index (BMI), which is the ratio of weight to height squared, is used to determine if an individual is overweight or obese. A high BMI is associated with an increased prevalence of mortality from heart disease, diabetes, and cancer when used in large population studies. This simplified approach works fairly well for most of our population but since it only looks at weight and height, it misses what really is increasing one's risk for diabetes, strokes, cancer, arthritis and premature death-fatness. A BMI does not reflect actual body fat content. A much better assessment of an individual's health risks is their percentage of body fat. It's excess fat that increases one's risk for disease, not excess weight. We need to avoid the use of height-weight tables and replace the concept of being overweight with the condition of being overfat (10).

Ideal body weights can be determined for an individual by first determining their body composition. The most common and widely used technique for assessing body composition today is through the measurement of skinfold thickness from selected sites with calipers. In this way, an individual's body fat percentage can be determined and it is this value that should be used to determine ideal body weights and the degree of fatness.

14. What percentage of body fat is thought to be associated with good health and fitness?

Ideal body composition depends on age and gender. The following table lists the percentages of body fat for men (11) and women (12) that correlate with excellent to poor health/fitness ratings according to age. This can be used as a guideline to determine ideal body weight.

As a general rule, no man at any age should have greater than 18 percent body fat and no woman should exceed 25 percent if they want to remain optimally fit and healthy. The accumulation of body fat of more than 25 percent for men and 33 percent for women puts them in the obese, high-health-risk category.

15. What is the best way to measure body fat?

There are numerous methods to assess percentages of body fat, but most require expensive and large pieces of laboratory equipment. Hydrostatic weighing has been considered the gold standard by which all other methods have been validated even though there is a 4% error. Air-displacement plethysmography is a new, also very costly, method equally accurate as hydrostatic weighing that appeals to individuals that are unable or don't want to be submerged in water.

By far, the simplest and least expensive method for determining percentages of body fat is to measure subcutaneous fat at selected sites by measuring skinfold thickness with calipers. This technique provides a good estimate of body fat percentages ( 3 to 5% of hydrostatic weighing values) when done by trained experienced people (13).

16. What is VO2 and why is this important?

VO2 is an important number that exercise physiologist use every day in their laboratories to measure how much oxygen people use while exercising. When individuals reach their maximal ability to consume and utilize oxygen during exercise this is called their VO2max.

VO2max is determined by an individual's genetic makeup and exercise history. Most authorities regard it to be the single best measurement of cardio-respiratory endurance and aerobic fitness. After the age of 25 to 30, VO2max values decrease about 1 percent per year in people that remain sedentary (14).

Fortunately, individuals are able to prevent this decline and can actually increase their VO2max through endurance training (also called aerobic and cardio exercise)-at any age, regardless of their physical condition (15). In fact, the least fit people can increase their VO2max values the most.

17. What is the best endurance-training program an individual can use to improve their VO2max (aerobic capacity)?

Two variables of endurance training, volume (duration of training) and intensity (the degree of difficulty of training), play the key roles in increasing an individual's VO2max.

For a long time many authorities believed that gains in aerobic capacity and endurance were directly related to the volume of training an individual performed. Consequently, people were advised to spend a great deal of time, every day, training slow and easy. Recent research, however, has shown, that the amount of improvement in aerobic capacity does not depend on the volume of exercise performed. It is the intensity of the exercise that directly improves aerobic capacity (VO2max) and enables people to reach their maximum performance levels (16).

Long-distance, low-intensity training just doesn't produce the biochemical and physiological changes needed to increase people's VO2max. It takes high-intensity training (which can include intermittent high-intensity exercise or continuous exercise at near-competition pace) to maximize endurance performance and aerobic fitness.

Intermittent exercise, also called interval training, consisting of fast-paced, brief exercise bouts with short rest periods between these bouts, achieves the same aerobic benefits as long, continuous, high-intensity exercise without the boredom many experience. Some people, however, like the near-meditative state associated with continuous training and prefer this form of exercise.

The recommendation is; do one or the other or mix them together, keeping in mind that intensity is the critical factor in improving performance, not volume.

18. What is the best way to determine oxygen consumption levels?

The best and simplest way to determine the percentage of VO2max at which an individual is training is by using their heart rate as a guide (17). First, determine their maximal heart rate by using the formula 220-age = Max Heart Rate (MHR). If he or she is already in excellent physical condition, use 205- age = MHR. MHR can be considered to be equivalent to the VO2max and the heart rate achieved during exercise can be converted into the percentage of MHR and this will reflect the percentage of VO2max.

19. What heart rates should people attempt to achieve in order to burn the most body fat for a given amount of exercise?

Contrary to past beliefs, the Fat Burning Heart Rate Zone of 50 percent to 65 percent of the MHR is no longer believed to be the best heart-rate range to burn fat. The Target Heart Rate Zone of 65 percent to 85 percent of the MHR is now considered by most exercise physiologists to be the best level of intensity for improving endurance, achieving ultimate fitness, increasing VO2max and getting rid of body fat (18). The term "Fat Burning Zone" is therefore misleading because exercising in the Target Heart Rate Zone will burn more calories and produce greater weight loss with the same amount of exercise time as in the Fat Burning Zone.

If, however, an individual is just starting out with aerobic training, it is best to train in the Fat Burning Zone until he or she is ready to move into the Target Heart Rate Zone.

20. What is the best exercise program one can use to increase cardiorespiratory endurance and physical fitness?

The best and most efficient method one can use to increase aerobic fitness and cardio-respiratory endurance (the most important component of physical fitness) is to perform high-intensity training for 30 minutes after a 5 minute warm-up and before a 5 minute cool-down, 5 times a week in the Target Heart Rate Zone (16).

It is important, however, that resistance strength training be included in one's overall exercise program to achieve maximum health benefits. The most recently published guidelines for resistance strength training include using at least 8 to 10 different exercises, with a minimum of one exercise per major muscle group, 2 to 3 times a week on alternate days. Younger individuals should use 8 to 12 repetitions per set and older people and cardiac patients should use 10 to 15 repetitions per set (1). All sets should be performed at moderate to maximal effort.

It is essential that both aerobic and strength training programs must be started only after an individual has his or her doctor's approval!

21. How can people (especially men) get rid of their "spare tire"?

Abdominal obesity is a common problem for almost all men and many women in today's society. This results mostly from fat being deposited inside the abdominal cavity-the so-called intra-abdominal fat. This is the worst kind of fat because it not only adds inches to the waistline but is also one of the major causes of poor health in America today. This kind of fat doesn't just hang out quietly inside the belly like subcutaneous fat under the skin. It is very much alive, actively producing harmful hormones and other chemicals that many scientists believe can cause cancer, elevate blood sugars, and produce insulin resistance that leads to hyperinsulinemia and diabetes (19). The reasons for this are not fully understood, but many experts believe that intra-abdominal fat not only produces harmful hormones but also produces free fatty acids much more readily than subcutaneous fat. These free fatty acids are directly transported to the liver, where they can interfere with insulin metabolism and create a state of hyperinsulinemia, poor blood sugar control, salt retention and high blood pressure (Syndrome X)-all major causes of heart disease, high blood pressure, and many other degenerative diseases. This is of special importance to men because their intraabdominal fat is the body fat depot that increases the most with age.

Abdominal girth has been shown to be a better predictor of future coronary artery disease and type-2 diabetes than BMI-even though BMI is considered to be the gold standard and is used by doctors, nutritionists, and other health professionals to assess health risks. Unfortunately many individuals can have a normal, "healthy" BMI and at the same time have significant amounts of disease-causing intra-abdominal fat.

It is easy to determine if an individual has too much intra-abdominal fat by simply measuring waist circumference at the umbilicus. Circumferences of 40 inches or greater in men, or 35 inches or greater in women markedly increase their risks for hypertension, diabetes and heart disease.

The better individuals are at breaking down their body fat into its free fatty acids (lipolysis) and transporting these fatty acids to muscle tissue for oxidation, the leaner they become and the less problem they have with abdominal obesity. This can best be achieved through a program of proper nutrition and exercise.

Typically, a 1 to 4% reduction in overall percent of body fat occurs with endurance training in older adults, which is similar to that seen in younger adults. Of special note, however, is that in older men, intraabdominal fat is specifically targeted and can decrease by as much as 25% with exercise training.

22. Are there any contraindications to exercise testing and training for older men and women?

The contraindications to exercise testing and exercise training are the same regardless of an individual's gender or age. The major relative contraindications precluding exercise testing are recent ECG changes, recent myocardial infarction, unstable angina, uncontrolled arrhythmias, third degree heart block, acute congestive heart failure, severe aortic stenosis, suspected dissecting aneurysm, myocarditis, thrombophlebitis, recent systemic or pulmonary embolus, acute infection, and significant emotional distress. The major relative contraindications for exercise testing include elevated blood pressures, cardiomyopathies, valvular heart disease, complex ventricular ectopy, and uncontrolled metabolic disease.

The adherence to the general American College of Sports Medicine testing guidelines with respect to the necessity for exercise testing as well as exercise recommendations and for the medical supervision of such testing and recommendations is imperative (20).

23. Are losses of muscle mass, strength and increases in body fat stores inevitable functions of aging?

Age-related loss of muscle mass (sarcopenia) accounts for the decreases in basal metabolic rate (BMR), muscle strength, and activity levels often observed in the elderly. Energy requirements decline as the BMR declines. This decreased caloric need is frequently not matched by an appropriate decrease in caloric intake and body fat content increases. Increased body fatness and the accompanying increase in abdominal obesity promote many disease states. The decrease in muscle mass is the direct cause of diminished strength. Decreased strength in the elderly is a major cause for their disability.

Recent data suggest the changes in body composition and aerobic capacity that are associated with age are not a function of aging at all. A study of endurance-trained individuals of different ages revealed that body fat stores and maximal aerobic capacity were not related to age but rather, to the total number of hours these people exercised per week (21).

Resistance strength training is also especially important in the elderly. This form of training increases muscle size as a result of an increase in the number of muscle contractile proteins. As muscle mass increases so does strength. Although both aerobic and strength training are necessary, sarcopenia can only be stopped and reversed with strength training. Increased muscle mass and strength are the first steps toward reversing the syndrome of physical frailty and promoting a lifetime of increased physical activity, good functional capacity and independence.

24. Does exercise help prevent osteoporosis?

Aerobic exercise and weight bearing physical activities are both important in maintaining overall health as well as healthy bones, but they do little to preserve bone density. High-intensity progressive strength training, however, has been shown in several well-controlled studies to have significant clinical application in the prevention and treatment of osteoporosis and other degenerative bone diseases in both men and women (22). Progressive resistance training helps premenopausal women achieve the highest peak bone mass possible and is also thought to help maintain or increase bone density in postmenopausal women. Studies continue to demonstrate that muscle mass, strength, balance, physical activity and functional capacity are all increased substantially with high-intensity progressive resistance training in men and women of all ages, including the very old.

25. What are the differences between aerobic endurance training and resistance strength training on health and fitness?

Research has clearly shown that resistance training is essential for the development of muscle mass, strength, power and endurance. Only recently, however, has the focus of importance of resistance training shifted from a fitness goal to that of health and disease prevention.

A recent symposium on resistance training for health and disease has addressed the scientific evidence for the importance of strength training for the development and maintenance of muscle and bone and its importance in the prevention and rehabilitation of many chronic disease problems, such as physical dysfunction, obesity/metabolism, weight control, osteoporosis, low back pain, and disability (23).

Pollock and Vincent, in a recent issue of The President's Council on Physical Fitness and Sports Research Digest, reviewed the effects of resistance training on health as described in the following table (24):

26. What form of exercise has been shown to help with low back problems?

One of the best ways to treat chronic back injuries and chronic back pain is the adherence to a program that includes both aerobic and strength-training exercises. This approach helps prevent future injuries by maintaining physical fitness and leanness throughout life. Back injuries occur ten times less often in people who perform aerobic and resistance training.

While all forms of exercise have been shown to benefit people with chronic low-back pain, an intense, integrated approach that includes regular resistance training has been proven to be the most effective. This form of exercise not only improves endurance and activity tolerance but also increasing the strength and flexibility of back muscles. In addition, it promotes weight loss (obesity is a major cause of acute and chronic back pain) and provides beneficial psychological effects.

In a study published in the Archives of Physical Medicine and Rehabilitation, Dr. B.W. Nelson and colleagues set out to determine if back-pain patients recommended for spinal surgery could avoid their surgery through an aggressive strengthening program (25). After following a 10-week intensive back-strengthening regimen, 57 of the 60 patients no longer required surgery and were virtually pain free.

There are well over 100 other studies that have shown that cardiovascular and strength-training exercises can alleviate chronic back pain by strengthening and increasing the flexibility of back muscles.

27. Is weight lifting advisable for individuals with heart disease?

Doctors have traditionally discouraged people with heart disease or older people from engaging in strength training with weights or exercise machines because they believed that this would put dangerous stress on their hearts.

Recently, an expert panel of scientists, organized by the American Heart Association, has finally put to rest the age-old myth that weight training and other forms of resistance exercise are bad for the heart. This committee now advises physicians to actually start recommending this form of exercise for their healthy older patients, as well as those with heart disease, including some people with recent heart attacks, as long as they are closely monitored and supervised by experienced health professionals (26).

We now know that aerobic exercise and resistance training work hand-in-hand very nicely to prevent, reduce, or even reverse heart disease by preventing or controlling diabetes, hyperlipidemia and hypertension. Aerobic exercise does a good job at lowering systolic blood pressure, while both aerobic and resistance exercise help reduce diastolic blood pressures. Both forms of exercise also strengthen the heart muscle.

Patients with healthy hearts (no matter what their age or gender) and those with unhealthy hearts can now be encouraged to start using resistance training along with their aerobic training as an important part of their heart-disease prevention and/or treatment program.

28. What, if any, exercise restrictions should be instituted during pregnancy?

Despite the often-publicized fears of exercise during pregnancy, there is ample evidence that regular exercise is beneficial to both mother and fetus as long as certain guidelines are followed. The American College of Gynecology recommends aerobic exercise performed 3 times a week for up to 15 minutes. Lokey and others state that no evidence exists to indicate that exercise performed 3 times per week for up to a 45-minute duration at a heart rate of 144 beats per minute is harmful (27). Exercise performed for longer durations, at higher intensities, at altitude or during thermal stress (hot or humid conditions) may be harmful to the fetus. It is important to recognize that what may be beneficial to the mother may be detrimental to the fetus.

29. Do we need to worry about the present state of our children's levels of fitness and health?

The Surgeon General's Report on Exercise has revealed that nearly half of America's youth aged 12 to 21 years are not vigorously active on a regular basis (28). Participation in all types of physical activity has dramatically declined in recent years as age or grade in school increases. Daily enrollment in physical education classes has dropped from 42% to 25% among high school students between 1991 and 1995 and is even lower now. Several large-scale studies of the upper-body strength of our children have showed them to rank in the very poor category. American children, when compared to children in Europe, Great Britain, Australia, and Canada, also have much poorer cardiovascular endurance.

Childhood physical inactivity has become a national crisis, contributing significantly to our current epidemic of childhood obesity (1). The percentage of overweight and obese children and adolescents has more than doubled since the early 1970s and much of this is blamed on physical inactivity, although poor nutritional habits play an equally important role. Every year that a child remains overweight, his or her chance of growing into an overweight adult increases. The single most important predictor of developing diabetes is being overweight. Childhood and adolescent type II diabetes, previously almost unheard of, has now become a major health problem in America, adding to the epidemic we are now experiencing of type II diabetics in our adult population.

To make matters even worse, we now know that the origins of coronary artery disease, the number one killer of Americans, can and do start in childhood. As many as 40% of our children ages 5 to 8 have at least one heart disease risk factor (high cholesterol, physical inactivity, obesity, or high blood pressure).

Clearly, there is an insidious disease in our country that is seriously impacting the quality of life of today's children and tomorrow's adults-physical inactivity. Healthy lifestyle habits can reduce the risk of developing diabetes by greater than 90 percent and can also prevent the development of heart disease and other degenerative diseases. We must urgently begin to incorporate healthy exercise and nutritional practices into the daily lives of our children that will follow them into adulthood.

30. What principles of resistance training should be used in children?

Evidence continues to mount that children as young as 7 years of age can increase their strength when they participate in a structured resistance-training program. The safety and efficacy of resistance strength training for prepubescent children is well documented (29). Recommendations to minimize the risks of injury include the following (1):

• Medical clearance must be obtained.
• Proper supervision by trained experienced individuals is essential.
• The facility must be safe for children
• Maximal lifts, sudden explosive movements, and competition with others must be discouraged.
• Proper breathing and lifting techniques must be taught and used.
• Adequate rest of at least one minute between exercise sets.
• Adequate fluid intake is essential.
• Participation in a wide range of exercises should be encouraged to promote overall development.
• A brief warm-up should precede the exercise session and a brief cool-down should follow the session.

Exercise sets should employ high repetitions (12-15) and relatively low resistance to achieve the most improvement in muscle strength and growth with no adverse effect on bone, muscle, or connective tissue.

31. Is there any real benefit to hyped-up sports drinks?

Over the last few years there has been an ever increasing number of sports drinks on the shelves of the supermarkets that claim to not only provide fluid, but also essential nutrients that will improve muscle strength, endurance, and overall performance. The truth is, there is nothing "magical" about any of these beverages. They all contain carbohydrates, which have been clearly shown to be beneficial when muscle glycogen levels are near depletion and blood glucose levels are low.

Research has shown, however, that carbohydrate ingestion is only beneficial during prolonged exercise. If pre-exercise nutrition is adequate, there is no metabolic or ergogenic (performance enhancing) need to ingest carbohydrate during continuous exercise lasting less than 90 minutes. In fact, when carbohydrates are ingested during short-term exercise it simply increases the calories we take in and interferes with efforts to get rid of body fat.

As far as electrolytes are concerned, only small amounts are lost during very heavy exercise and these can easily be replaced by eating fruits or vegetables. Only endurance athletes that sweat heavily for extended periods of time need to replenish their electrolytes while exercising.

It is important to be sure and consume plenty of water when exercising. Individuals should drink more than they think they need. People are notorious for underestimating the amount of water they think they require.

32. Are there any supplements that can enhance exercise performance?

There are many supplements on the market that claim to enhance exercise performance, but there is only one that has stood up to the rigors of scientific investigation-creatine (30). Creatine continues to get rave reviews in the face of extensive ongoing scientific research. Many think creatine will be viewed in the years to come as the most important natural performance-enhancing supplement ever to be discovered. Research continues to confirm that creatine produces significant improvements in sports that demand high levels of strength, power, and speed in both men and women. Increases in lean body mass associated with creatine supplementation, once thought to be due to water retention, have now been shown to be due to actual gains in muscle tissue. Recent studies have shown that creatine supplementation works much better if it is combined with a liquid carbohydrate-it can increase, by as much as 60 percent, the amount stored in muscle tissue.

Creatine truly is a major key to successfully achieving greater strength, muscularity and peak performance. It should be remembered, however, that because creatine has only been on the market for less than 10 years, long-term studies are unavailable.

Just how does it work? The kidneys and liver naturally produce creatine from three nonessential amino acids. It is then transported into muscle cells where it is converted into creatine phosphate (CP). CP provides an instant source of additional ATP, the metabolic fuel needed to carry out most of the energy consuming processes, including muscle contraction. CP thus gives an extra boost of energy lasting for several seconds just when it is needed-during the last few high-intensity, muscle-building reps of a resistance exercise or during the last high-intensity aerobic interval.

Since humans synthesize creatine from food sources, one may ask-why supplement? Only about one gram of creatine per day can be endogenously synthesized (even less if one follows a vegan diet) and this has been shown to be insufficient for enhancing strength training, muscle building and exercise performance.

33. Can older people benefit from taking creatine?

A study by Pirola et al in patients over 60 years of age with muscle atrophy after femoral fractures showed a 1.9-fold greater increase in thigh and leg muscle mass when receiving 500 mg of creatine daily for 20 days in conjunction with physical therapy, as compared to subjects not receiving creatine (31). Other studies have shown that older individuals can demonstrate a significant reduction in muscle fatigue while taking creatine (30). In another study, Dr. Mark Tarnopolsky gave creatine supplements to 81 patients with neuromuscular diseases associated with muscle weakness and wasting and showed that creatine supplementation increased their strength (32). He believes that creatine, when combined with an exercise program, will also help healthy elderly individuals retain muscle strength and mobility.

In another study, a group of scientists compared people ages 25 to 35 with people ages 54 to 62 after ingesting 0.3g/kg/day of creatine for 5 days (about 27 grams per day for a 200 lb. man). They found that resting phosphocreatine levels (the amount of energy available for muscular work) increased by 15% in the younger group and by an amazing 30% in the older group as a result of simply taking the extra creatine(33). It appears that these more mature men and women were better at utilizing the energy from creatine to exercise their muscle fibers. They could also exercise at a higher intensity level for a longer period of time than they could prior to taking creatine.

These studies demonstrate that highly trained athletes and young people are not the only individuals who can benefit from using creatine. It appears that older people can get even more out of taking this supplement.

34. What are the psychological benefits to exercise?

There are numerous studies that have demonstrated that low-to-moderate intensity physical exercise is associated with improvements in mood and well-being and reduces anxiety, depression and stress (34). Positive effects on self-concept, self-esteem, and self-assurance have also been reported.

Improvements in psychological functioning associated with exercise are poorly studied but believed to be a result of an increased sense of mastery, control, and self-sufficiency that accompany improved levels of fitness. Because exercise is a form of meditation that triggers an altered and more relaxed state of consciousness, it is thought that this may also provide additional help in dealing with life's many stresses. Exercise is a form of biofeedback that can teach exercisers to regulate their own autonomic nervous systems enabling them to better control their emotional and psychological states.

Health care providers have a significant responsibility to inform their patients about the physical and psychological benefits physical activity can play in their lives and motivate them to regularly participate in these activities.

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