Chapter 10

Question 1

The ability to perform routine physical activities without undue fatigue, and with enough reserve energy to enjoy leisure time pursuits and respond to emergencies and mental stresses.

Answer 1

Physical fitness

Question 2

Planned, structured, and repetitive bodily movement that promotes or maintains physical fitness.

Answer 2

exercise

Question 3

A competitor in any sport, exercise, or game requiring physical skill; for the purpose of this book, anyone who trains at a high level of physical exertion, with or without competition.

Answer 3

athlete

Question 4

Regular practice of an activity, which leads to physical adaptations of the body with improvement in flexibility, strength, and/or endurance.

Answer 4

training

Question 5

Benefits of Fitness:

Answer 5

Improved body composition and adipose tissue distribution

Improved bone density

Enhanced resistance to colds and other infectious diseases

Reduced risks of some types of cancers

Improved circulation and lung function

Reduced risk factors for cardiovascular disease

Reduced risk and improved management of type 2 diabetes

Reduced risk of gallbladder disease

Reduced incidence and severity of mental anxiety and depression, some forms of dementia, and Parkinson’s disease

Improved cognition

Improved sleep

Increased resistance to falls and injury from falls

Longer life and higher quality of life in the later years

Question 6

Small improvements in blood vessel function and blood glucose regulation are detectable after just a single bout of exercise. Some of the credit for these and other benefits of exercise is in part attributable to these. These are signaling proteins secreted by working skeletal muscles that contribute to widespread beneficial effects of exercise on body systems. In other words, small hormone-like molecules released by working muscles. Also promote muscle synthesis and they may alter metabolism in ways that oppose chronic diseases.
Why not manufacture these molecules and press them into “fitness pills” to capture their benefits without physical work?
These are just one part of an intricate metabolic choreography of almost 10,000 molecular changes arising with exercise that affect energy use, inflammation, tissue repair, and many other functions. Pills simply cannot replace exercise, so keep moving.

Answer 6

Myokines

Question 7

Anything that gets your heart beating faster counts. At least 150 minutes a week. Involves running (75 mins a week). Physical activity that involves the body’s large muscles working at light to moderate intensity for a sustained period of time. Brisk walking, running, swimming, and bicycling are examples.

Answer 7

aerobic activity

Question 8

Do activities that make your muscles work harder than usual. 2 days a week along with aerobic activity for best health benefits. physical activity that develops muscle strength, power, endurance, and mass. Resistance can be provided by free weights, weight machines, other objects, or the person’s own body weight. Also called weight training, resistance exercise, or strength exercise.

Answer 8

resistance training

Question 9

Talk Test for level of intensity from a workout:

Answer 9

light: Able to sing
Moderate: Able to have a conversation
High: Conversation is difficult or broken

Question 10

Learn: Most people with weight loss goals are best served by combining calorie-restricted diets with increased physical activity.

Question 11

Guidelines that aim to improve physical fitness and the health of the nation.

Answer 11

The Physical Activity Guidelines

Question 12

To be considered physically fit you need to have enough of what? (8)

Answer 12

-flexibility
-muscle strength
-muscle endurance
-cardiovascular endurance
- muscle power
- reaction time
- agility
- resistance to muscle fatigue

Question 13

The capacity of the joints to move through a full range of motion; the ability to bend and recover without injury.

Answer 13

flexibility

Question 14

The ability of muscles to overcome physical resistance. This muscle characteristic develops with increasing workload rather than repetition and is associated with muscle size.

Answer 14

muscle strength

Question 15

The ability of a muscle to contract repeatedly within a given time without becoming exhausted. This muscle characteristic develops with increasing repetition rather than increasing workload and is associated with cardiorespiratory endurance.

Answer 15

muscle endurance

Question 16

The ability of the heart, lungs, and metabolism to sustain large-muscle exercise of moderate to high intensity for prolonged periods.

Answer 16

cardiovascular endurance

Question 17

The efficiency of a muscle contraction, measured by force and time.

Answer 17

muscle power

Question 18

The interval between stimulation and response.

Answer 18

reaction time

Question 19

nimbleness; the ability to quickly change directions.

Answer 19

agility

Question 20

Diminished force and power of muscle contractions despite consistent or increasing conscious effort to perform a physical activity.

Answer 20

muscle fatigue

Question 21

How muscles adapt to physical activity. An extra physical demand placed on the body; an increase in the frequency, duration, or intensity of an activity. A principle of training is that for a body system to improve, it must be worked at frequencies, durations, or intensities that increase by increments. Repeated physical activity prompts the body to build the structures needed to meet the demand.

Answer 21

overload

Question 22

How Muscles Rebuild:

Answer 22

Muscles are constantly undergoing renovation. Every day, particularly during the fasting periods between meals, a healthy body degrades a portion of its muscle protein to amino acids and later rebuilds it as amino acids become available during fed periods. A balance between degradation and synthesis maintains the body’s lean tissue.

Question 23

To gain muscle strength and size, this balance must more often tip towards synthesis than toward muscle breakdown, known as this condition. It’s an increase in size (for example, of a muscle) in response to use. Physical activity tips the balance toward this.

Answer 23

hypertrophy

Question 24

A reduction in size (for example, of a muscle) because of disuse. Muscle breakdown. Unused muscle diminish in size and weaken overtime known as this.

Answer 24

atrophy

Question 25

Muscle synthesis:

Answer 25

The muscles adapt and build only the proteins they need to cope with the work performed. Muscles engaged in activities that require strength develop greater bulk, whereas those engaged in endurance activities develop more metabolic equipment to combat muscle fatigue. Thus, a tennis player may have one superbly strong arm, while the other is just average; cyclists often have well-developed legs that can pedal for many hours but less development of the arms or chest.

Question 26

This involved with training can induce the development of specific muscle tissues and fuel systems.

Answer 26

planned program

Question 27

This of a rained weightlifter store extra glycogen granules, build up strong connective tissues, and add bulk to the special proteins that contract the muscles, increasing their strength. In contrast, these cells of a distance swimmer build more of the enzymes and structures needed for aerobic metabolism. Therefore, if you wish to become a better jogger, swimmer, or biker, you should train in ways that benefit your sport. Your performance will improve as your muscles adapt to the activity.

Answer 27

muscle cells

Question 28

What form of endurance improves cardiovascular health, diminishes diabetes risk and hypertension and heart disease, while improving blood lipid profile along with leanness and conferring a fit, toned appearance to the limbs and torso?

Answer 28

aerobic endurance

Question 29

What form of endurance enables the working body to remain active with an elevated heart rate over time. As this improves, the body delivers oxygen to the tissues and removes cellular wastes more efficiently. As the heart muscle grows stronger and larger, the heart’s cardiac output increases. Each beat empties the heart’s chambers more completely, so the heart pumps more blood per beat—its stroke volume increases. The resting heart rate slows because a greater volume of blood is moved with fewer beats. Capillary networks proliferate, circulation through the arteries and veins improves, blood moves easily, and blood pressure falls.

Answer 29

Cardiorespiratory endurance

Question 30

In fact, the accepted measure of this for a person, is the rate at which the tissues consume oxygen-the maximal oxygen uptake (VO2max)–> This measure reflects many facets of oxygen delivery that improve with regular aerobic exercise.

Answer 30

cardiorespiratory fitness

Question 31

Cardiorespiratory System: Delivery of Oxygen by the Heart and Lungs to the Muscles:

Answer 31

1.) Air (O2 and CO2 with other gases) are inhaled
2.) Respiratory system—> delivers oxygen to the blood
3.) Circulatory system–> carries oxygenated blood throughout the body
4.)The muscles and other tissues receive oxygen from the blood and release CO2 into it.
5.) The blood carries the CO2 back to the lungs

Question 32

Cardiorespiratory endurance is characterized by:

Answer 32

Increased heart strength and stroke volume

Slowed resting pulse

Increased breathing efficiency

Increased capillary networks.

Improved circulation and oxygen delivery

Reduced blood pressure

Increased blood HDL cholesterol

Question 33

Effective cardiorespiratory training activities have these characteristics:

Answer 33

They elevate the heart rate for sustained periods of time.

They use most of the large-muscle groups of the body (for example, legs and buttocks, or chest and shoulders).

Examples are swimming, cross-country skiing, rowing, fast walking, jogging, running, fast bicycling, soccer, hockey, basketball, in-line skating, lacrosse, and rugby.

Question 34

What association warns that vigorous physical activity, particularly in unfit individuals can increase risk of heart attack and even death to those who are susceptible?

Answer 34

American Heart Association

Question 35

Keeping safe during physical activity depends on both common sense and education. The United States Department of Agriculture (USDA) suggests following these guidelines:

Choose activities appropriate for your current fitness level.

Gradually increase the amount of physical activity you perform.

Be active all week, not just on the weekends.

Wear appropriate safety gear, including the correct shoes, helmet, pads, and other protection.

Develop the flexibility and balance needed in your activity.

Use forethought when choosing when and where to exercise; for example, avoid the hottest hours of the day in summer, choose safe bike paths away from heavy traffic, and run with a buddy on isolated trails.

Stop the activity and get immediate medical attention for serious symptoms, such as abnormal heartbeat, dizziness, confusion, or pain or pressure in the chest, jaw, neck, or arm.

People with medical problems or increased disease risks should consult their physicians before beginning any program of physical activity.

Many people can benefit from consulting with a Certified Personal Trainer (CPT), who can help develop a safe and effective individualized exercise program. Some personal trainers have a more advanced credential, the Certified Strength and Conditioning Specialist (CSCS), which requires completion of a college curriculum that includes human anatomy and exercise physiology; they must also pass a nationally recognized examination. Also, unless a trainer possesses a legitimate nutrition credential, he or she is not qualified to dispense diet advice.

Question 36

Whether belonging to an athlete, a growing child, or an office worker, the human body uses the same energy systems, performing multiple chemical reactions, to fuel its work known as Energy Systems. What are the three Energy Systems that function continuously, supplying energy for the heartbeat, breathing, cellular activities, and other life-sustaining work. Then, when physical activity demands arise, they respond in ways that meet the body’s additional energy needs of the moment.

Answer 36

-Energy reservoir
-anaerobic fuel system
-the aerobic fuel system

Question 37

A system of high-energy compounds that hold, store, and release energy derived from the energy-yielding nutrients and transfer it to cell structures to fuel cellular activities. This in the body is composed of high-energy compounds that trap and store energy. In the muscles, these high-energy compounds are found exactly where they are needed for muscular work—on the microscopic fibers that contract the muscles. Whenever muscles move, say, to blink the eyes or type on a keyboard, these high-energy molecules split apart, releasing and transferring their load of pent-up energy to power the work of the muscle tissue.
This ready pool of energy also drives short bursts of intense physical activity lasting up to about 20 seconds, such as when a weightlifter heaves a heavy weight or a child darts to grab the best swing on the playground. Using energy from this requires no oxygen input, but the reservoir’s capacity is very limited, and once depleted, it must be replenished by way of anaerobic and aerobic energy nutrient breakdown.

Answer 37

energy reservoir

Question 38

Not requiring oxygen. Muscles performing high-intensity work lasting more than a few seconds rely heavily on this system, sometimes called the lactic acid system because it generates the compound lactate (an energy-yielding compound produced during the breakdown of glucose in anaerobic metabolism; with training, muscles gain efficiency in using lactate as fuel.) This system speeds up as the energy reservoir runs down, drawing on the body’s supply of glucose.
Intense ongoing physical activity that makes it hard “to catch your breath” uses so much energy so quickly that the energy demand outpaces the human body’s ability to provide it through its efficient oxygen-using fuel system. The lungs, heart, and blood vessels simply cannot keep up. A person exercising intensely for 3 or 4 minutes—for example, a sprinter racing for 800 meters of distance or a late student running hard to get to class—obtains about half of the needed energy from the anaerobic energy system.
This in the metabolism can nerate copious energy, but it extracts only a fraction of the available energy from each glucose molecule by partially breaking it down and quickly moving on to the next, casting aside the by product lactate. No other fuel—not amino acids or fatty acids—can replace glucose in this system. Thus, this system draws heavily on glucose stores, Its key advantage, however, is the capacity to produce abundant energy quickly to fuel intense exercise without requiring the input of oxygen.

Answer 38

anaerobic

Question 39

Requiring oxygen. This system wrings every last calorie of energy from each energy nutrient molecule. Glucose, certain amino acids, the body’s abundant fatty acids, and even some lactate, are used as fuels. This system demands the input of sufficient oxygen, and although it always delivers a steady stream of energy to the breathing body, the system speeds up during exercise. This is metabolism supplies almost half of a sprinter’s energy, whose effort lasts just seconds, but it supplies more than 90 percent of the energy used by a long-distance swimmer who swims for hours on end. Likewise, a jogger can go long distances, breathing easily, the heart beating steadily, relying on this metabolism to supply most of the needed energy. In contrast to anaerobic metabolism, this metabolism depends more heavily on fatty acids for fuel, sparing glucose and conserving glycogen.

Answer 39

aerobic

Question 40

Highly active people require copious amounts of fuel for their physical activities, and even more to sustain normal body functions, such as immunity and reproduction. Without this, the hormones, muscles, bones, and other major body organs become impaired. The amount of food energy consumed in a day minus the energy expended in physical activity; measured in calories per kilogram of lean body mass. An athlete in training, for example, requires hundreds or even thousands of calories a day above off-season intakes. So does an adolescent athlete, who must take in sufficient calories of food to support both physical activity and growth.

Answer 40

energy availability

Question 41

Pinpointing the energy need of an individual athlete requires special consideration, and methods used for other people. Some reasons why include:

Answer 41

Body composition. An athlete’s body composition differs significantly from average.

Resting metabolism. An athlete may use half or less of the total daily energy expenditure to maintain basic body functions, whereas a sedentary person may use up to 80 percent.

Work intensity. An athlete’s work intensity is often far greater than average.

Question 42

Intensive physical work costs more energy to perform and also to recover from. For some minutes or hours following intense activity, the body’s metabolism stays high, expending extra fuels even during rest. This phenomenon, known as this. It’s a measure of increased metabolism (energy expenditure) that continues for minutes or hours after cessation of exercise. It can demand significant energy in athlete and other highly active people.

In contrast, the great majority of physically active people who work out lightly two or three times a week for fitness or weight management require few or no extra calories. These active people need only consume a nutritious calorie-controlled diet that follows the dietary patterns of the Dietary Guidelines for Americans, along with proper hydration, to perfectly meet their needs. Fitness seekers who, on learning about this, dream of quick and easy workout that “burns fat while they sleep” should be aware that a significant threshold of intensity and duration must be met to induce even small postexercise energy expenditures.

Answer 42

excess postexercise oxygen consumption (EPOC)

Question 43

Glucose and how it is vital for physical activity:

Answer 43

Glucose is vital to physical activity. In the first few minutes of an activity, muscle glycogen provides the great majority of the extra energy that muscles use for action. This is beneficial to exercisers because glucose quickly yields energy needed for fast action. Glycogen molecules are continually broken down throughout physical activity, and the process speeds up as exercise intensity increases.

Question 44

Quick Energy from Blood Glucose:
In addition to using their own glycogen, exercising muscles draw available glucose from the bloodstream. You might suspect, then, that exercise would cause a large drop in blood glucose concentration, but this is not the case. Before a fall in the blood glucose can occur, exercise triggers the release of a host of molecular messengers into the bloodstream, including the pancreatic hormone glucagon. Glucagon signals the liver to liberate glucose from its glycogen stores and to make new molecules of glucose for release into the bloodstream. This fresh supply of glucose is rapidly picked up and used by working muscles.

Question 45

Prolonged Energy from Glycogen:
Stored glycogen is not inexhaustible. It can yield 2,000 calories of glucose at most. An athlete’s fat stores, in contrast, can yield 70,000 calories or more, enough to fuel several marathon races, but fat cannot sustain physical work without glucose. At some point during physical activity, glycogen begins to run out. The liver simply cannot make glucose fast enough to meet the demand.
Athletes who begin an activity with full glycogen stores have enough glucose fuel to last during sustained exercise. For most active people, a normal, balanced diet keeps glycogen stores full. For athletes engaged in heavy training or competition, the more carbohydrate they eat, the more glycogen the muscles will store (within limits), and the longer the stores will last to support physical activity.

A classic study compared endurance during physical activity in three groups of runners, each on a different diet. For several days before testing, one of the groups ate a normal mixed diet; the second group ate a high-carbohydrate diet; and the third group ate a high-fat diet. High-carbohydrate diet enabled the athletes to work longest before exhaustion. Current evidence supports high intakes of dietary carbohydrate (about 60 percent of calories) to help sustain endurance by ensuring ample glycogen stores.

Question 46

Exercise Duration and Intensity Affect Glycogen Use:
The duration of a physical activity, as well as its intensity, affects how long glycogen supplies will last. Muscle cells pack their stored glycogen close to their contractile fibers and energy-processing structures to ensure quick access to glucose energy. As the muscles devour their own glycogen, they become ravenous for more glucose and dramatically increase their uptake of blood glucose. Within the first 20 minutes of moderate activity, a person uses up about one-fifth of the available glycogen.

A person who exercises moderately for longer than 20 minutes begins to use less glucose and more fat for fuel. Still, glucose use continues, and if the activity goes on long enough and at a high enough intensity, muscle and liver glycogen stores will run out almost completely
When glycogen depletion reaches a certain point, it brings nervous system function almost to a halt, making continued activity at the same intensity impossible. Marathon runners refer to this point of exhaustion as “hitting the wall.”

Question 47

Degree of Training Affects Glycogen Use:
Consistent training affects glycogen use during activity in two major ways. First, muscles adapt to their work by storing the extra amounts of glycogen needed to support that work. Second, trained muscles burn more fat, and at higher intensities, than untrained muscles, so they require less glucose to perform the same work. A person first attempting an activity uses up much more glucose per minute than an athlete trained to perform it.

Question 48

What three factors specifically affect glycogen use during physical activity?

Answer 48

• Carbohydrate intake
• Intensity and duration of the activity
• Degree of training

Question 49

Inflow of Glucose from Food:
In addition to the body’s stored glycogen, glucose from the digestive tract makes its way to the working muscles during activity. For example, carbohydrate taken in during an ultramarathon may have helped some runners to finish a 100-mile race. During the race, the finishers consumed almost twice as many calories and carbohydrates per hour as nonfinishers. The extra carbohydrate may have helped them win, but an alternative explanation exists: the runners who ate more and finished the race may have been less prone to digestive disturbances. Many long-distance runners develop digestive disturbances, such as vomiting, that interfere with eating, and these problems can become severe enough to cause a runner to forfeit a race.
Competitors in sports that require repeated bursts of intense activity, such as basketball or soccer, may also benefit from taking in extra carbohydrate during an event, but research has yet to pinpoint optimal intakes. Before concluding that extra glucose during activity might boost your own exercise performance, consider first whether you engage in sustained endurance activity or repeated high-intensity activity. Do you run, swim, bike, or ski nonstop at a rapid pace for more than an hour at a time? Do you compete in high-intensity games lasting for several hours? Does your sport or training demand several bouts of high-intensity activity in one day, or is it repeated on several successive days? If not, you may not need extra glucose during your activity; a nutrient-dense diet with ample carbohydrate may better serve your needs.

Question 50

Glucose from Lactate:
As glucose fuels anaerobic metabolism, it generates lactate. Muscles working aerobically (at low intensity) readily use up or clear away the small quantities of lactate they produce. At higher intensities, anaerobic metabolism generates excess lactate that accumulates and overflows into the bloodstream which carries it to the liver. The liver possesses enzymes to convert this lactate into new glucose molecules, which then cycle back to the working muscles. Thus, lactate’s value during high-intensity exercise becomes clear: it serves as a raw material for new glucose molecules that the muscles can use.
In addition, the presence of lactate acts as a signal to the muscles, including heart muscles, to build more of the metabolic equipment needed to perform high-intensity work.

Most people know the burning sensation caused in part by lactate accumulating in a working muscle. However, lactate is not likely a major cause of muscle fatigue. Instead, muscle fatigue consistently follows depletion of muscle glycogen. Other causes may include a drop in muscle pH, depletion of the energy reservoir, excess free radicals, neurotransmitter activities, and other factors. The human experience of fatigue, however, resides in the mind as well as in the muscles, and physiology alone cannot fully explain why one competitor can push past a point where another must stop.

Question 51

A theory that suggests an occasional low-carb training day may increase endurance by forcing muscles to use more fat for fuel and to develop more metabolic equipment for doing so. This scheme may be tolerable for light training, but when athletes want to work their hardest and longest, ample carbohydrate is necessary before, during, and after training and competition.

Answer 51

“train low, compete high”

Question 52

Best foods to consume during prolonged activity to improve athletic endurance:

Answer 52

bananas, fruit juices, dried fruits, and energy bars and alternatives are high carb energy drinks and high carb gels which ensure hydration

Question 53

What can fuel the body for hours during activity without running out and is an unlimited source of energy for exercise?

Answer 53

fat

Question 54

How fat is used for fuel:
Early in activity, muscles begin to draw on fatty acids from two sources—fats from stores within the working muscles and fats from fat deposits such as the adipose tissue under the skin. Areas with the most fat to spare donate the greatest amounts. This is why “spot reducing” doesn’t work: muscles do not own the fat that surrounds them. Instead, adipose tissue cells release fatty acids into the blood for all the muscles to share. Proof is once again found in a tennis player’s arms: the skinfolds measure the same in both arms, even though the muscles of one arm are more developed than those of the other.

Question 55

Activity Intensity and Duration Affect Fat Use:
Fat can be broken down for energy only by aerobic metabolism. During physical activity of light or moderate intensity, adipose tissue releases fatty acids into the bloodstream that provide most of the fuel for muscular work through aerobic metabolism. When the intensity of activity becomes so great that energy demand surpasses the ability to provide more energy aerobically, the muscles cannot burn more fat. They burn more glucose instead. Adipose tissue seems to adjust its delivery of fatty acids to match the needs of the muscles at work, releasing more during moderate activity and releasing less during high-intensity exercise.

The duration of activity also affects fat use. At the start of activity, the blood fatty acid concentration falls, but a few minutes into moderate activity, blood flow through the adipose tissue capillaries greatly increases, and hormones, including epinephrine, signal the fat cells to dismantle their stored triglycerides. Fatty acids flow into the bloodstream at double or triple the normal rate. After about 20 minutes of sustained, moderate aerobic activity, the fat cells begin to shrink in size as they draw on their lipid stores.

Question 56

Degree of Training Affects Fat Use:
Training, performed consistently, stimulates the muscles to develop more fat-burning metabolic enzymes, so trained muscles can use more fat at greater exercise intensities than untrained muscles do. With aerobic training, the heart and lungs also become stronger and better able to deliver oxygen to the muscles during high-intensity activities. The improved oxygen supply, in turn, helps the muscles to use more fat for fuel.

Question 57

Fat Recommendations for Athletes:
For endurance athletes, eating a high-fat, low-carbohydrate diet for even a day or two depletes precious glycogen stores and makes exercise more difficult. Eventually, muscles do adapt to such a diet and use more fat and ketones to fuel activity, but athletes on high-fat diets report greater fatigue and become exhausted much sooner than those consuming high-carbohydrate diets. Ketogenic diets offer no performance advantages, despite the claims made in the popular press.

Essential fatty acids and fat-soluble nutrients are as important for athletes as they are for everyone else, so experts recommend a diet with 20 to 35 percent of calories from fat. Omega-3 fatty acids, in particular, may reduce inflammation—and tissue inflammation is both the result and the enemy of physical performance. This doesn’t mean that athletes need fish oil supplements; rather, they need to consume the amounts of fatty fish recommended for health.
As for saturated and trans fats, they pose the same heart disease risk for athletes as they do for other people. Physical activity reduces the risk of cardiovascular disease, but athletes still suffer heart attacks and strokes; low saturated and trans fat intakes reduce these risks.

Question 58

These three factors affect fat use during physical activity:

Answer 58

Fat intake

Intensity and duration of the activity

Degree of training

Question 59

Protein for Building Muscles and for fuel:
The active body uses amino acids from protein to build and maintain muscle and, to some extent, to provide fuel. Physical activity provides the primary signal for building needed muscle proteins and for breaking down other, unneeded ones. Sufficient high-quality dietary protein is of critical importance in this regard.

Question 60

Does Timing of Protein Intake Matter?
In the hours following exercise, muscle protein synthesis accelerates, increasing the demand for amino acids. Some amino acids become available for reuse when old unneeded muscle structures are dismantled to make way for new needed ones. The rest of the demand must be met by diet.

Gradually, over the course of a day or so, muscle synthesis and breakdown slow to a normal resting pace. Repeated over time, these processes build and reshape the muscles to better meet the physical demands placed on them.

Question 61

In laboratory rats, an infusion of branched chain amino acids (BCAA), particularly this injected into a vein causes the rate of protein synthesis to triple for a time, after which the rate drops automatically. Supplement sellers have used this evidence to imply that people can take oral amino acids or these as pills to build bigger muscles without exercise, but research does not support this idea. Such supplements provide no athletic advantages, and they present a risk of amino acid imbalance. Muscles can safely obtain all the needed amino acids in the right balance from protein-rich foods.

Answer 61

leucine

Question 62

Learn:
To support muscle tissue synthesis during training or competition, many experts suggest 4 to 5 small meals that provide moderate amounts (20 to 30 grams) of high-quality protein, consumed at regular intervals throughout the day. In doses too large, say, 40 grams at a sitting, the amino acid influx exceeds the ability of the muscles to synthesize protein, and any excess protein is used as fuel. For most U.S. athletes, eating extra protein or amino acids will not improve muscle size or strength because their regular intakes are ample.

Question 63

Protein Use for Fuel:
Studies of nitrogen balance show that the body speeds up its use of amino acids for fuel during physical activity, just as it speeds up its use of glucose and fatty acids. The factors that regulate protein use during activity are the same three that regulate the use of glucose and fat: diet, exercise intensity and duration, and degree of training.

Regarding diet, sufficient carbohydrate spares protein from being used as fuel. Too little carbohydrate necessitates the conversion of amino acids to glucose.

Exercise intensity and duration also affect the use of protein fuel. Endurance athletes often deplete their glycogen stores and as a result they depend more on amino acids for energy. In contrast, intense anaerobic strength training does not use as much protein for fuel but demands more protein for building muscle tissue.

Question 64

The extent of training also affects the use of protein. Particularly in strength sports such as powerlifting, the higher the degree of training, the less protein fuel a person uses during activity of a given intensity. To summarize, the factors that affect protein use during physical activity include:

Answer 64

Dietary carbohydrate sufficiency.

Intensity and duration of the activity.

Degree of training.

Question 65

Protein Recommendations for Athletes:
The DRI committee does not recommend greater-than-normal total protein intakes for athletes, but other authorities do. These greater recommendations vary by the nature of the activities performed. As is true for carbohydrates, the protein recommendations are stated in grams per kilogram of body weight per day (g/kg/d). The protein amounts suggested for athletes range from 1.2 to 2 grams per kilogram of body weight.

On learning of the protein demands of physical activity, many athletes go to extremes, doubling or tripling the protein-rich foods they eat or taking amino acid supplements “just to be sure.” When protein foods crowd out other needed foods and nutrients, this can be a costly mistake in terms of health and performance. Everyday foods, such as milk, beans and rice, chili, omelets, or turkey sandwiches, deliver high-quality protein with the right mix of amino acids and other nutrients to meet the athlete’s need. Foods also present no risk of amino acid imbalances, a known drawback of supplements.

You may be wondering whether you eat enough protein for your own activities. In general, a nutritious diet that provides enough total energy and follows the USDA Dietary Patterns provides enough protein for almost everyone.

Question 66

What vitamins participate in releasing energy from fuels?

Answer 66

Vitamin B

Question 67

What vitamin is needed for the formation of the protein collagen, the foundation material of bones, cartilage, and other connective tissues?

Answer 67

Vitamin C

Question 68

What 2 vitamins help to build red blood cells, and iron carries oxygen to working muscles?

Answer 68

Folate and B12

Question 69

What vitamin helps protect tissues from oxidation?

Answer 69

Vitamin E

Question 70

What two minerals allow muscles to contract?

Answer 70

Calcium and magnesium

Question 71

Do Athletes Need Nutrient Supplements?
Many athletes take vitamin and mineral supplements. One of the most common reasons athletes at all levels give for supplement use is “to improve performance.”

In truth, most athletes don’t need such supplements. In particular, vitamins and most minerals taken just before competition are useless because these nutrients function as small parts of larger working units. After entering the blood from the digestive tract, they must wait for the cells to combine them with their other parts before they can function. This takes time—hours or days. This is true, even if the person is deficient in those nutrients. Also, strenuous physical activity requires abundant energy, and athletes and active people who choose enough nutrient-dense food to meet their greater energy needs effortlessly obtain the vitamins and minerals they need from their diets.

Athletes may incur nutrient deficiencies if they habitually eat too little food or make poor food choices, and deficiencies impede performance. Some active people simply cannot eat enough food to meet the demands of intense training and competition, and so they lose weight. Others starve themselves to meet a sport’s weight requirement. (Most authorities oppose rigid weight requirements because athletes often risk their health to meet them.) These people often fail to obtain all of the vitamins and minerals they need, and a daily balanced multivitamin-mineral tablet not exceeding the DRI amounts may prevent damaging deficiencies.

Question 72

Impairs performance because iron must be present to deliver oxygen to the working muscles. The iron-containing molecules of aerobic metabolism and the iron-containing hemoglobin and muscle protein myoglobin play key roles in physical performance. With insufficient iron, aerobic work capacity is compromised, and the person tires easily. This can develop when athletes habitually include too few iron-rich foods in their meals. Athletes may also lose iron in blood loss, such as from menstruation or from digestive tract bleeding that may occur during prolonged endurance activities. Another contributor is the overuse of certain pain-relieving medications, such as aspirin or ibuprofen, which can cause bleeding and iron loss from the digestive tract. Whatever its cause, iron deficiency impairs athletic performance, an effect that can often be resolved with an iron supplement.

Answer 72

iron deficiency

Question 73

Strenuous endurance training is associated with this, a condition of low blood iron. Its causes are not clear, but increased iron losses in sweat and small blood losses from the digestive tract are thought to play roles. In addition, training enlarges the blood’s fluid volume; with fewer red cells distributed in more fluid, the red blood cell count per unit of blood is diminished. Training also accelerates destruction of older, more fragile red blood cells: blood cells are squashed when body tissues, such as the soles of the feet, make high-impact contact with an unyielding surface, such as the ground. However, the body soon replaces the lost red blood cells with new ones, improving the oxygen-carrying capacity of the blood. Most researchers view this as an adaptive, temporary response to endurance training that goes away by itself without treatment.

Answer 73

sports anemia

Question 74

In iron deficiency, the body releases more of this iron-suppressing hormone, during endurance exercise, further impairing the athlete’s iron status.

Answer 74

hepcidin

Question 75

Factors Affecting Iron Status of Athletes:

Answer 75

• Increased iron demand
• Low dietary intake
• Blood loss (menstruations; digestive tract bleeding)
• red blood cell destruction
• Increased blood fluid volume (red cell dilution)

Question 76

Athletes who consume this diet lack iron, because iron from plants is less available than from animal sources. To protect against iron deficiency, these athletes should make a point of consuming fortified cereals, legumes, nuts, and seeds and including some vitamin C–rich foods with each meal—vitamin C enhances iron absorption. A well-chosen diet of nutrient dense foods can meet nutrient needs, and some athletes even credit this diet with boosting their performance.

Answer 76

Vegetarians

Question 77

Water Losses during Physical Activity:
The exercising body loses water primarily via sweat; second to that, breathing excretes water, exhaled as vapor. Endurance athletes can lose a quart and a half or more of fluid during each hour of activity.

During physical activity, both routes of water loss can be significant, and dehydration is a real threat.

A water loss of greater than 2 percent of body weight can reduce a person’s capacity for muscular work. A person with a water loss of about 7 percent is likely to collapse.

Question 78

What is the first symptom of dehydration?

Answer 78

fatigue

Question 79

Sweat and Temperature Regulation:
Sweat is the body’s coolant. The conversion of water to vapor uses up a great deal of heat, so as sweat evaporates, it cools the skin’s surface and the blood flowing beneath it. During exercise, blood flow shifts from the body’s internal core to just below the skin’s surface, permitting accumulated heat to radiate away. Sufficient water in the bloodstream is therefore crucial to provide sweat, accommodate blood flow to the skin, and still supply muscles with the blood flow they need to perform.

Question 80

In hot, humid weather, sweat may fail to evaporate because the surrounding air is already laden with water. Little cooling takes place, and body heat builds up. In such conditions, athletes must take precautions to avoid this. An acute and life-threatening reaction to heat buildup in the body. It’s a potentially fatal medical emergency and to reduce the risk of getting this, competitors should adjust gradually to hot, humid climates by increasing their workloads incrementally over several days. Never wear rubber or heavy suits sold with promises of weight loss during physical activity. They promote profuse sweating, prevent sweat evaporation, and invite this to happen.

Answer 80

Heat Stroke

Question 81

Life threatening symptoms of heat stroke:

Answer 81

Clumsiness, stumbling

Confusion, dizziness, other mental changes, loss of consciousness

Headache, nausea, vomiting

Internal (rectal) temperature above
104F

Lack of sweating

Muscle cramping (early warning)

Racing heart rate

Rapid breathing

Skin may feel cool and moist in early stages; hot, dry, and flushed as body temperature rises

Question 82

Even in cold weather, the body still sweats and needs fluids. However, the fluids should be warm or at room temperature to help prevent this. It is a below-normal body temperature. Inexperienced runners in long races on cold or wet chilly days may produce too little body heat to keep warm, especially if their clothing is inadequate. Early symptoms of this include shivers, apathy, and cool arms and legs. As body temperature continues to fall, shivering stops; fine motor skills and memory fail; disorientation and slurred speech ensue. People with these symptoms soon become helpless to protect themselves from further body heat losses and need immediate medical attention.

Answer 82

hypothermia

Question 83

Fluid and Electrolyte Needs during Physical Activity:
Current guidelines urge athletes to prepare for fluid losses by hydrating before activity and to replace lost fluids both during and after activity. Such factors as body weight, genetic tendencies, type of sport, exercise intensity, degree of training, and variations in ambient temperature and humidity all affect the extent of fluid and sodium losses through sweat. Sodium lost in sweat sometimes collects visibly as white salts on clothing.

Question 84

This of an athlete can be determined by weighing before and after exercise. The weight difference is almost all water, and it should be replaced pound for pound (a pound of water measures a little more than 2 cups). Even then, in hot weather, the digestive tract may not be able to absorb enough water fast enough to keep up with an athlete’s sweat losses, and some degree of dehydration may be inevitable. A thirsty athlete shouldn’t wait to drink. During activity, thirst is an indicator that some degree of fluid depletion has already taken place. After an activity that has produced heavy sweat loss, accelerated sweating continues for a time, and this fluid must also be replaced.

Answer 84

hourly sweat rate

Question 85

What is the best fluid to support physical activity? In most cases, just plain cool water, for two reasons:

Answer 85

(1)
water rapidly leaves the digestive tract to enter the tissues, and

(2)
it cools the body from the inside out. Endurance athletes are an exception: they may need more from their fluids than water alone.

Endurance athletes do need water, but they also may need carbohydrate during prolonged activity to supplement their limited glycogen stores. Sports drinks are designed to provide both fluid and carbohydrate, along with extra electrolytes.

Question 86

Electrolyte Losses and Replacement:
During physical activity, the body loses electrolytes—the minerals sodium, potassium, and chloride—in sweat. Beginners lose these electrolytes to a much greater extent than do trained athletes because the trained body adapts to conserve them.

To replenish lost electrolytes, a person ordinarily needs only to eat a regular diet that meets energy and nutrient needs, and not restrict normal sodium intake. During intense activity lasting more than 45 minutes in hot weather, sports drinks provide a convenient way to replace both fluids and electrolytes. Friendly, leisure sporting games almost never require electrolyte replacement. However, even casual exercisers can require fluid replacement, particularly in hot weather, and, as mentioned, water is the best fluid source under these conditions. Salt tablets can worsen dehydration and do nothing to improve performance. They increase potassium losses, irritate the stomach, and cause vomiting.

Question 87

A dangerous electrolyte imbalance. It’s an abnormally low concentration of sodium in the blood. Can arise when athletes sweat profusely for hours and quench their thirst with plain water, but fail to replace lost sodium. The symptoms overlap somewhat with those of dehydration. Salt is needed to reverse this; mistakenly giving more water makes the condition worse. Eating salty food can reverse mild cases, but serious symptoms demand immediate medical help.

Answer 87

hyponatremia

Question 88

Symptoms and Rising Factors of Hyponatremia:

Answer 88

Symptoms:
Bloating, puffiness from water retention (shoes tight, rings tight)

Confusion

Seizures

Severe headache

Vomiting

Risk Factors:
Excessive water consumption before or during an event (>1.5 L/hr)

Exercise duration greater than 4 hours

Low body weight/BMI ˂20

Nonsteroidal anti-inflammatory drug use (for example, aspirin or ibuprofen)

Question 89

Athletes who lose a great deal of sodium in their sweat may be prone to this. Painful cramps of the abdomen, arms, or legs, often occurring hours after exercise; associated with inadequate intake of fluid or electrolytes or heavy sweating.
To prevent both cramps and hyponatremia, endurance athletes who sweat heavily for four or more hours need to replace sodium during the exertion (not more than one gram of sodium per hour of activity has been recommended). Sports drinks and gels, salty pretzels, and other sodium sources can provide sodium when needed. In the days before the event, especially in hot weather, athletes should not restrict their salt intakes.

Although hyponatremia can pose a threat to some competitive athletes, most exercisers need not make any special effort to replace sodium. Most people’s regular diets present more than the UL of sodium, and more than enough for physical activity.

Answer 89

heat cramps

Question 90

Imagine two thirsty people, both in motion:

Jack, an accountant, striving to shed some pounds, is panting after his 30-minute jog. He wipes the sweat from his eyes and tries to catch his breath.

Candace, point guard for her college basketball team, powers into her second hour of training, dripping with sweat from her exertion. She’s training every muscle fiber for competition.

Both of these physically active people need to replace the fluid they’ve lost in sweat. Which kind of fluid best meets their needs?

Answer 90

1.) Fluid: Both sports drinks and plain water replace fluid lost in sweat during physical activity. Some people find sports drinks tasty, and if a drink tastes good, they may drink more of it, ensuring adequate hydration. Commercial coconut water or fruit-flavored waters also taste good, but so does plain water with a squirt of lemon or other fruit juice, and it costs much less.
2.) Glucose: Unlike water, sports drinks offer monosaccharides or glucose polymers ( compounds that supply glucose not as single molecules but linked in chains somewhat like starch. The objective is to attract less water from the body into the digestive tract.) that can help maintain hydration, contribute to blood glucose, and enhance performance under specific circumstances. An athlete performing an endurance activity at moderate or vigorous intensity for longer than an hour may benefit from some extra carbohydrate. An athlete like Candace who participates in a prolonged game that demands repeated intermittent strenuous activity benefits from extra glucose during activity.

For competitive athletes, not just any sugary beverage will do. To ensure water absorption while providing glucose, most sports drinks contain about 7 percent glucose (half the sugar of ordinary soft drinks). Less than 6 percent glucose may not enhance performance, and more than 8 percent can delay fluid passage from the stomach to the intestine, slowing delivery of the needed water to the tissues.
Sports drinks provide easy-to-consume glucose, but research shows that for athletes who can eat during activity, such as cyclists, half of a banana taken every 15 minutes during a
- to 3-hour bicycle race sustains blood glucose equally well. Bananas satisfy hunger better, and they supply vitamins, minerals, and fiber in a mix of carbohydrates that the body is well equipped to handle.

Jack, the jogger of our example, needs fluids to replace lost sweat. Sports drink advertisements may claim that he needs extra glucose in his fluid for rapid hydration, but for him, such drinks deliver only unneeded sugar calories in a nutrient-poor beverage. In fact, for anyone who goes for a walk, takes a spin on a bicycle, or exercises to lose weight, the extra carbohydrate of sports drinks is not beneficial because their own glycogen is ample for their efforts. In addition, sipping the drinks may lead to dental caries by continuously bathing their teeth in sugar. Plain, cool, water best meets their fluid needs.

3.) Sodium and Other Electrolytes: Sports drinks offer sodium and other electrolytes to help replace those lost during physical activity, and they increase fluid retention. The sodium they contain may also help maintain the drive to drink fluid because the sensation of thirst depends partly on the sodium concentration of the blood. Most athletes do not need to replace the other minerals lost in sweat immediately; a meal eaten within hours of competition replaces these minerals soon enough.

Most sports drinks are relatively low in sodium (55 to 110 milligrams per serving), so they pose little threat of excessive intake in healthy people. In Jack’s case, the sodium in sports drinks is unnecessary.

Question 91

Carbohydrates:
Techniques to achieve full glycogen stores vary with the intensity and duration of the activity. Those performing at high intensities over short times, such as sprinters, weightlifters and hurdlers, require only moderate intakes of carbohydrate from ordinary nutritious balanced diets. Ultraendurance athletes, such as triathletes or bicycle racers who compete in multiday events, need much more.

A method used by professional sports nutritionists to maximize an endurance athlete’s energy and carbohydrate intakes is to choose vegetable and fruit varieties that are high in both nutrients and energy. A whole cupful of iceberg lettuce supplies few calories or nutrients but a half-cup portion of cooked sweet potatoes is a powerhouse of vitamins, minerals, and carbohydrate energy. Similarly, it takes a whole cup of cubed melon to equal the calories and carbohydrate in a half-cup of fruit canned in juice. Small choices like these, made consistently, can contribute significantly to energy and carbohydrate intakes.

Athletes can have some fun exploring new carbohydrate-rich foods. Try Middle Eastern hummus (chickpea spread) and pita breads, African winter squash or peanut stews, Latin American bean and rice dishes, or Mediterranean tabouli salads. In truth, even the bun of a fast-food sandwich can help fill glycogen stores. Just before a competition is not the time to experiment with new foods—try them early in training or during the off-season.

Adding carbohydrate-rich foods is a sound and reasonable option for increasing intakes, up to a point. It becomes unreasonable when an athlete cannot eat enough nutrient-dense food to meet the need. At that point, some foods with added sugars may be needed, such as breakfast bars, “trail mix” or energy bars, sugar-sweetened milk beverages, liquid meal replacers, or commercial products designed to supply carbohydrate.

Question 92

Protein:
Meats, poultry, and cheeses often head the list of protein-rich foods, but others, such as fish and seafood, eggs, yogurt, plant-based meat replacers, legumes with grains, and peanuts and other nuts boost protein intakes while keeping saturated fats within bounds.

Question 93

Involves pacing carbohydrate and protein intake throughout the day for the purpose of favorably influencing some aspect of physical performance or adaptation to exercise. The practice is supported by some, but not all, research.
Example: pregame meal. Athletes who train or compete at moderate or vigorous intensity for longer than an hour may benefit from a small, easily digested, high-carbohydrate meal taken in the hours before physical activity. This pregame meal should provide enough carbohydrate to “top off” the athlete’s glycogen stores but be low enough in fat and fiber to facilitate digestion. It can be moderate in protein and should provide plenty of fluid to maintain hydration in the work ahead.
Breads, potatoes, pasta, and fruit juices—carbohydrate-rich foods that are low in fat and fiber—form the base of pregame meals. Although generally desirable, bulky, fiber-rich foods can cause stomach discomfort during activity, so they should be avoided in the hours before exercise.

The size of the meal depends on the activity and the weight of the athlete.

With just an hour remaining before training or competition, an athlete should eat very lightly, because a substantial meal eaten within the hour before exercise can inhibit performance and cause digestive distress.

Answer 93

Nutrient timing

Question 94

At 3 to 4 hours or more before activity, a regular mixed meal providing plenty of carbohydrate with a moderate amount of protein and fat is suitable. Here are some suggestions:

Answer 94

Try these: toasted deli chicken or turkey sandwich; hard-boiled egg with toast; oatmeal with yogurt; fruit juices; pasta with red sauce; trail mix, granola bars, or energy bars that contain sufficient carbohydrate.

Avoid these: high-fat meats, cheeses, and milk products; other high-fat foods; high-fiber breads, cereals, and bars; raw vegetables; gas-forming foods (such as broccoli, Brussels sprouts, and onions).

In a fast-food restaurant, avoid the higher-fat choices, such as fried chicken patties or big burgers; order grilled chicken soft tacos, a grilled chicken sandwich, or the like, and reject add-ons, such as sour cream or full-fat cheese.

Most importantly, athletes should choose what works best for them. One athlete may feel best supported by eating pancakes, eggs, and juice, while another develops nausea and cramps after such a hearty meal. During intense physical activity, blood is shunted away from the digestive system to the working muscles, making digestion difficult. If this is a problem, finish the pregame meal 4 hours before exercise, or eat less food.

Question 95

Learn: Recovery Meals:
Athletes who perform intense practice sessions several times daily or who compete for hours on consecutive days need to quickly replenish both energy and glycogen to be ready for the next effort. Several small recovery meals consumed within several hours after exercise may help to speed the process. A turkey sandwich and a homemade milkshake, taken in divided doses, provide the glucose needed to speed up glycogen replenishment. Its protein can speed up protein synthesis, too.

Athletes who have no appetite for solid food after hard work might try drinking carbohydrate-rich beverages, such as low-fat or fat-free chocolate milk. Paying for high-priced, brand-name pregame or recovery drinks is needless. Chocolate milk or homemade shakes are inexpensive and easy to prepare, they allow athletes to decide what to add or leave out, and they serve the need as well as or better than commercial products. For safety, don’t drop a raw egg in the blender, because raw eggs may carry bacteria that can cause illness—see Chapter 12.

In contrast to the athletes just described, most people who work out moderately for fitness or weight loss need only to replace lost fluids and resume their normal, healthy diets after activity. If you meet this description but enjoy a postworkout snack, by all means have one. Just remember to eliminate a similar number of calories from your other meals to keep calorie intake in check.

Question 96

Commercial Products:
What about drinks, gels, or candy-like sport bars claiming to provide a competitive edge? These mixtures of carbohydrate, protein (usually amino acids), fat, some fiber, and certain vitamins and minerals often taste good, can be convenient to store and carry, and offer extra calories and carbohydrate in compact packages. Read the labels, though: a chocolate candy-based bar may be too high in fat to be useful. Such products tend to be expensive, and they have no edge over real food for boosting performance. Chocolate milk is a delicious and effective postexercise recovery meal.

Question 97

Many athletes are willing to try almost anything that is sold with promises of producing a winning edge or improved appearance, so long as they perceive it to be safe. Store shelves and the Internet abound with these that are heavily advertised, each striving to appeal to performance-conscious people: protein powders, amino acid supplements, caffeine pills, steroid replacers, “muscle builders,” vitamins, and more. products that supposedly enhance performance, although few actually do so; the term ergogenic implies “energy giving”. Some people spend huge sums of money on these products, often heeding advice from trusted friends, coaches, or mentors.

Answer 97

ergogenic aids

Question 98

Paige and DJ:
The story of two college roommates, Paige and DJ, demonstrates the decisions athletes face about their training regimens. After enjoying a freshman year when the first things on their minds were tailgate parties and the last thing—the very last thing—was exercise, Paige and DJ have taken up running to shed the “freshman 15” pounds that have crept up on them. Their friendship, once defined by bonding over extra-cheese pizzas, now focuses on competing in 5-K races.

Paige and DJ both take their nutrition regimens and prerace preparations seriously, but otherwise they are as opposite as can be. DJ sticks to the tried-and-true advice of her older brother, an all-state track and field star. He tells her to train hard, eat a nutritious diet, get enough sleep, drink plenty of fluid on race day, and warm up lightly for 10 minutes before the starting gun. He offers only two other bits of advice: buy the best-quality running shoes available every four months without fail, and always buy them on a Wednesday. Many athletes admit laughingly to such superstitions.

Paige finds DJ’s routine boring and woefully out of date. Paige surfs the internet for the latest supplements and buys ergogenic aids advertised in her fitness magazines. She mixes various powders into her beverages, chugs down beet juice, and takes a handful of caffeine pills and “ergogenic” supplements to get “pumped up” for a race. No matter what her goal, online stores seem to have “best-selling” products for the job. Sure, it takes money (a lot of money) to purchase the products and time to mix the potions and return the occasional wrong shipment—often cutting into her training time. But Paige feels smugly smart in her modern approach.

It seems that DJ’s brother has given her some helpful advice, but how about Paige? Is she right to expect an athletic edge from taking supplements? Is she safe in taking them?

Ergogenic Aid Terms:

anabolic steroid hormones chemical messengers related to the male sex hormone testosterone that stimulate the building up of body tissues (anabolic means “promoting growth”; sterol refers to compounds chemically related to cholesterol). In drug form, steroids have serious side effects and are banned in sports.

androstenedione (AN-droh-STEEN-die-own) a precursor of testosterone that elevates both testosterone and estrogen in the blood of both males and females. Often called andro, its drug form is sold with claims of producing increased muscle strength, but controlled studies disprove such claims.

beetroot the root portion of the ordinary beet plant; the root vegetable, beet.

beta- alanine a nonessential amino acid that enhances the buffering capacity of skeletal muscle.

caffeine a naturally occurring stimulant found in many common foods and beverages, including chocolate, coffee, and tea, that can produce alertness and reduce reaction time when used in small doses but that causes headaches, trembling, an abnormally fast heart rate, and other undesirable effects in high doses.

creatine a nitrogen-containing compound that combines with phosphate to form a high-energy compound stored in muscle. Some studies suggest that creatine enhances energy and stimulates muscle growth, but long-term studies are lacking; digestive side effects may occur.

DHEA (dehydroepiandrosterone) a hormone made in the adrenal glands that serves as a precursor to the male hormone testosterone; recently banned by the U.S. Food and Drug Administration (FDA) because it poses the risk of life-threatening diseases, including cancer. Falsely promoted to burn fat, build muscle, and slow aging.

dietary nitrate a compound composed of one nitrogen and three oxygen atoms, often concentrated in extracts of vegetables, particularly beetroot, celery, and spinach; nitrate releases oxygen as it undergoes chemical conversions in the body.

energy drinks and energy shots sugar-sweetened beverages in various concentrations with supposedly ergogenic ingredients, such as vitamins, amino acids, caffeine, guarana, carnitine, ginseng, and others. Regulation of these drinks by the FDA is lax, and they are often high in caffeine or other stimulants.

ergogenic (ER-go-JEN-ic) aids products that supposedly enhance performance, although few actually do so; the term ergogenic implies “energy giving” (ergo means “work”; genic means “give rise to”).

Question 99

Antioxidant Supplements:
Exercise accelerates metabolism, and speeded-up metabolism creates extra free radicals that contribute to inflammation and oxidative stress. It stands to reason, then, that if exercise produces free radicals and oxidative stress and if antioxidants from foods can quell oxidative stress, then athletes may benefit from taking in more antioxidants. Like many other logical ideas, however, this one falls apart upon scientific examination—research does not support taking antioxidant supplements for athletic performance. In fact, free radical production is a necessary part of a complex signaling system that promotes many of the beneficial responses of the body to physical activity. Flooding the system with excess antioxidants can short-circuit this system and prevent health benefits and improvements in athletic performance from occurring.

Question 100

Vegetables and Nitrate:
Nitrate is a common compound of nitrogen and oxygen present in air and water, and also in certain vegetables, notably green leafy vegetables, beets (also called beetroot), and beet juice. Nitrate and the related compound nitrite are also preservatives added to bacon, hot dogs, lunch meats, and other processed meats.

In laboratories, small increases in high-intensity exercise tolerance are noted among young, healthy, male athletes given nitrate supplements, and some improvements may also occur at lower intensities. Among middle-aged and elderly people, higher nitrate intake from about a cupful of green vegetables each day correlates with greater muscle strength regardless of activity levels, a finding that, if supported by clinical research, holds some promise for preventing muscle strength loss in the later years. The mechanisms by which nitrate improves exercise tolerance and muscle strength are not fully known, but may involve improved blood flow or oxygen supply in the tissues.

Not all studies support performance benefits from nitrate supplementation. Particularly, no improvement is reported among highly trained elite athletes, who may already perform at their biological peak for oxygen efficiency.

In high doses, nitrate or nitrite supplements may interact with medications, and their long-term safety is an open question (see Chapter 11). High nitrate doses pose a clear threat to infants, and supplements should be kept out of the reach of children.

Question 101

Coffee:
Many athletes report that caffeine from coffee, tea, energy drinks, energy “shots,” and other sources provides a physical boost during sports. Caffeine in safe doses (3 mg/kg of body weight) sometimes enhances performance, both in tests of endurance, such as cycling and rowing, and in high-intensity training. Other times, researchers report no caffeine-related improvement in performance. Caffeine is a mild stimulant used by many people to enhance alertness and concentration.

In higher doses, caffeine causes stomach upset, anxiety, irritability, sleep disturbances, dehydration, and irregular heartbeats. Such doses also constrict blood vessels, often increasing blood pressure, and increase the heart rate at a given workload. In addition, other ingredients often added to caffeinated “energy beverages” can have unpredictable effects. Overdoses of caffeine from energy drinks and other sources have caused several deaths among athletes and others in recent years.

Competitors should be aware that college sports authorities prohibit the use of caffeine in amounts greater than 700 milligrams, or the equivalent of eight cups of coffee, prior to competition. Controversy 11 lists caffeine doses in common foods and beverages.

Instead of taking caffeine pills before an event, Paige might be better off engaging in some light activity, as DJ does. Pregame activity stimulates the release of fatty acids and warms up the muscles and connective tissues, making them flexible and resistant to injury. Caffeine does not offer these benefits. Instead, caffeine in high doses acts as a diuretic. DJ enjoys a cup or two of coffee an hour before her races for to boost her performance and her mood.

Question 102

Creatine:
Creatine supplements are widely recommended to and widely used by athletes. Although they clearly do not benefit endurance athletes such as runners, evidence does hint at some other potential benefits. For performance of short-term, repetitive, high-intensity activities such as weight lifting or sprinting, some studies report small but significant increases in muscle strength, power, and size—attributes that support high-intensity activities. However, other studies suggest that resistance training alone, and not creatine supplements, may account for the improvements seen in those studies.

Creatine functions in muscles as part of the high-energy storage compound creatine phosphate (or phosphocreatine), and theoretically the more creatine phosphate in muscles, the higher the intensity at which an athlete can train. The confirmed effect of creatine, however, is weight gain—a potential boon for some athletes but a bane for others. Unfortunately, the gain may be mostly water because creatine causes muscles to hold water.

Meat is a good source of dietary creatine, but there is no need to eat a lot of meat or take supplements to obtain creatine. The obvious best source is the body’s own creatine—human muscles can make all the creatine they need.

Question 103

Buffers:
Sodium bicarbonate (baking soda) acts as a buffer, a compound that neutralizes acids. During high-intensity exercise, acids form in the muscles and may contribute to fatigue. Some, but not all, studies suggest a possible benefit from bicarbonate in sports involving repeated bursts of activity, such as many team sports. Unpleasant side effects, such as gas and diarrhea, may make this ergogenic aid impractical.

A buffering effect associated with the amino acid beta-alanine has recently received attention from exercise researchers. Although beta-alanine may increase the body’s buffering capacity, research has reported mixed effects on exercise performance. A “pins and needles” sensation side effect has been noted.

Paige believes that by taking a handful of amino acid pills and eating a couple of protein bars she can go easier on training and still gain speed on the track, but this is just wishful thinking. Muscles require physically demanding activity, not just protein, to gain in size and performance. Instead of getting faster, Paige will likely get fatter: at 250 calories each, her protein bars contribute 500 calories to her day’s intake, an amount that exceeds her exercise expenditures.

Recently, DJ, who snacks on plain raisins and nuts, placed ahead of Paige in 7 of their 10 shared competitions. In one of these races, Paige dropped out because of light-headedness—perhaps a consequence of too much caffeine? Still, Paige remains convinced that to win, she must have chemical help, and she is venturing over the danger line by considering hormone-related products. What she doesn’t know is very likely to hurt her.

Question 104

Hormones and Hormone Imitators:
The dietary supplements discussed so far are controversial in the sense that they may or may not enhance athletic performance, but most—in the doses healthy adults commonly take—probably do not pose immediate threats to health or life. In contrast, hormones, such as human growth hormone, DHEA, androstenedione, testosterone, or others, are risky and they are banned by the World Anti-Doping Agency of the International Olympic Committee and by most professional and amateur sports leagues.

Question 105

Anabolic Steroid Hazards:

Among the most dangerous ergogenic practices is the use of anabolic steroid hormones. The body’s natural steroid hormones stimulate muscle growth in response to physical activity in both men and women. Injections of “fake” hormones produce muscle size and strength far beyond that attainable by training alone—but at great risk to health. These drugs are both dangerous and illegal in sports, yet athletes often use them without medical supervision, simply taking someone’s word for their safety. The list of damaging side effects of steroids is long and includes:

Extreme mental hostility; aggression; personality changes; suicidal thoughts.

Swollen face; severe, scarring acne; yellowing of whites of eyes (jaundice).

Elevated risk of heart attack, stroke; liver damage, liver tumors, fatal liver failure; kidney damage; bloody diarrhea.

In females, irreversible deepening of voice, loss of fertility, shrinkage of breasts, permanent enlargement of external genitalia.

In males, breast enlargement, permanent shrinkage of testes, prostate enlargement, sexual dysfunction, and loss of fertility.

Don’t even consider using these products—just steer clear.