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Chapter 14 – Fitness: Physical Activity, Nutrients, and Body Adaptations
Learning Objectives
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List the benefits of regular physical activity.
Explain the components of fitness and conditioning.
Describe the energy systems of physical activity, including ATP and CP.
Describe the use of glucose and glycogen as body fuels during exercise.
Describe a diet to minimize glucose depletion during exercise.
Explain the principle of carbohydrate loading, including the diet to build glycogen stores.
Explain the role of dietary and body fats during prolonged exercise.
Describe the uses of protein during exercise and determine the protein needs of the athlete.
Discuss the roles of vitamin E and iron in the athlete.
Explain sports anemia and the iron requirements for the athlete.
Discuss fluid needs of the athlete and the symptoms and consequences of inadequate intake.
Describe the hydration schedule for physical activity and the need for electrolyte replacement.
Discuss the effects of caffeine and alcohol on an athlete’s performance.
Plan meals for pre-game and post-game to promote health and performance.
Define ergogenic and identify products classified as ergogenic aids.
Identify supplements commonly used by the athlete and discuss their safety and efficacy.
Identify the hormonal supplements that are promoted to athletes and are illegal or dangerous.
Lecture Presentation Outline
I.
Fitness
Fitness involves physical activity or exercise. The components of fitness are cardiorespiratory endurance, flexibility,
muscle strength, and muscle endurance. All of these characteristics describe a healthy body. Today’s world encourages
sedentary lifestyles that foster the development of several chronic diseases.
A. Benefits of Fitness
1. There are many benefits:
a. Restful sleep.
b. Nutritional health.
c. Optimal body composition.
d. Optimal bone density.
e. Resistance to colds and other infectious diseases.
f. Low risks of some types of cancer.
g. Strong circulation and lung function.
h. Low risk of cardiovascular disease.
i. Low risk of type 2 diabetes.
j. Reduced risk of gallbladder disease.
k. Low incidence and severity of anxiety and depression.
l. Promotes strong self-image
m. Long life and high quality of life in the later years.
2. The 2008 Physical Activity Guidelines for Americans state that people should avoid inactivity and stay physically
active to promote health.
a. Aerobic physical activity is necessary to obtain substantial health benefits.
b. The duration of activity recommended is dependent on whether the activity is a moderate-intensity activity
or a vigorous-intensity activity.
B. Developing Fitness
1. Guidelines for conditioning that is achieved through training.
a. Cardiorespiratory Endurance
1. Frequency – 5-7 days per week.
2. Intensity – moderate.
3. Duration – at least 30 minutes.
b.
Strength
1. Frequency – 2 or more nonconsecutive days per week.
2. Intensity – enough to enhance muscle strength, enhance muscle endurance, and improve body
composition.
3. Duration – 8 to 12 repetitions of 8 to 10 different exercises.
c. Flexibility
1. Frequency – 2-3 days per week.
2. Intensity – enough to develop and maintain a full range of motion.
3. Duration – 4 repetitions of 10-30 seconds per muscle group.
2. The Overload Principle – to slightly increase comfortable capacity in each area. This is also called the
progressive overload principle.
a. Increase frequency – how often an activity is performed.
b. Increase intensity – the degree of exertion while exercising.
c. Increase duration – the length of time.
3. The Body’s Response to Physical Activity
a. Hypertrophy is muscle gain in size and strength, the result of repeated work.
b. Atrophy is muscle loss in size and strength, the result of lack of activity.
c. Other Tips
1. Be active all week.
2. Use proper equipment and attire.
3. Use proper form when exercising.
4. Include warm-ups and cool-downs.
5. Challenge yourself, but not every time you exercise.
6. Pay attention to body signals.
7. Build intensity slowly.
4. Cautions on Starting a Fitness Program
a. Healthy people can start with a moderate exercise program without seeking medical advise first.
b. People with risk factors may need medical advice.
C. Cardiorespiratory Endurance
1. Cardiorespiratory conditioning is measured by maximum oxygen uptake (VO2max).
a. Increases cardiac output and oxygen delivery.
b. Increases stroke volume.
c. Slows resting pulse.
d. Increases breathing efficiency.
e. Improves circulation.
f. Reduces blood pressure.
2. Muscle Conditioning
a. Muscles use oxygen efficiently.
b. Muscles can burn fat longer.
3. A Balanced Fitness Program
a. Individualized.
b. Choose an activity that is enjoyed.
c. Should improve cardiorespiratory fitness, flexibility, muscle strength, muscle power, and muscle endurance.
D. Resistance Training is also called weight training.
1. Increases muscle strength, power, and endurance.
2. Prevents and manages cardiovascular disease.
3. Enhances psychological well-being.
4. Maximizes and maintains bone mass.
5. Improves posture and decreases the risk for back injury.
5. Enhances performance in other sports.
II. Energy Systems and Fuels to Support Activity
The mixture of fuels used during physical activity depends on diet, intensity and duration of the activity, and training.
Well-nourished active people and athletes do not need nutritional supplements. Water, iron, and sodium are nutrients that
may need attention.
A. The Energy Systems of Physical Activity—ATP and CP
1. ATP is adenosine triphosphate – a high-energy compound that delivers energy instantaneously.
2. CP is creatine phosphate – a high-energy compound in the muscles, used anaerobically.
3. The Energy-Yielding Nutrients
a. Nutrients work together while one may predominate.
b. Depends on diet, intensity and duration of the activity, and training.
1. Extremely intense activity
a. 8-10 seconds.
b. ATP-CP (immediately available).
c. No oxygen needed (anaerobic).
d. Activity examples – 100 yard dash and shot put.
2. Very highly intense activity
a. 20 seconds to 3 minutes.
b. ATP from carbohydrate.
c. No oxygen needed (anaerobic).
d. Activity example – ¼ mile run at maximum speed.
3. Highly intense activity
a. 3-20 minutes.
b. ATP from carbohydrate.
c. Oxygen needed (aerobic).
d. Activity examples – cycling, swimming, and running.
4. Moderately intense activity
a. More than 20 minutes.
b. ATP from fat.
c. Oxygen needed (aerobic).
d. Activity example – hiking.
B. Glucose Use during Physical Activity
1. Diet Affects Glycogen Storage and Use
a. High-carbohydrate diets increase glycogen stores.
b. Enhance endurance.
2. Intensity of Activity Affects Glycogen Use
a. Moderate activities use glycogen slowly.
b. Intense activities use glycogen quickly.
3. Lactate
a. Low-intensity activities can clear lactate from the blood.
b. During highly intense activities lactate accumulates and activity can only be maintained for 1-3 minutes.
c. Lactate is converted to glucose in the liver (Cori cycle).
4. Duration of Activity Affects Glycogen Use
a. First 20 minutes – primarily use glycogen.
b. After 20 minutes – use glycogen and fat.
5. Glucose Depletion
a. “Hitting the wall” – exhaustion of glucose stores.
b. Maximizing glucose supply
1. High-carbohydrate diet – 8 g/kg body weight or 70% of total energy intake.
2. Glucose during activities if activity lasts longer than 1 hour (sports drinks or diluted fruit juice).
3. Eat approximately 60 g of high-carbohydrate foods after activity.
4. Carbohydrate loading is a regime of diet and exercise that maximizes glycogen storage. It is also
called glycogen loading or glycogen super compensation.
6. Glucose during Activity
a. Activities lasting longer than 1 hour.
b. Should consume 30-60 grams of carbohydrate per hour.
7. Glucose after Activity
a. High-carbohydrate meal within 15 minutes accelerates glycogen storage by 300%.
b. Within 2 hours, rate of glycogen storage after a high-carbohydrate meal declines by half.
c. High-glycemic index foods.
8. Training Affects Glycogen Use
a. Muscles that repeatedly deplete glycogen through hard work will store greater amounts of glycogen.
b. Conditioned muscles rely less on glycogen and more on fat for energy.
c. Trained muscle cells have more mitochondria and can use oxygen better.
d. Untrained muscle cells depend more heavily on anaerobic pathways.
C. Fat Use during Physical Activity
1. Duration of Activity Affects Fat Use
a. Beginning of activity uses fatty acids in the blood.
b. After 20 minutes, uses body fat as major fuel.
2. Intensity of Activity Affects Fat Use
a. As intensity increases, fat makes less of a contribution to the fuel mix.
b. Oxygen must be abundant to break down fat.
3. Training Affects Fat Use
a. The better trained the muscles, the more fat is used.
b. The better trained, the stronger the heart and lung to deliver oxygen.
c. If better trained, then hormones prevent glucose release from the liver, so they rely more on fat.
D. Protein Use during Physical Activity—and between Times
1. Protein Used in Muscle Building
a. Synthesis of protein is suppressed during activity.
b. After activity protein synthesis accelerates.
c. Repeated activities cause body adaptations to support needs.
d. Remodeling.
e. Daily, ¼ to 1 ounce of body protein is added to muscle mass during muscle-building phase.
2. Protein Used as Fuel
a. During physical activity muscles use amino acids for fuel.
b. 10% of total fuel used.
3. Diet Affects Protein Use during Activity
a. Diets rich in energy and carbohydrate allow the body to use less protein for fuel.
b. Carbohydrates spare protein.
4. Intensity and Duration of Activity Affect Protein Use during Activity
a. If glycogen stores get depleted, then more reliance on protein.
b. Anaerobic strength training demands more protein to build muscles but not large amounts.
5. Training Affects Protein Use – the more trained the less protein used for energy.
6. Protein Recommendations for Active People
a. Athletes in training need more protein than sedentary people.
b. Athletes in training need to meet energy and carbohydrate needs first.
c. Adult RDA: for males 56 g/day, for females 44 g/day.
d. Strength athletes: for males 84-119 g/day, females 66-94 g/day.
e. Endurance athletes: for males 84-98 g/day, females 66-77 g/day.
f. U.S. average intake of protein: for males 102 g/day, females 70 g/day.
III.
Vitamins and Minerals to Support Activity
A. Supplements
1. Do not enhance performance.
2. Deficiencies may impede performance.
3. Timing makes a difference; supplements take hours or days to combine with cells.
4. Nutrient-dense foods provide nutrients needed.
B. Nutrients of Concern
1. Vitamin E supplements have shown inconsistent results with the vitamin’s effects on free radicals.
2. Iron deficiency
a. Common in physically active young women.
b. Consume good dietary sources of iron.
3. Iron-Deficiency Anemia
a. Impairs physical performance.
b. Cannot perform aerobic activity and tire easily.
4. Sports Anemia
5.
IV.
a. Low blood hemoglobin for a short time.
b. Adaptive, temporary response to endurance activity.
c. Does not require supplementation.
Iron Recommendations for Athletes
a. Blood tests should guide the decision.
b. Depends on the individual.
Fluids and Electrolytes to Support Activity
A. Temperature Regulation
1. Introduction
a. Muscle heat is 15-20 times greater when active than at rest.
b. Cooling mechanism.
c. 1 liter of sweat dissipates 600 kcalories of heat.
2. Hyperthermia – an above-normal body temperature.
a. Body heat builds up.
b. Triggers maximum sweating without sweat evaporation.
c. Symptoms of heat stroke – a dangerous accumulation of body heat with accompanying loss of body fluid.
1. Headache.
2. Nausea.
3. Dizziness.
4. Clumsiness.
5. Stumbling.
6. Hot, dry skin.
7. Confusion or other mental changes.
3. Hypothermia – a below-normal body temperature. Symptoms begin with shivering and euphoria and progress to
weakness, disorientation, and apathy.
4. Fluid Replacement via Hydration
a. Full hydration is imperative for athletes.
b. Those who are aware of their hourly sweat rate can replace lost fluids.
c. Plain, cool water is recommended.
d. Endurance athletes may require carbohydrate-containing beverages.
e. Hydration schedule
1. Two to three hours before activity – 2-3 cups.
2. 15 minutes before activity – 1-2 cups.
3. Every 15 minutes during activity – ½-1 cup.
4. After activity – 2 cups for every pound of body weight lost.
5. Electrolyte Losses and Replacement
a. Greater in the untrained.
b. Training improves electrolyte retention.
c. Eat regular diet meeting energy and nutrient needs.
d. Endurance athletes may need sports drinks.
e. Salt tablets worsen dehydration and impair performance.
6. Hyponatremia
a. Decreased concentration of sodium in the blood.
b. Causes
1. Excessive sweat.
2. Overhydration.
c. Symptoms
1. Severe headache.
2. Vomiting.
3. Bloating.
4. Confusion.
5. Seizure.
d. Prevention
1. Replace sodium during prolonged events.
2. Do not restrict salt in the diet in the days leading up to events.
B. Sports Drinks
1. Provide fluids to replace losses.
2. Provide glucose polymers that maintain hydration and blood sugar.
3. Provide sodium and other electrolytes.
4. Manufactured to have a pleasing taste.
C. Enhanced Water – Enhanced waters contain lower amounts of carbohydrates and electrolytes than traditional sports
drinks.
D. Poor Beverage Choices: Caffeine and Alcohol
1. Caffeine is a stimulant.
2. Alcohol should not be used to replace fluids and carbohydrate.
V. Diets for Physically Active People
A diet that provides ample fluids and nutrient-dense foods to meet energy needs will enhance an athlete’s activity and
overall health. Pregame and postgame meals should be light and carbohydrate rich.
A. Choosing a Diet to Support Fitness
1. Water
a. Thirst mechanisms are not as reliable.
b. Must be replenished.
2. Nutrient Density – consume nutrient-dense foods that are high in carbohydrate, moderate in fat, and adequate in
protein.
3. Carbohydrate
a. 60%-70% total energy intake.
b. Avoid fiber-rich foods in the pregame meal.
c. Added sugar and fat may be needed during intensive training.
d. Liquid supplements should not replace foods.
e. 8-10 g carbohydrate/kg body weight during heavy training.
4. Protein
a. Strength athletes: for males 84-119 g/day, females 66-94 g/day.
b. Endurance athletes: for males 84-98 g/day, females 66-77 g/day.
5. A Performance Diet Example
a. Energy-dense foods should be chosen.
b. See Figure 4-14.
B. Meals Before and After Competition
1. Pregame Meals
a. Fluids.
b. 300-800 kcalories.
c. Carbohydrate-rich foods low in fat and fiber.
d. Light and easy to digest.
2. Postgame Meals
a. High-carbohydrate meals.
b. Liquids often preferred.
VI. Highlight: Supplements as Ergogenic Aids
It is difficult to distinguish valid versus bogus claims about ergogenic aids. Many individuals believe these drugs,
supplements, or procedures will enhance physical performance in activities. Some are harmless, some have dangerous
side effects, and some are costly. Most do not fulfill claims.
A. Ergogenic Aids
1. Problems with distinguishing valid claims versus bogus claims.
2. Marketing techniques are used to generate sales.
3. Substances promoted as ergogenic aids
a. Arginine is a nonessential amino acid.
b. Boron is a nonessential mineral.
c. Coenzyme Q10 is not effective in improving athlete performance.
d. Gamma-oryzanol has been found to be ineffective in increasing muscle mass.
e. Ginseng has many side effects.
f. Glycerol may improve hydration and the regulation of body temperature.
g. HMB (beta-hydroxy-beta methylbutyrate) claims to increase muscle mass and strength.
h. Pyruvate has common side effects of gas and diarrhea.
i. Ribose has some false claims.
j. Royal jelly is falsely promoted.
k. Sodium bicarbonate may cause intestinal bloating and diarrhea.
B. Dietary Supplements
1. Carnitine
a. Non-essential nutrient.
b. Facilitates transfer of fatty acids across mitochondria membranes.
c. Supplementation does not increase muscle carnitine or enhance exercise performance.
2. Chromium Picolinate
a. Essential mineral in carbohydrate and lipid metabolism.
b. Supplementation has no effect on strength, lean body mass, or body fat.
3. Complete Nutrition Supplements
a. Taste good and provide food energy, but do not provide complete nutrition.
b. Should not replace regular meals.
4. Creatine
a. Some studies suggest improvement in muscle strength and size, cell hydration, and glycogen loading
capacity.
b. Safety issues and side effects.
5. Conjugated Linoleic Acid (CLA)
a. Derived from linoleic acid, an essential fatty acid.
b. Increases lean body mass in animals.
c. Few human studies have been performed.
6. Caffeine
a. Caffeine can enhance performance by stimulating fatty acid release.
b. Adverse effects include stomach upset, nervousness, irritability, headaches, and diarrhea.
c. Use in moderation.
d. Use as an addition to other fluids, not as replacement.
C. Hormonal Supplements
1. Anabolic Steroids
a. Illegal.
b. Authorities ban use.
c. Plant sterols from herbs are poorly absorbed.
d. Dangerous side effects on the body and the mind.
2. DHEA (dehydroepiandrosterone) and Androstenedione
a. Hormones that are precursors to testosterone.
b. No evidence to support claims.
c. Short-term side effects are identified.
3. Human Growth Hormone (hGH)
a. Used to build lean tissue and increase height if still growing.
b. Extremely high cost.
c. Many adverse side effects.
1.
As discussed in this chapter, there are many benefits of physical activity. For clients participating in a weight-loss
program, what are some of the benefits of physical activity that a client might gain greater benefit from, and in what areas
might the dietitian want to be more cautious and provide more frequent assessments?
Answer: A client undergoing weight loss can often benefit even more from the advantages of physical activity. For
instance, physical activity can help to enhance self esteem and reduce anxiety and depression—aspects especially
important in the individual that is overweight. Individuals that suffer from anxiety or depression do benefit from exercise.
Imagine the individual that is obese and eats as a result of anxiety or depression. What a benefit exercise or physical
activity can make for anxiety and depression as well as weight and weight loss. Physical activity for such things as stress
can dissipate stress hormones. This can be so helpful for the obese individual that learned to eat in response to stress.
If an individual’s self-esteem has been lowered because of their overweight, exercise can generally help to improve self
esteem and reduce stress.
Many chronic diseases such as cardiovascular disease, including poor circulation and lung function, and type 2 diabetes
can be reduced or at times managed with physical activity. Obesity is a major determinant of these diseases. Physical
activity can postpone or prevent their onset, depending on many factors including genetics, progression of the disease,
need to lose weight, and amount of weight lost, etc. When comparing two individuals with one of these chronic diseases,
one who exercises and one who does not, the one that exercises will do significantly better than the one that does not.
Exercise does have to be at the intensity, duration, and frequency necessary to render an overload outcome at each session
to achieve a fitness level and body fat level appropriate for height, age, and health conditions.
Resistance from colds, other infections, and perhaps cancer: An individual that is in better health and consumes a nutrientdense diet is more able to resist infections and other health issues. Often, while the obese individual appears to be well
fed, they are not eating nutrient-dense foods, often leading to malnutrition of sorts. A weight-loss program that provides
nutrient-dense foods actually improves immune function for the client and optimal health for resisting colds, other
infections, and perhaps cancer.
Gallbladder: This organ functions by storing bile to break down fatty acids. In the obese client, a diet high in fatty acids
may overload the gallbladder. When these clients start to consume a diet that is proportioned with less fat and far less
saturated fat, the gallbladder is eased of its load and gallbladder disease can be reduced.
Body composition: This is directly related to longevity via BMI and body fat. The obese individual retains a higher BMI
and higher % body fat, both correlated with a lower life span. Weight loss can improve not only one’s body composition
but also life expectancy, ability to move and exercise, chronic disease outcomes, and one’s overall life. Seems like a great
deal for good nutrition!
Any client undergoing changes in diet and lifestyle, including exercise, should be monitored closely. One would want to
check the client’s cardiovascular and respiratory systems on a regular basis. Also include blood sugar levels for type 2
diabetes and watch mood and behavior for signs of anxiety, depression, and eating disorders.
Clients undergoing weight loss can change their biochemical parameters (blood lipids, blood sugar, and beyond) quickly.
Depending on the patient’s medical history, severity of problem, progress, etc., patients/clients must be monitored for
relapse or development of a problem that is not anticipated. Weight loss is a great goal; however, some clients do have
underlying issues that can make them highly vulnerable to compromise with many changes. It is always best to be alert.
2.
Discuss the body’s use of high-energy compounds and energy nutrients during physical activity. In other words,
differentiate between an athlete’s energy needs for short-distance and sprint events vs. endurance events.
Answer: The body retains many sources of energy for exercise.
The most immediate source of energy is two compounds called ATP and CP: these are adenosine triphosphate and
creatine phosphate. These energy sources are used by the muscles and are quickly available to them for their immediate
needs. ATP is utilized in both anaerobic and aerobic activity and ATP-CP can be utilized only in very short bursts of less
those 10 seconds of anaerobic activity.
The body utilizes glucose, fatty acids, and protein to produce ATP for energy.
Glucose: Glucose does provide for immediate energy when stored as glycogen. About 2000 kcalories are stored as energy
for the muscles and the more the athlete is conditioned the more efficiently that athlete can utilize that glycogen, allowing
the athlete to utilize the glycogen over a longer period of time. This is a preferable situation because glycogen can be
utilized quickly as opposed to fatty acids that require an extensive period for breakdown prior to utilization. Energy from
glycogen provides approximately 20 minutes of performance. Both anaerobic and aerobic activities are supported by
glycogen stores.
A high-carbohydrate diet provides more energy for the athlete over the short term.
Fatty acids: Epinephrine signals the fat cells to break down fat for use in physical activity. Once glycogen is utilized or
when performance is at 60% or less than VO2 max, the body uses fatty acid for energy. These types of athletic events are
primarily aerobic events rather than quick, short bursts of intense exercise, and are characterized as the endurance types of
sports. Fatty acids are a rich source of energy, depending on the individual, allowing for greater than 70,000 kcal of
energy. Clearly fat is a great energy source for distance events, but fatty acids are unavailable for short events that are
anaerobic.
Proteins: Amino acids only provide 10% of the fuel for activity. Protein’s main functions involve tissue repair, enzymes,
and many other important components in the body. Whether athletes require more protein is controversial. After anaerobic
events, protein is utilized for muscle development, while in aerobic events, protein is utilized for energy. Training,
intensity, and duration all affect the body’s use of protein. A well-trained athlete can better utilize their glycogen stores
and will use their protein intake for tissue repair and muscle development.
3.
Manufacturers of sports drinks select top athletes to speak in commercials for this multi-billion dollar business. In your
opinion, are the benefits of sports drinks worth their cost? There is no right or wrong answer!
Answer: Table 14-7 provides a start for the students to start thinking about this question. In the field of sports nutrition,
athletes will take anything that they hear will benefit their “game.” The RD that is not prepared to substantiate their point
of view will not have credibility in the athletic world. It is always best to work with the athlete on their beliefs without
doing harm. Sports drinks are a perfect example!! Let the students think through this and use the literature to support their
cause with a classroom discussion. If some have worked with athletes, let them share their experiences as this is always
helpful. In the end and after a good debate, let the class decide together what they think is the best course of action!
4.
As your chapter points out, physical activity provides many great benefits for an individual’s cardiovascular and
respiratory systems and emotional well being, and helps to maintain their bone health and flexibility. Yet, exercises done
improperly can be harmful to an individual, and there are also many products on the market that are promoted to improve
a person’s game—products that may truly have no value. Imagine yourself as a famous sports dietitian with a broad
clientele. Discuss areas of concern that you would need to address with the following clients.
These are two vary different athletes that are motivated and working hard. What are your assessment concerns for each,
what are your recommendations, and why?
A 45-year-old male “weekend warrior” has decided to return to his favorite college team sport of running to get back into
shape and lose some weight. At present, he is 20 pounds overweight and has not been to his physician for about 1.5 years,
but at that time he states he was in perfect health. He has decided to go on a popular high-protein diet to help hasten his
weight loss and support tissue repair from the running. His eating plan includes protein bars, protein shakes, and protein
water drinks. He is also taking chromium, zinc, vitamins C and E, and tryptophan supplements. He is presently running 3
miles a day, 4 days a week, and 10 miles a day, 2 days a week. His goal is to be able to do a marathon in six months.
Your second client is a world-class female figure skater aged 13 years. At present, she is 5’ 2” tall and weighs 95 pounds.
She has not started her menstrual cycle but appears to be in Tanner stage 5 or full sexual development. Her coach does not
want her to gain any further weight for her height; however, if she does get taller, then he may be amenable. Her diet is
approximately 60% protein, 35% carbohydrate, and 5% fat. She eats lean meats but tries to stay with the vegetarian
proteins, complex carbohydrates, and monounsaturated fatty acids. She is very motivated about her diet and her mother is
constantly watching her as well as her coach. She does eat salads and fruits and of course exercises or works out
approximately 10 hours a day, if not more at times. Along with diet, this athlete consumes unknown supplements and
ergogenic aids to support her athletic training. At her young age, she has won several world championships and is
considered the next Olympic gold medal champion. The Olympics are two years away and she is highly motivated to be
there and win.
Answer: For the instructor, the point of the exercise is to demonstrate to the student some of the issues that can arise with
athletic clients, taking athletic issues from two very different perspectives.
First client: With a “weekend warrior” the RD must be careful to assess all physiological and medical parameters as well
as his diet to protect him from injury and more importantly long-term damage from his new regime. First, it is great that
he has decided to get active and undertake a more healthful diet; however, when a client decides to undergo some of these
drastic changes he may sometimes overdo it in the short term, injure himself, and then not resume. We would like him to
adapt changes long term without any physiologic problems or injury. He also may have an underlying medical problem
that he is unaware of that can be exacerbated by the exercise. It is always best when starting a new exercise program after
being away from exercise for a while to have a complete medical physical. After that, the best way to do this is to take
some moderation to the approach for which this client needs to gain some perspective. The RD wants to keep him
involved and active and if he is immediately depleted he will not continue.
The client appears to be fairly well educated and articulate; therefore, it would be in the best interests of the RD to
approach this client through a focused nutrition education mode, allowing the client to help the RD put the new dietary
program together. In that manner, the RD is assured that the client understands the information and the client takes
ownership of the process.
The RD would do well to help the client change his regime to a more moderate-protein diet, such as a 25-35% protein
diet. In that manner, it is still somewhat high in protein but not as high. A carbohydrate level of 55% to allow for complex
carbohydrates with fruits and vegetables should be suggested. This adds variety and flavor to the diet. The last is about
10% fat which is needed for many steroid hormones, skin, and the cellular membranes. This diet will provide for all
necessary vitamins and minerals. Because this is an endurance event, he can increase his fatty acid intake up to 20% of his
diet by decreasing his protein intake to 25% and adjust the rest of his diet accordingly. For the purposes of weight loss, he
may prefer the diet to stay at the former level for the time being and adjust the fat percentage upward after he has lost
some of his weight.
Given the client is 20 pounds overweight, the RD would set a goal of a 1-2 pounds a week weight loss, which can be
accomplished by his running regime and diet. It would be important to have some information on the caloric and nutrient
content of his previous baseline diet. A goal of removing 500 kcal a day from a combination of diet and increased exercise
usually results in a one pound a week weight loss, a very reasonable plan for this client. His exercise in addition to
replacing empty calories with nutrient-dense food choices should help to make this an easy goal to reach.
It is best to encourage this athlete to consume a multivitamin rather than all the different supplements, at random. Given
that these supplements will not enhance performance, this individual can benefit more from a multivitamin supplement,
given the diet, rather than taking supplements that have no proven benefit. It is also a better balance for the nutrients
overall in the body. To help influence this client toward this direction, the RD might discuss the benefits of gaining
vitamins and minerals through the foods one eats rather than in supplement form because of the variety of factors that
influence their uptake and use in the body. However, if the client insists on taking these supplements, no harm will come
from their use and the RD can thus remain flexible with clients. This flexibility increases trust between the client and
nutrition professional.
The use of protein shakes, etc. should be balanced into the overall diet to establish the protein level at no more than 35%
of the overall diet. Alternatives to these between-meal snacks are fruits, dried fruits, plain popcorn, cheese and crackers,
etc. The RD can work with the client to establish a long list of snack foods that are quick to make or can be purchased in
order to increase the variety of foods in this client’s diet and avoid an excessive amount of protein.
From this case, it is unclear whether the client is warming up and cooling down or doing any weight training as well. The
RD should ask about these processes and remind the client that all of these areas are quite important to injury prevention,
thus staying on task with his goals. As a sports nutritionist, the RD may work with trainers or be one; therefore, a
suggestion to see a trainer at least initially and occasionally during work toward the client’s goal would be helpful to
ensure he stays on task and avoids any major injuries or problems.
Second client: This world-class skater is under constant medical and training care. Therefore, we know that she has been
assessed medically. In general, most of these athletes have an athletic trainer that provides some nutrition information. At
times there may be an RD. Her diet is too high in protein, so she needs to increase the fat intake to 10% and increase the
carbohydrate intake to 65%. At her age, she is especially in need of the fat for steroid production as well as cellular
membranes, etc. Given that she consumes more of a vegetarian diet, I would also suggest that she take a multivitamin
with iron to ensure that she is receiving all her necessary vitamins and minerals.
Overall, it would be important to work with the skater and her mother (perhaps separately and then together) on some
cycle menus and snack ideas. Given the age and energy expenditure of this skater, her energy requirements are very high.
Her estimated energy expenditure is 4549.22 on a daily basis. To consume this many calories can be difficult and with
everyone watching the skater, it is important for the mother, coach, and skater to understand her needs and to work with
each other to plan healthful food choices that can be available and also made quickly. World-class skaters train early in
the morning, often, and travel frequently. Therefore, they will be eating many meals on the run and eating out. Helping
her and her mom to put together a sorted selection of handy snacks that she can grab quickly will be important. It will also
be important to help her select healthy meals at restaurants and learn to order off a menu that does not appear to have
anything that she could eat.
The more the RD can empower the skater, the more the RD will gain trust with the skater. Yet the RD will also have to
work closely with mom and the coach and gain trust equally from them. However, it is the skater that is often left
powerless and in this age period it will be especially important for the RD to assist the skater in making her own food
choice decisions and learning about the importance of nutrition for her body and the work it needs to do. Once some trust
is built between the skater and the RD, the RD can approach the issue of supplements, ergogenic aids, etc. While this may
have been approached before, if nothing was gained from the conversation, when trust is built, more pertinent information
may be gleaned. The skater will not take anything that will compromise her ability to compete but will take anything that
is thought to enhance her performance. Assess all supplements thoroughly and decide if any are causing harm to the
client. If not, it is best to let the supplements go and the skater continue to take them. It is important to be flexible with the
athlete and understand that even if the literature indicates that there is no benefit to a particular supplement, in the mind of
an athlete, it benefits them!
The weight of this skater is borderline low for her height; i.e., she is on the lower end of normal for her height. In athletic
events that are judged, one will find much attention paid to weight; therefore, given that she is still within normal limits,
the RD should pay close attention to making her diet as nutrient-dense as possible and as noted, increasing the fatty acid
and carbohydrate intakes. She does appear to be missing her menstrual cycle considering that she is Tanner stage 5. An
increase in fatty acid intake to 10% or adjusted up to 15% for a period of time may assist in helping her body to begin
menstruation. At that time it will be particularly important to include iron as a supplement if she continues to maintain a
vegetarian diet.
Most of all, while this particular skater appears to enjoy what she is doing, this sport can become very stressful and many
skaters become disillusioned early in their careers. Remind her to have fun with her skating and with what she eats. A
good diet includes a variety of foods so that boredom does not set in while still nourishing one’s body to perform.
5.
Differentiate between moderate-intensity and vigorous-intensity aerobic activity. How does “the overload principle”
impact the outcome of the physical activity that an individual participates in?
Answer: Aerobic physical activity is basically cardiovascular fitness training. It is the type of activity that allows an
individual to move all body parts and work the cardiovascular and respiratory systems as well as the muscular and skeletal
systems for a positive influence on health status.
Moderate-intensity physical activity allows the individual to be engaged in a sport with an increase in heart rate and
respirations but not to the point where the individual cannot carry on a conversation. Your book points out that moderate
intensity would be jogging or walking fast at 3-4 miles in an hour.
Vigorous-intensity physical activity, in contrast, increases the heart rate and respirations significantly so that the
individual is unable to carry on a conversation with a colleague. A run beyond 4.5 miles in one hour would be a vigorousintensity activity for many individuals.
The overload principle indicates that an individual can improve their abilities in a sport by increasing their frequency of
participating in that activity, increasing the intensity of the activity, and increasing the duration of their participation.
Coaches will use all three of these factors to improve the performance of an athlete. Over time, use of the overload
principle will take a moderate-intensity activity for one individual and make it a low-intensity activity for that same
individual. Therefore, the person would need to increase the intensity of exercise to achieve moderate or vigorous
intensities and further improve cardiorespiratory endurance.
Formulas:
MHR = 220 – Age
THRR = MHR x 60% to MHR x 85% or MHR x 0.6 to MHR x 0.85
(As one ages, the MHR decreases and the range between THRR narrows.)