© 2008 thomson - wadsworth chapter 14 fitness: physical activity, nutrients, and body adaptations

© 2008 Thomson - Wadsworth

Chapter 14

Fitness: Physical Activity, Nutrients, and Body

Adaptations


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.


Fitness

• Benefits of FitnessRestful sleepNutritional healthOptimal body composition

Optimal bone density

Resistance to colds and other infectious diseases

Low risks of some types of cancer

Strong circulation and lung function

Low risk of cardiovascular disease

Low risk of type 2 diabetes

Reduced risk of gallbladder disease in women

Low incidence and severity of anxiety and depression

Long life and high quality of life in the later years


Fitness

• The 2005 Dietary Guidelines for Americans state that people need to participate in 30 minutes of physical activity most days of the week for health benefits and 60 minutes to maintain a healthy body weight.

• Developing FitnessGuidelines for conditioning that are achieved through training.• Cardiorespiratory Endurance

– Frequency – 3-5 days per week– Intensity – 55-90% maximum heart rate– Duration – 20-60 minutes


Fitness

• Guidelines for conditioningStrength

• Frequency – 2-3 days per week• Intensity – enough to enhance muscle strength, muscle endurance, and improve body composition

• Duration – 8 to 12 repetitions of 8 to 10 different exercises

Flexibility• Frequency – 2-3 days per week• Intensity – enough to develop and maintain a full range of motion

• Duration – 4 repetitions of 10-30 seconds per muscle group


Fitness

• Developing FitnessThe Overload Principle – to slightly increase comfortable capacity in each area. •This is also called the progressive overload principle.

•Increase frequency – how often an activity is performed

•Increase intensity – the degree of exertion while exercising

•Increase duration – the length of time


Fitness

• Developing FitnessThe Body’s Response to Physical Activity

• Hypertrophy is muscle gain in size and strength, the result of repeated work.

• Atrophy is muscle loss in size and strength, the result of lack of activity.

• Other Tips– Be active all week.– Use proper equipment and attire.– Use proper form when exercising.– Include warm-ups and cool-downs.– Challenge yourself, but not every time you exercise.

– Pay attention to body signals.– Build intensity slowly.


Fitness

• Developing FitnessCautions on Starting

•Healthy people can start with a moderate exercise program without seeking medical advise first.

•People with risk factors may need medical advice.


Fitness

• Cardiorespiratory EnduranceCardiorespiratory conditioning is measured by maximum oxygen uptake (VO2max).• Increases cardiac output and oxygen delivery

• Increases stroke volume• Slows resting pulse• Increases breathing efficiency• Improves circulation• Reduces blood pressure


Fitness

• Cardiorespiratory EnduranceMuscle Conditioning

•Muscles use oxygen efficiently.•Muscles can burn fat longer.

A Balanced Fitness Program•Individualized•Cardiorespiratory•Muscle strength and endurance•Flexibility•Choose an activity you enjoy


Fitness

• Weight Training Also called resistance trainingIncreases muscle strength and endurance

Prevents and manages cardiovascular disease

Enhances psychological well-beingMaximizes and maintains bone massEnhances performance in other sports


Energy Systems, Fuels, and Nutrients to Support

Activity• The mixture of fuels used during physical activity depends on diet, and 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.



Activity• The Energy Systems of Physical Activity—ATP and CPATP is adenosine triphosphate – a high-energy compound that delivers energy instantaneously.

CP is creatine phosphate – a high-energy compound in the muscles, used anaerobically.

The Energy-Yielding Nutrients• Nutrients work together while one may predominate.

• Depends on diet, intensity and duration of the activity, and training



Activity• Extremely intense activity

8-10 secondsATP-CP (immediately available)No oxygen needed (anaerobic) Activity example – 100 yard dash, shot put

• Very highly intense activity20 seconds to 3 minutesATP from carbohydrate (lactic acid)No oxygen needed (anaerobic)Activity example – ¼ mile run at maximum speed



Activity• Highly intense activity

3-20 minutesATP from carbohydrateOxygen needed (aerobic)Activity example – cycling, swimming, running

• Moderately intense activityMore than 20 minutesATP from fatOxygen needed (aerobic)Activity example – hiking



Activity• Glucose Use during Physical ActivityDiet Affects Glycogen Storage and Use •High-carbohydrate diets increase glycogen stores

•Enhance endurance



ActivityIntensity of Activity Affects Glycogen Use•Moderate activities use glycogen slowly.

•Intense activities use glycogen quickly.



Activity• Glucose Use during Physical Activity

Lactate• Low intensity activities can clear lactic acid from the blood.

• During highly intense activities lactic acid accumulates and activity can only be maintained for 1-3 minutes.

• Lactate is converted to glucose in the liver (Cori cycle).

Duration of Activity Affects Glycogen Use• First 20 minutes – primarily use glycogen• After 20 minutes – use glycogen and fat




Glucose Depletion• “Hitting the wall” – exhaustion of glucose stores

• Maximizing Glucose Supply– High-carbohydrate diet – 8 g/kg body weight or 70% of total energy intake

– Glucose during activities if activity last longer than 45 minutes (sports drinks, diluted fruit juice)

– Eat approximately 60 g of high-carbohydrate foods after activity.

– Carbohydrate loading is a regime of diet and exercise that maximizes glycogen storage. It is also called glycogen loading or glycogen super compensation.




Glucose during Activity• Activities lasting longer than 45 minutes• Light carbohydrate snacks under 200 kcalories

Glucose after Activity• High-carbohydrate meal within 15 minutes accelerates glycogen storage by 300%

• High-carbohydrate meal within 2 hours and rate of glycogen storage declines by half

• High-glycemic index foods



Activity• Glucose Use during Physical ActivityTraining Affects Glycogen Use

•Muscles that repeatedly deplete glycogen through hard work will store greater amounts of glycogen.

•Conditioned muscles rely less on glycogen and more on fat for energy.

•Trained muscle cells have more mitochondria and can use oxygen better.

•Untrained muscle cells depend more heavily on anaerobic pathways.



Activity• Fat Use during Physical Activity

Duration of Activity Affects Fat Use•Beginning of activity uses fatty acids in the blood

•After 20 minutes, uses body fat as major fuel

Intensity of Activity Affects Fat Use•As intensity increases, fat makes less of a contribution to the fuel mix

•Oxygen must be abundant to break down fat



Activity• Fat Use during Physical Activity

Training Affects Fat Use•The better trained the muscles, the more fat is used

•The better trained, the stronger the heart and lung to deliver oxygen

•If better trained, then hormones prevent glucose release from the liver, so they rely more on fat



Activity• Protein Use during Physical Activity—and between TimesProtein Used in Muscle Building

• Synthesis of protein is suppressed during activity.

• After activity protein synthesis accelerates.

• Repeated activities cause body adaptations to support needs.

• Remodeling• Daily, ¼ to 1 ounce of body protein is added to muscle mass during muscle-building phase.



Activity• Protein Use during Physical Activity—and between TimesProtein Used as Fuel

• During physical activity muscles use amino acids for fuel.

• 10% of total fuel used

Diet Affects Protein Use during Activity• Diets rich in energy and carbohydrate allow the body to use less protein for fuel.

• Carbohydrates spare protein.



Activity• Protein Use during Physical Activity—and between TimesIntensity and Duration of Activity Affect Protein Use during Activity• If glycogen stores get depleted, then more reliance on protein

• Anaerobic strength training demands more protein to build muscles but not large amounts.

Training Affects Protein Use • The more trained the less protein used for energy



Activity• Protein Use during Physical Activity—and between TimesProtein Recommendations for Active People

• Athletes in training need more protein than sedentary people.

• Athletes in training need to meet energy and carbohydrate needs first.

• Adult RDA: for males 56 g/day, for females 44 g/day

• Strength athletes: for males 112-119 g/day, females 88-94 g/day

• Endurance athletes: for males 84-112 g/day, females 66-88 g/day

• U.S. average intake of protein: for males 95 g/day, females 65 g/day



Activity• Vitamins and Minerals to Support ActivitySupplements

•Do not enhance performance•Deficiencies may impede performance•Timing makes a difference; supplements take hours or days to combine with cells.

•Nutrient-dense foods provide nutrients needed.



Activity• Vitamins and Minerals to Support ActivityVitamin E

• Protects against oxidative stress• Does not improve performance• More research needed• Vegetables oils and antioxidant fruits and vegetables

Iron• Iron losses in sweat• Small blood losses in digestive tract• Poor iron absorption



Activity• Vitamins and Minerals to Support ActivityIron Deficiency

•Common in physically active young women

•Consume good dietary sources of iron

Iron-Deficiency Anemia•Impairs physical performance•Cannot perform aerobic activity and tire easily



Activity• Vitamins and Minerals to Support ActivitySports Anemia

•Low blood hemoglobin for a short time•Adaptive, temporary response to endurance activity

•Does not require supplementationIron Recommendations for Athletes

•Blood tests should guide the decision•Depends on the individual



Activity• Fluids and Electrolytes to Support ActivityFluid Losses via Sweat

•Muscle heat is 15-20 times greater when active than at rest

•Cooling mechanism•1 liter of sweat dissipates 600 kcalories of heat



Activity• Fluids and Electrolytes to Support ActivityHyperthermia – an above-normal body temperature•Body heat builds up•Triggers maximum sweating without sweat evaporation



Activity• Symptoms of heat

stroke – a dangerous accumulation of body heat with accompanying loss of body fluid Headache Nausea Dizziness Clumsiness Stumbling Hot, dry skin Confusion or other mental changes

• Prevention of heat strokeDrink fluidsRest in the shade when tired

Wear appropriate clothing



Activity• Fluids and Electrolytes to Support ActivityHypothermia – a below-normal body temperature• Symptoms

– Shivering and euphoria– Weakness, disorientation, and apathy

• Prevention– Drink fluids– Wear appropriate clothing

• Water Recommendations– 1.0 to 1.5 mL/kcal expended– ½ cup per 100 kcal expended



Activity• Fluids and Electrolytes to Support ActivityFluid Replacement via Hydration

• Full hydration is imperative for athletes.• Those who are aware of their hourly sweat rate can replace lost fluids.

• Plain, cool water is recommended.• Endurance athletes may require carbohydrate-containing beverages.

• Hydration schedule– Two hours before activity – 2-3 cups– 15 minutes before activity – 1-2 cups– Every 15 minutes during activity – ½-2 cups– After activity – 2 cups for every pound of body weight lost



Activity• Fluids and Electrolytes to Support ActivityElectrolyte Losses and Replacement

•Greater in the untrained•Training improves electrolyte retention.

•Eat regular diet meeting energy and nutrient needs

•Endurance athletes may need sports drinks.

•Salt tablets worsen dehydration and impair performance.



Activity• Fluids and Electrolytes to Support ActivityHyponatremia

•Decreased concentration of sodium in the blood

•Causes– Excessive sweat– Overhydration– Drinking sports drinks during an activity; sports drinks offer glucose polymers



Activity• Symptoms of hyponatremiaSevere headacheVomitingBloatingConfusionSeizure

• PreventionReplace sodium during prolonged events.

Do not restrict salt in diets the days before events.



Activity• Poor Beverage Choices: Caffeine and AlcoholCaffeine is a stimulant.Alcohol is not the beverage to replace fluids and carbohydrate.


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.



• Choosing a Diet to Support FitnessWater

•Thirst mechanisms are not as reliable

•Must be replenished

Nutrient Density – consume nutrient-dense foods that are high in carbohydrate, moderate in fat, and adequate in protein



• Choosing a Diet to Support FitnessCarbohydrate

• 60-70% total energy intake• Avoid fiber-rich foods in the pregame meal.• Added sugar and fat may be needed during intensive training.

• Liquid supplements should not replace foods.• 8-10 g carbohydrate/kg body weight during heavy training

Protein• Strength athletes: for males 112-119 g/day, females 88-94 g/day

• Endurance athletes: for males 84-112 g/day, females 66-88 g/day



• Choosing a Diet to Support FitnessA Performance Diet Example

•Total kcalories – 3000•63% kcal from carbohydrate•22% kcal from fat•15% kcal from protein•All vitamin and mineral RDAs are met



• Meals Before and After CompetitionPregame Meals

•Fluids•300-800 kcalories•Carbohydrate-rich foods low in fat and fiber

•Light and easy to digestPostgame Meals

•High-carbohydrate meals•Liquids often preferred


Supplements as Performance-Enhancing

Aids


Supplements as Performance-Enhancing

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 meet claims.


Ergogenic Aids

• Problems with distinguishing valid claims versus bogus claims

• Marketing techniques are used to generate sales.


Ergogenic Aids

• Substances promoted as ergogenic aids Arginine – a nonessential

amino acid Boron – a nonessential

mineral Brewer’s yeast is falsely

promoted as an energy booster.

Cell salts are sold as health promoting.

Coenzyme Q10 is not effective in improving athlete performance.

DNA (deoxyribonucleic acid) is falsely promoted as an energy booster.

Epoetin is illegally used to increase oxygen capacity.

Gelatin is not a strength enhancer.

Ginseng has many side effects.

Glycine – a nonessential amino acid

Growth hormone releasers do not enhance performance.

High doses of guarana can stress the heart and cause panic attacks.

Herbal steroids or plant sterols do not enhance hormone activity.

HMB (beta-hydroxy-beta methylbutyrate) claims to increase muscle mass and strength.

Inosine has been shown to reduce endurance of runners.


Ergogenic Aids

• Ma huang has many dangerous side effects.

• Niacin does not enhance performance and has side effects.

• Octacosanol has false promotions.

• Ornithine – a nonessential amino acid

• Oryzanol – a plant sterol• Pangamic acid does not

speed oxygen delivery.• Phosphate pills do not

extend endurance or increase efficiency of aerobic metabolism.

• Pyruvate has common side effects of gas and diarrhea.

• Ribose has some false claims.

• RNA (ribonucleic acid) does not enhance performance.

• Royal jelly is falsely promoted.

• Sodium bicarbonate may cause intestinal bloating and diarrhea.

• Spirulina is potentially toxic.

• Succinate is not a metabolic enhancer.

• Superoxide dismutase (SOD) is useless; it is digested.

• Wheat germ oil is not an energy aid.


Dietary Supplements

• CarnitineNon-essential nutrientFacilitates transfer of fatty acids across mitochondria membranes

Supplementation does not increase muscle carnitine or enhance exercise performance.

• Chromium PicolinateEssential mineral in carbohydrate and lipid metabolism

Supplementation has no effect on strength, lean body mass, or body fat.


Dietary Supplements

• Complete Nutrition SupplementsTaste good and provide food energy, but do not provide complete nutrition

Should not replace regular meals

• CreatineSome studies suggest improvement in muscle strength and size, cell hydration and glycogen loading capacity

Safety issues and side effects


Dietary Supplements

• Conjugated Linoleic Acid (CLA) Derived from linoleic acid, an essential fatty acid Increases lean body mass in animals Few human studies have been performed.

• Caffeine Caffeine can enhance performance by stimulating fatty

acid release. Adverse effects include stomach upset, nervousness,

irritability, headaches, and diarrhea. Use in moderation. Use as an addition to other fluids, not as

replacement. • Oxygenated Water

Oxygen cannot enter the bloodstream by way of the GI tract.

The body gets oxygen from the lungs.


Hormonal Supplements

• Anabolic SteroidsIllegalAuthorities ban usePlant sterols from herbs are poorly absorbed.

Dangerous side effects on the body and the mind


Hormonal Supplements

• DHEA (dehydroepiandrosterone) and AndrostenedioneHormones that are precursors to testosterone

No evidence to support claimsShort-term effects are identified

• Human Growth Hormone (hGH)Used to build lean tissue and increase height if still growing

Extremely high costMany adverse side effects

© 2008 thomson - wadsworth chapter 14 fitness: physical activity, nutrients, and body adaptations

Documents

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