Chapter 14 Fitness: Physical Activity, Nutrients, and Body Adaptations © 2008 Thomson - Wadsworth.
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Chapter 14 Fitness: Physical Activity, Nutrients, and Body Adaptations © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Fitness • Benefits of Fitness Restful sleep Nutritional health Optimal 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 © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth 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 Fitness Guidelines 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 © 2008 Thomson - Wadsworth Fitness • Guidelines for conditioning Strength • 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 © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Fitness • Developing Fitness The 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 © 2008 Thomson - Wadsworth Fitness • Developing Fitness The 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. © 2008 Thomson - Wadsworth Fitness • Developing Fitness Cautions on Starting • Healthy people can start with a moderate exercise program without seeking medical advise first. • People with risk factors may need medical advice. © 2008 Thomson - Wadsworth Fitness • Cardiorespiratory Endurance Cardiorespiratory 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 © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Fitness • Cardiorespiratory Endurance Muscle 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 © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Fitness • Weight Training Also called resistance training Increases muscle strength and endurance Prevents and manages cardiovascular disease Enhances psychological well-being Maximizes and maintains bone mass Enhances performance in other sports © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • The Energy Systems of Physical Activity— ATP and CP ATP is adenosine triphosphate – a highenergy 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Extremely intense activity 8-10 seconds ATP-CP (immediately available) No oxygen needed (anaerobic) Activity example – 100 yard dash, shot put • Very highly intense activity 20 seconds to 3 minutes ATP from carbohydrate (lactic acid) No oxygen needed (anaerobic) Activity example – ¼ mile run at maximum speed © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Highly intense activity 3-20 minutes ATP from carbohydrate Oxygen needed (aerobic) Activity example – cycling, swimming, running • Moderately intense activity More than 20 minutes ATP from fat Oxygen needed (aerobic) Activity example – hiking © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Glucose Use during Physical Activity Diet Affects Glycogen Storage and Use • High-carbohydrate diets increase glycogen stores • Enhance endurance © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity Intensity of Activity Affects Glycogen Use • Moderate activities use glycogen slowly. • Intense activities use glycogen quickly. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Glucose Use during Physical Activity 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Glucose Use during Physical Activity 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Glucose Use during Physical Activity Training 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Protein Use during Physical Activity—and between Times Protein 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Protein Use during Physical Activity—and between Times Protein 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Protein Use during Physical Activity—and between Times Intensity 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Protein Use during Physical Activity—and between Times Protein 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Vitamins and Minerals to Support Activity Supplements • 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Vitamins and Minerals to Support Activity Vitamin 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Vitamins and Minerals to Support Activity Iron 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Vitamins and Minerals to Support Activity Sports Anemia • Low blood hemoglobin for a short time • Adaptive, temporary response to endurance activity • Does not require supplementation Iron Recommendations for Athletes • Blood tests should guide the decision • Depends on the individual © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Fluid 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Hyperthermia – an above-normal body temperature • Body heat builds up • Triggers maximum sweating without sweat evaporation © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support 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 stroke Drink fluids Rest in the shade when tired Wear appropriate clothing © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Hypothermia – 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Fluid 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 carbohydratecontaining 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 © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Electrolyte 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. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Fluids and Electrolytes to Support Activity Hyponatremia • Decreased concentration of sodium in the blood • Causes – Excessive sweat – Overhydration – Drinking sports drinks during an activity; sports drinks offer glucose polymers © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Symptoms of hyponatremia • Prevention Severe headache Vomiting Bloating Confusion Seizure Replace sodium during prolonged events. Do not restrict salt in diets the days before events. © 2008 Thomson - Wadsworth Energy Systems, Fuels, and Nutrients to Support Activity • Poor Beverage Choices: Caffeine and Alcohol Caffeine is a stimulant. Alcohol is not the beverage to replace fluids and carbohydrate. © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Diets for Physically Active People • Choosing a Diet to Support Fitness Water • Thirst mechanisms are not as reliable • Must be replenished Nutrient Density – consume nutrientdense foods that are high in carbohydrate, moderate in fat, and adequate in protein © 2008 Thomson - Wadsworth Diets for Physically Active People • Choosing a Diet to Support Fitness Carbohydrate • 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 © 2008 Thomson - Wadsworth Diets for Physically Active People • Choosing a Diet to Support Fitness A 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 © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Diets for Physically Active People • Meals Before and After Competition Pregame Meals • Fluids • 300-800 kcalories • Carbohydrate-rich foods low in fat and fiber • Light and easy to digest Postgame Meals • High-carbohydrate meals • Liquids often preferred © 2008 Thomson - Wadsworth © 2008 Thomson - Wadsworth Supplements as Performance-Enhancing Aids © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Ergogenic Aids • Problems with distinguishing valid claims versus bogus claims • Marketing techniques are used to generate sales. © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Dietary Supplements • Carnitine Non-essential nutrient Facilitates transfer of fatty acids across mitochondria membranes Supplementation does not increase muscle carnitine or enhance exercise performance. • Chromium Picolinate Essential mineral in carbohydrate and lipid metabolism Supplementation has no effect on strength, lean body mass, or body fat. © 2008 Thomson - Wadsworth Dietary Supplements • Complete Nutrition Supplements Taste good and provide food energy, but do not provide complete nutrition Should not replace regular meals • Creatine Some studies suggest improvement in muscle strength and size, cell hydration and glycogen loading capacity Safety issues and side effects © 2008 Thomson - Wadsworth 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. © 2008 Thomson - Wadsworth Hormonal Supplements • Anabolic Steroids Illegal Authorities ban use Plant sterols from herbs are poorly absorbed. Dangerous side effects on the body and the mind © 2008 Thomson - Wadsworth Hormonal Supplements • DHEA (dehydroepiandrosterone) and Androstenedione Hormones that are precursors to testosterone No evidence to support claims Short-term effects are identified • Human Growth Hormone (hGH) Used to build lean tissue and increase height if still growing Extremely high cost Many adverse side effects © 2008 Thomson - Wadsworth