Presentation on theme: "Lecture Outline Chapter 11"— Presentation transcript:
1 Lecture Outline Chapter 11 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
2 Nutrition for Physically- Active Lifestyles Chapter 11 Insert chapter opener photo
3 Chapter Learning Outcomes List five health benefits of a physically-active lifestyle.Differentiate between anaerobic and aerobic use of energy, and identify advantages and disadvantages of each.Plan nutritionally adequate, high-carbohydrate menus.Estimate an athlete’s energy and protein needs.List at least five ergogenic aids that athletes often use, and describe their effects on health and physical performance.Design a personal fitness regimen that suits your interests and lifestyle.
4 Quiz Yourself True or False Quiz Yourself True or FalsePeople who exercise regularly can reduce their risk of type 2 diabetes. T FSports drinks are not useful for fluid replacement. T FProtein is the body’s preferred fuel for muscular activity. T FHeatstroke is a serious illness that requires immediate professional medical treatment. T FWhile at rest, skeletal muscles metabolize more glucose than fat for energy. T F
5 Quiz Yourself True or False Quiz Yourself True or FalseTrue Engaging in exercise regularly can reduce the risk of type 2 diabetes.False Sports drinks can be useful for fluid replacement.False Protein is not the body’s preferred fuel for muscular activity.True Heatstroke is a serious illness that requires immediate professional medical treatment.False While at rest, skeletal muscles metabolize more fat for energy.
6 Key Terms Physical Activity Movement resulting from skeletal muscle contractionExercisePhysical activities that are usually planned and structured for a purposePhysical FitnessAbility to perform moderate- to vigorous-intensity activities without becoming excessively fatigued
8 Determining the Intensity of Physical Activity Insert figure 11.1
9 Determining the Intensity of Physical Activity Level of exertion used to perform an activityFactors that influence intensity:DurationType of activityBody weightMethods of determining intensity:Assess breathing rateAssess heart rate
10 Calculating Age-Related Maximum Heart Rate To calculate your age-related maximum heart rate, subtract your age from 220Target heart rate zone: range of heart rate that reflects the intensity of exertion during physical activityModerate intensity — target zone is 50 to 70% of age-related maximumVigorous intensity — target zone is 70 to 85% of age-related maximum
12 Aerobic and Resistance Exercises Aerobic exerciseSustained, rhythmic contractions of large muscle groupsRaises heart rate giving the heart an effective workoutResistance exerciseActivities that increase muscle mass and strengthResistance exercises also increase bone mass.
13 Energy for Muscular Work Cells obtain energy through a series of chemical reactionsCatabolism of glucose, fatty acids, amino acids, or alcoholEnergy stored in carbon-hydrogen bonds is captured in the high energy compound ATPATP forms when an inorganic phosphate group (Pi ) bonds with ADP.
15 Energy from GlucoseGlucose can be catabolizd anaerobically or aerobicallyCatabolism involves oxidation, removal of electrons from one compound to create another.The first stage of glucose oxidation is glycolysis — splitting of a glucose molecule to form two pyruvate molecules.Occurs under anaerobic conditionsA small amount of ATP is formed by glycolysis.
17 Further Oxidation of Glucose If oxygen is available, pyruvate can enter aerobic respiration pathways.Pyruvate moves from cytoplasm into mitochondria — “powerhouses” of cells.In mitochondria, pyruvate is completely oxidized, forming ATP, CO2, and H2O.
21 Energy Systems for Exercising Muscles Why is glucose best biological fuel for intense, brief exercise?Fatty acids have fewer oxygen atoms in relation to carbons.Thus, cells require more oxygen to metabolize fat.During brief bouts of intense exercise, lungs and heart cannot deliver enough oxygen to muscles for fatty acid oxidation.
22 Three Major Energy Systems Phosphocreatine (PCr)anaerobicLactic acidOxygenaerobicInsert photo of man from bottom of page 379
23 PCr-ATP Energy System Insert figure 11.8 Muscles contain enough ATP to last about 1 second.PCr provides the energy by providing Pi to ADPforming ATP .PCr supplies muscles with ~ 6 seconds of energy.
24 Lactic Acid Energy System In anaerobic conditions, glucose is converted to pyruvate and then lactic acid.Enough ATP is formed to last 30 to 40 sec.Lactic acid releases hydrogen ions, and becomes lactate.Certain muscles can use some lactate for energy.Most lactate enters the bloodstream.Liver removes lactate and converts it to glucose.
26 Oxygen Energy SystemDuring low- to moderate-intensity exercise (aerobic conditions), muscle cells can completely metabolize glucose.Produces ~18 times more ATP than during anaerobic conditionsInsert photo of runner from page 383
27 Fat or Carbohydrate for Fueling Exercise? Intensity of activity influences type of fuel useFat predominates when at rest and during low- to moderate-intensity activitiesCarbohydrate is main fuel for high-intensity activitiesProtein contributes a small amount of energy, with slightly more during endurance exercise
28 General Dietary Advice for Athletes Factors that influence athletic performance:Genetic endowmentPhysical trainingDietMany athletes and coaches believe sports nutrition misinformation often in advertisements, magazines articles, and the Internet.Sports nutrition: applying nutrition principles and research findings to improving athletic performance
29 Energy for Athletic Performance Most athletes need at least 3000 kcal/day.Males generally need 50 kcal/kg/day.Females generally need kcal/kg/day.Methods to determine adequate caloric intake:Keep a food logMonitor body weightFat should supply 20 to 35% of energy.
30 Focusing on Carbohydrate Intake Athletes should consume >60% of kcal from carbohydrates.Do the math to determine % kcal from carbohydrates:A person consumes 3000 kcal/day:Step 1 Determine 60% of 3000 kcal:60% = 0.600.60 x 3000 = 1800 kcalStep 2 Determine grams of carbohydrate in 1800 kcal by dividing kcal by 4. (Note: 1 g of “carbs” supplies 4 kcal)1800 kcal 4 kcal/g = 450 g
31 Carbohydrate IntakeTo maintain adequate glycogen stores, athletes need 6 to 10 g of carbohdrate/kg body weightTo determine carbohydrate intake range:Example: A person weighs 145 lbs.Step 1. Convert lbs to kg by dividing weight by 2.2145 2.2 = 66 kgStep 2. To determine the range of carbohydrate intake, multiply body wt in kg by 6 and then by 10For 6 g/kg 6 g x 66 kg = 396 g of “carbs”For 10 g/kg 10g x 66 kg = 660 g of “carbs”
32 Pre-Event Meal Recommendations: Insert Table 11.3 About 2 to 4 hrs before event, eat a low-fat meal.Provides ~ 100 g of carbohydrateTotal meal should supply ~ 500 to 600 kcalInsert Table 11.3
33 Energy and Macronutrient Content of Selected Foods Insert Table 11.4
34 What Is Carbohydrate Loading? CHO loading: manipulating physical activity and dietary patterns, a few days before an eventGoal is to increase muscle glycogen storesTypical technique: 7 days before eventDay 1 - Train intenselyDays 2 to 4 - Gradually taper off training with moderate carbohydrate (~ 300 g) intakeDays 5 to 7 - Exercise lightly and rest on the last day with high carbohydrate (400 to 700 g) intakeThe diet and training manipulation greatly increase glycogen stores.
35 Consuming Carbohydrate During and After Events Vigorous exercise >60 minutes depletes glycogen stores:Athletes “hit the wall”Recommendation: Consume 30 to 60 g carbohydrates/hr.Food sources: Sports drinks, sports gels, or other sources of carbohydrateAfterTrained athletes can replenish most of their glycogen stores in a few days.Recommendation: 8 to 10 g carbohydrate/kg body wt/dayTo replenish glycogen quickly after intense exercise: sports drinks, sugar-sweetened soft drinks, fruit, or fruit juices
36 Raising the Bar? What about energy bars, gels and drinks? Energy bars are made from soy or milk proteins fortified with vitamins, minerals, and fiber.No scientific evidence for benefits to performanceRegular granola bars are cheaper source of nutrients and fiber.Energy drinks typically contain sugars and caffeine.Some contain ginsengmay enhance effects of caffeine
37 What About Proteins?For many athletes, protein intakes are higher than recommendations.Protein recommendations for athletes:Endurance: 1.2 to 1.4 g/kg of body weight/dayResistance: 1.6 to 1.7 g/kg of body weight/day
39 Focusing on Fluids Insert photo of man drinking water from page 390 Adequate Intake for Total Water:11 cups for young women15.5 cups for young menWater needs vary, depending on:SportFitness levelEnvironmental conditions
41 Replenishing Fluids To reduce risk of heat-related illness: Avoid exercising in extremely hot, humid weather and replace lost fluids.To estimate fluid needs, weigh yourself prior to exercising and again after.If difference is >2%, fluid replacement is needed.General recommendation: Drink 20 to 24 oz of fluids for each 1 pound of body weight lost during exercise.
42 Do I Need a Sports Drink?Sports drinks provide benefits over plain waterCarbohydrateSports drinks provide desirable carbohydrate content (6%)Soft drinks and juices provide >10% carbohydrateSodium and electrolytesEnhance water and carbohydrate absorption and stimulate thirstSports drinks generally recommended when event lasts longer than 30 minutes
43 Antioxidant VitaminsFree radical formation increases during aerobic exercise.Oxidative stress may contribute to muscle fatigue and damage.Intense exercise may stimulate the body’s natural antioxidant defense system .Taking antioxidant supplements may block this process.Therefore, taking antioxidant supplements is not recommended.
44 IronIron is needed to produce red blood cells, transport oxygen, and obtain energy.Athletes at risk for iron deficiency include:FemalesDistance runnersVegetarians (especially vegans)Sports anemia — temporary condition resulting from an increase in plasma (liquid portion of blood)May be difficult to distinguish between sports anemia and true anemia
45 CalciumVegans and people who restrict intake of milk and milk products are at risk for calcium deficiency.Weak bones or osteoporosis may result.Female athletes who have irregular or no menstrual cycles may be deficient in estrogen.Weight bearing exercise increases bone density, but estrogen is needed to maintain healthy bones.
46 Ergogenic Aids What are ergogenic aids? Foods, devices, dietary supplements, or drugs used to improve physical performanceAre they effective?Little reliable scientific evidence supports effectiveness of most dietary supplements.Sufficient water and electrolytes, carbohydrates, and a balanced and varied diet are the most important ergogenic aids.
47 Evaluation of Some Ergogenic Aids Insert table 11.7
48 Caffeine Caffeine -- most widely used ergogenic aid How caffeine affects athletic performance:BenefitsRaises blood fatty acid levelsEnhances contraction of skeletal and heart musclesIncreases mental alertnessAdverse effectsShakinessRapid heart beatSleep disturbancesDiarrhea and frequent urination
49 Caffeine Content of Selected Beverages Insert Table 11.8
50 Chapter 11 Highlight: Developing a Personal Physical Fitness Plan Most healthy people can gradually increase physical activity levels.Older adults or those with any chronic health condition should consult a physician before starting a physical fitness program.
51 Stages of Fitness Plan Initiation—first 3to 6 weeks Incorporate short periods of activity to total 30 minutes on most days. (For example, gardening or taking the stairs instead of elevators)Improvement—the next 5 to 6 monthsIncrease intensity and duration of exercises.Exercise near the lower end of target heart rate zone.Maintenance—at 5 to 6 monthsFitness goals are reachedContinue present program
52 Components of a Workout Regimen Warm-upAerobic workoutTypeDurationFrequencyIntensityProgressionCool down
53 Types of Training What about strength (resistance) training? Include strength training 2 to 3 days per weekMay use weight, machines or elastic exercise cordsMixing it upInclude several types of physical activity each week.Having an exercise partner provides motivation and encouragement.Include variety, balance, and moderation in the exercise routine.