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Lecture Outline Chapter 11

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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
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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 False People who exercise regularly can reduce their risk of type 2 diabetes. T F Sports drinks are not useful for fluid replacement. T F Protein is the body’s preferred fuel for muscular activity. T F Heatstroke is a serious illness that requires immediate professional medical treatment. T F While at rest, skeletal muscles metabolize more glucose than fat for energy. T F

5 Quiz Yourself True or False
Quiz Yourself True or False True 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 contraction Exercise Physical activities that are usually planned and structured for a purpose Physical Fitness Ability to perform moderate- to vigorous-intensity activities without becoming excessively fatigued

7 Benefits of Regular Exercise
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8 Determining the Intensity of Physical Activity
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9 Determining the Intensity of Physical Activity
Level of exertion used to perform an activity Factors that influence intensity: Duration Type of activity Body weight Methods of determining intensity: Assess breathing rate Assess heart rate

10 Calculating Age-Related Maximum Heart Rate
To calculate your age-related maximum heart rate, subtract your age from 220 Target heart rate zone: range of heart rate that reflects the intensity of exertion during physical activity Moderate intensity — target zone is 50 to 70% of age-related maximum Vigorous intensity — target zone is 70 to 85% of age-related maximum

11 Physical Activity Pyramid
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12 Aerobic and Resistance Exercises
Aerobic exercise Sustained, rhythmic contractions of large muscle groups Raises heart rate giving the heart an effective workout Resistance exercise Activities that increase muscle mass and strength Resistance exercises also increase bone mass.

13 Energy for Muscular Work
Cells obtain energy through a series of chemical reactions Catabolism of glucose, fatty acids, amino acids, or alcohol Energy stored in carbon-hydrogen bonds is captured in the high energy compound ATP ATP forms when an inorganic phosphate group (Pi ) bonds with ADP.

14 ATP Insert figure 11.4

15 Energy from Glucose Glucose can be catabolizd anaerobically or aerobically Catabolism 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 conditions A small amount of ATP is formed by glycolysis.

16 Glycolysis Insert Figure 11.5

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.

18 Aerobic Respiration Insert Figure 11.5

19 Summary of ATP Formation
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20 How Do Cells Use ATP? Insert figure 11.7

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) anaerobic Lactic acid Oxygen aerobic Insert 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 ADP forming 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.

25 Lactic Acid Insert figure 11.9

26 Oxygen Energy System During low- to moderate-intensity exercise (aerobic conditions), muscle cells can completely metabolize glucose. Produces ~18 times more ATP than during anaerobic conditions Insert photo of runner from page 383

27 Fat or Carbohydrate for Fueling Exercise?
Intensity of activity influences type of fuel use Fat predominates when at rest and during low- to moderate-intensity activities Carbohydrate is main fuel for high-intensity activities Protein contributes a small amount of energy, with slightly more during endurance exercise

28 General Dietary Advice for Athletes
Factors that influence athletic performance: Genetic endowment Physical training Diet Many 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 log Monitor body weight Fat 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% = 0.60 0.60 x 3000 = 1800 kcal Step 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 Intake To maintain adequate glycogen stores, athletes need 6 to 10 g of carbohdrate/kg body weight To determine carbohydrate intake range: Example: A person weighs 145 lbs. Step 1. Convert lbs to kg by dividing weight by 2.2 145  2.2 = 66 kg Step 2. To determine the range of carbohydrate intake, multiply body wt in kg by 6 and then by 10 For 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 carbohydrate Total meal should supply ~ 500 to 600 kcal Insert 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 event Goal is to increase muscle glycogen stores Typical technique: 7 days before event Day 1 - Train intensely Days 2 to 4 - Gradually taper off training with moderate carbohydrate (~ 300 g) intake Days 5 to 7 - Exercise lightly and rest on the last day with high carbohydrate (400 to 700 g) intake The 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 carbohydrate After Trained athletes can replenish most of their glycogen stores in a few days. Recommendation: 8 to 10 g carbohydrate/kg body wt/day To 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 performance Regular granola bars are cheaper source of nutrients and fiber. Energy drinks typically contain sugars and caffeine. Some contain ginseng may 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/day Resistance: 1.6 to 1.7 g/kg of body weight/day

38 Popular Energy Bars and Gels
Insert table 11.5

39 Focusing on Fluids Insert photo of man drinking water from page 390
Adequate Intake for Total Water: 11 cups for young women 15.5 cups for young men Water needs vary, depending on: Sport Fitness level Environmental conditions

40 Heat-Related Illnesses
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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 water Carbohydrate Sports drinks provide desirable carbohydrate content (6%) Soft drinks and juices provide >10% carbohydrate Sodium and electrolytes Enhance water and carbohydrate absorption and stimulate thirst Sports drinks generally recommended when event lasts longer than 30 minutes

43 Antioxidant Vitamins Free 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 Iron Iron is needed to produce red blood cells, transport oxygen, and obtain energy. Athletes at risk for iron deficiency include: Females Distance runners Vegetarians (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 Calcium Vegans 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 performance Are 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
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48 Caffeine Caffeine -- most widely used ergogenic aid
How caffeine affects athletic performance: Benefits Raises blood fatty acid levels Enhances contraction of skeletal and heart muscles Increases mental alertness Adverse effects Shakiness Rapid heart beat Sleep disturbances Diarrhea 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 months Increase intensity and duration of exercises. Exercise near the lower end of target heart rate zone. Maintenance—at 5 to 6 months Fitness goals are reached Continue present program

52 Components of a Workout Regimen
Warm-up Aerobic workout Type Duration Frequency Intensity Progression Cool down

53 Types of Training What about strength (resistance) training?
Include strength training 2 to 3 days per week May use weight, machines or elastic exercise cords Mixing it up Include several types of physical activity each week. Having an exercise partner provides motivation and encouragement. Include variety, balance, and moderation in the exercise routine.

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