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Fitness: Physical Activity, Nutrients, and Body Adaptations

Fitness: Physical Activity, Nutrients, and Body Adaptations. Chapter 14. Fitness . Depends on physical activity and exercise Regular physical activity Promotes health Reduces risk of developing many diseases Heart disease Cancer Stroke Diabetes Hypertension . Benefits of Fitness.

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Fitness: Physical Activity, Nutrients, and Body Adaptations

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  1. Fitness: Physical Activity, Nutrients, and Body Adaptations Chapter 14

  2. Fitness • Depends on physical activity and exercise • Regular physical activity • Promotes health • Reduces risk of developing many diseases • Heart disease • Cancer • Stroke • Diabetes • Hypertension

  3. Benefits of Fitness • Restful sleep • Nutritional health • Optimal body composition • Optimal bone density • Resistance to infectious diseases • Low incidence of anxiety & depression • Low risk for some types of cancer • Strong circulation & lung function • Low risk of cardio-vascular disease • Low risk of type 2 diabetes • Strong self image

  4. Benefits of Fitness • Physical Activity Guidelines for Americans • Minimum amount of aerobic physical activity http://www.health.gov/paguidelines/ fact sheetprof.aspx • Intensity of activity • Extensive health benefits • Develop and maintain fitness • Cardiorespiratory endurance • Body composition • Strength & flexibility

  5. Fitness and Mortality

  6. Physical Activity Pyramid

  7. Guidelines for Physical Fitness from American College of Sports Medicine

  8. Developing Fitness • Goals • Meet everyday demands of life • Reasonable body weight & body composition • Components • Flexibility- freely moving joints, less risk of injury • Muscle strength and endurance- longer, harder without fatigue • Cardiorespiratory endurance

  9. Developing Fitness • Principles of conditioning (physical effect of training) • Progressive overload principle • Frequency – more often • More intensity • Longer duration • Body’s adaptation to physical activity • Hypertrophy vs. atrophy • Work different muscle groups from day to day • Make sure it is safe to start a program • Progress slowly • Alternate muscle groups from day to day

  10. Build Fitness Minimize Injuries • Be active all week • Use proper equipment and attire • Use proper form (body mechanics) • Include warm-up and cool-down activities • Challenge your strength and endurance a few times a week • Pay attention to body signals • Work out wisely

  11. Cardiorespiratory Endurance • Length of time a person can remain active with an elevated heart rate • Enhances capacity of heart, lungs, and blood • Oxygen Delivery • Aerobic • VO2 max is maximal O2 uptake, THE measure of Cardiorespiratory fitness • Waste Removal • Brain and body benefit from more O2

  12. Target Heart Rate

  13. CardiorespiratoryEndurance / Conditioning • Aerobic workouts improve heart and lung activities • Cardiac output increases • Enhanced oxygen delivery • Increases blood volume per heartbeat (stroke volume) • Slower resting heart rate • Breathing is more efficient • Circulation improves • Blood pressure falls

  14. Cardiorespiratory Endurance and Conditioning • Cardiorespiratory conditioning • Activity must be sustained for 20 minutes or more • Must use most of large-muscle groups • Intensity must elevate heart rate • Perceived effort • Still able to talk comfortably

  15. Delivery of Oxygen by the Heart & Lungs to the Muscles

  16. Air (O2, CO2), other gases The respiratory system delivers oxygen to the blood. 1 O2 CO2 CO2 O2 The circulatory system carries oxygenated blood throughout the body. 2 O2 CO2 4 The blood carries the carbon dioxide back to the lungs. O2 CO2 The muscles and other tissues obtain oxygen from the blood and release carbon dioxide into it. 3

  17. Cardiorespiratory Endurance • Muscle conditioning • Fit muscles use oxygen efficiently • Reduces heart’s workload • Burns fat longer • Balanced fitness program • Level of intensity varies • Can exercise at up to 90% of max. heart rate • Activities you enjoy doing • Addresses all aspects of fitness

  18. Resistance Training • Purpose • Build muscle mass • Develop and maintain muscle strength, muscle power, and muscle endurance • Benefits for prevention of chronic diseases • Maximize and maintain bone mass • Improve posture & reduce risk of back injury • Strength vs. power vs. endurance

  19. Nutrition and Exercise • CHO and fat as fuel • Protein to maintain and build LBM • Vitamins & minerals to support energy metabolism and tissue building • Water to distribute the fuels and dissipate heat and wastes

  20. Energy Systems and Fuels to Support Activity • Adenosine triphosphate (ATP) • Small amounts in all body tissues all the time • Delivers energy instantly • Driving chemical force for muscle contraction • When ATP is split, energy is released as • Mechanical movement • Heat

  21. Energy Systems and Fuels to Support Activity • Creatine phosphate (CP) • Stored in the muscles • Employed before ATP pools dwindle • Split anaerobically to release phosphate to replenish ATP supplies • CP supplies last 10 sec. for fast energy (100-meter dash) • CP reformed from P in ATP post-exercise, during rest

  22. Energy Systems and Fuels to Support Activity • Energy-yielding nutrients • Prolonged demands of sustained activity require continual ATP • Breakdown of CHO, fat, protein produces ATP • Muscles use a mixture of these fuels • Factors influencing fuel use • Diet, intensity & duration of activity, training • Anaerobic activities – glucose • Endurance activities – fats

  23. Fuels Used for Activities of Different Intensities & Durations

  24. Split second energy surge to lift the barbells involves anaerobic work.

  25. Sustained muscular efforts involve aerobic work

  26. Moderate to high-intensity exercise uses some fat but more glucose for fuel.

  27. Low to moderate-intensity exercise that can be sustained for more than 20 min uses some glucose but more fat for fuel.

  28. Glucose Use During Physical Activity • Exertion • Liver breaks down glycogen • Releases glucose into bloodstream • Muscles use serum glucose and stored glycogen • Muscle fatigue when glycogen is depleted • Glycogen storage = 2000 kcal of energy • Intensity of activity impacts how long glycogen will last • Moderate exercise uses glycogen slowly and fatty acids / glucose as well

  29. The Effect of Diet on Physical Endurance Maximum endurance time: Fat and protein diet 57 min Normal mixed diet 114 min High-carbohydrate diet 167 min

  30. Glucose Use During Physical Activity • Lactate • Glycolysis rate exceeds capacity of mitochondria to accept H+ for ETC • Accumulating pyruvate is converted to lactate • Recent news: Lactate in muscles does not cause fatigue/soreness • Lactate leaves muscle and travels to liver • Liver enzymes convert lactate back into glucose to return to the muscles • Cori cycle

  31. Glucose Use During Physical Activity • Duration of activity affects glycogen use • First 20 minutes or so of moderate activity uses mostly glycogen • Then liver gives up its glycogen • After 20 minutes, fat starts to displace glycogen as fuel • Eventual glucose depletion • Nervous system function declines • Athlete “hits the wall”

  32. Guidelines to Maximize Glucose Supply • Eat high-carbohydrate diet (70%) all the time • Drink glucose or sugar-sweetened drinks during exercise • Eat carbohydrate-rich food, at least 60 g. CHO immediately after activity • Train the muscles to store as much glycogen as possible

  33. Glucose Use During Physical Activity • Glucose during activity • Foods and beverages to be consumed during activity • 30 to 60 grams of carbohydrate per hour during prolonged events (all-day hike) • Glucose after activity • Enlarges glycogen stores • Best within 2 hours of activity • High glycemic index better

  34. Glucose Use During Physical Activity • Training affects glycogen storage • Adaptation to continual hard work • Conditioned muscles • Rely less on glycogen • Rely more on fat for energy • Trained muscles use oxygen more efficiently • Have more mitochondria

  35. Fat Use During Physical Activity • High-fat, low-carbohydrate diets impair performance • Smaller glycogen stores • Some adaptation from more fat than CHO • May experience greater fatigue, higher perception of difficulty level • Sports nutrition experts recommend 20 to 35% of energy from fat • Body fat stores are another matter

  36. Stored Fat Use During Physical Activity • Fat is liberated from internal fat stores and fat under the skin • Areas with most to spare, donate the most • Fatty acids released into blood not muscles being used • Blood delivers amount of fat each muscle needs • One arm can be stronger but both arms store the same % fat • Body fat is essential (remember body composition ranges from Ch. 8)

  37. StoredFat Use During Physical Activity • Strength/resistance training tone muscles under the fat • Duration of activity • Epinephrine signals fat cells to break down their TG and release fatty acids into blood • Sustained, moderate activity raises serum TG and continues to use TG for fuel for hours later • Intensity of activity • As intensity increases, less and less fat used. Are you too out of breath? Less fat is being burned. • Training (repeated aerobic activity) • More use of fat for fuel instead of glucose • More and larger mitochondria, stronger heart/lungs

  38. Fat breakdown comes only from aerobic metabolism.

  39. Protein Use During Physical Activity – and Between Times • Protein not a major fuel for physical activity • Used to build muscle and other lean tissue between exercise times • To some extent to fuel activity • Protein is handled differently during activity and rest

  40. Protein Used in Muscle Building • Synthesis of body proteins suppressed during activity, accelerates during hours of recovery • Repeated activity with slight overload enhances muscle protein synthesis • High-quality protein consumption • Exercise signals DNA and RNA to synthesize protein • Weight training can add 1 oz muscle/day

  41. Protein Used as Fuel • Muscles speed up their use of amino acids as fuel during an activity • 10% of total fuel during activity and rest • Diet adequate in energy and rich in carbohydrate spare protein • Intensity and duration • Protein needs are higher for endurance and strength athletes • 1.2 - 1.7 g/kg/d protein for athletes

  42. Protein Use During Physical Activity – and Between Times • Training affects protein use • Higher degree of training, less protein used during activity • Protein recommendations • Needs are greater for athletes in training • Need adequate carbohydrate intake

  43. Recommended Protein Intakes for Athletes

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