Chapter 10 Lecture

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  • 1. Chapter 10 Lecture Outline Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display
  • 2. Physical Fitness
    • “ The ability to perform moderate to vigorous activity without undue fatigue”
    • Fat usage by the body
      • Increased physical fitness means improved usage of fat for energy
  • 3. Benefits of Physical Activity
  • 4. Nutrition and Physical Activity
    • Only 15% of adults are regularly physically active
    NUTRITION (intake) Physical Performance Nutrient Use
  • 5. Healthy People 2010
    • Decrease inactivity in adults by 50%
    • Increase the number of people who exercise regularly
    • Increase the development of vigorous physical activity
    • Increase adults who perform muscular strength and endurance activities
  • 6. Beginning an Exercise Program
    • Start out slowly
    • Vary your workout — Make it fun
    • Include others — Keep accountable
    • Set attainable goals
    • Set aside specific time
    • Reward yourself
    • Focus on long-term and not on occasional setbacks
  • 7. 2005 Dietary Guidelines for Americans
    • 30 minutes/day physical activity
      • Reduce risk of chronic disease
    • 60 minutes/day physical activity
      • Manage body weight and prevent weight gain
    • 90 minutes/day physical activity
      • Sustain weight loss
  • 8. Fuel for Muscle Work
    • ATP
    • Chemical energy
      • Used by cells for muscle contractions
    • Only small amount is stored in resting cells
      • 2-4 seconds worth of work
    • Other sources of energy are needed
  • 9. Phosphocreatine (PCr)
    • High-energy compound
      • Formed and stored in muscle cells
      • PCr + ADP Cr + ATP
    • Activated instantly
      • Replenishes ATP
    • Sustains ATP (work) for a few minutes
  • 10. Anaerobic Glycolysis
    • Limited oxygen — Intense physical activity (sprinting)
    • Pyruvate is converted to lactate
    • Produces 2 ATP per glucose
      • ~5% of energy potential
    • Replenishes ATP quickly
    • Cannot sustain ATP production
      • 30 seconds to 2 minutes of work
    • Lactate build-up
      • Changes acidity that inhibits glycolysis enzymes
  • 11. Aerobic Glycolysis
    • Plenty of oxygen available
    • Low to moderate intensity (jogging)
    • Produces 36-38 ATP per glucose
      • 95% of energy potential
    • ATP replenished slowly
    • Sustained ATP production
      • 2 minutes to 3 hours of work
  • 12. Glucose Utilization
  • 13. Glycogen
    • Temporary storage of glucose in liver and muscle
    • Muscle glycogen
      • Used only by that muscle
    • Liver glycogen released into bloodstream
    • During low to moderate intensity
      • Can sustain work for up to 2 hours
    • “Bonking”
      • Depleted glycogen
      • Work at ~50% of maximal capacity
  • 14. ATP Formation
  • 15. Maintaining Normal Blood Glucose Level
    • Important
      • For activity lasting longer than 20-30 minutes
    • Intake of 30-60 gm carbohydrates per hour
      • During strenuous endurance activity
      • Delays fatigue by 30-60 minutes
  • 16. Fat Fuel (Fatty Acid)
    • Majority of stored energy in the body
    • Fatty acids
      • Converted to ATP by muscle cells
    • 12 ATP produced
      • Per each turn of the Citric Acid Cycle
      • 108 ATP for each 16 C fatty acid chain
    • Trained muscles
      • Have more mitochondria
      • Have greater ability to use fat as fuel
  • 17. Fat Fuel
    • Rate of fat use
      • Dependent on concentration of fatty acids in the bloodstream
    • Prolonged exercise
      • Fat becomes main fuel source
    • Intense activity
      • Fat is not a major source of fuel
      • Requires more oxygen for aerobic breakdown (than glucose)
  • 18. Protein — Minor Source of Fuel
    • During rest and low/moderate exercise
      • Provides 2%-5% of energy needs
    • During endurance exercise
      • Provides 10%-15% of energy needs
    • Branched-chain amino acids provide most of the energy
    • Resistance exercise uses protein less
    • Average diet
      • Provides ample amount of these amino acids
      • Supplements not needed
  • 19. Fuel Use During Physical Activity
  • 20. Calorie Needs
    • Individual needs vary
    • Monitoring weight and body fat
      • If weight falls, increase intake
      • If body fat increases, cut back in fat (& kcal) and maintain activity
    • Desirable body fat for male athletes: 5%-18%
    • Desirable body fat for female athletes: 17%-28%
  • 21. Carbohydrate Needs
    • Main fuel for many types of activity
    • Consume ~60% of total kcal from carbohydrate
    • Adhere to the Food Guide Pyramid
    • > 5 gm of carbohydrate/kg body weight
    • Aerobic and endurance athletes
      • 7-10 gm carbohydrates/kg body weight
      • ~ 500-600 gm of carbohydrates/day
  • 22. Carbohydrate Loading
    • Events lasting longer than 60-90 minutes
    • Maximize glycogen stores
    • Tapering of exercise while increasing carbohydrate intake
    • Additional water weight
  • 23. Carbohydrate (CHO) Loading 600 600 600 450 450 450 CHO (grams) rest 20 20 40 40 60 Exercise Time 1 2 3 4 5 6 Days Before Com- petition
  • 24. Fat Needs
    • ~35% of total kcal
    • Rich in monounsaturated fats
    • Limit saturated fats
    • Limit trans fat
  • 25. Protein Needs
    • Recommend 1.0 - 1.6 gm protein/kg body weight
    • Up to 1.7 gm/km body weight for athletes beginning strength training
    • Needs are easily met by a normal diet
      • Protein supplements are not necessary
      • Excessive protein has not been shown to be beneficial
  • 26. Current Protein Recommendations
  • 27. Vitamins and Minerals
    • Vitamin E and C
      • Slightly higher needs
      • Antioxidant properties
    • Thiamin, riboflavin, vitamin B-6, potassium, magnesium, iron, zinc, copper, and chromium needs
      • May also be higher (role in metabolism or sweat)
    • Increase intake of fruits and vegetables
  • 28. Iron Needs
    • Iron deficiency affects performance
    • Sports anemia
      • Increase in plasma volume but not RBCs
    • Women at risk because of menstruation
    • Focus on iron-rich foods
    • Use of iron supplement may cause toxic effects
  • 29. Calcium Needs
    • Restriction of dairy products by women
    • Irregular menstruation/Amenorrhea
      • Severe bone loss and osteoporosis
      • Extra calcium does not compensate for effects of menstrual irregularities
      • Compromises bone health
    • Calcium deficiency increases risk of stress fractures
  • 30. Fluid Needs
    • Needs of average adults
      • 9 cups per day for women
      • 13 cups per day for men
    • Athletes need more
    • Maintenance of body’s cooling system
      • Water helps dissipate heat from working muscles
    • Avoid losing more than 2% of body weight during exercise
    • For every 1lb. lost replace 2.5-3 cups of fluid
  • 31. Hydration
    • Thirst: Not reliable indicator of fluid needs
    • General guidelines:
      • Drink 3 C of fluids per each pound of weight loss during activity
      • Check urine color
      • Drink fluid freely 24 hours before event
      • Drink 1 ½ -2 ½ C 2-3 hours before event
      • Consume ½ - 1 ½ C every 15 minutes for events lasting longer than 30 min.
      • Lose no more than 2% of body weight
  • 32. Heat Exhaustion
    • Heat stress causes depletion of blood volume due to fluid loss
    • Body heat is dissipated through evaporation of sweat (fluid)
    • Fluid loss (sweat): ~3-8 C per hour
    • Humidity interferes with sweat production
    • Dehydration decreases endurance, strength, performance
    • Signs: Profuse sweating, headache, dizziness, nausea, weakness, visual disturbances
  • 33. Heat Cramps
    • Frequent complication of heat exhaustion
      • Exercising in heat
      • Significant sweating
      • Consuming water without sodium
    • Painful muscle contractions
      • 1-3 minutes at a time
    • Ensure adequate salt and fluid intake
    • Exercise moderately at first in the heat
  • 34. Heat Stroke
    • High blood flow to working muscles
      • Overloads body’s cooling system
      • Sweating ceases
      • Internal body temperature reaches 104 ° F
      • Fatality rate high
    • Symptoms:
      • Nausea, confusion, irritability, poor coordination, seizures, coma
    • Replace fluids
    • Monitor weight change (fluid loss)
    • Avoid exercising in hot humid conditions
  • 35. Sports Drinks For Endurance Exercise
    • Recommended for activity > 60 minutes
      • Help maintain blood glucose level and blood volume
      • Delay “bonking”
    • Supply electrolytes
    • <60 minutes
      • Nutrients are easily replaced by diet
  • 36.  
  • 37. Gels and Bars
    • Provide additional fuel
    • Should be taken with fluids
    • Expensive source of nutrients
    • Ideal bars for endurance athletes
      • Contain 40 gm carbohydrate, 10 gm of protein, 4 gram fat, 5 gm of fiber
      • Fortified with vitamins and minerals
      • Toxicities possible with overuse
  • 38. Content of Energy Bars and Gels
  • 39. Hyperhydration
    • Excessive intake of water
    • Intake without sodium and chloride
    • During prolonged low-intensity activities
    • Results in low blood sodium and low blood chloride
  • 40. Pre-Endurance Event Meal
    • Light meal 2-4 hours prior to event
    • Consisting primarily of carbohydrate (top off glycogen stores)
    • Low fat (<25% of energy intake)
    • Little fiber (prevent bloating, gas)
    • Moderate protein
    • Avoid fatty, fried foods
    • Blended or liquid meal recommended for meals eaten 1-2 hours prior
  • 41. Recovery Meal
    • Carbohydrate-rich meal within 2 hours after endurance event
      • Glycogen synthesis is the greatest
      • 1-2 gm CHO/kg body weight
    • Repeat meal over the next 2 hours
    • Choose high glycemic index foods
    • Aim for 3:1 carbohydrate-to-protein
    • Fluid and electrolyte replacement
  • 42. Replenishing Muscle Glycogen
    • Availability of adequate carbohydrate
    • Ingestion of carbohydrate soon after exercise
    • Selection of high-glycemic-load carbohydrate
    • Combination of carbohydrate and protein foods
  • 43. Ergogenic Aids
  • 44.