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chapter 3

chapter 3. Fat as a Fuel for Exercise. chapter. 3. Fat as a Fuel for Exercise. Author name here for Edited books. Things to Know. Be able to identify sources of fat in the diet by type Be able to explain fat metabolism during exercise

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chapter 3

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  1. chapter3 Fat as a Fuel for Exercise chapter 3 Fat as a Fuel for Exercise Author name here for Edited books

  2. Things to Know • Be able to identify sources of fat in the diet by type • Be able to explain fat metabolism during exercise • Be able to understand changes in fat metabolism as a result of training • Be able to provide recommendations for fat intake for athletic individuals • Including those on weight restrictive programs

  3. Function • Primary source of energy at rest • Twice as energy dense as other macronutrients • Great storage (Why?) • Provides essential fatty acids • Omega 3 • α-linolenic acid (leafy greens, soy, seafood) • EPA (fish oils) • DHA (fish oils) • Omega 6 • Linoleic acid (sunflower, corn, soy, and peanut oil) • Growing evidence of cardioprotective ability • Fat soluble vitamins require fat • A, D, E, K

  4. Classification • Short (<6), medium (6-12), long (>12) • Absorbed and transported differently • Saturated (no double bonds) vs. unsaturated (one or more double bonds) • Animal fats 40-60% saturated and 30-50% monounsaturated • Plant fats 10-20% saturated rest are mono or polyunsaturated • Configuration • Trans vs. cis • Trans negatively affect blood lipids • Function differently and require different biochemical breakdown • Hydrogenation • Increases saturation

  5. Changes in Dietary Macronutrients in Diet (g)

  6. Changes in Dietary Macronutrients in Diet (%)

  7. Decreased Fat Intake During Weight Restriction

  8. Factors Determining the Use of Fat During Exercise • Training level • Type of exercise • Intensity and duration • Available fat reserves in muscle • Ability to mobilize and transport FA from adipose • Composition of prior meal • Availability of stored glycogen or amount of carbohydrate fed during exercise

  9. Adipose Tissue Lipolysis • ↑ SNA stimulates production of epinephrine • Epinephrine binds to adipose tissue ↑cAMP • ↑cAMP phosphorylates HSL • HSL breaks off two FA from stored TG • MGL breaks off the other • Glycerol transported across adipose into circulation for gluconeogenesis • FFA must cross adipose cell membrane • Passively • Or by, FABP or FAT/CD36 • Circulates in blood bound to albumin • Actively transported across muscle cell

  10. Lipolysis

  11. Ra Glycerol Expresses Lipolysis (40% VO2)

  12. Ra FFA During Exercise (40% VO2)

  13. Ra FFA During Exercise • Initially, Ra FFA may decrease • Due to increased uptake of FFA in muscle • As exercise progresses up to approximately 65% intensity, Ra FFA increases significantly • So much so, that after exercise ceases, the majority of FFA in blood are re-esterified

  14. Hormonal Influence on Lipolysis • Catecholamines are strongest stimulators • Insulin strongest inhibitor • Other hormones that play a role • GH, cortisol, TSH all stimulate lipolysis

  15. Increased Reliance on IMTG After Training?

  16. No Increase in IMTG Use After Training?

  17. Differences in IMTG Use • Differing methodologies • Endurance training vs. resistance training • IMTG is not equally dispersed throughout muscle • Regardless • Increased reliance on glycogen at same absolute intensity suggest • Increased reliance on fat for fuel either from • Adipose or IMTG

  18. As Intensity Increases Energy from Fat Reduced

  19. FFA Transport

  20. Training Increases Fat Utilization

  21. Training Increases Uptake of FFA

  22. Discussion Time • Can you alter substrate usage through diet manipulation? • What effect could this have on increasing or decreasing fat loss? • What recommendations would you say provide for someone wanting to target fat loss? • What does the shift in substrate utilization mean for endurance trained athletes? • What effect does this have on endurance trained athletes at the end of a race? • So based on this what do you think the effect of high fat diets and diet infusion would be?

  23. Fat Oxidation HighestTrained 59-65%Untrained 47-52%

  24. Long Term Fat Diets Does Not Improve Exercise Performance > High CHO Diet

  25. Medium Chain TG • Made available more easily than long chain TG • However, supplementation does not spare muscle glycogen even though contributes approximately 7-8% total energy • Cause GI distress • Expensive

  26. Caffeine Increases Exercise Performance

  27. Caffeine Effects • Caffeine appears to increase plasma catecholamines • While it does effect fat oxidation at rest, it does not impact fat oxidation during exercise • What does this mean? • More on caffeine to come

  28. Carnitine • Doesn’t work • Why?

  29. Fat Recommendations • 20-35% of energy intake • <10% saturated • Remaining coming from monounsaturated and polyunsaturated • Monounsaturated • Olive oil • Canola oil • Polyunsaturated • Soy • Fish • Corn oil • How do you do this since not recommended as g/kg as is the case with CHO and PRO as we will see

  30. Fat Intake and Health • Increasing evidence that athletes may have hyperlipidemic disorders (especially football linemen) • This involves and increased risk after collegiate or pro level play • Why?

  31. QUESTIONS?

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