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Sports Nutrition_Chapter 5_Protein
- 2. What are proteins? • Amino acids linked together • Composed of: – Carbon – Hydrogen – Oxygen – Nitrogen
- 3. Protein Structure • Peptide bonds
- 4. Amino Acids • 20 amino acids • 9 essential amino acids – Come from diet • 11 nonessential amino acids • Conditionally essential amino acids – Tyrosine – Cysteine
- 5. Protein Classification • Number of amino acids • Composition – Complete – Incomplete • Quality – High – Low
- 6. High-Quality Protein • A complete protein • Contains extra amino acids for protein synthesis • Good digestibility • Usually from animal- derived foods Photo © Mark Adams/Superstock
- 7. Low-Quality Protein • An incomplete protein • One or more limiting amino acids • Usually from plant- derived foods Photos courtesy of the USDA
- 8. Complementing Proteins • Complementing proteins are incomplete proteins that when eaten together provide a full complement of all essential amino acids. • It’s not necessary to eat complementing protein sources together at same meal but at least within same day. Photo © PhotoDisc
- 9. Complementary Protein Combinations Examples of complementary protein combinations: Rice and beans Peanut butter on whole wheat bread
- 10. Protein Functions • Tissue building: important for athletes trying to put on muscle mass. • Cell functioning – Enzymes • Body functioning – Hormones – Immune function – Fluid balance • Energy source: prefer not to use protein as energy source but if athlete isn’t taking in enough calories then protein will be diverted from other important functions to be used for energy.
- 11. What is nitrogen balance? Nitrogen balance is an indicator of nitrogen status and thus protein intake. Equals: (Nitrogen in) – (Nitrogen out)
- 12. How much protein is needed?
- 13. Factors Influencing Protein Requirements • Total energy intake • Desire to lose or gain weight • Carbohydrate availability • Exercise intensity and duration • Training status/fitness level • Dietary protein quality • Age
- 14. Protein Sources
- 15. Questions to Ask About Protein Supplements • What is the quantity of protein or amino acids in the product? • Is the supplement necessary? • What is the cost? • Will it enhance performance? • Does the supplement have any harmful effects?
- 16. What should an athlete eat in the hours leading up to competition or training? • 4 to 24 hours prior to exercise: – Balanced high- CHO meals/snacks – Familiar foods – CHOs, not proteins, should predominate Photo © Photodisc
- 17. How much protein should be consumed 4 to 24 hours before competition? • Depends on how much time before exercise is initiated • Lean protein sources – 3 to 6 oz turkey, fish, soy or – 8 to12 fl oz dairy or – Complementing low-fiber plant sources
- 18. How much protein should be consumed 1 to 4 hours before competition? • Focus should be on CHO • Small amounts of protein okay (i.e., 2–4 oz lean meat) • Lean protein sources preferable
- 19. What about protein consumption during competition? • Protein can serve as an energy source. • Consumption during exercise is questionable. • There is some research support for branched chain amino acids during competition.
- 20. What about protein consumption after competition? • 6 to 20 grams of high-quality protein – Casein – Whey – Soy • Essential amino acids are key. • Should be consumed within 3 hours after competition. • Hydrolyzed protein sources are absorbed more quickly.