Debate in Protein Needs for Athletes

1. Ex Nutr c8-protein Debate in Protein Needs for Athletes • Ancient Greece Olympic Game • Consumed meat…. • What is the truth? • Scientificevidence

2. Ex Nutr c8-protein 非常非常非常不容易 ?

3. Ex Nutr c8-protein Amino Acids • Amino acids transporters • According to AA shapes and chemical properties (neutral, basic, anionic) • ConcentrationGradient • Sodium dependent, sodium independent • Amino acid metabolism • 120 g free amino acid in muscle

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9. Ex Nutr c8-protein Incorporation of Amino acid into other compounds • Nurotransmitters- glutamate, tyrosine, tryptophan • Tyrosine – precursor of catecholamies • Tryptophan- precursor of serotonin

10. Ex Nutr c8-protein Techniques to Study Protein and Amino Acid Metabolism • Urea in urine and sweat • 3-methylhistidine in urine • Myofibrillar protein breakdown • Nitrogen balance • N intake – (N excretion in sweat, feces, and urine) for days • Arteriovenous differences • Tracer methods – Isotopes • Tracer incorporation into specific protein • Fractional synthetic rate • Fractional breakdown rate • Usually use leucine, essential AA, cannot be synthesized within the body • phenylalanine

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12. Ex Nutr c8-protein Models and measurement of protein turnover • AA in plasma • Appear: Intake (I), protein breakdown (B), de novo synthesis (NEAA) • Remove: protein synthesis (S), oxidation (O), incorporation after transamination/deamination • For Essential AA (e.g. leucine) • Only source to enter body: I or B • Leucine completely oxidized in human to CO2  O, used as marker for overall AA oxidation • Flux (Q) of leucine = intake + breakdown • Q = I + B = S + O • AA tracer (isotope) to measure Q and O • If intake =0, then Q=B; S= Q – O • Simplified model • Lack of reliable marker for muscle protein breakdown • Urinary excretion of 3-methylhistidine (in actin, myosin) • Sample collection issues, other assumption

13. Ex Nutr c8-protein Models and measurement of protein turnover • Fractional synthetic rate (FSR) • Infusion of isotope • Measure incremental increase in isotopic enrichment within tissue or specific protein over time • Combine with muscle biopsy • Measure collagen synthesis in muscle and tendon • Muscle protein synthesis account ~25% whole-body synthesis • May be negated by reciprocal change in other proteins • Nitrogen balance • Nitrogen intake – nitrogen output (urine, feces, sweat…) • Arteriovenous balance

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15. Ex Nutr c8-protein Protein Requirements for Exercise • Endurance exercise • ↑Leucine oxidation • ↑ muscle uptake of glutamate, BCAA from blood • ↑ Release of Ala, Glutamine from muscle • No change in [AA] in muscle <70% VO2max • Sharp↓ in [AA] in muscle >70% VO2max • Resistance exercise • ↑ turnover,↑ Degradation < ↑ synthesis • FBR and FSR ↑after resistance exercise, FSR > FBR, more positive balance • FBR return to baseline before FSR • Still present 3-24 hr after exercise • Protein as energy source • 5-15% to energy expenditure at rest • ↓during exercise (in percentage) • ~10% in prolonged exercise, especially CHO limited

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19. Ex Nutr c8-protein Protein Requirements for Endurance Athletes • The better trained, the lower protein breakdown • Using nitrogen balance method on elite athletes • Male endurance athletes 1.6 g/kg/d • Simulated Tour de France cycling: 1.5-1.8 g/kg/d • Well-trained runners: 1.49 g/kg/d • Recommendation – 1.2-1.8 g/kg bw • No problem meeting the requirement • protein supplement unnecessary • Tour de France cyclists: 12 en% from protein (total 6500 kcal), ~2.5 g/kg/d • 3000 kcal, 15 en% from protein, 450 kcal = 112.5 g protein • Chronic endurance training spare AA oxidation • Higher BCOAD kinase, inactivate BCOAD • CHO spare AA during endurance ex • CHO loading/intake ↓leucine oxidation, ↓plasma/sweat urea excretion, during endurance ex

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22. Ex Nutr c8-protein Protein Requirements for Strength Athletes • Resistance exercise NOT increase leucine oxidation • Different from endurance exercise • ↑protein requirement due to ↑muscle hypertrophy • Initiation of resistance program • Requirement may be highest, calculated 1.65 g/kg/d • At 2.8 g/kg/d, leucine oxidation ↑~2X, protein above requirement oxidized for energy • Protein intake above requirement (2.8 vs 1.8 g/kg/d) ↑AA oxidation, no effect on protein synthesis • 2.6 g/kg/d with resistance ex no addition effect vs 1.35 g/kg/d • Excess protein above requirement oxidized as energy, no anabolic effect • Recommendation – 1.6-1.7 (2.0) g/kg bw • Negative N balance disappear after ~12 days of training • Protein requirement may ↑again after ↑training load

23. Ex Nutr c8-protein Resistance exercise

24. Ex Nutr c8-protein Protein Requirements for Strength Athletes • No problem meeting the requirement • protein supplement unnecessary, although commonly used • Need more protein during energy restriction • Prevent muscle breakdown • Resistance exercise in fasted state • Negative protein balance before ex • Less negative protein balance after ex • Post-exercise period important for nutrients (AA) delivery, in order to ↑protein synthesis

25. Ex Nutr c8-protein Protein intake by athletes and athlete at risk • Most elite athletes consume 1.0~3.0 g/kg/d • Protein and energy deficiency • Result in muscle atrophy • Amenorrheic female runners, male wrestlers, male/female gymnasts, female dancers • Vegetarian • Plant food usually contain lower-quality proteins • Careful selection of foods can still provide sufficient protein amount and quality • Body adapt to training by becoming more efficient with protein • ↓protein turnover, ↓net protein degradation

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28. Ex Nutr c8-protein Prealbumin: marker for short-term protein status Loucks AB, JSS, 2004

29. Ex Nutr c8-protein Loucks AB, JSS, 2004

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32. Ex Nutr c8-protein Effect of Protein intake on Protein synthesis • Hours after exercise, protein synthesis may > protein degradation • ONLY after feeding, provide substrate and insulin stimulation • Amino acids (EAA)+ CHO or protein + CHO • Feeding delayed 24-48 hr – no hypertrophy • If sufficient protein consumed during the day, post-exercise window may not necessary

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37. Ex Nutr c8-protein 6 g EAA + 35 g sucrose

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40. Ex Nutr c8-protein 重量訓練後補充蛋白質時機與效果 Kerksick, 2012

41. Ex Nutr c8-protein 各種蛋白質來源對肌肉合成的效果結合長期重量訓練 Kerksick, 2012

42. Ex Nutr c8-protein 常見食物胺基酸成分比較 □：支鏈胺基酸 ■：必需胺基酸 Hulmi et al, 2010

43. Ex Nutr c8-protein mTOR (mammalian target of rapamycin) 訊息傳遞路徑：上游 Laplante & Sabatini, 2012

44. Ex Nutr c8-protein mTOR 訊息傳遞路徑：下游 Laplante & Sabatini, 2012

45. Ex Nutr c8-protein 白胺酸活化 mTOR 路徑C2C12肌肉細胞 Atherton et al, 2010

46. Ex Nutr c8-protein Amino Acids as Ergogenic Aids • Arginine • Stimulate growth hormone and insulin after infusion 30 g in 30 min • Also Lysine and ornithine • Oral dose may be too low • Gut discomfort for high dose • ↑ GH can be achieve by exercise • Provide nitric oxide (NO) • Synthesized by nitric oxide synthase (NOS) • Vasodilator, other various health benefits • ↑exercise performance in cardiovascular patients • Effect on athletes?

47. Ex Nutr c8-protein Amino Acids as Ergogenic Aids • Aspartate • Improve aerobic performance? • A TCA cycle precursor • Reduce ammonia accumulation? • No effect • Maughan and Sadler 1983, 6g/24hr-75%-80%VO2max….

48. Ex Nutr c8-protein Amino Acids as Ergogenic Aids • BCAA, branched-chain amino acids • Provide extra fuel (may not important) • During exercise: BCAA oxidation ↑2-3X, CHO/fat oxidation ↑10-20X • CHO ingestion during exercise ↓BCAA oxidation • No effect on protein balance in muscle • Depends on protein intake, energy intake • ↓ fatigue – Central fatigue • Central fatigue hypothesis • Tryptophan  Serotonin in brain  perception of pain, Fatigue • fTrp:BCAA in blood stream • Mostly no effect in humans • ↑NH3? • May effective in hot environment

49. Ex Nutr c8-protein Central fatigue theory

50. Ex Nutr c8-protein Central fatigue – supplementation of CHO and BCAA