the role of protein in promoting muscle growth · " resistance exercise & protein both...
TRANSCRIPT
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Department of Nutrition & Metabolism
The Role of Protein in Promoting Muscle Growth
Blake B. Rasmussen, PhD Professor & Chair
Department of Nutrition & Metabolism University of Texas Medical Branch
Department of Nutrition & Metabolism
Presentation Outline
• Building Muscle - Why is it Important? • Role of Protein Synthesis • Effect of Resistance Exercise on Protein Synthesis • Effect of Dietary Protein on Protein Synthesis • Protein Supplementation and Exercise Training • What Protein Source is Best? • Timing of Protein Supplementation? • How Much Protein Should Athletes Consume? • Summary & Recommendations
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Why Study Muscle Biology?
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Muscle Wasting Conditions " Injury
" Following Surgery
" Elderly (Sarcopenia)
" Forced Inactivity / Bed Rest
" Cancer, AIDS, Space Flight, Muscular Dystrophy
" Trauma, Burns, Type 1 Diabetes
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Sports Nutrition - Protein
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Building Muscle
Protein Degradation Protein Synthesis
Exercise Feeding
Unloading Starvation
Muscle Growth Muscle Atrophy
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The Muscle Biopsy Bergström, 1962
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Role of Protein Synthesis
Proteins Muscle Cell
Synthesis Breakdown
Blood
Net Protein Balance = Synthesis - Breakdown
TORC1 Signaling m
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Effect of Resistance Exercise on Muscle Protein Synthesis
Exercise
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Resistance Exercise Increases Muscle Protein Synthesis
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mTORC1 Activation
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Is mTORC1 Activation Required for Muscle Contraction to Increase
Muscle Protein Synthesis?
mTORC1 Rapamycin
Muscle Protein Synthesis
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Yes! - mTORC1 is Required to Increase Muscle Protein Synthesis
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Effect of Dietary Protein on Muscle Protein Synthesis
Leucine Essential Amino Acids
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Response to Essential Amino Acids
Control Nutrition
mTO
R (
Ser24
48)
(AU
)
Adapted from Fujita et al. J Physiol, 2007
mTOR Activation
Mus
cle
Prot
ein
Synt
hesi
s (%⋅hr
-1)
Control Nutrition
Muscle Protein Synthesis
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EAA is Responsible for the Stimulation of Muscle Protein
Synthesis
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Gln
Na+
PAT1 Rag
GTPases
Rheb
S6K1 4E-BP1
eIF4F
BCAA
rpS6
? ?
Translation Initiation
raptor
Gln
K+
hVps34
MAP4K3
mTORC1
raptor
?
?
Rab ?
?
Protein Synthesis
Akt
Insulin
mTORC1
Rapamycin
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Protein / Amino Acids Activate mTORC1 to Increase Muscle Protein Synthesis
Basal
Mus
cle
Prot
ein
Synt
hesi
s (%⋅hr
-1)
P<0.05 vs. Basal
# *
P<0.05 vs. Rapamycin # *
Post EAA
Dickinson et al, Journal of Nutrition, 2011!Dickinson et al, Metabolism, 2012!
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Stimulating Muscle Growth with Protein
Department of Nutrition & Metabolism
Exercise Enhances the Nutrition-Induced Increase in Protein Synthesis
Adapted from Fry et al., Skeletal Muscle, 2011; & Drummond et al. J Appl Physiol, 2008
Mus
cle
Prot
ein
Synt
hesi
s (%
•hr-1
)
Young Older
↑ ~50%
↑ ~100% ↑ ~100%
RE = Resistance Exercise
EAA = Essential Amino Acids
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Effect of Protein + Exercise
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Summary " Resistance Exercise & Protein both stimulate muscle
protein synthesis primarily through mTORC1 activation
" mTORC1 should be considered a target when designing nutritional supplements to enhance muscle growth
" Consuming Protein After Exercise Enhances Muscle Protein Synthesis
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Protein Supplementation During Exercise Training
Does it Enhance Muscle Growth?
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Protein Supplementation and Exercise Training
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Whey and Soy Protein Supplementation Improves
Muscle Mass
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Milk vs Soy Supplementation During Training
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What Protein Source is Best?
Must Consider Protein Quality
Which Means a Sufficient Amount of Essential Amino Acids
Especially Leucine
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Why is Whey Considered the Gold Standard?
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Whey vs Soy: Effects on Muscle Protein Synthesis
Fasting
N=6 per group
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Comparing Apples to Oranges?
20 grams = 1.9 g leucine
20 grams = 1.5 g leucine
27 grams = 1.9 g leucine
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Protein Blends
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The Theory
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Journal of Nutrition 143: 410-416, 2013
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Study Aim
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Subjects
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Methods
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Methods
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Results
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Leucine
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Area Under The Curve
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Mixed Muscle Protein Synthesis
Whey Blend
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mTORC1 Signaling
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Conclusions A soy-dairy protein blend ingested following exercise is capable of prolonging in human skeletal muscle:
• blood aminoacidemia • mTORC1 signaling • protein synthesis Protein blends are an effective postexercise nutritional supplement
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When Should an Athlete Supplement with Protein?
Is Timing Important?
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EAA Ingestion 1 or 3 hours After Exercise Produces the Same Response in Muscle
Protein Synthesis
Rasmussen et al, J Appl Physiol 88: 386-392, 2000
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Ingesting EAA Before Exercise Has No Additional Benefit on Muscle
Protein Synthesis
Fujita et al, J Appl Physiol 106: 1730-1739, 2009
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After Exercise is Best
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Muscle Remains “Sensitive” to Protein For At Least 24 Hours After Exercise
Burd et al, Journal of Nutrition 141: 568-573, 2011
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How Much Protein Does it Take to Maximize Muscle
Protein Synthesis?
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Dose-Response Study
10 grams of EAA or ~20-25 grams of Protein
Cuthbertson et al, FASEB J., 2005
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Department of Nutrition & Metabolism
30-30-30
Maximal
Protein
Synthesis
Breakfast
protein
Lunch
protein
Dinner
protein
Breakfast
~10 g
protein
Lunch
~20 g
protein
Dinner
~60 g
protein
Breakfast
~30 g
Lunch
~30 g
Dinner
~30 g
A. Adequate Protein Distribution B. Inadequate Protein Distribution
Paddon-Jones & Rasmussen, Current Opinion in Clinical Nutrition & Metabolic Care, 2009
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Concept of Protein Distribution
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24 Hour Protein Synthesis
Preliminary data from D. Paddon-Jones
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Bolus = 40 g x 2
Intermediate = 20 g x 4
Pulse = 10 g x 8
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Summary Exercise and Protein Both Increase Muscle Protein Synthesis by Activating the mTORC1 pathway Ingesting Protein After Exercise is Best for Enhancing Muscle Protein Synthesis Protein Supplementation During Exercise Training can Enhance Muscle Growth High Quality Protein Sources Produce Similar Increases in Muscle Protein Synthesis and Muscle Growth During Exercise Training
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Summary (cont.) Best to Eat Protein After Exercise but Muscle Remains Sensitive for at Least 24 hours post-ex Ingesting a Large Amount of Protein is not Necessary for Maximizing Muscle Protein Synthesis Distributing Protein Intake Evenly and Moderately Throughout the Day is Likely to Improve Muscle Growth During Training
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Recommendations Use a High Quality Protein Source to Supplement within the First Hour Post-Exercise. Eat a Sufficient Amount of High Quality Protein at Each Meal - Distributed Evenly Throughout the Day. 20-30 grams for Most Athletes. More for Larger Athletes? Moderation is the Key - Avoid Excessive Protein Intake. Practical Example Considering Glycogen Replenishment
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Acknowledgments
Univ of Utah
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Acknowledgments
Elena Volpi, MD, PhD
Paul Reidy PhD Student Univ Kentucky Univ Wisconsin Texas A&M Arizona State
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Funding
NIAMS R01 AR049877 NIA P30 AG024832 NICHD T32 HD007539 Solae, LLC