The Role of Protein in Promoting Muscle Growth · " Resistance Exercise & Protein both stimulate muscle protein synthesis primarily through mTORC1 activation! " mTORC1 should be considered

5/26/13

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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


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


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


Sports Nutrition - Protein


Building Muscle

Protein Degradation Protein Synthesis

Exercise Feeding

Unloading Starvation

Muscle Growth Muscle Atrophy

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The Muscle Biopsy Bergström, 1962


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


Resistance Exercise Increases Muscle Protein Synthesis


mTORC1 Activation

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Is mTORC1 Activation Required for Muscle Contraction to Increase

Muscle Protein Synthesis?

mTORC1 Rapamycin

Muscle Protein Synthesis


Yes! - mTORC1 is Required to Increase Muscle Protein Synthesis


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


EAA is Responsible for the Stimulation of Muscle Protein

Synthesis


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!


Stimulating Muscle Growth with Protein


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


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


Protein Supplementation During Exercise Training

Does it Enhance Muscle Growth?

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Protein Supplementation and Exercise Training


Whey and Soy Protein Supplementation Improves

Muscle Mass


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


Why is Whey Considered the Gold Standard?


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




Protein Blends


The Theory

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Journal of Nutrition 143: 410-416, 2013


Study Aim


Subjects

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Methods


Methods


Results

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Leucine


Area Under The Curve


Mixed Muscle Protein Synthesis

Whey Blend

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mTORC1 Signaling


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


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


Ingesting EAA Before Exercise Has No Additional Benefit on Muscle

Protein Synthesis

Fujita et al, J Appl Physiol 106: 1730-1739, 2009


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


How Much Protein Does it Take to Maximize Muscle

Protein Synthesis?


Dose-Response Study

10 grams of EAA or ~20-25 grams of Protein

Cuthbertson et al, FASEB J., 2005

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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


Concept of Protein Distribution


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


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


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


Acknowledgments

Univ of Utah


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

[email protected]

Documents

The Role of Protein in Promoting Muscle Growth · " Resistance Exercise & Protein both stimulate muscle protein synthesis primarily through mTORC1 activation! " mTORC1 should be considered