dietary manipulations strength training volek
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Jeff S. Volek, Ph.D., R.D.Jeff S. Volek, Ph.D., R.D.
Human Performance LaboratoryHuman Performance LaboratoryDepartment of KinesiologyDepartment of KinesiologyUniversity of ConnecticutUniversity of Connecticut
Storrs, ConnecticutStorrs, ConnecticutUSAUSA
Dietary manipulations to enhance Dietary manipulations to enhance adaptations to strength trainingadaptations to strength training
Paradigm
Diet is a powerful method to alter substrate and hormone availability to skeletal muscle…
…which in turn affects metabolic processes and adaptations to training.
Diet can alter events that impact Diet can alter events that impact acute responses to exercise and acute responses to exercise and chronic adaptations to training by chronic adaptations to training by a variety of mechanismsa variety of mechanisms
Factors to consider: nutrient Factors to consider: nutrient quantityquantity, , qualityquality, and , and timingtiming
Most research has focused on Most research has focused on how diet affects the how diet affects the acuteacute response to resistance exercise, response to resistance exercise, with little work linking this to with little work linking this to chronicchronic adaptations adaptations
BackgroundBackground
ProteinCarbohydrate
Fat
Intake of Macronutrients
Exercise Stimulus
Triglycerides
Glucose
GH
IGF-I
Testosterone
Cortisol
Insulin
Amino Acids
Alteration in Plasma
Metabolites
Alteration in Plasma Hormones
TAG FA
PRO AA
Nutrients & Hormones Interact at Target Tissues to Regulate Carbohydrate, Fat,
& Protein Balance
Cell Growth/Body Composition
Resistance Exercise
ACUTE RESPONSETO RESISTANCE
EXERCISE
REPEATED ACUTE RESPONSES [CHRONIC
TRAINING]
Release of Endocrine Hormones
Interaction w/ Target
Cell Receptors & Genes
Muscular Strength and Performance
Muscle Fiber Hypertrophy
Lean Body Mass
InsulinIGF-I
TestosteronehGH
CytokinesCortisol
Protein Accretion
Amino Acid/Glucose
Uptake
Protein/Carbohydrate Intake
(Before & After Exercise)
Resistance exercise with
nutritional intake (quantity, quality,
and timing)
Alteration of nutrient and hormonal milieu in the circulation
Nutrient & hormonal uptake interact w/
contraction-induced mechanical & chemical
events in muscle to regulate enzyme activity &
genes
Metabolic effects on carbohydrates, lipids, and proteins can affect acute performance and chronic
adaptations
Protein Synthesis Protein Degradation
Carbohydrate Balance
Lipid Balance
Protein Balance
PATHWAY OF PATHWAY OF ADAPTATIONADAPTATION
Volek et al. MSSE. 2004
Gene Transcription/Translation
Enzyme activity
1. Acute effects of carbohydrate, protein, and carbohydrate 1. Acute effects of carbohydrate, protein, and carbohydrate + protein+ protein
- Quantity- Quantity - Quality- Quality - Timing- Timing - Digestion Rate- Digestion Rate
2. Acute effects of nutrients on hormonal responses to 2. Acute effects of nutrients on hormonal responses to resistance exerciseresistance exercise
3. Chronic effects of protein supplementation on 3. Chronic effects of protein supplementation on adaptations to trainingadaptations to training
4. Effects of macronutrient manipulation: maintaining 4. Effects of macronutrient manipulation: maintaining muscle during weight lossmuscle during weight loss
ApproachApproach
Resistance training alone protein synthesis and breakdown
In the absence of nutritional intake, protein balance is still negative
Protein Balance
Protein Synthesis
Protein Breakdown
Net Pro Balance
Resting/Fasting Post-Exercise/Fasting
Borsheim et al. 2004
Carb (100 g)Carb (100 g) PlaceboPlacebo
Carbohydrate After Resistance Exercise Carbohydrate After Resistance Exercise Favorably Affects Protein Balance, But Favorably Affects Protein Balance, But
Still Remains NegativeStill Remains Negative
-40-40
-30-30
-20-20
-10-10
1010
2020
3030
4040
00
Phenylalanine Net BalancePhenylalanine Net Balance(nmol/min/100 mL leg)(nmol/min/100 mL leg)
Pre-Pre-ExEx
Post-Post-ExEx
11stst h h 22ndnd h h 33rdrd h h
DrinkDrink
Rasmussen et al. 2000
Amino Acids After Resistance Exercise Amino Acids After Resistance Exercise Transiently Increases Protein BalanceTransiently Increases Protein Balance
Ph
enylalan
inP
hen
ylalanin
e e
Net B
alance
Net B
alance
(nm
ol/m
in/100
mL
leg)
(nm
ol/m
in/100
mL
leg)
00
5050
100100
-50-50
00
5050
100100
-50-500-10-1 1-21-2 2-32-3 3-43-4
Hours PostexerciseHours Postexercise
0-10-1 1-21-2 2-32-3 3-43-4
Hours PostexerciseHours Postexercise
6 g EAA 6 g EAA 35 g CHO35 g CHO
1 h Post-Ex1 h Post-Ex
6 g EAA 6 g EAA 35 g CHO35 g CHO
3 h Post-Ex3 h Post-Ex
2525
5050
7575
100100
125125
4343
107107
Miller et al. Miller et al. 20032003
Rasmussen Rasmussen et al. 2000et al. 2000
Pro
tein S
ynth
esisP
rotein
Syn
thesis
(net p
hen
ylalanin
e up
take (n
et ph
enylalan
ine u
ptake
mg
/h/leg
)m
g/h
/leg)
00
6 g AA (3 g EAA)6 g AA (3 g EAA)35 g CHO35 g CHO
6 g EAA 6 g EAA 35 g CHO35 g CHO
Only Essential Amino Acids (AA) Stimulate Only Essential Amino Acids (AA) Stimulate Protein Synthesis After Resistance ExerciseProtein Synthesis After Resistance Exercise
Beverages provided 1 hr after resistance exercise
Effects of Glucose and Amino Acids After Resistance Exercise are Additive
CHO AA Mix
Net P
hen
yla
lan
ine U
pta
ke
(mg/3
hr/le
g)
0
40
120
80
Miller et al. 2003
35 g Glucose35 g Glucose
6 g AA6 g AA35 g Glucose35 g Glucose
6 g AA 6 g AA (3 g EAA)(3 g EAA)
Beverages provided intermittently each 30 min post resistance exercise over 6 hr
CHO = 0.3 g/kg/hr (50% glucose/50% maltodextrin)
CHO + PRO = Same amount of CHO + 0.2 g/kg/hr whey protein hydrolysate
CHO + PRO + Leucine = Same amount of CHO and PRO + 0.1 g/kg/hr leucine
Co-Ingestion of Protein and Leucine Stimulate Protein Synthesis
Koopman et al. 2004
Tipton et al. 2001
Amino Acids Before Exercise Increases Protein Amino Acids Before Exercise Increases Protein Balance More Than After ExerciseBalance More Than After Exercise
Ph
enylalan
inP
hen
ylalanin
e e
Net B
alance
Net B
alance
(nm
ol/m
in/100
mL
leg)
(nm
ol/m
in/100
mL
leg) 5050
100100
150150
200200
-50-50
00
RestRest ExerciseExercise 11stst h h 22ndnd h h
Pre-Ex DrinkPre-Ex Drink Post-Ex DrinkPost-Ex Drink
6 g EAA 6 g EAA 35 g CHO35 g CHO
6 g EAA 6 g EAA 35 g CHO35 g CHO
Quick gastric emptying
Rapid, but short-lived, large increase in plasma amino acids
Large, rapid, transient increase in protein synthesis
No effect on protein oxidation/breakdown
Protein Quality: Slow and Fast Protein Quality: Slow and Fast Digesting ProteinsDigesting Proteins
Slow gastric emptying
Sustained moderate increase in plasma amino acids
Moderate, sustained increase in protein synthesis
Moderate decrease in protein oxidation/breakdown
Net protein balance over several hours slightly better with casein
Whey Protein Casein Protein
Dangin et al. 2001
Importance of Protein Digestion RateImportance of Protein Digestion Rate Single meal of casein (30 g): slow-digesting Single meal of free amino acids same as casein (30 g): fast digesting Single meal whey (30 g): fast digesting Repeated meals of whey (30 g) to mimic casein (13 meals ea 20 min): slow digesting
-50
0
100
50
AACAS WP WPRepeated
Leucine B
alance(
mo
l/kg)
Identical AA
Identical AA Fast meals induce strong, rapid, transient increase in plasma amino acids and oxidation
Slow meals induce moderate increases in amino acids and oxidation, but a significant larger protein balance over 7 hr
Stimulation of protein synthesis should not be Stimulation of protein synthesis should not be the only method to evaluate protein needsthe only method to evaluate protein needs
Protein is most thermogenic nutrientProtein is most thermogenic nutrient
Promotes inefficiency “Metabolic Advantage”Promotes inefficiency “Metabolic Advantage”
Protein enhances satietyProtein enhances satiety
Protein impacts hormonal milieuProtein impacts hormonal milieu
Protein: Additional ConsiderationsProtein: Additional Considerations
1. Acute effects of carbohydrate, protein, and carbohydrate 1. Acute effects of carbohydrate, protein, and carbohydrate + protein+ protein
- Quantity- Quantity - Quality- Quality - Timing- Timing - Digestion Rate- Digestion Rate
2. Acute effects of nutrients on hormonal responses to 2. Acute effects of nutrients on hormonal responses to resistance exerciseresistance exercise
3. Chronic effects of protein supplementation on 3. Chronic effects of protein supplementation on adaptations to trainingadaptations to training
4. Effects of macronutrient manipulation: maintaining 4. Effects of macronutrient manipulation: maintaining muscle during weight lossmuscle during weight loss
ApproachApproach
TAG FA
Lipolysis
Lipogenesis
Hormonal Regulation of Body CompositionHormonal Regulation of Body Composition
GHGH
IGF-IIGF-I
TestosteroneTestosterone
CortisolCortisol
InsulinInsulin
(-)(-)
(-)(-)
(+)(+)
(-)(-)
(+)(+)
lipolysislipolysis lipogenesislipogenesis glucose uptake/oxidationglucose uptake/oxidation LPL expressionLPL expression
lipolysislipolysis glucose transport/oxidationglucose transport/oxidation
lipolysis lipolysis lipogenesislipogenesis LPL expressionLPL expression
LPL expressionLPL expression lipolysislipolysis
lipolysis lipolysis LPL expressionLPL expression
(+)(+)
(+)(+)
(+)(+)
(-)(-)
(+)(+)
amino acid uptakeamino acid uptake PRO synthesisPRO synthesis
PRO breakdownPRO breakdown
amino acid oxidationamino acid oxidation PRO synthesisPRO synthesis
PRO breakdownPRO breakdown
PRO synthesisPRO synthesis PRO breakdown?PRO breakdown?
PRO synthesisPRO synthesis PRO breakdown?PRO breakdown?
PRO breakdownPRO breakdown
Adipose Tissue
Balance
Skeletal MuscleBalance
PRO AA
PRO Breakdown
PRO Synthesis
Promotes positive nitrogen balance by increasing protein synthesis, maybe inhibit protein degradation
Partially mediated through stimulation of hepatic IGF-I
Promotes lipolysis
Inhibits lipogenesis
Nutrient partitioning effects
Growth Hormone
Response to food is quite variable
Carbohydrate generally decreases GH
Sensitive to glucose levels
Hypoglycemia stimulates, hyperglycemia inhibits of GH
Responsive to certain AA (arginine, lysine, ornithine)
FA inhibit GH
Metabolic Effects Response to Meals
Gro
wth
Ho
rmo
ne (
Gro
wth
Ho
rmo
ne (
g/L
)g
/L)
Kraemer et al. J. Appl. Physiol. 85:1544-1555, 1998
0
5
10
15
20
25
30
35
Pre 0 15 30 45 60
25 g PRO 25 g PRO 50 g CHO50 g CHO
Protein-Protein-CarbohydrateCarbohydrate
PlaceboPlacebo
Protein-carbohydrate feeding enhances the GH response to whole body resistance exercise
Insulin promotes glucose uptake, glycogen formation, and protein Insulin promotes glucose uptake, glycogen formation, and protein synthesis (in presence of sufficient AA)synthesis (in presence of sufficient AA)
Certain AA can Certain AA can insulin and there has been interest in combining insulin and there has been interest in combining protein and carbohydrate to maximize insulin secretion in hopes of protein and carbohydrate to maximize insulin secretion in hopes of enhancing post-exercise glycogen resynthesis and protein anabolismenhancing post-exercise glycogen resynthesis and protein anabolism
Protein and carbohydrate speeds glycogen resynthesis after Protein and carbohydrate speeds glycogen resynthesis after prolonged submaximal cycling exercise compared to same amount of prolonged submaximal cycling exercise compared to same amount of carbohydrate only, but no research with resistance exercisecarbohydrate only, but no research with resistance exercise
No benefit of protein if carbohydrate intake is very high (1.2 g/kg/hr)No benefit of protein if carbohydrate intake is very high (1.2 g/kg/hr)
InsulinInsulin
25 g PRO 25 g PRO 50 g CHO50 g CHO
25 g PRO 25 g PRO 50 g CHO50 g CHO
25 g PRO 25 g PRO 50 g CHO50 g CHO
Insu
lin (p
mo
l/L)
Insu
lin (p
mo
l/L)
Day 1Day 1 Day 2Day 2 Day 3Day 3
Kraemer et al. J. Appl. Physiol. 85:1544-1555, 1998
0
200
400
600
800
1000
1200
Pre 0 15 30 45 60 Pre 0 15 30 45 60 Pre 0 15 30 45 60
Protein-CarbohydratePlacebo
00 100100 300300200200
00
33
22
11
Jenson et al. Diabetes. 38:1591-1601, 1989
Insulin (pmol/L)Insulin (pmol/L)
Palm
itate P
almitate
Flu
xF
lux
12 12
50%50%
22 22
75%75%
NondiabeticsNondiabetics
100%100%(Max (Max
Lipolysis)Lipolysis)
Lipolysis is exquisitely sensitive Lipolysis is exquisitely sensitive to insulinto insulin
The effect is virtually immediateThe effect is virtually immediate Insulin also stimulates Insulin also stimulates
lipogenesis:lipogenesis: glucose uptakeglucose uptake Activating lipogenic enzymesActivating lipogenic enzymes
Insulin Regulation of LipolysisInsulin Regulation of Lipolysis
Testosterone has potent anabolic effects on muscle tissue
Feeding testosterone and the composition of meals, particularly the amount and type of fat, influences postprandial testosterone response
Insulin & testosterone tend to be inversely related but probably not cause and effect
Similar to feeding, pre- and post-exercise meals consistently testosterone response to resistance exercise
TestosteroneCHCH33
CHCH33OHOH
OO
800 kcal57% FAT9% PRO34% CHO
800 kcal1% FAT26% PRO73% CHO
Metabolism 39:943-6, 1990
Volek et al. Metabolism 50:1351-5, 2001
Seru
m T
estostero
ne
Seru
m T
estostero
ne
(nm
ol/L
)(n
mo
l/L)
1010
1515
2020
2525
3030
PrePre 00 1515 3030 4545 6060 PrePre 00 1515 3030 4545 6060 PrePre 00 1515 3030 4545 6060
Day 1Day 1 Day 2Day 2 Day 3Day 3
Protein-CarbohydrateProtein-CarbohydratePlaceboPlacebo
Kraemer et al. J. Appl. Physiol. Kraemer et al. J. Appl. Physiol. 85:1544-1555, 199885:1544-1555, 1998
25 g PRO 25 g PRO 50 g CHO50 g CHO
25 g PRO 25 g PRO 50 g CHO50 g CHO
25 g PRO 25 g PRO 50 g CHO50 g CHO
Could be due to synthesis/secretion and/or in metabolic clearance
testosterone not associated with LH suggesting a possible in testosterone uptake at the tissue level
Decreased Testosterone
Post-Exercise Shake or Placebo (Water)
8 kcal/kg1.1 g Carbohydrate/kg0.3 g Protein/kg0.25 g Fat/kg
0 10 20 30 40 50 60Pre-EX
Workout
BloodDraws
(min post-exercise)
Muscle Biopsy
Kraemer et al.Kraemer et al., 2006, 2006
10
12
14
16
18
20
22
Pre IP 10 20 30 40 50 60
Time After Exercise (min)
Te
stos
tero
ne
(nm
ol/L
)
Water
PRO/CHO
Exercise
24
26
2
4
6
8
10
12
14
16
0BL Water PRO/
CHO
Androgen ReceptorBand Intensity (AU)
Kraemer et al.Kraemer et al., 2006, 2006
Cortisol lipolysis and proteolysis to fuel gluconeogenesis to protect blood glucose and glycogen levels
Postprandial responses must consider diurnal variation
Cortisol
Reynolds et al. J Clin Endocrinol Metab. 86:1149-53, 2001
75 g glucose
00 2020 4040 6060 8080 100100 1201201010
1414
1818
2222
2626 CarbohydrateCarbohydrate
ControlControl
ExerciseExercise RecoveryRecovery
Time (min)Time (min)
Co
rtiso
l C
ortis
ol
(( g
/dL
)g
/dL
)
Effects of carbohydrate supplementation on cortisol responses
and adaptations to strength training
Tarpenning et al.Tarpenning et al., 2006, 2006
1. Acute effects of carbohydrate, protein, and carbohydrate 1. Acute effects of carbohydrate, protein, and carbohydrate + protein+ protein
- Quantity- Quantity - Quality- Quality - Timing- Timing - Digestion Rate- Digestion Rate
2. Acute effects of nutrients on hormonal responses to 2. Acute effects of nutrients on hormonal responses to resistance exerciseresistance exercise
3. Chronic effects of protein supplementation on 3. Chronic effects of protein supplementation on adaptations to trainingadaptations to training
4. Effects of macronutrient manipulation: maintaining 4. Effects of macronutrient manipulation: maintaining muscle during weight lossmuscle during weight loss
ApproachApproach
PRO-CHO Supplement More Effective Immediately After Exercise than 2 h Post-Exercise in Elderly
Men During 12 wk Resistance Training
Esmarck et al., J. Physiol. 535:301-311, 2001.
Immediately Post-Workout2 h Post-Workout
-10-10
-5-5
00
55
1010
1515
2020
2525
Percen
t Ch
ang
eP
ercent C
han
ge
Quadriceps Cross-
Sectional Area
Muscle Fiber Cross-
Sectional Area
Lean Body Mass
Anderson et al. 2005
Protein Supplementation More Effective than Carbohydrate for Enhancing Muscle Fiber Hypertrophy
14 wk resistance training untrained men
25 g of carbohydrate or 25 g of protein (17 g whey, 3 g casein + egg white + glutamine)
Provided 1 hr before and immediately after exercise
0
30
20
10
Type I
Perce
nt In
crease
C
ross-S
ectio
nal A
rea
Protein Carbohydrate
Type II
Type I Type II
Willoughby et al. 2006
Protein Supplementation More Effective than Carbohydrate for Improving
Anabolism and Performance 10 wk resistance training untrained men 20 g of carbohydrate or 20 g of protein (14 g whey and casein + 6 g AA) Provided 1 hr before and immediately after exercise Protein supplementation resulted in:
LBM (5.6 vs 2.7 kg) Thigh mass Muscle strength Serum IGF-1 Muscle IGF-1 mRNA MHC I and IIa expression Myofibrillar protein expression
1. Acute effects of carbohydrate, protein, and carbohydrate 1. Acute effects of carbohydrate, protein, and carbohydrate + protein+ protein
- Quantity- Quantity - Quality- Quality - Timing- Timing - Digestion Rate- Digestion Rate
2. Acute effects of nutrients on hormonal responses to 2. Acute effects of nutrients on hormonal responses to resistance exerciseresistance exercise
3. Chronic effects of protein supplementation on 3. Chronic effects of protein supplementation on adaptations to trainingadaptations to training
4. Effects of macronutrient manipulation: maintaining 4. Effects of macronutrient manipulation: maintaining muscle during weight lossmuscle during weight loss
ApproachApproach
Krieger et al. Am J Clin Nutr 83:260-74, 2006
Meta-regression 87 studies
Low carbohydrate diets associated with greater weight loss percentage body fat
High protein diets associated with better retention of fat-free mass
Effects independent of energy intake
Macronutrient Composition Strongly Affects Body Composition
Diet: Isocaloric 5% CHO, 60% FAT, 35% PRO
Protein synthesis/proteolysis, plasma hormones, and muscle IGF mRNA at 2 and 7 d
24 h plasma insulin ( 50%), GH and IGF-I (no ), free IGF-I ( 30%)
2-fold Muscle IGF-I mRNA
20% leucine Ra
2-fold muscle fractional synthetic rate
J Clin Endocrinol Metab. 90:5175-81, 2005.
-4
-3
-2
-1
0
1
2
Cha
nge
in k
g
Very Low-CHO Diet
Control Group
BM FM FFM
A 6 wk Very Low Carbohydrate Diet Enhances Fat Loss and Increases Lean Body Mass
Volek et al. Metabolism. 50(11):1351-1355, 2001.
P < 0.05P < 0.05
P < 0.05
00 -2-2 -4-4 -6-6 88
Weight Loss (kg)Weight Loss (kg)
Low-FatLow-Fat Low-CHOLow-CHO
-10-10 -12-12
6 mo6 mo
6 mo6 mo
6 mo6 mo
6 mo6 mo
3 mo3 mo
6 mo6 mo
6 mo6 mo
6 mo6 mo
6 mo6 mo
3 mo3 mo
Brehm et al.Brehm et al.20032003
Yancy et al.Yancy et al. 20042004
Foster et al.Foster et al.20032003
Samaha et al.Samaha et al.20032003
Sondike et al.Sondike et al.20032003
-6-6
-5-5
-4-4
-3-3
-2-2
-1-1
00
Whole Body Whole Body Fat Loss (kg)Fat Loss (kg)
*Low-CHOLow-CHO
Low-FatLow-Fat
-4-4
-3-3
-2-2
-1-1
00
PrePre MidMid PostPost
Trunk Fat Trunk Fat Loss (kg)Loss (kg)
Low-FatLow-Fat
Low-CHOLow-CHO
*
Volek et al. Nutr Metab. 2004 Nov 8;1(1):13.
Layman et al J Nutr. 135(8):1903-10, 2005
-6
0
-2
-4
Pro Pro+Ex CHO CHO+ExChan
ge in
Perce
nt B
od
y
Fat
Low Carbohydrate/High Protein Diet and Resistance Exercise Have Additive Effects on Body Composition
4 mo weight loss intervention
Group
Pro CHOHi Pro 30% 18%
Hi Carb 38% 61%
-8
-6
0
2
-2
-4
-10LF LC LF+RE LC+RE
-3.7
-2.0
-7.3
-3.5
-6.2
0.21.8
-3.6
3 mo weight loss intervention with low carbohydrate (LC) vs low fat (LF) with and without resistance exercise (RE).
Fat Mass
Lean Body Mass
Change in
Kilogram
s
Volek Unpublished
Muscle Glycogen and Metabolic Regulation
Glycogen is not just a substrate for exercise metabolism
Low muscle glycogen signals: Translocation of GLUT4 Glucose uptake AMPK Lipid oxidation Net protein degradation Branched-chain oxoacid dehydrogenase Glycogen synthase Rate of glycogen resynthesis Transcription rates and mRNA levels of
metabolic genes
Carbohydrate
Protein
TG + Amino Acids
Glycogen Tank Chronic Low Carbohydrate Diet
GH IGF-I (muscle) Testosterone
Insulin
FA AminoAcids
Glycogen Protein
Glu
AcetylCoA
Fat Storage FA TG
Carbohydrate
Protein
Glucose + Amino Acids
Fat Storage
Glycogen Tank
GH IGF-I (plasma, muscle)
Testosterone Insulin
FA AminoAcids
Glycogen Protein
Glu
AcetylCoA
Short-Term High Carbohydrate
Carbohydrate
Protein
Glucose + Amino Acids
Glycogen Tank
GH IGF-I (muscle) Testosterone
Insulin
FA AminoAcids
Glycogen Protein
Glu
AcetylCoA
Chronic High Carbohydrate
Fat Storage
HH
HH22NN NHNH22
CC
NNHH33CC
CHCH22
COOCOO--
CreatineCreatine
PhosphocreatinePhosphocreatineA
TPA
TP
AD
PA
DP NN POPO33
--HH22NN
HNHN
CC
NN
CHCH33
CC
NN
CHCH22
OO
HH
CC
NNHH33CC
CHCH22
COOCOO--
CreatinineCreatinine
PP ii + H + H22OO
CreatineCreatine
• Over two dozen studies have reported that creatine supplementation Over two dozen studies have reported that creatine supplementation enhances lean body mass and/or muscle strength responses to enhances lean body mass and/or muscle strength responses to resistance training resistance training
• Could be due to several mechanisms:Could be due to several mechanisms:
lean body masslean body mass protein synthesisprotein synthesis myosin heavy chain mRNA and protein expressionmyosin heavy chain mRNA and protein expression expression of myogenic transcription factorsexpression of myogenic transcription factors satellite cell mitotic activitysatellite cell mitotic activity protein synthesis secondary to increased cellular swelling protein synthesis secondary to increased cellular swelling intensity of individual workoutsintensity of individual workouts muscle glycogenmuscle glycogen
Muscle Fiber Cross-Sectional Area Muscle Fiber Cross-Sectional Area
A
rea (A
rea ( mm
22))
Volek et al. 1999
0
300
600
900
1200
1500
I IIA IIAB IIB
CreatinePlacebo
• One challenge in the future will be to match One challenge in the future will be to match the varying nutritional demands associated the varying nutritional demands associated with periodized resistance training with periodized resistance training programs with periodized diet strategiesprograms with periodized diet strategies
• Ultimately, “timing or cycling” of diet on an Ultimately, “timing or cycling” of diet on an hourly, daily, weekly, or monthly basis to hourly, daily, weekly, or monthly basis to match the unique demands of each match the unique demands of each workout or phase of training, may enhance workout or phase of training, may enhance adaptations to training over one single diet adaptations to training over one single diet strategy strategy
The FutureThe Future
• Diet can influence “pathway of adaptation” and adaptations to resistance training
• Nutrient timing can alter energy substrates and the hormonal environment to favor anabolism
• Protein provided before and after exercise represents an easy an effective method to alter muscle protein balance
SummarySummary
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