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Nutrient Timing: The Means to Improved Exercise Performance, Recovery, and Training Adaptation


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As the incidence rate of lifestyle-related chronic conditions such as cardiovascular disease, obesity, and type 2 diabetes continues to increase, the importance of regular exercise and a healthy diet for improving or maintaining good health is critical. Exercise training is known to improve fitness and many health risk factors, as well as to improve the performance of competitive athletes. It has become increasingly clear, however, that nutrient intake before, during, and after exercise sessions has a powerful influence on the adaptive response to the exercise stimuli. In this review, the science behind nutrient timing will be discussed as it relates to exercise performance, recovery, and training adaptation. Evidence will be provided that validates intake of appropriate nutrients before, during, and immediately after exercise not only to improve exercise performance but also to maximize the training response. Ultimately, the combined response to exercise and proper nutrient intake leads to not only better performance in athletes but also greater health benefits for all exercisers.
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American Journal of Lifestyle Medicine
The online version of this article can be found at:
DOI: 10.1177/1559827613502444
2014 8: 246 originally published online 7 October 2013AMERICAN JOURNAL OF LIFESTYLE MEDICINE
John L. Ivy and Lisa M. Ferguson-Stegall
Nutrient Timing: The Means to Improved Exercise Performance, Recovery, and Training Adaptation
Published by:
On behalf of:
American College of Lifestyle Medicine
can be found at:American Journal of Lifestyle MedicineAdditional services and information for Alerts:
What is This?
- Oct 7, 2013OnlineFirst Version of Record
- Jul 10, 2014Version of Record >>
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Jul Aug 2014American Journal of Lifestyle Medicine
AnAlytic John L. Ivy, PhD, and
Lisa M. Ferguson-Stegall, PhD
502444AJLXXX10.1177/1559827613502444American Journal of Lifestyle MedicineAmerican Journal of Lifestyle Medicine
Nutrient Timing: The Means to
Improved Exercise Performance,
Recovery, and Training
Without proper nutrition, exercise
goals will not be fully realized.
DOI: 10.1177/1559827613502444. Manuscript received March 7, 2013; revised May 10, 2013; accepted March 29, 2013. From the Exercise Physiology and Metabolism
Laboratory, Department of Kinesiology and Health Education, University of Texas at Austin, Austin, Texas (JLI); and the Integrative Physiology Laboratory, Department of
Biology, Hamline University, Saint Paul, Minnesota (LMFS). Address correspondence to John L. Ivy, PhD, Department of Kinesiology and Health Education, University of Texas
at Austin, 1 University Station D3700, Austin, TX 78712; e-mail:
For reprints and permissions queries, please visit SAGE’s Web site at
Copyright © 2013 The Author(s)
Abstract: As the incidence rate of
lifestyle-related chronic conditions such
as cardiovascular disease, obesity, and
type 2 diabetes continues to increase,
the importance of regular exercise
and a healthy diet for improving or
maintaining good health is critical.
Exercise training is known to improve
fitness and many health risk factors,
as well as to improve the performance
of competitive athletes. It has become
increasingly clear, however, that
nutrient intake before, during, and
after exercise sessions has a powerful
influence on the adaptive response to
the exercise stimuli. In this review, the
science behind nutrient timing will
be discussed as it relates to exercise
performance, recovery, and training
adaptation. Evidence will be provided
that validates intake of appropriate
nutrients before, during, and
immediately after exercise not only to
improve exercise performance but also
to maximize the training response.
Ultimately, the combined response to
exercise and proper nutrient intake
leads to not only better performance in
athletes but also greater health benefits
for all exercisers.
Keywords: glycogen; endurance;
strength; skeletal muscle; protein
synthesis; body composition
Exercise training has many
purposes. The average person may
exercise train to maintain or
improve body weight, lower risk factors
associated with disease, or to simply
maintain a healthy lifestyle. For the
athlete, the goal is generally to improve
athletic performance. While the goals of
the average person and the athlete may
differ substantially, their physiological
and cellular responses to exercise will be
similar as long as exercise intensity and
volume are made relative to fitness level.
However, an important determinant of
the adaptive response to exercise is the
nutritional status of the individual. It has
long been known that diet can have a
major impact on exercise performance as
well as training adaption, and its
influence cannot be overstated. Simply
put, without proper nutrition, exercise
goals will not be fully realized.
While proper nutrition is certainly
important in achieving exercise goals, it
has become increasingly evident that
when one eats can be just as important
as what one eats. That is, the timing of
nutrient intervention or “nutrient timing”
can have a significant impact on exercise
performance, recovery, and training
adaptation. These responses to nutrient
timing are not limited to the elite athlete.
Everyone, young and old, male and
female, untrained and trained, will
respond to nutrient timing.
The type of exercise one performs will
dictate the training response of the body.
For example, weightlifting will increase
muscle mass, while endurance cycling
will increase cardiovascular fitness and
muscle endurance. The type of nutrients
consumed and when they are consumed,
however, will substantially affect the
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quality of an exercise session, rate of
recovery, and magnitude of training
adaptation. In essence, to have quality
exercise sessions, recover fully, and
maximize exercise-training adaptation,
appropriate nutrient supplementation
during and immediately postexercise is
essential. Nutrient supplementation at
critical times of the day and developing a
meal plan that is strategically positioned
around the exercise-training program are
also advantageous.
In this review, the science behind
nutrient timing will be discussed as it
relates to exercise performance, recovery,
and training adaptation. Evidence will be
provided that validates intake of
appropriate nutrients before, during, and
immediately after exercise to improve
exercise performance and maximize the
training response. Nutrient
supplementation and meal planning
throughout the day as it relates to
exercise training will also be discussed.
Nutrient Timing
Simply stated, nutrient timing is the
delivery of appropriate macronutrients
during the time in which the body is
primed to use them most effectively.1
Nutrient timing as it relates to exercise
can be divided into 3 phases: the energy
phase, the anabolic phase, and the
adaptation phase. The energy phase
represents the period immediately prior
to and during exercise. The anabolic
phase is the period immediately after
exercise and lasts for about 60 to 90
minutes. During this time, often referred
to as the anabolic or metabolic window,1
the exercised muscle is highly sensitive
to nutrient intervention. The adaptation
phase follows the anabolic phase, and if
appropriate supplements and meals are
continued during this period an elevated
response to nutrient intervention can be
sustained for many hours, resulting in a
faster recovery and training adaptation.
The Energy Phase
The energy phase is divided into 2
critical time periods: pre-exercise and
during exercise. The pre-exercise period,
which will be discussed first, represents
the 4 hours before exercise when
nutrient supplementation can have a
positive influence on exercise
performance. We will then discuss the
primary focus of the energy phase—
nutrient supplementation during
The Pre-Exercise Period: 4 Hours or Less
Before Exercise. Dietary strategies such
as carbohydrate loading are designed to
maximize muscle glycogen stores in the
days before an endurance event2 and
have been shown to be effective in not
only increasing glycogen storage to
above-average levels but also to improve
exercise performance in bouts lasting
more than 90 minutes.3-5 However, it has
been demonstrated that ingesting a meal
containing 150 to 200 g of carbohydrate
4 hours before exercise can also
significantly increase muscle glycogen
stores6 and improve exercise
Pre-exercise carbohydrate intake has
not been without controversy, however.
Early research suggested that
carbohydrate consumption 30 to 45
minutes prior to exercise elevated plasma
insulin, resulting in early exercise
hypoglycemia and reduced time to
exhaustion.11 However, the majority of
studies do not support this finding. Most
investigations report either no adverse
effects on performance12-16 or significant
performance improvements2,7-10 following
pre-exercise carbohydrate
supplementation. In addition, some have
demonstrated an additive, positive effect
on performance when supplementation
is provided both before and during
exercise.17,18 Intake of 150 to 200 g
carbohydrate 2 to 4 hours before a long,
intense exercise bout is a reasonable
strategy (Figure 1); however, one should
determine which pre-exercise feeding
strategy works best through experience.
Supplementation During Exercise. Blood
glucose and muscle glycogen are
essential fuel sources during intense,
prolonged exercise, yet the carbohydrate
stores of the body are limited. Skeletal
muscle stores about 300 to 500 g
glycogen, the liver stores 60 to 100 g
glycogen, and only about 15 to 20 g
glucose are available in the blood.19 The
primary purpose of carbohydrate
supplementation during exercise,
especially when prolonged and intense,
is to maintain euglycemia, or normal
blood glucose levels. When blood
glucose becomes low and muscle
glycogen stores are depleted, prolonged
intense exercise simply cannot continue.
Exercise performance. It is well
established that endurance exercise
performance is significantly improved
when carbohydrate is ingested
Figure 1.
Recommended Nutrient Supplementation During the Energy Phase.
Ingestion of a meal containing 150 to 200 g carbohydrate is recommended 2 to 4 hours pre-
exercise. During prolonged exercise of a moderate to high intensity, ingestion of ~200 mL of a
carbohydrate/protein beverage is recommended. The beverage should contain 2% to 6% carbo-
hydrate + 1% to 2% protein at a ratio of 2:1 carbohydrate/protein for resistance training, or 3-4:1
carbohydrate/protein for endurance training. If exercise intensity is light and the duration is less
than 30 minutes, no supplementation is warranted.
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during exercise compared to placebo
beverages.20-25 As exercise intensity
increases to ~70% Vo2max or greater,
muscle glycogen is the primary fuel
source.26 As duration increases and
muscle glycogen becomes less available,
metabolism shifts from reliance on
muscle glycogen to blood glucose.20,21
Blood glucose levels have been shown
to decrease to hypoglycemic levels of
~3 mmol L−1 after about 2.5 to 3 hours
of cycling when no supplementation is
provided during exercise, and exercise
cannot continue; however, when
carbohydrate is provided, carbohydrate
oxidation rates can be maintained and
exercise can continue significantly
longer.27 While carbohydrate intake
during exercise maintains blood glucose
levels, it does not appear to spare
muscle glycogen from being used for
fuel during continuous prolonged
exercise at intensities around 70% to
75% Vo2max. Rather, carbohydrate
intake maintains euglycemia and delays
the onset of fatigue.27 However, during
continuous, low-intensity exercise or
variable-intensity exercise, carbohydrate
supplementation has been found
to improve endurance performance
by sparing muscle glycogen.24,25,28
Supplementation does not have to
start at the onset of exercise to be
effective. It has been shown that starting
supplementation before a significant
decline in blood glucose occurs can still
prolong aerobic endurance.20
Carbohydrate supplementation has also
been found to benefit resistance exercise.
Wax et al provided 1 g carbohydrate per
kg body mass immediately before and
0.17 g carbohydrate per kg body mass
every 6 minutes during an isometric
resistance exercise protocol to fatigue
and found that total force output was
higher when carbohydrate was provided
compared with placebo.29 Likewise, Haff
et al found that carbohydrate
supplementation increased the total
amount of work that could be performed
during an isokinetic resistance exercise
session consisting of 16 sets of 10
repetitions at 120° s−1 consisting of knee
extension and flexion.30 Therefore,
carbohydrate intake can benefit
resistance exercise performance, as well
as endurance performance.
Effect of multiple carbohydrate types
on endurance performance. Several
investigations have demonstrated that
when multiple carbohydrate types (eg,
dextrose, fructose, and maltodextrin) are
ingested, the maximal rate of exogenous
carbohydrate oxidation can be increased
significantly.31-33 Recent investigations
have demonstrated that endurance
performance can be improved as well.
Currell and Jeukendrup reported an
8% improvement in time to complete
a simulated time trial when cyclists
ingested a glucose–fructose (2:1 ratio)
supplement compared to isocaloric
glucose only supplement provided
immediately before and every 15
minutes during exercise.34 Others have
shown significant improvements in time
to exhaustion when supplementing
with a combination of dextrose,
maltodextrin, and fructose with added
whey, compared to dextrose only.35
It is believed that ingesting multiple
carbohydrates optimizes the use
of various intestinal carbohydrate
transporters such that the rate of
absorption is increased beyond that
of a single carbohydrate and leads to
increased exogenous carbohydrate
oxidation, which spares endogenous
carbohydrate stores.31
Effect of Carbohydrate Supplementation
on Immune System Function. While
moderate to vigorous endurance exercise
is associated with bolstered immune
system function, prolonged and
exhaustive exercise can negatively
impact the immune system, resulting in
decreased immune function and higher
rates of upper respiratory tract
infections.36-39 Many nutritional
countermeasures have been investigated
for immune system protection, including
glutamine, bovine colostrum,
carbohydrate beverages, phytonutrients
such as quercetin, and antioxidants such
as vitamins C and E.40-44 Of these,
carbohydrate ingestion has been
demonstrated to be the most
Carbohydrate ingestion can attenuate
exercise-induced changes in plasma
cortisol and epinephrine, which can
suppress immune function during and
after prolonged endurance events such
as marathons.45,46 Compared to runners
ingesting a placebo treatment, those who
ingested carbohydrate during exercise
had significantly lower plasma cortisol
levels and decreased leukocyte
trafficking.37,45 Similar results have been
shown in exhaustive, prolonged cycling.
Scharhag et al provided placebo, 6%, or
12% carbohydrate beverages during 4
hours of cycling and reported that the
ingestion of 6% carbohydrate
significantly attenuated the exercise-
induced immune response, of phagocytic
neutrophils and monocytes via a
reduction in cortisol release. Moreover,
increasing the concentration to 12%
carbohydrate provided no additional
improvement in immune function over
that of the 6% beverage.47
Others have demonstrated that
ingesting carbohydrate compared to
placebo during prolonged endurance
cycling or running attenuates the
increase in both pro- and anti-
inflammatory cytokines, which are
potent mediators of the immune system
and the inflammatory response.40,46,48-51
Taken together, these results strongly
indicate that carbohydrate intake can
have a significant positive effect in
attenuating suppressed immune function
and the inflammatory cascade during
and after intense, prolonged exercise.
Carbohydrate/Protein Supplementation
During Exercise. Several investigations
have reported significant improvements
in endurance exercise performance when
a carbohydrate/protein beverage is
ingested during exercise compared to a
carbohydrate-only beverage.35,52-56 Ivy et
al compared the effects of placebo,
carbohydrate only, and carbohydrate/
protein supplementation on endurance
performance in trained cyclists. The
participants cycled at intensities
alternating between 45% and 75%
Vo2max for 3 hours, and then at 74% to
85% Vo2max until exhausted.
Supplements (200 mL) were provided
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every 20 minutes during exercise. While
carbohydrate supplementation
significantly increased time to
exhaustion, the carbohydrate/protein
supplementation extended time to
exhaustion by 36.5%.52 Saunders et al
reported similar time to exhaustion
improvements with carbohydrate/protein
compared to carbohydrate
supplementation during exercise. Fifteen
cyclists exercised at 75% Vo2max to
exhaustion, followed 12 to 15 hours later
by a second ride to exhaustion at 85%
Vo2max. Participants received
supplements every 15 minutes of
exercise and immediately postexercise.
The cyclists rode 29% longer in the first
and 40% longer in the second ride when
consuming carbohydrate/protein
compared to the carbohydrate
beverage.54 Saunders and colleagues also
demonstrated a 13% improvement in
time to exhaustion when a carbohydrate/
protein gel was compared to a
carbohydrate-only gel ingested every 15
minutes during a cycling bout to
exhaustion.55 It should be noted that in
some of the above-referenced studies,
the supplements provided were not
isocaloric but rather
isocarbohydrate.52,54-56 However, other
investigations using a carbohydrate/
protein supplement that contained fewer
calories compared to a carbohydrate
supplement demonstrated significant
performance improvements.35,53 These
collective findings demonstrate the
potential for improved time to
exhaustion when carbohydrate and
protein are co-ingested during endurance
As discussed earlier, a mixture of
carbohydrate types has been shown to
be more effective than a single type in
improving performance. Given that
adding protein to a carbohydrate
supplement can improve endurance
performance compared to carbohydrate
only, recent studies investigated the
combined effects of multiple
carbohydrate types plus added whey
protein on endurance performance.
Ferguson-Stegall et al compared the
effects of a 6% carbohydrate beverage or
a 3% carbohydrate/1.2% protein
beverage on time to exhaustion during
cycling exercise.35 The carbohydrate
beverage contained 6% dextrose, and the
carbohydrate/protein beverage contained
1% each of dextrose, maltodextrin, and
fructose, and 1.2% whey protein isolate.
Supplementation was provided every 20
minutes during exercise. Time to
exhaustion was 28.7% greater in the low
carbohydrate/protein treatment
compared to the carbohydrate treatment
when exercise intensity was near
ventilatory threshold.35 McCleave and
colleagues also found significantly
improved time to exhaustion in trained
female cyclists and triathletes when
comparing a mixed carbohydrate/
moderate protein supplement with a
higher calorie carbohydrate
supplement.53 These results suggest that
the efficacy of a supplement in
benefitting endurance performance can
be optimized by using multiple
carbohydrate types and adding a
moderate amount of protein. This may
be of particular interest to athletes and
exercisers who desire a lower-calorie
alternative when exercising to meet
weight loss or body composition goals.
While the benefits of carbohydrate/
protein supplementation have been
demonstrated during endurance exercise,
a recent investigation found improved
performance in simulated soccer-type
exercise.57 Using the Loughborough
Intermittent Shuttle Test, which includes
jogging, running, and sprinting,58
Highton and colleagues demonstrated a
trend for improved distance covered and
sustained speed when participants
ingested at 15 minutes intervals during
exercise a beverage containing 6%
carbohydrate and 2% whey protein
compared to 8% carbohydrate only.57
Moreover, carbohydrate/protein
supplementation has been shown to
attenuate muscle damage during
resistance exercise.59 Therefore, the
benefits of carbohydrate/protein
supplementation extend beyond
endurance exercise and have relevance
to sport-specific performance and
resistance exercise training as well.
Despite the many reports of improved
endurance and sport performance with
carbohydrate/protein, some studies using
isocaloric carbohydrate and
carbohydrate/protein treatments found
no difference in time to exhaustion60-62 or
in time trial performance.63 Given the
conflicting findings across studies, and
the relatively small sample sizes used in
many of the investigations, Saunders et al
examined data across multiple studies to
determine if performance was in fact
related to changes in physiological
measures during exercise.64 To
accomplish this, 38 subjects were
combined from 3 studies in which
cyclists performed rides to exhaustion at
75% Vo2peak. In each study analyzed,
cyclists received carbohydrate (7.3%) or
carbohydrate/protein (7.3% + 1.8%)
every 15 minutes during exercise.
Despite finding no differences in oxygen
consumption, blood glucose, or
respiratory exchange ratio between
carbohydrate and carbohydrate/protein
treatments, time to exhaustion was 19%
longer during the carbohydrate/protein
treatment compared to the carbohydrate
treatment across studies. Thus, the
authors concluded that the combined
data showed significant improvements in
endurance performance with
carbohydrate/protein versus
carbohydrate supplementation.64
Effect on Carbohydrate/Protein
Supplementation on Muscle Damage and
Soreness. In 2 investigations previously
described by Saunders and colleagues,
carbohydrate/protein supplements
ingested during endurance exercise
resulted in longer times to exhaustion
compared to carbohydrate alone, and
also demonstrated lower levels of plasma
creatine kinase (CPK) in the
carbohydrate/protein treatment
compared to carbohydrate only.54,55
Saunders et al also compared the effects
of a 6% carbohydrate beverage with a
6% carbohydrate/1.8% protein
hydrosylate beverage taken during and
immediately after a 60 km simulated time
trial on plasma CPK levels as well as
muscle soreness ratings 24 hours
postexercise.56 Plasma CPK and ratings
of muscle soreness were significantly
increased compared to pre-exercise
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levels in the carbohydrate only treatment,
but no significant increases were found
when the combination beverage was
While the early research of Saunders
and colleagues54-56 suggested that the
addition of protein was in some way
protective against muscle damage and
soreness 24 hours postexercise, it was
not evident if this effect was due to the
protein itself or the additional energy
provided in the nonisocaloric beverage.
To address this question, Valentine et al
investigated the effects of carbohydrate
and carbohydrate/protein beverages
matched for both carbohydrate and
caloric content on plasma CPK and
myoglobin.62 Participants ingested 250
mL of placebo, carbohydrate (7.75%),
carbohydrate plus carbohydrate (9.69%),
and carbohydrate/protein (7.75%
carbohydrate and 1.94% protein) every
15 minutes during cycling exercise at
75% Vo2max to exhaustion. Time to
exhaustion did not differ between the 2
isocaloric, higher calorie treatments;
however, plasma CPK and myoglobin
were lower in the carbohydrate/protein
treatment, and leg strength, assessed 24
hours postexercise, was higher in the
carbohydrate/protein treatment. This
suggests that improvements in
postexercise muscle damage occurs
independent of caloric content and is
likely related to the addition of protein.62
Summary of the Energy
Phase. Carbohydrate is an essential fuel
source for exercise, and ingesting
carbohydrate before as well as during
endurance exercise can improve exercise
performance, delay the onset of fatigue,
and protect immune system function. A
supplement containing a mixture of
carbohydrate sources can increase time
to exhaustion compared to ingestion of a
single carbohydrate source, presumably
by sparing endogenous carbohydrate
stores. The addition of protein to a
carbohydrate supplement has been
found to reduce muscle damage that
occurs after intense endurance as well as
resistance exercise. It also may improve
exercise performance beyond that of
carbohydrate alone, although this has not
been a universal finding. The benefits of
supplementation are relevant for both
endurance exercise and resistance
training and apply to both recreational
exercisers and elite athletes. A practical
strategy for supplementation during
exercise is to ingest a beverage
containing 3.0% to 6.0% carbohydrate
every 15 to 20 minutes during prolonged
exercise (Figure 1). One should also
consider the addition of 1.0% to 1.5%
protein to their supplement.
The Anabolic Phase
It has often been said that breakfast is
the most important meal of the day, and
recent research appears to support this
claim. However, a claim can be made
that the second most important meal of
the day is the postexercise supplement.
Immediately after an intense exercise
training session the body is in a
catabolic state. Blood insulin is low,
cortisol and other catabolic hormones
are elevated, muscle and liver glycogen
levels are reduced or depleted, muscle
protein breakdown is elevated, and
substrate availability is low. Once
exercise has ceased, this catabolic state
will prevail for many hours unless
actions are taken to shift the body into a
predominately anabolic state. To make
this metabolic shift, nutrient intervention
is required.
The exercised skeletal muscle is very
responsive to nutrient intervention
postexercise. When carbohydrate and
protein are ingested in the minutes
post-exercise, the glucose and amino
acids derived from these macronutrients
initiate the shift to an anabolic state by
raising blood insulin levels, lowering
cortisol and other catabolic hormones,
and increasing substrate availability.
Because muscle is highly insulin sensitive
postexercise, this ensures the rapid
uptake of blood glucose and amino
acids, which promotes muscle glycogen
and protein synthesis, while also
reducing protein breakdown. Since
insulin sensitivity declines with time, the
effectiveness of nutrient intervention will
also decline. Consuming the appropriate
types and amounts of nutrients
immediately to 45 minutes after an acute
bout of exercise can increase the rate of
muscle glycogen storage, reduce muscle
damage, increase protein accretion, and
speed exercise recovery. When
incorporated into an exercise-training
program, this results in greater training
Muscle Glycogen Storage. Although
muscle glycogen represents less than 4%
of the total energy stores in the body, it
is the most important fuel source during
prolonged moderate-to-high exercise,
high-intensity interval exercise, and
resistance exercise. Moreover, research
suggests that the activity of a number of
metabolic enzymes including those
controlling glucose transport and protein
metabolism is influenced by the
glycogen level of the muscle. For these
reasons, the restoration of muscle
glycogen is paramount in the exercise
recovery process.
Timing of carbohydrate
supplementation. Postexercise muscle
glycogen synthesis occurs more rapidly
when carbohydrate is consumed
immediately after exercise as opposed
to waiting several hours.65 Muscle
glycogen synthesis rates range between
5 and 7 µmol g−1 wet wt h−1 over 4
hours of recovery when carbohydrate
is consumed immediately postexercise,
and these rates can be maintained for 6
to 8 hours by continuing carbohydrate
supplementation at 2-hour intervals.65-67
Moreover, synthesis rates have been
reported to be in excess of 15 µmol
g−1 wet wt h−1 during the first 30 to 40
minutes after exercise.68,69 Delaying
supplementation for 2 hours reduces
the rates of muscle glucose uptake and
glycogen synthesis by 50% or more
and occurs despite normal increases in
blood glucose and insulin levels.65,70 If
carbohydrate is not adequately supplied
postexercise, the rate of muscle glycogen
synthesis can be extremely low.66
Therefore, providing a carbohydrate
supplement soon after exercise has the
added benefit of starting the muscle
glycogen recovery process immediately,
thereby maximizing the effective
recovery time.
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The frequency and amount of
carbohydrate supplementation can have
dramatic effects on the rate of glycogen
storage. Ivy et al found that
supplementing at 2-hour intervals with
1.2 to 1.5 g glucose kg−1 body mass
increased the glycogen synthesis rate up
to 5 to 7 µmol g−1 wet wt h−1.66 When
supplements exceeded 1.5 g glucose kg−1
body mass, the synthesis rate did not
increase further. However, research
suggests that faster rates of synthesis can
be obtained during the immediate hours
postexercise with greater amounts of
carbohydrate if frequency of
supplementation is also increased.71-74
For example, Jentjens et al72 and van
Loon et al74 reported synthesis rates of 8
to 10 µmol g−1 wet wt h−1 when subjects
were provided 1.2 g glucose kg−1 body
mass h−1 at 30-minute intervals over 3 to
5 hours of recovery. Increasing the
amount of carbohydrate ingested to 1.6 g
kg−1 body mass h−1, however, did not
have an additional benefit.75 While
muscle glycogen synthesis can be
maximized with carbohydrate intake of
approximately 1.2 g kg−1 body mass h−1
provided in 15- to 30-minute increments,
this amount of carbohydrate is excessive
and the frequency of supplementation
Addition of protein to a carbohydrate
supplement. Many investigators have
demonstrated that the addition of protein
to a carbohydrate supplement can
significantly enhance the rate of muscle
glycogen synthesis during the first 4
hours of recovery.69,76-79 However, not
all studies support these findings.72-75
The differences in findings can most
likely be attributed to differences in
experimental design, including frequency
of supplementation, and the amount
and type of carbohydrate and protein
provided. The evidence, however,
is considerable that the addition of
protein to a carbohydrate supplement
will increase the efficiency of muscle
glycogen storage when the amount
of carbohydrate ingested is below the
threshold for maximal glycogen synthesis
or when feeding intervals are 1 hour
or more apart.69,76-79 In fact, maximum
rates of muscle glycogen synthesis
can be achieved with substantially less
carbohydrate and reduced frequency
of supplementation when protein
and carbohydrate are coingested.
Furthermore, a carbohydrate/protein
supplement has the added benefits of
reducing muscle damage and soreness
and increasing protein synthesis.
Muscle Damage and Soreness. Muscle
damage during exercise occurs from the
mechanical stress placed on the muscle
fibers and the catabolic hormonal
environment that increases muscle
protein breakdown postexercise.80 The
longer nutrient supplementation is
delayed postexercise, the longer this
catabolic state prevails, leading to
increased muscle damage, inflammation,
and soreness.
Acute supplementation. Roy et al
found that consuming a carbohydrate
supplement (1 g kg−1 body mass)
immediately after resistance exercise
reduced 3-methylhistidine excretion and
urea nitrogen during the first 10 hours
of recovery.81 These results suggest that
adequate carbohydrate supplementation
can decrease myofibrillar protein
breakdown and limit muscle damage.
Etheridge et al reported that consuming
100 g of protein immediately after 30
minutes of downhill running prevented
a decline in maximal quadriceps
strength and power output during a
72-hour recovery period. However, the
supplement had no effect on limiting
the increase in blood markers of
muscle damage or ratings of muscle
soreness.82 Cockburn et al compared
the effects of water, a carbohydrate
sports drink, milk, and a milk-based
carbohydrate/protein supplement on
muscle soreness, isokinetic muscle
performance, and plasma CPK and
myoglobin concentrations. At 48 hours
postexercise, milk and milk-based
carbohydrate/protein supplementation
had attenuated the decrease in isokinetic
muscle performance and increases in
CPK and myoglobin relative to water
and the carbohydrate sports drink.83 In
a subsequent study, these researchers
found that consuming the milk-based
carbohydrate/protein supplement
postexercise as compared to pre-
exercise limited development of muscle
soreness and better maintained muscle
strength over 48 hours of recovery.84
However, White et al reported that
supplementing with carbohydrate/
protein before or after eccentric
quadriceps contractions on an isokinetic
dynamometer had no effect on muscle
damage, soreness, or performance
up to 96 hours postexercise.85 Also,
Wojcik and colleagues reported that
eccentric exercise increased muscle
protein breakdown as indicated by
urinary 3-methylhistidine levels and
increased plasma IL-6 with no effect of
carbohydrate or carbohydrate/protein
supplementation. Quadriceps isokinetic
peak torque was depressed similarly for
all groups 24 and 72 hours postexercise
as well.86 Of course, the differences in
findings may be accounted for by the
type of exercise used to induce muscle
damage, the degree of muscle damage
imposed, the type of supplement
provided, and the lack of controlling
participants’ dietary intake outside of the
experimental trials.
Chronic supplementation. The
benefits of carbohydrate/protein
supplement over subsequent days of
training have also been investigated.
Luden et al provided a carbohydrate or
carbohydrate/protein beverage to 23
runners immediately after each training
session for 6 days before a cross-
country race. After a 21-day washout
period, subjects repeated the protocol
with the alternate beverage. Although
postintervention CPK and soreness were
significantly lower after carbohydrate/
protein supplementation than after
carbohydrate supplementation, running
performance did not differ between
treatments. However, it was noted that
the runners with the highest training
mileage had the most improvement in
race performance after the carbohydrate/
protein supplement.87 Chronic
carbohydrate/protein supplementation
of US Marine recruits was found to be of
benefit to their health during 54 days of
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basic training.88 Recruits were randomly
assigned to placebo, carbohydrate,
or carbohydrate/protein treatment
groups. Compared with placebo and
carbohydrate groups, the carbohydrate/
protein supplementation group had
an average of 33% fewer total medical
visits, 28% fewer visits due to bacterial/
viral infections, 37% fewer visits due to
muscle/joint problems, and 83% fewer
visits due to heat exhaustion. Muscle
soreness immediately postexercise
was reduced by carbohydrate/protein
supplementation compared with placebo
and carbohydrate groups on both days
34 and 54.88
In summary, postexercise carbohydrate/
protein supplementation may be more
effective than carbohydrate only in
reducing indicators of muscle damage
and soreness. This may be especially
significant during periods of intense,
chronic exercise training.
Effect on Protein Accretion. Protein
accretion is determined by the difference
in protein synthesis and degradation.
Following an acute bout of exercise,
protein synthesis increases; however, net
protein balance is negative as the
increase in protein synthesis is offset by
increased protein breakdown.89 Ingestion
of amino acids or protein postexercise,
however, stimulates protein synthesis,
resulting in a positive net protein
Acute effect. The first study to
demonstrate the importance of nutrient
timing on muscle protein synthesis was
conducted by Okamura and colleagues.92
Dogs were exercised by treadmill
running and infused with a glucose/
amino acid mixture immediately or 2
hours postexercise. When the dogs were
infused immediately postexercise, muscle
protein synthesis increased significantly
within 15 minutes. When infusion of the
mixture was delayed for 2 hours, there
was no increase in protein synthesis;
furthermore, when the infusion was
started after the 2-hour delay, the
synthesis rate was significantly lower
than observed when infusion occurred
immediately postexercise. It was
concluded that stimulation of protein
accretion is better served by provision
of nutrients sooner rather than later
postexercise.92 This view was supported
by the research of Levenhagen et al.70
Cyclists were provided a carbohydrate/
protein supplement immediately or 3
hours after cycling at moderate intensity
for 1 hour. Whole body and muscle
protein synthesis were determined
during the 3 hours after supplementation.
When the supplement was provided
immediately postexercise, whole body
protein synthesis was 12% higher and
leg muscle protein synthesis 300% higher
than when the supplement was delayed.
Importantly, positive protein balance
was only reached when supplementation
occurred immediately post-exercise.70
Whether there is an advantage to
nutritional supplementation within the
first hour after exercise has been recently
challenged.93 It has been pointed out
that the rate of protein synthesis was the
same when a supplement composed of 6
g of an essential amino acid (EAA)
mixture and 36 g of carbohydrate was
provided either 1 or 3 hours after
resistance exercise.94 It was also reported
by Tipton et al that immediate pre-
exercise ingestion of an EAA/
carbohydrate solution resulted in a
significantly greater and more sustained
muscle protein synthesis response
compared to its immediate postexercise
ingestion.95 Moreover, the effect of an
acute bout of exercise on muscle protein
synthesis has been found to last for
several days.96,97
A closer evaluation of these studies,
however, shows they do not refute or
diminish the importance of
supplementation in the first hour
postexercise. First, Fujita et al found that
supplementing 1 hour before exercise
with an EAA/carbohydrate supplement
did not result in enhanced postexercise
muscle protein synthesis.98 Second,
Tipton et al later reported no significant
difference in net muscle protein
synthesis postexercise when 20 g of
whey was consumed immediately before
versus 1 hour postexercise.99 Third, when
the effect of timing of nutrient
supplementation on protein synthesis
postexercise is evaluated, the supplement
ingested closest in time to the exercise
generally has the greatest impact. For
example, the increases in muscle protein
synthesis reported by Phillips et al at 3,
24, and 48 hours after exercise were
112%, 65%, and 34%, respectively.97
Finally, there are few studies that actually
compare the response of
supplementation immediately or within
the first 45 minutes postexercise with
delaying supplementation for several
hours as evaluated by Okamura et al92
and Levenhagen et al.70 In summary,
most acute exercise studies clearly
support supplementation soon after
exercise for optimal stimulation of
protein synthesis and protein accretion.
Chronic effect. Results from a
number of exercise training studies using
various forms of exercise and subject
populations support the use of early
postexercise nutrient intervention to
enhance training adaptation. Suzuki et
al investigated the effect of meal timing
after exercise on body composition in 20
male rats assigned to groups fed either
immediately or 4 hours postexercise.
Resistance exercise (squatting) was
conducted 3 days per week for 10
weeks. At the completion of training,
body weight was comparable between
the groups. However, hind limb muscle
weight was 6% higher and adipose tissue
weight 24% lower in rats fed immediately
after exercise compared with rats fed 4
hours postexercise.100 One of the first
human studies addressing the effect of
nutrient timing on training adaptation
corroborated these results in elderly
men.101 Esmarck et al investigated
the effects of nutrient timing in 13
men (74 ± 1 years) who completed a
12-week resistance-training program
while receiving a carbohydrate/protein
supplement immediately after or 2 hours
after each exercise session. Subjects
receiving the supplement immediately
postexercise had a significant increase
in fat-free mass, cross-sectional
area of the quadriceps femoris, and
mean muscle fiber area, whereas no
significant increases in these parameters
were observed for subjects receiving
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supplementation 2 hours postexercise.
Increases in dynamic and isokinetic
muscle strength were also greater in
subjects supplemented immediately
Cribb and Hayes demonstrated the
efficacy of nutrient timing in young
resistance-trained men. Their exercise
program consisted of 12 weeks of
resistance training before
supplementation started, followed by 10
more weeks of resistance training after
onset of supplementation. The
supplement consisted of a mixture of
carbohydrate, protein, and creatine and
was provided immediately before and
after exercise in one group and before
breakfast and late evening before sleep
in a second group. At the completion of
training, the subjects that received the
supplement pre- and postexercise had a
100% greater increase in lean body mass
and a 33% greater increase in the
cross-sectional area of the IIa and IIx
muscle fibers from the vastus lateralis
than subjects receiving the supplement at
the beginning and end of the day.
Furthermore, improvements in strength
were significantly greater in subjects
supplemented immediately pre- and
postexercise.102 Similar results were
found by Hulmi et al.103 These
investigators provided protein (15 g of
whey) or nonenergetic placebo to
subjects immediately before and after
each resistance exercise session. Exercise
sessions were performed twice per week
over 21 weeks. Protein supplementation
increased muscle cross-sectional area
and altered muscle mRNA expression in
a manner advantageous for muscle
Supplementation during exercise has
also been found to improve training
adaptation to resistance exercise. Bird et
al conducted a 12-week resistance
exercise-training program in which
supplementation (6% carbohydrate, 6 g
EAA, 6% carbohydrate + 6 g EAA, or
placebo) was provided throughout each
exercise session.104 Bird et al reported
the carbohydrate/EAA supplementation
increased lean body mass and the
cross-sectional areas of type I, IIa, and
IIb muscle fibers compared with placebo
and reduced myofibrillar protein
breakdown as indicated by a reduced
urinary excretion of 3-methylhistidine 48
hours after the last exercise session.
Interestingly, the provision of
carbohydrate and EAA separately
improved body composition and muscle
fiber cross-sectional area relative to
placebo, but these improvements were
not as advantageous as those seen with
the carbohydrate/EAA supplement.104
These results support the additive effect
of carbohydrate and protein
supplementation on protein accretion.
Only a few studies have investigated
the effects of nutrient timing on
adaptation to aerobic exercise training.
Ferguson-Stegall et al compared the
effects of a carbohydrate/protein
supplement (low-fat chocolate milk),
isocaloric carbohydrate supplement, and
a calorie-free placebo on training
adaptation occurring over 4.5 weeks of
exercise training.105 Subjects cycled 60
min d−1, 5 d−1 wk−1 at 75% to 85% of
Vo2max. Supplements were ingested
immediately and 1 hour after each
exercise session. No supplementation
was allowed for 1 hour after the final
supplement was provided. Vo2max was
improved by 12.5% with carbohydrate/
protein supplementation, and this
improvement was twice as great as
occurred when consuming carbohydrate
only or placebo.105 Okazaki and
colleagues also found that carbohydrate/
protein supplementation provided
immediately after daily cycling exercise
in older male subjects increased Vo2max
compared to a placebo.106 Vo2max
increased 3.3% with placebo
supplementation and 6.8% with
carbohydrate/protein supplementation.
Significant increases in stroke volume
and plasma volume only occurred
following carbohydrate/protein
supplementation.106 Taken together, these
findings suggest a faster rate and
magnitude of training adaptation when
carbohydrate and protein are coingested
after endurance exercise.
Ferguson-Stegall et al also reported that
carbohydrate/protein supplementation in
the form of low-fat chocolate milk
resulted in greater improvements in body
composition.105 This result is supportive
of the findings of Josse and colleagues,
who studied the effects of daily exercise
and a hypoenergetic diet varying in
protein and calcium content from dairy
foods on the composition of weight lost
over 16 weeks in premenopausal,
overweight, and obese women.107
Participants were randomly assigned to a
high protein, high dairy (HPHD; total
protein, 1.33 ± 0.04 g/kg d−1), adequate
protein, medium dairy (APMD; total
protein, 0.84 ± 0.02 g/kg d−1), or
adequate protein, low dairy (APLD; total
protein, 0.72 ± 0.02 g/kg d−1) treatment
group. The quantity of total dietary
protein and dairy food-source protein
was 30% and 15%, 15% and 7.5%, and
15% and less than 2% for the HPHD,
APMD, and APLD groups, respectively.
Dairy protein consumption for each
group was controlled by the number of
supplements per day. Weight loss was
the same for all groups; however, fat loss
during the last 8 weeks of treatment was
greater in the HPHD group than in the
APMD and APLD groups. Also, the
HPHD group demonstrated a significant
gain in lean mass, whereas the APLD and
APMD groups lost lean mass. These
findings highlight the importance of
protein supplementation in exercise
programs designed for weight
Not all studies have found that nutrient
supplementation postexercise results in a
faster training adaptation. Verdijk et al
trained 2 groups of elderly men (72 ± 2
y) for 3 d wk−1 for 12 weeks.108 One
group ingested 10 g of protein before
and immediately after each exercise
session, and the other group received a
placebo. All training occurred 90 minutes
after a standardized breakfast. Leg
strength and quadriceps mass increased
significantly with no difference between
groups. The investigators concluded that
protein supplementation immediately
before and after exercise does not further
augment the increase in skeletal muscle
mass and strength after prolonged
resistance-type exercise training in
healthy elderly men when their daily
protein consumption is normal.108 While
a well-controlled study, it has notable
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limitations. The amount of protein
provided was rather small, as it has been
reported that a much higher amount of
protein is required to maximize
postexercise protein synthesis in elderly
men.109-111 The exercise sessions were
also carried out only 90 minutes after
breakfast. It is highly likely that nutrients
from breakfast were still being
metabolized during and following the
exercise sessions in both the placebo
and protein groups and therefore
prevented a true evaluation of effects of
protein supplement ingestion
immediately before and after exercise on
the adaptive response.
Hoffman et al112 and Erskine et al113
also found no improvement in training
adaptation when supplementing with
protein around each exercise session.
Hoffman et al studied the effect of 10
weeks of protein supplement timing on
strength, power, and body composition
in resistance-trained men.112 Erskine et al
evaluated the effect of protein
supplementation over 12 weeks of elbow
flexor resistance exercise. Participants
were randomly assigned to receive
protein or placebo before and after each
exercise session.113 However, in neither
the Hoffman et al112 nor Erskine et al113
studies was nutrient consumption
controlled after the exercise training
sessions. In summary, most investigations
demonstrate that supplementation that
ensures appropriate nutrient levels within
the first 45 minutes postexercise results
in the greatest adaptive response to
endurance as well as resistance exercise
Appropriate postexercise nutrient
supplement. Both amino acid and
protein supplementation postexercise
stimulates protein synthesis. However,
the type and amount of these nutrients
affects the magnitude of response.
Several studies have reported that only
the EAA are necessary for stimulation of
muscle protein synthesis.114,115 Of these,
leucine appears to be of most importance
because of its ability to activate the
mTOR signaling pathway, which controls
mRNA translation.116 Whey protein, which
comprises about 20% of milk protein,
has a high leucine content and is rapidly
digested. Milk protein has been found to
promote greater muscle protein accretion
than soy protein after exercise.117
Moreover, isolated whey protein was
found to stimulate muscle protein
synthesis to a greater degree than casein
and soy protein.118 There are few studies
comparing protein mixtures. However,
Riedy et al recently reported that a blend
of whey and soy protein prolonged the
elevation in blood amino acid levels
after ingestion relative to whey protein
alone and produced a greater total
muscle protein synthesis.119 However,
simply maintaining an elevated blood
amino acid profile does not guarantee
that protein synthesis will continue,120,121
suggesting that more research needs
to be conducted to determine if
combinations of fast and slow digesting
proteins will have an overall greater
effect on protein synthesis and accretion
(Figure 2).
Carbohydrate ingestion has also been
found to stimulate protein synthesis
postexercise, most likely as a result of
increased insulin secretion.81,122,123 Insulin
is also a strong inhibitor of muscle
protein breakdown,91 and many studies
suggest that the combination of
carbohydrate and either protein or EAA
can have an additive effect on muscle
protein synthesis and net whole body
protein balance.75,123,124 Chronic training
studies comparing carbohydrate plus
protein or EAA supplementation with
protein supplementation alone also
support the superiority of a combination
of macronutrients to stimulate recovery
and training adaptation.104-106 The
amount of supplementation is also of
importance. Cuthbertson and colleagues
have estimated that consuming 10 g of a
mixture of EAA could maximize muscle
protein synthesis,125 and Moore et al
reported that 20 g of whey protein
provided soon after resistance exercise
maximized muscle protein synthesis in
young adults.126 However, for older
individuals, the requirement may be as
high as 40 g.109-111 These results have
been used to make recommendations
regarding postexercise protein
supplementation. However, the rate of
protein accretion is also affected by the
rate of protein breakdown. Recently,
Deutz and Wolfe provided strong
evidence that with increased
carbohydrate/protein intake, there is a
progressively greater insulin response,
resulting in a proportional inhibition of
muscle protein breakdown and increased
protein accretion.127 If true, this suggests
that there is no practical upper limit to
the anabolic response to protein when
combined with carbohydrate in a
supplement or in the context of a meal.
The Adaptation Phase
The adaptation phase represents the 4
to 6 hours after the effects of the initial
postexercise supplement have dissipated.
As described earlier, a rapid rate of
muscle glycogen storage that follows
postexercise supplementation can be
maintained up to 6 to 8 hours with
periodic carbohydrate feedings.65-67 A
similar pattern is likely to occur with
protein synthesis. Phillips et al found that
supplementing with a carbohydrate/
protein supplement 24 and 48 hours
Figure 2.
The relative Increase and Duration
in Muscle Protein Synthesis
(MPS) Following Postexercise
Supplementation With Different
Proteins or Protein Mixtures.
Milk protein is approximately 20% whey
and 80% casein. The protein blend was
50% protein from sodium caseinate, 25%
protein from whey isolate, and 25% protein
from soy isolate.11 Results from References
117, 118, and 119 were used to generate
Figure 2.
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after exercise resulted in an increase in
muscle protein synthesis, although the
response was not as high as when
supplementing 3 hours postexercise.97
Continuously maintaining high blood
amino acid levels, however, does not
mean that protein synthesis will be
sustained as protein synthesis is only
elevated for about 1 to 2 hours following
carbohydrate/amino acid
supplementation.94,128 Likewise, raising
blood amino acid levels to 1.7-fold above
basal level via intravenous infusion
increases muscle protein synthesis within
0.5 hours of infusion onset; however,
despite maintaining elevated blood
amino acid levels with continuous
infusion the rate of muscle protein
synthesis declines to near baseline level
within 2 hours.121
Recently, West et al provided whey
protein either as a single 25-g bolus or as
repeated, small, “pulsed” 2.5-g protein
drinks every 20 minutes for 200 minutes
in a nonexercised state and after
resistance exercise.129 Providing the
protein as a bolus increased blood EAA
levels above those when pulsing the
supplementation the first 60 minutes
postexercise. Pulsed supplementation
resulted in a smaller but sustained
increase in aminoacidemia that remained
elevated above that produced by the
bolus supplement from 180 to 220
minutes after exercise. Despite an
identical net area under the essential
amino acid curve, muscle protein
synthesis was elevated to a greater extent
after bolus supplementation than after
pulsed supplementation, and the
increased rate of synthesis following
bolus supplementation was related to
greater activation of signaling proteins in
the mTOR signaling pathway.129
Based on these results, we propose that
supplementing at 2 to 3 hour intervals
postexercise will maintain a relatively
rapid rate of muscle glycogen storage
and protein synthesis if supplementation
starts soon after the completion of
exercise. While the supplement must
contain sufficient amounts of
carbohydrate and protein, they need not
to be as high as used to initiate the
recovery process. It is important to note
that from a practical perspective, not all
feedings must be supplements. Exercise
training and nutrient supplementation
can be intermixed with regular daily
meals and snacks. Table 1 provides
eating schedules that accommodate
several different exercise-training
schedules. Even a snack before retiring
to bed can be an effective strategy to
optimize protein accretion.
Late night snacking is not normally
recommended. Research clearly shows
that obese individuals tend to skip
breakfast and eat the majority of their
daily calories from late afternoon to
bedtime.130-132 However, if one is trying
to build muscle and increase lean body
mass, a low-calorie protein supplement
before bedtime may help. Beelen et al
found that ingestion of a carbohydrate/
protein supplement following a late
afternoon resistance exercise session
increased protein synthesis for
approximately 2 hours.133 However,
protein synthesis was found to be
remarkably low during the sleeping
Table 1.
Examples of Possible Timing of Workouts, Supplements, and Meals for 3 Different
Daily Training Schedules.a
Daily Workout Schedules
Time of Day AM Workout PM Workout 2×/Day Workouts
7:00 am Breakfast Breakfast Breakfast
8:00 am
9:00 am Workout Workout
10:00 am CP supplement CP supplement
11:00 am
12:00 pm Lunch Lunch Lunch
1:00 pm
2:00 pm
3:00 pm CP snack CP snack
4:00 pm Workout
5:00 pm Workout CP supplement
6:00 pm Dinner CP supplement
7:00 pm Dinner
8:00 pm Protein snack Dinner
9:00 pm
10:00 pm Protein snack Protein snack
aFollowing prolonged, intense workouts, the postexercise supplement should provide sufficient car-
bohydrate to maximize muscle glycogen storage during the first hours of recovery (1.0 to 1.5 g kg−1
body wt) and contain between 20 and 30 g protein. For light to moderate intensity workouts, a light
carbohydrate (0.3 to 0.8 g kg−1 body wt)/protein (10 to 12 g protein) supplement is recommended.
Between-meal snacks should be approximately a 1:1 ratio of carbohydrate/protein and contain 100
to 200 kcal. The bedtime snack should contain approximately 20 g protein with minimal carbohy-
drate and fat. CP, carbohydrate protein.
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hours. Res et al134 repeated the study by
Beelen et al,133 but provided a 40-g
casein supplement or placebo 30
minutes before bedtime. When the
casein supplement was provided, whole
body protein synthesis was increased
throughout the night and net protein
balance remained positive. In addition,
muscle protein synthesis also remained
Nutrient timing can have a dramatic
effect on exercise performance, recovery,
and training adaption. Carbohydrate
supplementation provided in the hours
before exercise can improve exercise
performance, and carbohydrate intake
during exercise can delay the onset of
fatigue and protect immune function.
Research suggests that the addition of
protein to an exercise supplement may
be more efficacious than carbohydrate
alone, and carbohydrate/protein
supplementation during exercise has the
added benefit of attenuating exercise-
induced muscle damage and soreness.
Carbohydrate/protein supplementation
immediately postexercise will significantly
increase the rate of muscle glycogen
synthesis, while delaying supplementation
for several hours will significantly slow
the rate of glycogen synthesis and its rate
of recovery. Supplementing with protein
or EAA postexercise will increase protein
synthesis and accretion, but again the
combination of carbohydrate plus protein
or EAA appears to be more efficacious. If
postexercise supplementation is
performed routinely and with the
appropriate protein/carbohydrate
mixture, it can have a significant
beneficial influence on body composition
and rate of training adaptation. The
principles of nutrient timing are relative
easy to implement and apply to
recreational exercisers and elite athletes
1. Ivy J, Portman R. Nutrient Timing: The
Future of Sports Nutrition. North Bergen,
NJ: Basic Health Publications; 2004.
2. Sherman W, Peden M, Wright D.
Carbohydrate feedings 1 h before exercise
improves cycling performance. Am J Clin
Nutr. 1991;54:866-870.
3. Bergström J, Hermansen L, Hultman
E, Saltin B. Diet, muscle glycogen and
physical performance. Acta Physiol Scand.
4. Hermansen L, Hultman E, Saltin B. Muscle
glycogen during prolonged severe exercise.
Acta Physiol Scand. 1967;71:129-139.
5. Walker JL, Heigenhauser GJF, Hultman
E, Spriet LL. Dietary carbohydrate,
muscle glycogen content, and endurance
performance in well-trained women. J Appl
Physiol. 2000;88:2151-2158.
6. Coyle EF, Coggan AR, Hemmert MK, Lowe
RC, Walters TJ. Substrate usage during
prolonged exercise following a preexercise
meal. J Appl Physiol. 1985;59:429-433.
7. Francescato M, Puntel I. Does a pre-
exercise carbohydrate feeding improve a
20-km cross-country ski performance? J
Sports Med Phys Fitness. 2006;46:248-256.
8. Gleeson M, Maughan R, Greenhaff P.
Comparison of the effects of pre-exercise
feeding of glucose, glycerol and placebo
on endurance and fuel homeostasis in
man. Eur J Appl Physiol Occup Physiol.
9. Karamanolis I, Tokmakidis S. Effects of
carbohydrate ingestion 15 min before
exercise on endurance running capacity.
Appl Physiol Nutr Metab. 2008;33:441-449.
10. Okano G, Takeda H, Morita I, Katoh M, Mu
Z, Miyake S. Effect of pre-exercise fructose
ingestion on endurance performance in fed
men. Med Sci Sports Exerc. 1988;20:105-109.
11. Foster C, Costill D, Fink W. Effects of
preexercise feedings on endurance
performance. Med Sci Sports. 1979;11:1-5.
12. Chryssanthopoulos C, Williams C, Wilson
W, Asher L, Hearne L. Comparison
between carbohydrate feedings before and
during exercise on running performance
during a 30-km treadmill time trial. Int J
Sport Nutr. 1994;4:374-386.
13. Hargreaves M, Costill D, Fink W, King
D, Fielding R. Effect of pre-exercise
carbohydrate feedings on endurance
cycling performance. Med Sci Sports Exerc.
14. Jentjens R, Cale C, Gutch C, Jeukendrup A.
Effects of pre-exercise ingestion of differing
amounts of carbohydrate on subsequent
metabolism and cycling performance. Eur J
Appl Physiol. 2003;88:444-452.
15. Mitchell J, Braun W, Pizza F, Forrest
M. Pre-exercise carbohydrate and fluid
ingestion: influence of glycemic response
on 10-km treadmill running performance
in the heat. J Sports Med Phys Fitness.
16. Sparks M, Selig S, Febbraio M. Pre-exercise
carbohydrate ingestion: Effect of the
glycemic index on endurance exercise
performance. Med Sci Sports Exerc.
17. Chryssanthopoulos C, Williams C. Pre-
exercise carbohydrate meal and endurance
running capacity when carbohydrates are
ingested during exercise. Int J Sports Med.
18. Wright DA, Sherman WM, Dernbach AR.
Carbohydrate feedings before, during, or
in combination improve cycling endurance
performance. J Appl Physiol. 1991;71:
19. Bjorkman O, Wahren J. Glucose
homeostasis during and after exercise.
In: Horton ES, Terjung RL, eds. Exercise,
Nutrition, and Energy Metabolism. New
York, NY: MacMillan; 1988:100.
20. Coggan AR, Coyle EF. Reversal of fatigue
during prolonged exercise by carbohydrate
infusion or ingestion. J Appl Physiol.
21. Coggan AR, Coyle EF. Effect of
carbohydrate feedings during high-intensity
exercise. J Appl Physiol. 1988;65:1703-1709.
22. Coyle EF, Hagberg JM, Hurley BF, Martin
WH, Ehsani AA, Holloszy JO. Carbohydrate
feeding during prolonged strenuous
exercise can delay fatigue. J Appl Physiol.
23. Ivy JL, Miller W, Dover V, Goodyear L.
Endurance improved by ingestion of a
glucose polymer supplement. Med Sci
Sports Exerc. 1983;15:466-471.
24. Yaspelkis BB 3rd, Ivy JL. Effect of
carbohydrate supplements and water on
exercise metabolism in the heat. J Appl
Physiol. 1991;71:680-687.
25. Yaspelkis BB 3rd, Patterson JG, Anderla
PA, Ding Z, Ivy JL. Carbohydrate
supplementation spares muscle glycogen
during variable-intensity exercise. J Appl
Physiol. 1993;75:1477-1485.
26. van Loon LJC, Greenhaff PL, Constantin-
Teodosiu D, Saris WHM, Wagenmakers
AJM. The effects of increasing exercise
intensity on muscle fuel utilisation in
humans. J Physiol. 2001;536:295-304.
27. Coyle EF, Coggan AR, Hemmert MK, Ivy
JL. Muscle glycogen utilization during
prolonged strenuous exercise when fed
carbohydrate. J Appl Physiol. 1986;61:
28. Tsintzas OK, Williams C, Boobis L,
Greenhaff P. Carbohydrate ingestion and
glycogen utilization in different muscle fibre
types in man. J Physiol. 1995;489:243-250.
at HAMLINE UNIV on October 19, 2014ajl.sagepub.comDownloaded from
vol. 8 no. 4 American Journal of Lifestyle Medicine
29. Wax B, Kavazi A, Brown SP, Webb HE.
Effects of supplemental carbohydrate
ingestion during superimposed
electomyostimulated exercise in elite
weight lifters [published online February
25, 2013]. J Strength Cond Res. doi:10.1519/
30. Haff GG, Schroeder CA, Koch AJ, Kuphal
KE, Comeau MJ, Potteiger JA. The effects
of supplemental carbohydrate ingestion on
intermittent isokinetic leg exercise. J Sports
Med Phys Fitness. 2001;41:216-222.
31. Jentjens RL, Achten J, Jeukendrup AE.
High oxidation rates from combined
carbohydrates ingested during exercise.
Med Sci Sports Exerc. 2004;36:1551-1558.
32. Jentjens RLPG, Venables MC, Jeukendrup
AE. Oxidation of exogenous glucose,
sucrose, and maltose during prolonged
cycling exercise. J Appl Physiol.
33. Jeukendrup AE. Carbohydrate intake
during exercise and performance.
Nutrition. 2004;20:669-677.
34. Currell K, Jeukendrup AE. Superior
endurance performance with ingestion of
multiple transportable carbohydrates. Med
Sci Sports Exerc. 2008;40:275-281.
35. Ferguson-Stegall L, McCleave EL, Ding
Z, et al. The effect of a low carbohydrate
beverage with added protein on cycling
endurance performance in trained athletes.
J Strength Cond Res. 2010;24:2577-2586.
36. Gleeson M. Interleukins and exercise. J
Physiol. 2000;529:1.
37. Nieman DC. Immune response to heavy
exertion. J Appl Physiol. 1997;82:
38. Nieman DC. Exercise, upper respiratory
tract infection, and the immune system.
Med Sci Sports Exerc. 1994;26:128-139.
39. Pedersen BK, Hoffman-Goetz L. Exercise
and the immune system: regulation,
integration, and adaptation. Physiol Rev.
40. Nieman DC, Davis JM, Henson DA, et
al. Carbohydrate ingestion influences
skeletal muscle cytokine mRNA and plasma
cytokine levels after a 3-h run. J Appl
Physiol. 2003;94:1917-1925.
41. Nieman DC, Henson DA, McAnulty SR, et
al. Vitamin E and immunity after the Kona
Triathlon World Championship. Med Sci
Sports Exerc. 2004;36:1328-1335.
42. Nieman DC, Henson DA, Davis JM, et al.
Quercetin’s influence on exercise-induced
changes in plasma cytokines and muscle
and leukocyte cytokine mRNA. J Appl
Physiol. 2007;103:1728-1735.
43. Nieman DC, Henson DA, Gross SJ, et al.
Quercetin reduces illness but not immune
perturbations after intensive exercise. Med
Sci Sports Exerc. 2007;39:1561-1569.
44. Shing CM, Peake J, Suzuki K, et al. Effects
of bovine colostrum supplementation
on immune variables in highly trained
cyclists. J Appl Physiol. 2007;102:
45. Nieman DC, Fagoaga OR, Butterworth
DE, et al. Carbohydrate supplementation
affects blood granulocyte and monocyte
trafficking but not function after 2.5 h or
running. Am J Clin Nutr. 1997;66:153-159.
46. Nieman DC, Henson DA, Davis JM, et
al. Blood leukocyte mRNA expression
for IL-10, IL-1Ra, and IL-8, but not IL-6,
increases after exercise. J Interferon
Cytokine Res. 2006;26:668-674.
47. Scharhag J, Meyer T, Auracher M, Gabriel
HH, Kindermann W. Effects of graded
carbohydrate supplementation on the
immune response in cycling. Med Sci Sports
Exerc. 2006;38:286-292.
48. Febbraio MA, Hiscock N, Sacchetti M,
Fischer CP, Pedersen BK. Interleukin-6 is a
novel factor mediating glucose homeostasis
during skeletal muscle contraction.
Diabetes. 2004;53:1643-1648.
49. Nehlsen-Cannarella SL, Fagoaga OR,
Nieman DC, et al. Carbohydrate and the
cytokine response to 2.5 h of running. J
Appl Physiol. 1997;82:1662-1667.
50. Nieman DC, Henson DA, Smith LL, et al.
Cytokine changes after a marathon race. J
Appl Physiol. 2001;91:109-114.
51. Nieman DC. Influence of carbohydrate
on the immune response to intensive,
prolonged exercise. Exerc Immunol Rev.
52. Ivy JL, Res PT, Sprague RC, Widzer
MO. Effect of a carbohydrate-protein
supplement on endurance performance
during exercise of varying intensity. Int J
Sport Nutr Exerc Metab. 2003;13:382-395.
53. McCleave E, Ferguson-Stegall L, Ding Z, et
al. A low carbohydrate-protein supplement
improves endurance performance in
female athletes. J Strength Cond Res.
54. Saunders M, Kane M, Todd K. Effects of a
carbohydrate-protein beverage on cycling
endurance and muscle damage. Med Sci
Sports Exerc. 2004;36:1233-1238.
55. Saunders MJ, Luden ND, Herrick JE.
Consumption of an oral carbohydrate-
protein gel improves cycling endurance
and prevents postexercise muscle damage.
J Strength Cond Res. 2007;21:678-684.
56. Saunders MJ, Moore RW, Kies AK, Luden
ND, Pratt CA. Carbohydrate and protein
hydrolysate coingestions improvement of
late-exercise time-trial performance. Int J
Sport Nutr Exerc Metab. 2009;19:136-149.
57. Highton J, Twist C, Lamb K, Nicholas C.
Carbohydrate-protein coingestion improves
multiple-sprint running performance. J
Sports Sci. 2013;31:361-369.
58. Nicholas CW, Nuttall FE, Williams C. The
Loughborough Intermittent Shuttle Test: a
field test that simulates the activity pattern
of soccer. J Sports Sci. 2000;18:97-104.
59. Baty JJ, Hwang H, Ding Z, et al. The effect
of a carbohydrate and protein supplement
on resistance exercise performance,
hormonal response, and muscle damage. J
Strength Cond Res. 2007;21:321-329.
60. Osterberg KL, Zachwieja JJ, Smith JW.
Carbohydrate and carbohydrate+protein for
cycling time-trial performance. J Sports Sci.
61. Romano-Ely B, Todd M, Saunders M,
St Laurent T. Effect of an isocaloric
carbohydrate-protein-antioxidant drink on
cycling performance. Med Sci Sports Exerc.
62. Valentine RJ, Saunders MJ, Todd MK, St
Laurent TG. Influence of carbohydrate-
protein beverage on cycling endurance and
indices of muscle disruption. Int J Sport
Nutr Exerc Metab. 2008;18:363-378.
63. van Essen M, Gibala MJ. Failure of protein
to improve time trial performance when
added to a sports drink. Med Sci Sports
Exerc. 2006;38:1476-1483.
64. Saunders M, Todd M, Valentine R, et al.
Inter-study examination of physiological
variables associated with improved
endurance performance with carbohydrate/
protein administration. Med Sci Sports
Exerc. 2006;38:S113-S114.
65. Ivy JL, Katz AL, Cutler CL, Sherman WM,
Coyle EF. Muscle glycogen synthesis after
exercise: effect of time of carbohydrate
ingestion. J Appl Physiol. 1988;64:1480-1485.
66. Ivy JL, Lee MC, Brozinick JT, Reed MJ.
Muscle glycogen storage after different
amounts of carbohydrate ingestion. J Appl
Physiol. 1988;65:2018-2023.
67. Blom PCS, Høstmark AT, Vaage O, Kardel
KR, Mæhlum S. Effect of different post-
exercise sugar diets on the rate of muscle
glycogen synthesis. Med Sci Sports Exerc.
68. Price TB, Rothman DL, Taylor R,
Avison MJ, Shulman GI, Shulman RG.
Human muscle glycogen resynthesis
after exercise: insulin-dependent and
-independent phases. J Appl Physiol.
69. Ivy JL, Goforth HW, Damon BD, McCauley
TR, Parsons EC, Price TB. Early post-
exercise muscle glycogen recovery is
enhanced with a carbohydrate–protein
supplement. J Appl Physiol. 2002;93:
at HAMLINE UNIV on October 19, 2014ajl.sagepub.comDownloaded from
Jul Aug 2014American Journal of Lifestyle Medicine
70. Levenhagen DK, Gresham JD, Carlson MG,
Maron DJ, Borel MJ, Flakoll PJ. Postexercise
nutrient intake timing in humans is critical
to recovery of leg glucose and protein
homeostasis. Am J Physiol Endocrinol
Metab. 2001;280:E982-E993.
71. Doyle JA, Sherman WM, Strauss RL. Effects
of eccentric and concentric exercise on
muscle glycogen replenishment. J Appl
Physiol. 1993;74:1848-1855.
72. Jentjens RL, van Loon LJC, Mann CH,
Wagenmarkers AJM, Jeukendrup AE.
Addition of protein and amino acids
to carbohydrates does not enhance
postexercise muscle glycogen synthesis. J
Appl Physiol. 2001;91:839-846.
73. van Hall G, Shirreffs SM, Calbert JAL.
Muscle glycogen resynthesis during
recovery from cycle exercise: no effect of
additional protein ingestion. J Appl Physiol.
74. van Loon LJC, Saris WHM, Kruijshoop
M, Wagenmakers AJM. Maximizing
postexercise muscle glycogen synthesis:
carbohydrate supplementation and the
application of amino acid or protein
hydrolysate mixtures. Am J Clin Nutr.
75. Howarth KR, Moreau NA, Phillips SM,
Gibala MJ. Coingestion of protein with
carbohydrate during recovery from
endurance exercise stimulates skeletal
muscle proteins synthesis in humans. J Appl
Physiol. 2009;106:1394-1402.
76. Berardi JM, Price TB, Noreen EE, Lemon
PW. Postexercise muscle glycogen
recovery enhanced with a carbohydrate-
protein supplement. Med Sci Sport Exerc.
77. Morifuji M, Kanda A, Koga J, Kawanaka K,
Higuchi M. Post-exercise carbohydrate plus
whey protein hydrolysates supplementation
increases skeletal muscle glycogen level in
rats. Amino Acids. 2010;38:1109-1115.
78. Ruby BC, Gaskill SE, Slivka D, Harger
SG. The addition of fenugreek extract
(Trigonella foenum-graecum) to glucose
feeding increases muscle glycogen
resynthesis after exercise. Amino Acids.
79. Zawadzki KM, Yaspelkis BB, Ivy JL.
Carbohydrate-protein complex increases
the rate of muscle glycogen storage after
exercise. J Appl Physiol. 1992;72:1854-1859.
80. Clarkson PM, Hubal MJ. Exercise-induced
muscle damage in humans. Am J Phys Med
Rehabil. 2002;81(suppl 11):S52-S69.
81. Roy BD, Tarnopolsky MA, MacDougall JD,
Fowles J, Yarasheski KE. Effect of glucose
supplement timing on protein metabolism
after resistance training. J Appl Physiol.
82. Etheridge T, Philp A, Watt PW. A single
protein meal increases recovery of muscle
function following an acute eccentric
exercise bout. Appl Physiol Nutr Metab.
83. Cockburn E, Hayes PR, French DN,
Stevenson E, St Clair Gibson A. Acute
milk-based protein-CHO supplementation
attenuates exercise-induced muscle
damage. Appl Physiol Nutr Metab.
84. Cockburn E, Stevenson E, Hayes PR,
Robson-Ansley P, Howatson G. Effect
of milk-based carbohydrate-protein
supplement timing on the attenuation of
exercise-induced muscle damage. Appl
Physiol Nutr Metab. 2010;35:270-277.
85. White JP, Wilson JM, Austin KG, Greer
BK, St John N, Panton LB. Effect of
carbohydrate-protein supplement timing on
acute exercise-induced muscle damage. J
Int Soc Sports Nutr. 2008;5:5.
86. Wojcik JR, Walber-Rankin J, Smith
LL, Gwazdauskas FC. Comparison of
carbohydrate and milk-based beverages
on muscle damage and glycogen following
exercise. Int J Sport Nutr Exerc Metab.
87. Luden ND, Saunders MJ, Todd MK.
Postexercise carbohydrate-protein-
antioxidant ingestion decreases plasma
creatine kinase and muscle soreness. Int J
Sport Nutr Exerc Metab. 2007;17:109-123.
88. Flakoll PJ, Judy T, Flinn K, Carr C, Finn
S. Postexercise protein supplementation
improves health and muscle soreness
during basic military training in Marine
recruits. J Appl Physiol. 2004;96:951-956.
89. Biolo G, Fleming RYD, Wolfe RR.
Physiologic hyperinsulinemia stimulates
protein synthesis and transport of selected
amino acids in human skeletal muscle. J
Clin Invest. 1995;95:811-819.
90. Biolo G, Tipton KD, Klein S, Wolfe RR. An
abundant supply of amino acids enhances
the metabolic effect of exercise on muscle
protein. Am J Physiol Endocrinol Metab.
91. Biolo G, Williams BD, Fleming RY, Wolfe
RR. Insulin action on muscle protein
kinetics and amino acid transport during
recovery after resistance exercise. Diabetes.
92. Okamura K, Doi T, Hamada K, et al.
Effect of amino acid and glucose
administration during postexercise recovery
on protein kinetics in dogs. Am J Physiol.
93. Aragon AA, Schoenfeld BJ. Nutrient timing
revisited: is there a post-exercise anabolic
window? J Int Soc Sports Nutr. 2013;10:5.
94. Rasmussen BB, Tipton KD, Miller SL, Wolf
SE, Wolfe RR. An oral essential amino acid-
carbohydrate supplement enhances muscle
protein anabolism after resistance exercise.
J Appl Physiol. 2000;88:386-392.
95. Tipton KD, Rasmussen BB, Miller SL, et
al. Timing of amino acid-carbohydrate
ingestion alters anabolic response of
muscle to resistance exercise. Am J Physiol
Endocrinol Metab. 2001;281:E197-E206.
96. Chesley A, MacDougall JD, Tarnopolsky
MA, Atkinson SA, Smith K. Changes
in human muscle protein synthesis
after resistance exercise. J Appl Physiol.
97. Phillips SM, Tipton KD, Aarsland A, Wolf
SE, Wolfe RR. Mixed muscle protein
synthesis and breakdown after resistance
exercise in humans. Am J Physiol
Endocrinol Metab. 1997;273:E99-E107.
98. Fujita S, Dreyer HC, Drummond MJ, Glynn
EL, Volpi E, Rasmussen BR. Essential amino
acid and carbohydrate ingestion before
resistance exercise does not enhance
postexercise muscle protein synthesis. J
Appl Physiol. 2009;106:1730-1739.
99. Tipton KD, Elliott TA, Cree MG, Aarsland
AA, Sanford AP, Wolfe RR. Stimulation
of net muscle protein synthesis by
whey protein ingestion before and after
exercise. Am J Physiol Endocrinol Metab.
100. Suzuki M, Doi T, Lee SJ, et al. Effect of
meal timing after resistance exercise
on hind limb muscle mass and fat
accumulation in trained rats. J Nutr Sci
Vitaminol (Tokyo). 1999;45:401-409.
101. Esmarck B, Andersen JL, Olsen S,
Richter EA, Mizuno M, Kjar M. Timing of
postexercise protein intake is important for
muscle hypertrophy with resistance training
in elderly humans. J Physiol. 2001;535:
102. Cribb PJ, Hayes A. Effects of supplement
timing and resistance exercise on skeletal
muscle hypertrophy. Med Sci Sports Exerc.
103. Hulmi JJ, Kovanen V, Selänne H, Kraemer
WJ, Häkkinen K, Mero AA. Acute and long-
term effects of resistance exercise with
or without protein ingestion on muscle
hypertrophy and gene expression. Amino
Acids. 2009;37:297-308.
104. Bird SP, Tarpenning KM, Marino E.
Independent and combined effects of
liquid carbohydrate/essential amino acid
ingestion on hormonal and muscular
adaptations following resistance training
in untrained men. Eur J Appl Physiol.
105. Ferguson-Stegall L, McCleave E, Ding
Z, et al. Aerobic exercise training
at HAMLINE UNIV on October 19, 2014ajl.sagepub.comDownloaded from
vol. 8 no. 4 American Journal of Lifestyle Medicine
adaptations are increased by postexercise
carbohydrate-protein supplementation.
J Nutr Metab. 2011;2011:623182.
106. Okazaki K, Ichinose T, Mitono H, et
al. Impact of protein and carbohydrate
supplementation on plasma volume
expansion and thermoregulatory adaptation
by aerobic training in older men. J Appl
Physiol. 2009;107:725-733.
107. Josse AR, Atkinson SA, Tarnopolsky MA,
Phillips SM. Increased consumption of
dairy foods and protein during diet- and
exercise-induced weight loss promotes
fat mass loss and lean gain in overweight
and obese premenopausal women. J Nutr.
108. Verdijk LB, Jonkers RAM, Gleeson BG, et
al. Protein supplementation before and
after exercise does not further augment
skeletal muscle hypertrophy after resistance
training in elderly men. Am J Clin Nutr.
109. Breen L, Phillips SM. Skeletal muscle
protein metabolism in the elderly:
interventions to counteract the “anabolic
resistance” of ageing. Nutr Metab.
110. Pennings B, Groen B, de Lange A, et al.
Amino acid absorption and subsequent
muscle protein accretion following
graded intakes of whey protein in elderly
men. Am J Physiol Endocrinol Metab.
111. Yang Y, Breen L, Burd NA, et al.
Resistance exercise enhances myofibrillar
protein synthesis with graded intakes of
whey protein in older men. Br J Nutr.
112. Hoffman JR, Ratamess NA, Tranchina CP,
Rashti SL, Kang J, Faigenbaum AD. Effect
of protein-supplement timing on strength,
power, and body-composition changes
in resistance-trained men. Int J Sport Nutr
Exerc Metab. 2009;19:172-185.
113. Erskine RM, Fletcher G, Hanson B,
Folland JP. Whey protein does not
enhance the adaptations to elbow flexor
resistance training. Med Sci Sports Exerc.
114. Borsheim E, Tipton KD, Wolf SE,
Wolfe RR. Essential amino acids and
muscle protein recovery from resistance
exercise. Am J Physiol Endocrinol Metab.
115. Tipton KD, Gurkin Be, Martin S, Wolfe RR.
Nonessential amino acids are not necessary
to stimulate net muscle protein synthesis
in healthy volunteers. J Nutr Biochem.
116. Anthony JC, Anthony TG, Kimball SR,
Vary TC, Jefferson LS. Orally administered
leucine stimulates protein synthesis in
skeletal muscle of postabsorptive rats in
association with increased eIF4F formation.
J Nutr. 2000;130:139-145.
117. Wilkinson SB, Tarnopolsky MA,
MacDonald MJ, MacDonald JR, Armstrong
D, Phillips SM. Consumption of fluid skim
milk promotes greater muscle protein
accretion following resistance exercise
than an isonitrogenous and isoenergetic
soy protein beverage. Am J Clin Nutr.
118. Tang JE, Moore DR, Kujbida GW,
Tarnopolsky MA, Phillips SM. Ingestion of
whey hydrolysate, casein, or soy protein
isolate: effects on mixed muscle protein
synthesis at rest and following resistance
exercise in young men. J Appl Physiol.
119. Reidy PT, Walker DK, Dickinson JM, et al.
Protein blend ingestion following resistance
exercise promotes human muscle protein
synthesis. J Nutr. 2013;143:410-416.
120. Atherton PJ, Etheridge T, Watt PW, et al.
Muscle full effect after oral protein: time-
dependent concordance and discordance
between human muscle protein synthesis
and mTORC1 signaling. Am J Clin Nutr.
121. Bohé J, Low JFA, Wolfe RR, Rennie M.
Latency and duration of stimulation of
human muscle protein synthesis during
continuous infusion of amino acids. J
Physiol. 2001;532:575-579.
122. Borsheim E, Cree MG, Tipton KD, Elliott
TA, Aarsland A, Wolfe RR. Effect of
carbohydrate intake on net muscle protein
synthesis during recovery from resistance
exercise. J Appl Physiol. 2004;96:674-678.
123. Miller SL, Tipton KD, Chinkes DL, Wolf
SE, Wolfe RR. Independent and combined
effects of amino acids and glucose after
resistance exercise. Med Sci Sports Exerc.
124. Levenhagen DK, Carr C, Carlson MG,
Maron DJ, Borel MJ, Flakoll PJ. Postexercise
protein intake enhances whole-body and
leg protein accretion in humans. Med Sci
Sports Exerc. 2002;34:828-837.
125. Cuthbertson D, Smith K, Babraj J, et al.
Anabolic signaling deficits underlie amino
acid resistance of wasting, aging muscle.
FASEB J. 2005;19:422-424.
126. Moore DR, Robinson MJ, Fry JL, et al.
Ingested protein dose-response of muscle
and albumin protein synthesis after
resistance exercise in young men. Am J
Clin Nutr. 2009;89:161-168.
127. Deutz NEP, Wolfe RR. Is there a maximal
anabolic response to protein intake with a
meal? Clin Nutr. 2013;32:309-313.
128. Paddon-Jones D, Sheffield-Moore M, Zhang
XJ, et al. Amino acid ingestion improves
muscle protein synthesis in the young and
elderly. Am J Physiol Endocrinol Metab.
129. West DWD, Burd NA, Coffey VG, et
al. Rapid aminoacidemia enhances
myofibrillar protein synthesis and anabolic
intramuscular signaling responses after
resistance exercise. Am J Clin Nutr.
130. Jakubowicz D, Froy O, Wainstein J, Boaz
M. Meal timing and composition influence
ghrelin levels, appetite scores and weight
loss maintenance in overweight and obese
adults. Steroids. 2012;77:323-331.
131. Ma Y, Bertone ER, Stanek EJ III, et al.
Association between eating patterns and
obesity in a free-living US adult population.
Am J Epidemiol. 2003;158:85-92.
132. Schlundt DG, Hill JO, Sbrocco T, Pope-
Cordle J, Sharp T. The role of breakfast
in the treatment of obesity: a randomized
clinical trial. Am J Clin Nutr. 1992;55:645-651.
133. Beelen M, Tieland M, Gijsen AP, et al.
Coningestion of carbohydrate and protein
hydrolysate stimulates muscle protein
synthesis during exercise in young men,
with no further increase during subsequent
overnight recovery. J Nutr. 2008;138:2198-
134. Res PT, Groen B, Pennings B, et al.
Protein ingestion before sleep improves
postexercise overnight recovery. Med Sci
Sports Exerc. 2012;44:1560-1569.
at HAMLINE UNIV on October 19, 2014ajl.sagepub.comDownloaded from
... Another critical factor to consider is the dose and timing of supplementation. Numerous studies on nutrient timing have examined this issue [19][20][21][22][23]. Athletes can use MIPS either before [7,12,22] or immediately after a workout [24]; however few studies have studied the effect of MIPS in both situations on resistance training [14,25]. ...
... Also, MIPS administered to types of athletes with different physiological demands are quite different and are associated with specific sports in which one or another component of physical activity is used (aerobic or anaerobic) [64]. Another aspect of MIPS research is that administration time also differs [19,20]. For these reasons, they complicate efforts to benchmark MIPS. ...
Full-text available
Multi-ingredient performance supplements (MIPS), ingested pre- or post-workout, have been shown to increase physiological level effects and integrated metabolic response on exercise. The purpose of this study was to determine the efficacy of pre-and post-training supplementation with its own MIPS, associated with CHO (1 g·kg−1) plus protein (0.3 g·kg−1) on exercise-related bench-marks across a training camp for elite cyclists. Thirty elite male cyclists participated in a randomized non-placebo-controlled trial for ten weeks assigned to one of three groups (n = 10 each): a control group treated with CHO plus protein after training (CG); a group treated with MIPS before training and a CHO plus protein after training, (PRE-MIPS); a group treated with CHO plus protein plus MIPS after training, (POST-MIPS). Performance parameters included (VO2max, peak; median and minimum power (W) and fatigue index (%)); hormonal response (Cortisol; Testosterone; and Tes-tosterone/Cortisol ratio); and muscle biomarkers (Creatine kinase (CK), Lactate dehydrogenase (LDH), and Myoglobin (Mb)) were assessed. MIPS administered before or after training (p ≤ 0.05) was significantly influential in attenuating CK, LDH, and MB; stimulating T response and modu-lating C; and improved on all markers of exercise performance. These responses were greater when MIPS was administered post-workout.
... The purported beneficial effects (i.e., increased muscle protein synthetic response) of protein timing are based on the hypothesis that a limited ''anabolic window of opportunity'' exists for post-workout anabolism (Lemon, Berardi & Noreen, 2002). To take advantage of this window of opportunity, common thought is that protein must be consumed within approximately 45 min to 1 h of completion of exercise to maximize post-workout muscle protein synthesis (MPS) (Ivy & Ferguson-Stegall, 2013). It has been postulated that the anabolic response to a resistance training bout is blunted if protein is ingested after this narrow window, thereby impairing muscular gains (Ivy & Ferguson-Stegall, 2013). ...
... To take advantage of this window of opportunity, common thought is that protein must be consumed within approximately 45 min to 1 h of completion of exercise to maximize post-workout muscle protein synthesis (MPS) (Ivy & Ferguson-Stegall, 2013). It has been postulated that the anabolic response to a resistance training bout is blunted if protein is ingested after this narrow window, thereby impairing muscular gains (Ivy & Ferguson-Stegall, 2013). ...
... The provision and timing of dietary intake may be critical during military training to maintain or improve physical and mental performance while enhancing recovery and promoting adaptation to training (Beals et al., 2015). The timing of macronutrient intake, particularly protein, and its subsequent effects on training adaptations, have been explored in both controlled laboratory and sports performance settings (Areta et al., 2013;Nosaka et al., 2006), where macronutrient intake is typically manipulated around a single bout of exercise to determine the influence on performance, muscle protein synthesis (MPS), or muscle damage (Ivy & Ferguson-Stegall, 2014;Kerksick et al., 2017). Typically, consuming protein immediately after resistance exercise, with an even distribution of intake throughout the day, is considered the most effective method for stimulating MPS compared with an excessively high protein intake at single and/or infrequent time points each day (Mamerow et al., 2014). ...
Full-text available
Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure. Thirteen participants (seven women) were monitored during three discrete periods of military training for 9 days on-camp, 5 days of field exercise, and 9 days of a mixture of the two. Dietary intake was measured using researcher-led food weighing and food diaries, and energy expenditure was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4,600 kcal/day) and women (3,500 kcal/day) during on-camp training (men = −16% and women = −9%), field exercise (men = −33% and women = −42%), and combined camp and field training (men and women both −34%). Carbohydrate intake of men and women were below guidelines (6 g·kg ⁻¹ ·day ⁻¹ ) during field exercise (men = −18% and women = −37%) and combined camp and field training (men = −33% and women = −39%), respectively. Protein intake was above guidelines (1.2 kcal·kg ⁻¹ ·day ⁻¹ ) for men and women during on-camp training (men = 48% and women = 39%) and was below guidelines during field exercise for women only (−27%). Energy and macronutrient intake during on-camp training centered around mealtimes with a discernible sleep/wake cycle for energy expenditure. During field exercise, energy and macronutrient intake were individually variable, and energy expenditure was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimize performance and adaptations during military training.
... For elite athletes the recommended energy intake may further exceed these levels [5]. It has to be mentioned that the fundamental factor of sports nutrition is nutrient timing and it refers to the time when the body is able to use macronutrients most effectively [6]. The timing of energy intake may enhance muscle protein synthesis, recovery and tissue repair [5]. ...
Full-text available
Nutrition is the aspect closely connected to physical activity and may affect body composition, sports performance and post-workout regeneration. Using an appropriate diet plan is a proven method to optimize performance improvements in combat sports. In the majority of combat sports athletes are classified according to their body mass in order to minimize differences between competitors. Many athletes induce weight loss in order to gain an advantage over their opponents. The review was undertaken to provide safe, evidence-based protocols helping athletes in weight reduction without negative effects on sports performance. The nutritional requirements for combat sports athletes, sports supplements, gradual and rapid weight reduction strategies are discussed in this review. Keywords: combat sports, nutrition, supplementation, weight reduction Citation: Paulina Januszko, Ewa Lange. Nutrition, supplementation and weight reduction in combat sports: a review[J]. AIMS Public Health, 2021, 8(3): 485-498. doi: 10.3934/publichealth.2021038
... Here, the significant increase in the intramuscular concentration of inorganic phosphate (Pi) and hydrogen ions (H + ) is strongly correlated with the onset of neuromuscular fatigue [7]. Considering the allostasis model, which proposes that efficient regulation of a biological system requires anticipating needs and preparing to satisfy them before they arise [8], nutritional strategies after exercise helps to refuel energy sources (e.g., muscle and liver glycogen), replace fluid and electrolytes, synthesize new proteins to counteract both catabolic state and exercise-induced damage, and improve immune system response [9][10][11]. All these aspects have a tremendous influence on the allostatic response and the allostatic load, which must be sustained for an appropriate interval of time. ...
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Post-exercise recovery is a broad term that refers to the restoration of training capacity. After training or competition, there is fatigue accumulation and a reduction in sports performance. In the hours and days following training, the body recovers and performance is expected to return to normal or improve. ScienceDirect, PubMed/MEDLINE, and Google Scholar databases were reviewed to identify studies and position declarations examining the relationship between nutrition and sports recovery. As an evidence-based framework, a 4R’s approach to optimizing post-exercise recovery was identified: (i) Rehydration—a fundamental process that will depend on the athlete, environment and sports event; (ii) Refuel—the consumption of carbohydrates is not only important to replenish the glycogen reserves but also to contribute to the energy requirements for the immune system and tissue reparation. Several bioengineered carbohydrates were discussed but further research is needed; (iii) Repair—post-exercise ingestion of high-quality protein and creatine monohydrate benefit the tissue growth and repair; and (iv) Rest—pre-sleep nutrition has a restorative effect that facilitates the recovery of the musculoskeletal, endocrine, immune, and nervous systems. Nutritional consultancy based on the 4R’s is important for the wise stewardship of the hydration, feeding, and supplementation strategies to achieve a timely recovery.
... To achieve maximum muscle adaptation to exercise, laboratory-based nutritional studies have reported that 'immediate' PE consumption of protein can elicit greater muscle protein synthesis, whereas fasting for 2-3 h after exercise blunts this response (2) . Therefore, carbohydrate-protein supplementation as soon as possible (at least within 45 min) after endurance exercise has been recommended; these recommendations are also applicable to resistance exercise (3) . ...
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This study examined the effects of post-resistance exercise protein ingestion timing on the rate of gastric emptying (GE) and blood glucose (BG) and plasma branched-chain amino acid (BCAA) responses. In all, eleven healthy participants randomly ingested 400 ml of a nutrient-rich drink containing 12 g carbohydrates and 20 g protein at rest (Con), at 5 min (post-exercise (PE)-5) or at 30 min (PE-30) after a single bout of strenuous resistance exercises. The first and second sets comprised ten repetitions at 50 % of each participant’s one-repetition maximum (1RM). The third, fourth and fifth sets comprised ten repetitions at 75 % of 1RM, and the sixth set involved repeated repetitions until exhaustion. Following ingestion of the nutrient-rich drink, we assessed the GE rate using ¹³ C-sodium acetate breath test and evaluated two parameters according to the Tmax-calc (time when the recovery per hour is maximised), which is a standard analytical method, and T1/2 (time when the total cumulative dose of [ ¹³ CO 2 ] reaches one-half). Tmax-calc and T1/2 were slower for the PE-5 condition than for either the PE-30 or Con condition ( Tmax-calc ; Con: 53 ( sd 7) min, PE-5: 83 ( sd 16) min, PE-30: 62 ( sd 9) min, T1/2 ; Con: 91 ( sd 7) min, PE-5: 113 ( sd 21) min, PE-30: 91 ( sd 11) min, P <0·05). BG and BCAA responses were also slower for the PE-5 condition than for either the PE-30 or Con condition. Ingesting nutrients immediately after strenuous resistance exercise acutely delayed GE, which affected BG and plasma BCAA levels in blood circulation.
... Another potential confounding issue was that the high protein group consumed 25 g of whey protein immediately before and after the workouts while the low protein group consumed only 5 grams during these periods. It has been suggested that there is an "anabolic window of opportunity" whereby preand post-workout protein consumption heightens the accretion of muscle proteins, and that intake of at least 20 grams of high quality protein is needed to maximize this response (Ivy and Ferguson-Stegall, 2014;Macnaughton et al., 2016). This raises the possibility that the timing of consumption may have been at least partly attributable to results. ...
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Aspiring female physique athletes are often encouraged to ingest relatively high levels of dietary protein in conjunction with their resistance-training programs. However, there is little to no research investigating higher vs. lower protein intakes in this population. This study examined the influence of a high vs. low protein diet in conjunction with an 8-week resistance training program in this population. Seventeen females (21.2±2.1 years; 165.1±5.1 cm; 61±6.1 kg) were randomly assigned to a high protein diet (HP: 2.5g/kg/day; n=8) or a low protein diet (LP: 0.9g/kg/day, n=9) and were assessed for body composition and maximal strength prior to and after the 8-week protein intake and exercise intervention. Fat-free mass (FFM) increased significantly more in the HP group as compared to the LP group (p=0.009), going from 47.1 ± 4.5kg to 49.2 ± 5.4kg (+2.1kg) and from 48.1 ± 2.7kg to 48.7 ± 2 (+0.6kg) in the HP and LP groups, respectively. Fat mass significantly decreased over time in the HP group (14.1 ± 3.6kg to 13.0 ± 3.3kg; p<0.01) but no change was observed in the LP group (13.2 ± 3.7kg to 12.5 ± 3.0kg). While maximal strength significantly increased in both groups, there were no differences in strength improvements between the two groups. In aspiring female physique athletes, a higher protein diet is superior to a lower protein diet in terms of increasing FFM in conjunction with a resistance training program.
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Bu kitap bölümü karbonhidrat tüketim zamanının performansa olumlu ve olumsuz etkilerini incelenmekte olup optimal tüketim aralığını ve optimal tüketim miktarını belirlemeyi amaç edinmiştir.
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Nutrient timing involves manipulation of nutrient consumption at specific times in and around exercise bouts in an effort to improve performance, recovery, and adaptation. Its historical perspective centered on ingestion during exercise and grew to include pre- and post-training periods. As research continued, translational focus remained primarily on the impact and outcomes related to nutrient consumption during one specific time period to the exclusion of all others. Additionally, there seemed to be increasing emphasis on outcomes related to hypertrophy and strength at the expense of other potentially more impactful performance measures. As consumption of nutrients does not occur at only one time point in the day, the effect and impact of energy and macronutrient availability becomes an important consideration in determining timing of additional nutrients in and around training and competition. This further complicates the confining of the definition of “nutrient timing” to one very specific moment in time at the exclusion of all other time points. As such, this review suggests a new perspective built on evidence of the interconnectedness of nutrient impact and provides a pragmatic approach to help frame nutrient timing more inclusively. Using this approach, it is argued that the concept of nutrient timing is constrained by reliance on interpretation of an “anabolic window” and may be better viewed as a “garage door of opportunity” to positively impact performance, recovery, and athlete availability.
It is well known that protein ingestion immediately after exercise greatly stimulates muscle protein synthesis during the postexercise recovery phase. However, immediately after strenuous exercise, the gastrointestinal (GI) mucosa is frequently injured by hypoperfusion in the organ/tissue, possibly resulting in impaired GI function (e.g., gastric emptying; GE). The aim of this study was to examine the effect of GI blood flow on the GE rate. Eight healthy young subjects performed an intermittent supramaximal cycling exercise for 30 min, which consisted of a 120% V̇o 2peak for 20 s, followed by 20 W for 40 s. The subjects ingested 300 ml of a nutrient drink containing carbohydrate-protein at either 5 min postexercise in one trial (PE-5) or 30 min postexercise in another trial (PE-30). In the control trial (Con), the subjects ingested the same drink without exercise. The celiac artery blood flow (CABF) and superior mesenteric artery blood flow (SMABF) and GE rate were assessed by ultrasonography. Before drink ingestion in PE-5, CABF significantly decreased from baseline, whereas in PE-30, it returned to baseline. Following drink ingestion in PE-5, CABF did not change from baseline, but it significantly increased in PE-30 and Con. SMABF increased significantly later in PE-5 than in PE-30 and Con. The GE rate was consistently slower in PE-5 than in PE-30 and Con. In conclusion, the CABF response after exercise seems to modulate the subsequent GE rate and SMABF response. NEW & NOTEWORTHY A carbohydrate-protein drink was ingested at either 5 min (i.e., profoundly decreased celiac artery blood flow; CABF) or 30 min (i.e., already recovered CABF) postexercise. In the 5-min postexercise trial, the gastric emptying (GE) rate and superior mesenteric artery blood flow (SMABF) response were slower than those in the 30-min postexercise trial. The GE rate and SMABF response may be altered depending on the postexercise CABF response.
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Background: Resistance exercise leads to net muscle protein accretion through a synergistic interaction of exercise and feeding. Proteins from different sources may differ in their ability to support muscle protein accretion because of different patterns of postprandial hyperaminoacidemia. Objective: We examined the effect of consuming isonitrogenous, isoenergetic, and macronutrient-matched soy or milk beverages (18 g protein, 750 kJ) on protein kinetics and net muscle protein balance after resistance exercise in healthy young men. Our hypothesis was that soy ingestion would result in larger but transient hyperaminoacidemia compared with milk and that milk would promote a greater net balance because of lower but prolonged hyperaminoacidemia. Design: Arterial-venous amino acid balance and muscle fractional synthesis rates were measured in young men who consumed fluid milk or a soy-protein beverage in a crossover design after a bout of resistance exercise. Results: Ingestion of both soy and milk resulted in a positive net protein balance. Analysis of area under the net balance curves indicated an overall greater net balance after milk ingestion (P < 0.05). The fractional synthesis rate in muscle was also greater after milk consumption (0.10 ± 0.01%/h) than after soy consumption (0.07 ± 0.01%/h; P = 0.05). Conclusions: Milk-based proteins promote muscle protein accretion to a greater extent than do soy-based proteins when consumed after resistance exercise. The consumption of either milk or soy protein with resistance training promotes muscle mass maintenance and gains, but chronic consumption of milk proteins after resistance exercise likely supports a more rapid lean mass accrual.
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The effect of 10 wk of protein-supplement timing on strength, power, and body composition was examined in 33 resistance-trained men. Participants were randomly assigned to a protein supplement either provided in the morning and evening ( n = 13) or provided immediately before and immediately after workouts ( n = 13). In addition, 7 participants agreed to serve as a control group and did not use any protein or other nutritional supplement. During each testing session participants were assessed for strength (one-repetition-maximum [1RM] bench press and squat), power (5 repetitions performed at 80% of 1RM in both the bench press and the squat), and body composition. A significant main effect for all 3 groups in strength improvement was seen in 1RM bench press (120.6 ± 20.5 kg vs. 125.4 ± 16.7 at Week 0 and Week 10 testing, respectively) and 1RM squat (154.5 ± 28.4 kg vs. 169.0 ± 25.5 at Week 0 and Week 10 testing, respectively). However, no significant between-groups interactions were seen in 1RM squat or 1RM bench press. Significant main effects were also seen in both upper and lower body peak and mean power, but no significant differences were seen between groups. No changes in body mass or percent body fat were seen in any of the groups. Results indicate that the time of protein-supplement ingestion in resistance-trained athletes during a 10-wk training program does not provide any added benefit to strength, power, or body-composition changes.
Increasing the plasma glucose and insulin concentrations during prolonged variable intensity exercise by supplementing with carbohydrate has been found to spare muscle glycogen and increase aerobic endurance. Furthermore, the addition of protein to a carbohydrate supplement will enhance the insulin response of a carbohydrate supplement. The purpose of the present study was to compare the effects of a carbohydrate and a carbohydrate-protein supplement on aerobic endurance performance. Nine trained cyclists exercised on 3 separate occasions at intensities that varied between 45% and 75% VO2max for 3 h and then at 85% VO2max until fatigued. Supplements (200 ml) were provided every 20 min and consisted of placebo, a 7.75% carbohydrate solution, and a 7.75% carbohydrate / 1.94% protein solution. Treatments were administered using a double-blind randomized design. Carbohydrate supplementation significantly increased time to exhaustion (carbohydrate 19.7 +/- 4.6 min vs. placebo 12.7 +/- 3.1 min), while the addition of protein enhanced the effect of the carbohydrate supplement (carbohydrate-protein 26.9 +/- 4.5 min, p < .05). Blood glucose and plasma insulin levels were elevated above placebo during carbohydrate and carbohydrate-protein supplementation, but no differences were found between the carbohydrate and carbohydrate-protein treatments. In summary, we found that the addition of protein to a carbohydrate supplement enhanced aerobic endurance performance above that which occurred with carbohydrate alone, but the reason for this improvement in performance was not evident.
The authors investigated the effects of postexercise carbohydrate-protein- anti-oxidant (CHO+P+A) ingestion on plasma creatine kinase (CK), muscle soreness, and subsequent cross-country race performance. Twenty-three runners consumed 10 mL/kg body weight of CHO or CHO+P+A beverage immediately after each training session for 6 d before a cross-country race. After a 21-d washout period, subjects repeated the protocol with the alternate beverage. Postintervention CK (223.21 ± 160.71 U/L; 307.3 ± 312.9 U/L) and soreness (medians = 1.0, 2.0) were significantly lower after CHO+P+A intervention than after CHO, despite no differences in baseline measures. There were no overall differences in running performance after CHO and CHO+P+A interventions. There were, however, significant correlations between treatment differences and running mileage, with higher mileage runners having trends toward improved attenuations in CK and race performance after CHO+P+A intervention than lower mileage runners. We conclude that muscle damage incurred during training was attenuated with postexercise CHO+P+A ingestion, which could lead to performance improvements in high-mileage runners.
• The aim of this study was to describe the time course of the response of human muscle protein synthesis (MPS) to a square wave increase in availability of amino acids (AAs) in plasma. We investigated the responses of quadriceps MPS to a ≈1.7-fold increase in plasma AA concentrations using an intravenous infusion of 162 mg (kg body weight)−1 h−1 of mixed AAs. MPS was estimated from D3-leucine labelling in protein after a primed, constant intravenous infusion of D3-ketoisocaproate, increased appropriately during AA infusion. • Muscle was separated into myofibrillar, sarcoplasmic and mitochondrial fractions. MPS, both of mixed muscle and of fractions, was estimated during a basal period (2.5 h) and at 0.5-4 h intervals for 6 h of AA infusion. • Rates of mixed MPS were not significantly different from basal (0.076 ± 0.008 % h−1) in the first 0.5 h of AA infusion but then rose rapidly to a peak after 2 h of ≈2.8 times the basal value. Thereafter, rates declined rapidly to the basal value. All muscle fractions showed a similar pattern. • The results suggest that MPS responds rapidly to increased availability of AAs but is then inhibited, despite continued AA availability. These results suggest that the fed state accretion of muscle protein may be limited by a metabolic mechanism whenever the requirement for substrate for protein synthesis is exceeded.