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How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution

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How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution

Abstract

Controversy exists about the maximum amount of protein that can be utilized for lean tissue-building purposes in a single meal for those involved in regimented resistance training. It has been proposed that muscle protein synthesis is maximized in young adults with an intake of ~ 20–25 g of a high-quality protein; anything above this amount is believed to be oxidized for energy or transaminated to form urea and other organic acids. However, these findings are specific to the provision of fast-digesting proteins without the addition of other macronutrients. Consumption of slower-acting protein sources, particularly when consumed in combination with other macronutrients, would delay absorption and thus conceivably enhance the utilization of the constituent amino acids. The purpose of this paper was twofold: 1) to objectively review the literature in an effort to determine an upper anabolic threshold for per-meal protein intake; 2) draw relevant conclusions based on the current data so as to elucidate guidelines for per-meal daily protein distribution to optimize lean tissue accretion. Both acute and long-term studies on the topic were evaluated and their findings placed into context with respect to per-meal utilization of protein and the associated implications to distribution of protein feedings across the course of a day. The preponderance of data indicate that while consumption of higher protein doses (> 20 g) results in greater AA oxidation, this is not the fate for all the additional ingested AAs as some are utilized for tissue-building purposes. Based on the current evidence, we conclude that to maximize anabolism one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6 g/kg/day. Using the upper daily intake of 2.2 g/kg/day reported in the literature spread out over the same four meals would necessitate a maximum of 0.55 g/kg/meal.
R E V I E W Open Access
How much protein can the body use in a
single meal for muscle-building?
Implications for daily protein distribution
Brad Jon Schoenfeld
1*
and Alan Albert Aragon
2
Abstract
Controversy exists about the maximum amount of protein that can be utilized for lean tissue-building purposes in a
single meal for those involved in regimented resistance training. It has been proposed that muscle protein synthesis is
maximized in young adults with an intake of ~ 2025 g of a high-quality protein; anything above this amount is
believed to be oxidized for energy or transaminated to form urea and other organic acids. However, these findings are
specific to the provision of fast-digesting proteins without the addition of other macronutrients. Consumption of
slower-acting protein sources, particularly when consumed in combination with other macronutrients, would delay
absorption and thus conceivably enhance the utilization of the constituent amino acids. The purpose of this paper was
twofold: 1) to objectively review the literature in an effort to determine an upper anabolic threshold for per-meal
protein intake; 2) draw relevant conclusions based on the current data so as to elucidate guidelines for per-meal daily
protein distribution to optimize lean tissue accretion. Both acute and long-term studies on the topic were evaluated
and their findings placed into context with respect to per-meal utilization of protein and the associated implications to
distribution of protein feedings across the course of a day. The preponderance of data indicate that while consumption
of higher protein doses (> 20 g) results in greater AA oxidation, this is not the fate for all the additional ingested AAs as
some are utilized for tissue-building purposes. Based on the current evidence, we conclude that to maximize anabolism
one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a
minimum of 1.6 g/kg/day. Using the upper daily intake of 2.2 g/kg/day reported in the literature spread out over the
same four meals would necessitate a maximum of 0.55 g/kg/meal.
Keywords: Protein feeding pattern, Amino acid oxidation, Protein intake, Protein metabolism, Lean tissue mass
Background
Controversy exists about the maximum amount of
protein that can be utilized for lean tissue-building pur-
poses in a single meal for those involved in regimented
resistance training. A long-held misperception in the lay
public is that there is a limit to how much protein can
be absorbed by the body. From a nutritional standpoint,
the term absorptiondescribes the passage of nutrients
from the gut into systemic circulation. Based on this
definition, the amount of protein that can be absorbed is
virtually unlimited. Following digestion of a protein
source, the constituent amino acids (AA) are transported
through the enterocytes at the intestinal wall, enter the
hepatic portal circulation, and the AA that are not
utilized directly by the liver, then enter the bloodstream,
after which almost all the AA ingested become available
for use by tissues. While absorption is not a limiting
factor with respect to whole proteins, there may be
issues with consumption of individual free-form AA in
this regard. Specifically, evidence shows the potential for
competition at the intestinal wall, with AA that are
present in the highest concentrations absorbed at the
expense of those that are less concentrated [1].
It has been proposed that muscle protein synthesis
(MPS) is maximized in young adults with an intake
of ~ 2025 g of a high-quality protein, consistent with
the muscle fullconcept; anything above this amount
is believed to be oxidized for energy or transaminated
* Correspondence: brad@workout911.com
1
CUNY Lehman College, Department of Health Sciences, 250 Bedford Park
Blvd West, Bronx, NY 10468, USA
Full list of author information is available at the end of the article
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Schoenfeld and Aragon Journal of the International Society of Sports Nutrition
(2018) 15:10
https://doi.org/10.1186/s12970-018-0215-1
to form alternative bodily compounds [2]. The pur-
pose of this paper is twofold: 1) to objectively review
the literature in an effort to determine an upper ana-
bolic threshold for per-meal protein intake; 2) draw
relevant conclusions based on the current data so as
to elucidate guidelines for per-meal daily protein dis-
tribution to optimize lean tissue accretion.
Speed of digestion/absorption on muscle anabolism
In a study often cited as support for the hypothesis that
MPS is maximized at a protein dose of ~ 2025 g, Areta
et al. [3] provided differing amounts of protein to
resistance-trained subjects over a 12-h recovery period
following performance of a multi-set, moderate repeti-
tion leg-extension exercise protocol. A total of 80 g of
whey protein was ingested in one of the following three
conditions: 8 servings of 10 g every 1.5 h; 4 servings of
20 g every 3 h; or 2 servings of 40 g every 6 h. Results
showed that MPS was greatest in those who consumed 4
servings of 20 g of protein, suggesting no additional
benefit, and actually a lower rise in MPS when consum-
ing the higher dosage (40 g) under the conditions
imposed in the study. These results extended similar
findings by Moore et al. [4] on whole-body nitrogen
turnover.
Although the findings of Areta et al. [3] provide inter-
esting insight into the dose-related effects of protein
intake on muscle development, it is important to note
that a number of factors influence dietary protein me-
tabolism including the composition of the given protein
source, the composition of the meal, the amount of pro-
tein ingested, and the specifics of the exercise routine
[5]. In addition, individual variables such as age, training
status, and the amount of lean body mass also impact
muscle-building outcomes. A major limitation in the
study by Areta et al. [3] is that total protein intake over
the 12-h study period was only 80 g, corresponding to
less than 1 g/kg of body mass. This is far below the
amount necessary to maximize muscle protein balance
in resistance-trained individuals who served as partici-
pants in the study [6,7]. Furthermore, the ecological
validity of this work is limited since habitual protein
intakes of individuals focused on muscle gain or reten-
tion habitually consume approximately 24 times this
amount per day [8,9].
It also should be noted that subjects in Areta et al. [3]
ingested nothing but whey protein throughout the post-
exercise period. Whey is a fast-actingprotein; its
absorption rate has been estimated at ~ 10 g per hour
[5]. At this rate, it would take just 2 h to fully absorb a
20-g dose of whey. While the rapid availability of AA
will tend to spike MPS, earlier research examining whole
body protein kinetics showed that concomitant oxida-
tion of some of the AA may result in a lower net protein
balance when compared to a protein source that is
absorbed at a slower rate [10]. For example, cooked egg
protein has an absorption rate of ~ 3 g per hour [5],
meaning complete absorption of an omelet containing
the same 20 g of protein would take approximately 7 h,
which may help attenuate oxidation of AA and thus pro-
mote greater whole-body net positive protein balance.
An important caveat is that these findings are specific to
whole body protein balance; the extent to which this re-
flects skeletal muscle protein balance remains unclear.
Although some studies have shown similar effects of
fast and slow proteins on net muscle protein balance
[11] and fractional synthetic rate [1214], other studies
have demonstrated a greater anabolic effect of whey
compared to more slowly digested sources both at rest
[15,16], and after resistance exercise [16,17]. However,
the majority of these findings were during shorter testing
periods (4 h or less), whereas longer testing periods (5 h
or more) tend to show no differences between whey and
casein on MPS or nitrogen balance [18]. Furthermore,
most studies showing greater anabolism with whey used
a relatively small dose of protein (20 g) [1517]; it re-
mains unclear whether higher doses would result in
greater oxidation of fast vs slow-acting protein sources.
Compounding these equivocal findings, research exam-
ining the fate of intrinsically labeled whey and casein con-
sumed within milk found a greater incorporation of casein
into skeletal muscle [19]. The latter finding should be
viewed with the caveat that although protein turnover in
the leg is assumed to be mostly reflective of skeletal
muscle, it is also possible that non-muscle tissues might
also contribute. Interestingly, the presence versus absence
of milk fat coingested with micellar casein did not delay
the rate of protein-derived circulating amino acid avail-
ability or myofibrillar protein synthesis [20]. Furthermore,
the coingestion of carbohydrate with casein delayed diges-
tion and absorption, but still did not impact muscle pro-
tein accretion compared to a protein-only condition [21].
The implication is that accompanying macronutrients
potential to alter digestion rates does not necessarily
translate to alterations in the anabolic effect of the protein
feeding at least in the case of slow-digesting protein
such as casein. More fat and/or carbohydrate coingestion
comparisons need to be made with other proteins, subject
profiles, and relative proximity to training before drawing
definitive conclusions.
Higher acute anabolic ceilingthan previously thought?
More recently, Macnaughton et al. [22] employed a ran-
domized, double-blind, within-subject design whereby
resistance-trained men participated in two trials sepa-
rated by ~ 2 weeks. During one trial subjects received
20 g of whey protein immediately after performing a
total body resistance training bout; during the other trial
Schoenfeld and Aragon Journal of the International Society of Sports Nutrition (2018) 15:10 Page 2 of 6
the same protocol was instituted but subjects received a
40-g whey bolus following training. Results showed that
the myofibrillar fractional synthetic rate was ~ 20%
higher from consumption of the 40 g compared to the
20 g condition. The researchers speculated that the large
amount of muscle mass activated from the total body
RT bout necessitated a greater demand for AA that was
met by a higher exogenous protein consumption. It
should be noted that findings by McNaughton et al. [22]
are somewhat in contrast to previous work by Moore
et al. showing no statistically significant differences in
MPS between provision of a 20 g and 40 g dose of whey
in young men following a leg extension bout, although
the higher dose produced an 11% greater absolute
increase [23]. Whether differences between intakes
higher than ~ 20 g per feeding are practically meaningful
remain speculative, and likely depend on the goals of the
individual.
Given that muscular development is a function of the
dynamic balance between MPS and muscle protein
breakdown (MPB), both of these variables must be
considered in any discussion on dietary protein dosage.
Kim et al. [24] endeavored to investigate this topic by
provision of either 40 or 70 g of beef protein consumed
as part of a mixed meal on two distinct occasions sepa-
rated by a ~ 1 week washout period. Results showed that
the higher protein intake promoted a significantly
greater whole-body anabolic response, which was pri-
marily attributed to a greater attenuation of protein
breakdown. Given that participants ate large, mixed
meals as whole foods containing not only protein, but
carbohydrates and dietary fats as well, it is logical to
speculate that this delayed digestion and absorption of
AAs compared to liquid consumption of isolated protein
sources. This, in turn, would have caused a slower
release of AA into circulation and hence may have con-
tributed to dose-dependent differences in the anabolic
response to protein intake. A notable limitation of the
study is that measures of protein balance were taken at
the whole-body level and thus not muscle-specific. It
therefore can be speculated that some if not much of
anti-catabolic benefits associated with higher protein in-
take was from tissues other than muscle, likely the gut.
Even so, protein turnover in the gut potentially provides
an avenue whereby accumulated amino acids can be re-
leased into the systemic circulation to be used for MPS,
conceivably enhancing anabolic potential [25]. This
hypothesis remains speculative and warrants further in-
vestigation. It would be tempting to attribute these
marked reductions in proteolysis to higher insulin re-
sponses considering the inclusion of a generous amount
of carbohydrate in the meals consumed. Although insu-
lin is often considered an anabolic hormone, its primary
role in muscle protein balance is related to anti-catabolic
effects [26]. However, in the presence of elevated plasma
AAs, the effect of insulin elevations on net muscle
protein balance plateaus within a modest range of 15
30 mU/L [27,28]. Given evidence that a 45 g dose of
whey protein causes insulin to rise to levels sufficient to
maximize net muscle protein balance [29], it would
seem that the additional macronutrients consumed in
the study by Kim et al. [24] had little bearing on results.
Longitudinal findings
Although the previously discussed studies offer insight
into how much protein the body can utilize in a given
feeding, acute anabolic responses are not necessarily as-
sociated with long-term muscular gains [30]. The topic
can only be answered by assessing the results of longitu-
dinal studies that directly measure changes in lean mass
with provision of varying protein dosages, as well as pro-
teins of varying speeds of digestion/absorption.
Wilborn et al. [31], found no difference in lean mass
gains after 8 weeks of pre- and post-resistance exercise
supplementation with either whey or casein. Similarly, a
lack of between-group differences in lean mass gain was
found by Fabre et al. [32] when comparing the following
whey/casein protein ratios consumed postexercise: 100/
0, 50/50, 20/80.
In a 14-day study of elderly women, Arnal et al. [33]
demonstrated that providing a majority of daily protein
(79%) in a single meal (pulse pattern) resulted in a
greater retention of fat-free mass compared to an evenly
distributed intake partitioned over four daily meals
(spread pattern). A follow-up study by the same lab in
young women reported similar effects of pulse versus
spread patterns of protein intake [34]. The combined
findings of these studies indicate that muscle mass is
not negatively affected by consuming the majority of
daily protein as a large bolus. However, neither study
employed regimented resistance training thereby lim-
iting generalizability to individuals involved in intense
exercise programs.
Insights into the effects of protein dosage can also be
gleaned from studies on intermittent fasting (IF). Typical
IF protocols require intake of daily nutrients, including
protein, in a narrow time-frame usually less than 8 h
followed by a prolonged fast. A recent systematic re-
view concluded that IF has similar effects on fat-free
mass compared with continuous eating protocols [35].
However, the studies reviewed in the analysis generally
involved suboptimal protein intakes consumed as part of
a low-energy diet without a resistance training compo-
nent, again limiting the ability to extrapolate findings to
resistance-trained individuals.
Helping to fill this literature gap is an 8-week trial by
Tinsley et al. [36], comparing a time-restricted feeding
(TRF) protocol of 20-h fasting/4-h feeding cycles done
Schoenfeld and Aragon Journal of the International Society of Sports Nutrition (2018) 15:10 Page 3 of 6
4 days per week, with a normal-diet group (ND) in un-
trained subjects doing resistance training 3 days per week.
The TRF group lost body weight via lower energy intake
(667 kcal less on fasting vs. non-fasting days), but did not
significantly lose lean mass (0.2 kg); ND gained lean mass
(2.3 kg), but not to a statistically significant degree, al-
though the magnitude of differences raises the possibility
that these findings may be practically meaningful. Perhaps
most interestingly, biceps brachii and rectus femoris cross
sectional area showed similar increases in both groups
despite the 20-h fasting cycles and concentrated feeding
cycles in TRF, suggesting that the utilization of protein
intake in the ad libitum 4-h feeding cycles was not ham-
pered by an acute ceiling of anabolism. Unfortunately,
protein and enrgy were not equated in this study. Subse-
quently, an 8-week trial by Moro et al. [37]using
resistance-trained subjects on a 16-h fasting/8-h TRF cycle
found significantly greater fat loss in TRF vs. ND (1.62 vs.
0.31 kg) while lean mass remained unchanged in both
groups. These findings further call into question the con-
cern for breaching a certain threshold of protein intake
permealforthegoalofmuscleretention.
In contrast to the above findings showing neutral-to-
positive effects of a temporally concentrated meal intake,
Arciero et al. [38] compared 3 diets: 2 high-protein (35%
of total energy) diets consisting of 3 (HP3) and 6 meals/
day (HP6), and a traditional protein intake (15% of total
energy) consumed in 3 meals/day (TD3). During the ini-
tial 28-day eucaloric phase, HP3 and HP6 consumed
protein at 2.27 & 2.15 g/kg, respectively, while TD3 con-
sumed 0.9 g/kg. HP6 was the only goup that significantly
gained lean mass. During the subsequent 28-day eucalo-
ric phase, HP3 and HP6 consumed protein at 1.71 &
1.65 g/kg, respectively, while TD3 consumed 0.75 g/kg.
HP6 maintained its lean mass gain, outperforming the
other 2 treatments in this respect (HP actually showed a
significant loss of lean mass compared to the control).
The discrepancy between the latter findings and those in
the IF/TRF trials remains to be reconciled. In any case,
it is notable that comparisons in this vein specifically
geared toward the goal of muscle gain, hypercaloric
comparisons in particular, are lacking.
Conclusions
An important distinction needs to be made between
acute meal challenges comparing different protein
amounts (including serial feedings in the acute phase
following resistance training) and chronic meal feedings
comparing different protein distributions through the
day, over the course of several weeks or months. Longi-
tudinal studies examining body composition have not
consistently corroborated the results of acute studies
examining muscle protein flux. Quantifying a maximum
amount of protein per meal that can be utilized for
muscle anabolism has been a challenging pursuit due to
the multitude of variables open for investigation. Per-
haps the most comprehensive synthesis of findings in
this area has been done by Morton et al. [2], who con-
cluded that 0.4 g/kg/meal would optimally stimulate
MPS. This was based on the addition of two standard
deviations to their finding that 0.25 g/kg/meal maximally
stimulates MPS in young men. In line with this hypoth-
esis, Moore et al. [39] mentioned the caveat that their
findings were estimated means for maximizing MPS, and
that the dosing ceilings can be as high as ~ 0.60 g/kg for
some older men and ~ 0.40 g/kg for some younger men.
Importantly, these estimates are based on the sole
provision of a rapidly digesting protein source that would
conceivably increase potential for oxidation of AA when
consumed in larger boluses. It seems logical that a slower-
acting protein source, particularly when consumed in
combination with other macronutrients, would delay
absorption and thus enhance the utilization of the con-
stituent AA. However, the practical implications of this
phenomenon remain speculative and questionable [21].
The collective body of evidence indicates that total daily
protein intake for the goal of maximizing resistance
training-induced gains in muscle mass and strength is ap-
proximately 1.6 g/kg, at least in non-dieting (eucaloric or
hypercaloric) conditions [6]. However, 1.6 g/kg/day should
not be viewed as an ironclad or universal limit beyond
which protein intake will be either wasted or used for
physiological demands aside from muscle growth. A re-
cent meta-analysis on protein supplementation involving
resistance trainees reported an upper 95% confidence
interval (CI) of 2.2 g/kg/day [6]. Bandegan et al. [7]also
showed an upper CI of 2.2 g/kg/day in a cohort of young
male bodybuilders, although the method of assessment
(indicator amino acid oxidation technique) used in this
study has not received universal acceptance for determin-
ing optimal protein requirements. This reinforces the
practical need to individualize dietary programming, and
remain open to exceeding estimated averages. It is there-
fore a relatively simple and elegant solution to consume
protein at a target intake of 0.4 g/kg/meal across a
minimum of four meals in order to reach a minimum of
1.6 g/kg/day if indeed the primary goal is to build
muscle. Using the upper CI daily intake of 2.2 g/kg/day
over the same four meals would necessitate a maximum
of 0.55 g/kg/meal. This tactic would apply what is cur-
rently known to maximize acute anabolic responses as
well as chronic anabolic adaptations. While research
shows that consumption of higher protein doses (> 20 g)
results in greater AA oxidation [40], evidence indicates
that this is not the fate for all the additional ingested AAs
as some are utilized for tissue-building purposes. Further
research is nevertheless needed to quantify a specific
upper threshold for per-meal protein intake.
Schoenfeld and Aragon Journal of the International Society of Sports Nutrition (2018) 15:10 Page 4 of 6
Acknowledgements
N/A
Funding
N/A
Availability of data and materials
N/A
Authorscontributions
Brad Schoenfeld conceived of the article. Both authors equally contributed
to the writing of the manuscript. Both authors read and approved the final
manuscript.
Ethics approval and consent to participate
N/A
Consent for publication
N/A
Competing interests
Brad Schoenfeld serves on the scientific advisory board for Dymatize
Nutrition. The authors declare no other conflicts of interest.
PublishersNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
CUNY Lehman College, Department of Health Sciences, 250 Bedford Park
Blvd West, Bronx, NY 10468, USA.
2
California State University, 18111 Nordhoff
St, Northridge, CA 91330, USA.
Received: 19 September 2017 Accepted: 20 February 2018
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Schoenfeld and Aragon Journal of the International Society of Sports Nutrition (2018) 15:10 Page 6 of 6
... Several factors impact the influence protein has on MPS, including the protein dose and protein quality, which is highly influenced by the relative amount of leucine in the protein consumed and the state of energy balance and hydration when the protein is consumed [5,6]. Dietary protein recommendations are typically presented in 24-h units, but it has become increasingly clear that the distribution of protein within each 24-h period is a critically important factor for sustaining and/or increasing musculature [7,8]. To maximize MPS an adequate protein quantity and quality per meal of 20-40 g (∼0.40 g/kg body mass) with 1-3 g leucine and 10-15 g essential amino acids (EAA) consumed when in a good energybalanced state has been proposed [9][10][11][12]. ...
... In the current study, volunteers whose total dietary protein intake reached at least 0.80 g·kg −1 ·d −1 before intervention were eligible to participate in the formal study. This inclusion criterion was based on the international society of sports nutrition position stand [8], where 0.80 g·kg −1 ·d −1 of "good-quality" protein denotes the recommended dietary allowance (RDA) for healthy adults [7]. According to the 3 days dietary record (2 weekdays and 1 weekend day), the subjects consumed 1.28 ± 0.49 g·kg −1 ·d −1 relative protein mass with no significant difference between groups at baseline. ...
... Because muscle protein synthesis has a saturable dose relationship with the quantity of dietary protein consumed, there is a shift in focus on protein intake from daily intake to individual meal intakes [7,16]. Several studies have confirmed that a more balanced protein distribution within meals and throughout the day is associated with more favorable MPS outcomes [19][20][21][22]37]. ...
Article
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There is increasing evidence that dietary protein intake with leucine and vitamin D is an important factor in muscle protein synthesis. This study investigated the combined effects of consuming whey protein and vitamin D3 in the evening before bedtime or in the morning after sleeping on muscle mass and strength. Healthy, untrained males (N = 42; Age = 18–24 year) were randomly assigned into three groups: before bedtime, after sleeping, and control. Subjects underwent a 6-week resistance training program in combination with supplements that provided 25 g whey protein and 4000 IU vitamin D3 for the before bedtime and after sleeping groups and a 5 g maltodextrin placebo for the control group. A significant increase in serum vitamin D was observed in both before bedtime and after sleeping groups. All groups experienced a significant gain in leg press. However, the control group did not experience significant improvements in muscle mass and associated blood hormones that were experienced by the before bedtime and after sleeping groups. No significant differences in assessed values were observed between the before bedtime and after sleeping groups. These findings suggest that the combination of whey protein and vitamin D supplements provided either before or after sleep resulted in beneficial increases in muscle mass in young males undergoing resistance training that exceeded the changes observed without these supplements.
... Conversely, Macnaughton et al. (2016) observed a greater anabolic response in resistance-trained males following full-body resistance training with ingestion of 40g compared to 20g. Collectively, researchers (Morton, McGlory, & Phillips, 2015;Schoenfeld & Aragon, 2018) suggest a per-meal relative protein dose of 0.4g.kg may be optimal for anabolic stimulation. ...
... However, visualization of the frequency graphs indicates many participants did not appear to consume adequate protein at the breakfast occasion according to Morton, McGlory, and Phillips (2015) who suggest that a per-dose protein intake of 0.4g.kg is likely to maximally stimulate muscle protein synthesis in young men and 79.9% of potential breakfast eating occasions contained less protein than this threshold. Consuming adequate protein regularly throughout the day may not always be practical for highlevel athletes due to various reasons including busy lifestyles and congested training schedules, appetite suppression due to intense exercise and fear of gastrointestinal disturbances (Burke et al., 2003) however this should be encouraged to stimulate and provide substrates for the anabolic processes required for supporting lean mass adaptations (Schoenfeld & Aragon, 2018). ...
... N=234 indicates the total number of eating occasions for the meal. Reference lines on each graph highlight 0.4g.kg as a recommended per-meal protein dose (Schoenfeld & Aragon, 2018). ...
Article
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Recent research in healthy adults suggests an even distribution of protein throughout the day may result in greater stimulation of muscle protein synthesis compared to a disproportionate intake, with 0.4g.kg per meal at a minimum of 4 eating occasions proposed to optimise anabolism. In rugby players, this may be of benefit to exercise adaptations, recovery, and performance. In the present study, semi-professional forwards (n = 19), semi-professional backs (n = 6) and professional (n = 10) rugby players recorded dietary intake for seven days. Both absolute (g) and relative to body mass (g.kg) protein intake was calculated across six eating occasions. Relative protein intake at breakfast, AM snack, lunch, PM snack, dinner and evening snack were 0.3, 0.1, 0.4, 0.2, 0.6 and 0.1g.kg, respectively. Total protein intake was significantly different between groups (p < 0.05). All groups demonstrated differences in protein intake between eating occasions (p < 0.01). Protein intake was highest at dinner in all athletes, with professionals consuming significantly greater protein than semi-professionals. Rugby players do not appear to meet the recommended per-meal protein dose of 0.4g.kg at a minimum of 4 eating occasions. Consumption of additional protein outside of main eating occasions as snacks may be beneficial to optimise muscle protein synthesis stimulation and thus adaptation, recovery and performance.
... This quantity can be obtained by combining different foods that are commonly consumed (Table I) or by formulations containing protein isolate, which is especially suitable when players have no appetite after exercise (11), given that its high content of essential amino acids and rapid transport to the bloodstream has proven to be effective in the recovery and repair of muscle damage (45). Later, the protein that comes with the diet should continue to stimulate the adaptation and the biological restoration , ensur- ing a minimum intake of 1,4 to 1,7 g/kg, which may be increased to 2,2 g/kg/day (46). This minimum quantity can be achieved by assuring ~20-30 grams of high biological value protein in each of the 3-4 main meals and 1-2 snacks that the player makes , through foods such as meat, fish, eggs, dairy and its derivatives, as well as some plant sources such as nuts, legumes and seeds. ...
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Introduction: only sparse scattered studies present a practical approach on the nutritional requirements of modern basketball players. Thispaper aims to gather and complete such a disseminated knowledge from a theoretical-practical perspective.Objectives: to analyze the fatigue produced during a basketball game, while offering a practical solution to accelerate its recovery through nutrition.Methods: database research over the reviews of the last 15 years and its original articles on basketball of the last 5 years.Results: the selection of nutrients and food supplements along with their proper timing and doses are key for a quicker and more effective recovery.Conclusions: nutrition before, during and after games or high intense practices, plays a fundamental role in the recovery of the basketball player (PDF) The role of nutrition in the recovery of a basketball player (English). Available from: https://www.researchgate.net/publication/360080845_The_role_of_nutrition_in_the_recovery_of_a_basketball_player_English [accessed May 17 2022].
... At this point in time, participants were provided with pre-packed meals, i.e., dinner on the night before the first biopsy as well as lunch and dinner between the 4 and 24 h biopsy. The meals were designed to meet protein guidelines of 0.4 g per kg body weight per meal for resistance-trained athletes (Schoenfeld and Aragon, 2018) corresponding to 1.2-1.4 g per kg bodyweight per day Konig et al., 2020), and complying with caloric requirements estimated using the Benedict Harris equation (PAL 1,6) . ...
Article
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Previous evidence suggests that resistance training in combination with specific collagen peptides (CP) improves adaptive responses of the muscular apparatus. Although beneficial effects have been repeatedly demonstrated, the underlying mechanisms are not well understood. Therefore, the primary objective of the present randomized trial was to elucidate differences in gene expression pathways related to skeletal muscle signal transduction following acute high-load resistance exercise with and without CP intake. Recreationally active male participants were equally randomized to high-load leg extension exercise in combination with 15 g CP or placebo (PLA) supplementation. Muscle biopsies from the vastus lateralis muscle were obtained at baseline as well as 1, 4 and 24 h post exercise to investigate gene expression using next generation sequencing analysis. Several important anabolic pathways including PI3K-Akt and MAPK pathways were significantly upregulated at 1 and 4 h post-exercise. Significant between-group differences for both pathways were identified at the 4 h time point demonstrating a more pronounced effect after CP intake. Gene expression related to the mTOR pathway demonstrated a higher visual increase in the CP group compared to PLA by trend, but failed to achieve statistically significant group differences. The current findings revealed a significantly higher upregulation of key anabolic pathways (PI3K-Akt, MAPK) in human skeletal muscle 4 h following an acute resistance training combined with intake of 15 g of specific collagen peptides compared to placebo. Further investigations should examine potential relationships between upregulated gene expression and changes in myofibrillar protein synthesis as well as potential long-term effects on anabolic pathways on the protein level.
... Differences in energy (kcal) and protein (g) between meals were compared. Meal protein consumption was also compared to the optimal 0.4 g protein/kg/meal threshold suggested for adults and older adults that are at risk of catabolic stress or malnutrition during a period of energy deficiency [7,9,19]. ...
Article
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Persistent malnutrition after COVID-19 infection may worsen outcomes, including delayed recovery and increased risk of rehospitalization. This study aimed to determine dietary intakes and nutrient distribution patterns after acute COVID-19 illness. Findings were also compared to national standards for intake of energy, protein, fruit, and vegetables, as well as protein intake distribution recommendations. Participants (≥18 years old, n = 92) were enrolled after baseline visit at the Post-COVID Recovery Clinic. The broad screening battery included nutritional assessment and 24-h dietary recall. Participants were, on average, 53 years old, 63% female, 69% non-Hispanic White, and 59% obese/morbidly obese. Participants at risk for malnutrition (48%) experienced significantly greater symptoms, such as gastric intestinal issues, loss of smell, loss of taste, or shortness of breath; in addition, they consumed significantly fewer calories. Most participants did not meet recommendations for fruit or vegetables. Less than 39% met the 1.2 g/kg/day proposed optimal protein intake for recovery from illness. Protein distribution throughout the day was skewed; only 3% met the recommendation at all meals, while over 30% never met the threshold at any meal. Our findings highlight the need for nutritional education and support for patients to account for lingering symptoms and optimize recovery after COVID-19 infection.
... Suboptimal protein utilization can also occur due to an unfavourable composition of the absorbed amino acids at a given time point, i.e., when the IAA ratios differ from those shown in Table 2. If one or more of the IAAs are lacking, the other IAAs cannot be utilized either and will eventually be oxidized [141]. Hence, supply of IAA needs to be synchronous for optimal utilization. ...
Article
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For design of healthy and sustainable diets and food systems, it is important to consider not only the quantity but also the quality of nutrients. This is particularly important for proteins, given the large variability in amino acid composition and digestibility between dietary proteins. This article reviews measurements and metrics in relation to protein quality, but also their application. Protein quality methods based on concentrations and digestibility of individual amino acids are preferred, because they do not only allow ranking of proteins, but also assessment of complementarity of protein sources, although this should be considered only at a meal level and not a diet level. Measurements based on ileal digestibility are preferred over those on faecal digestibility to overcome the risk of overestimation of protein quality. Integration of protein quality on a dietary level should also be done based on measurements on an individual amino acid basis. Effects of processing, which is applied to all foods, should be considered as it can also affect protein quality through effects on digestibility and amino acid modification. Overall, protein quality data are crucial for integration into healthy and sustainable diets, but care is needed in data selection, interpretation and integration.
... From a clinical perspective, the health benefits of resistance exercises are well-proven by over 30 years of research [33]. In summary, meta-analyses of short-term clinical exercise studies show that resistance training increases skeletal muscle mass and strength and improves the ability to perform daily life activities [34,35]. Resistance training is also shown to reduce the symptoms of depression and anxiety [36]. ...
Article
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Millions of people worldwide are infected with COVID-19, and COVID-19 survivors have been found to suffer from functional disabilities and mental disorders such as depression and anxiety. This is a matter of concern because COVID-19 is still not over. Because reinfection is still possible in COVID-19 survivors, decreased physical function and increased stress and anxiety can lower immune function. However, the optimal exercise intensity and volume appear to remain unknown. Therefore, the current systematic review aimed to evaluate the effect of resistance or aerobic exercises in post-COVID-19 patients after hospital discharge. We conducted searches in the Scopus, SciELO, PubMed, Web of Science, Science Direct, and Google Scholar databases. Studies that met the following criteria were included: (i) English language, (ii) patients with COVID-19 involved with resistance or aerobic exercise programs after hospital discharge. Out of 381 studies reviewed, seven studies met the inclusion criteria. Evidence shows that exercise programs composed of resistance exercise (e.g., 1–2 sets of 8–10 repetitions at 30–80% of 1RM) along with aerobic exercise (e.g., 5 to 30 min at moderate intensity) may improve the functional capacity and quality of life (reduce stress and mental disorders) in post-COVID-19 patients. In addition, only one study reported reinfection of three subjects involved with the exercise program, suggesting that exercise programs may be feasible for the rehabilitation of the patients. A meta-analysis was not conducted because the included studies have methodological heterogeneities, and they did not examine a control group. Consequently, the results should be generalized with caution.
... Furthermore, there is also a prejudice that plant-based protein sources do not enable maximum muscle synthesis as animal-based proteins do and that this can only be achieved through protein supplementation; however, these arguments are not supported by the facts. The required sufficient total protein intake (approximately 1.6 g per kg body mass/day) and protein intake per meal for maximum muscle synthesis is between 20-25 g, thus providing at least 1.2-3 g of leucine [202], which is fairly easy to achieve if there is a need; for example, a meal with 60 g of lentils and 60 g of buckwheat porridge exceeds 20 g of protein, while a meal with 100 g of whole grain spaghetti, 50 g of soy flakes/70 g of soy tofu and 100 g of corn contains approximately 25 g of protein [203]). In addition, sufficient intake of the amino acid leucin has been proposed as a key factor to trigger the muscle growth response. ...
Article
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Interest in vegan diets has increased globally as well as in Slovenia. The quantity of new scientific data requires a thorough synthesis of new findings and considerations about the current reserved position of the vegan diet in Slovenia. There is frequently confusion about the benefits of vegetarian diets that are often uncritically passed on to vegan diets and vice versa. This narrative review aims to serve as a framework for a well-designed vegan diet. We present advice on how to maximize the benefits and minimize the risks associated with the vegan diet and lifestyle. We highlight the proper terminology, present the health effects of a vegan diet and emphasize the nutrients of concern. In addition, we provide guidance for implementing a well-designed vegan diet in daily life. We conducted a PubMed search, up to November 2021, for studies on key nutrients (proteins, vitamin B12, vitamin D, omega-3 long chain polyunsaturated fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), calcium, iron, zinc, iodine and selenium) in vegan diets. Given the limited amount of scientific evidence, we focus primarily on the general adult population. A well-designed vegan diet that includes a wide variety of plant foods and supplementation of vitamin B12, vitamin D in the winter months and potentially EPA/DHA is safe and nutritionally adequate. It has the potential to maintain and/or to improve health. For physically active adult populations , athletes or individuals with fast-paced lifestyles, there is room for further appropriate sup-plementation of a conventional vegan diet according to individuals' health status, needs and goals without compromising their health. A healthy vegan lifestyle, as included in government guidelines for a healthy lifestyle, includes regular physical activity, avoidance of smoking, restriction of alcohol and appropriate sleep hygiene.
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Essential amino acids (EAAs) initiate amino acid-induced stimulation of muscle protein synthesis. Study objectives were to calculate intake of EAAs after creating an EAA database, to explore the association of EAAs and branched-chain amino acids (BCAAs) with handgrip strength (HS) in a younger (<50 y) and older (≥50 y) sample, and to identify major food groups contributing EAAs. The sample consisted of African American and White adults aged, 33-71 years from the Healthy Aging in Neighborhoods of Diversity across the Life Span study, 2009-2013. Intake of total EAAs and BCAAs/kg body weight were positively associated (p < 0.001) with HS per body mass index (HS/BMI) ratio. Being male, African American, a nonsmoker, physically active, euglycemic, and normotensive were associated with higher HS/BMI ratio. EAAs were mainly obtained from red meats/poultry and mixed dishes groups. Findings support the role of high-quality proteins and being active in promoting HS.
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Las proteínas ejercen en el ser humano unas funciones vitales. Cuando el organismo alcanza un estado de estrés o fatiga producido por el entrenamiento, es fundamental el proceso de recuperación para evitar un descenso en el rendimiento durante posteriores demandas físicas y para minimizar el riesgo de lesión. Las proteínas en polvo, siempre y cuando sean de calidad, han mostrado que pueden contribuir de forma eficiente, junto a los alimentos completos, a completar los requerimientos nutricionales del futbolista. El momento, la cantidad y la frecuencia de cada toma, puede ser importante para maximizar la síntesis de proteínas musculares. No obstante, la clave para ello es cubrir la cantidad total de proteína diaria necesaria, más allá del número de ingestas y su distribución en el tiempo.
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AIMS/HYPOTHESIS: We aimed to investigate the role of insulin in regulating human skeletal muscle metabolism in health and diabetes. METHODS: We conducted a systematic review and meta-analysis of published data that examined changes in skeletal muscle protein synthesis (MPS) and/or muscle protein breakdown (MPB) in response to insulin infusion. Random-effects models were used to calculate weighted mean differences (WMDs), 95% CIs and corresponding p values. Both MPS and MPB are reported in units of nmol (100 ml leg vol.)(-1) min(-1). RESULTS: A total of 104 articles were examined in detail. Of these, 44 and 25 studies (including a total of 173 individuals) were included in the systematic review and meta-analysis, respectively. In the overall estimate, insulin did not affect MPS (WMD 3.90 [95% CI -0.74, 8.55], p = 0.71), but significantly reduced MPB (WMD -15.46 [95% CI -19.74, -11.18], p < 0.001). Overall, insulin significantly increased net balance protein acquisition (WMD 20.09 [95% CI 15.93, 24.26], p < 0.001). Subgroup analysis of the effect of insulin on MPS according to amino acid (AA) delivery was performed using meta-regression analysis. The estimate size (WMD) was significantly different between subgroups based on AA availability (p = 0.001). An increase in MPS was observed when AA availability increased (WMD 13.44 [95% CI 4.07, 22.81], p < 0.01), but not when AA availability was reduced or unchanged. In individuals with diabetes and in the presence of maintained delivery of AA, there was a significant reduction in MPS in response to insulin (WMD -6.67 [95% CI -12.29, -0.66], p < 0.05). CONCLUSIONS/INTERPRETATION: This study demonstrates the complex role of insulin in regulating skeletal muscle metabolism. Insulin appears to have a permissive role in MPS in the presence of elevated AAs, and plays a clear role in reducing MPB independent of AA availability.
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Objective We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength. Data sources A systematic search of Medline, Embase, CINAHL and SportDiscus. Eligibility criteria Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation. Design Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM). Results Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength—one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size—muscle fibre cross-sectional area (CSA; 310 µm² (51, 570)) and mid-femur CSA (7.2 mm² (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (−0.01 kg (−0.02,–0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM. Summary/conclusion Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.
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While effects of the two classes of proteins found in milk (i.e. soluble proteins, including whey, and casein) on muscle protein synthesis have been well investigated after a single bout of resistance exercise (RE), the combined effects of these two proteins on the muscle responses to resistance training (RT) have not yet been investigated. Therefore, the aim of this study was to examine the effects of protein supplementation varying by the ratio between milk soluble proteins (fast-digested protein) and casein (slow-digested protein) on the muscle to a 9-week RT program. In a double-blind protocol, 31 resistance-trained men, were assigned to 3 groups receiving a drink containing 20g of protein comprising either 100% of fast protein (FP(100), n=10), 50% of fast and 50% of slow proteins (FP(50), n=11) or 20% of fast protein and 80% of casein (FP(20), n=10) at the end of training bouts. Body composition (DXA), and maximal strength in dynamic and isometric were analyzed before and after RT. Moreover, blood plasma aminoacidemia kinetic after RE was measured. The results showed a higher leucine bioavailability after ingestion of FP(100) and FP(50) drinks, when compared with FP(20) (p<0.05). However, the RT-induced changes in lean body mass (p<0.01), dynamic (p<0.01), and isometric muscle strength (p<0.05) increased similarly in all experimental groups. To conclude, compared to the FP(20) group, the higher rise in plasma amino acids following the ingestion of FP(100) and FP(50) did not lead to higher muscle long-term adaptations.
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Background: Despite a number of studies indicating increased dietary protein needs in bodybuilders with the use of the nitrogen balance technique, the Institute of Medicine (2005) has concluded, based in part on methodologic concerns, that "no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise." Objective: The aim of the study was to assess the dietary protein requirement of healthy young male bodybuilders (with ≥3 y training experience) on a nontraining day by measuring the oxidation of ingested L-[1-¹³C]phenylalanine to ¹³CO2 in response to graded intakes of protein [indicator amino acid oxidation (IAAO) technique]. Methods: Eight men (means ± SDs: age, 22.5 ± 1.7 y;weight, 83.9 ± 11.6 kg; 13.0% ± 6.3%body fat) were studied at rest on a nontraining day, on several occasions (4-8 times) each with protein intakes ranging from 0.1 to 3.5 g · kg⁻¹ · d⁻¹, for a total of 42 experiments. The diets provided energy at 1.5 times each individual's measured resting energy expenditure and were isoenergetic across all treatments. Protein was fed as an amino acid mixture based on the protein pattern in egg, except for phenylalanine and tyrosine, which were maintained at constant amounts across all protein intakes. For 2 d before the study, all participants consumed 1.5 g protein · kg⁻¹ ·d⁻¹.On the study day, the protein requirement was determined by identifying the breakpoint in the F¹³CO2 with graded amounts of dietary protein [mixed-effects change-point regression analysis of F¹³CO2 (labeled tracer oxidation in breath)]. Results: The Estimated Average Requirement (EAR) of protein and the upper 95% CI RDA for these young male bodybuilders were 1.7 and 2.2 g · kg⁻¹ ·d⁻¹, respectively. Conclusion: These IAAO data suggest that the protein EAR and recommended intake for male bodybuilders at rest on a nontraining day exceed the current recommendations of the Institute of Medicine by ~2.6-fold.
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Background Intermittent fasting (IF) is an increasingly popular dietary approach used for weight loss and overall health. While there is an increasing body of evidence demonstrating beneficial effects of IF on blood lipids and other health outcomes in the overweight and obese, limited data are available about the effect of IF in athletes. Thus, the present study sought to investigate the effects of a modified IF protocol (i.e. time-restricted feeding) during resistance training in healthy resistance-trained males. Methods Thirty-four resistance-trained males were randomly assigned to time-restricted feeding (TRF) or normal diet group (ND). TRF subjects consumed 100 % of their energy needs in an 8-h period of time each day, with their caloric intake divided into three meals consumed at 1 p.m., 4 p.m., and 8 p.m. The remaining 16 h per 24-h period made up the fasting period. Subjects in the ND group consumed 100 % of their energy needs divided into three meals consumed at 8 a.m., 1 p.m., and 8 p.m. Groups were matched for kilocalories consumed and macronutrient distribution (TRF 2826 ± 412.3 kcal/day, carbohydrates 53.2 ± 1.4 %, fat 24.7 ± 3.1 %, protein 22.1 ± 2.6 %, ND 3007 ± 444.7 kcal/day, carbohydrates 54.7 ± 2.2 %, fat 23.9 ± 3.5 %, protein 21.4 ± 1.8). Subjects were tested before and after 8 weeks of the assigned diet and standardized resistance training program. Fat mass and fat-free mass were assessed by dual-energy x-ray absorptiometry and muscle area of the thigh and arm were measured using an anthropometric system. Total and free testosterone, insulin-like growth factor 1, blood glucose, insulin, adiponectin, leptin, triiodothyronine, thyroid stimulating hormone, interleukin-6, interleukin-1β, tumor necrosis factor α, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured. Bench press and leg press maximal strength, resting energy expenditure, and respiratory ratio were also tested. ResultsAfter 8 weeks, the 2 Way ANOVA (Time * Diet interaction) showed a decrease in fat mass in TRF compared to ND (p = 0.0448), while fat-free mass, muscle area of the arm and thigh, and maximal strength were maintained in both groups. Testosterone and insulin-like growth factor 1 decreased significantly in TRF, with no changes in ND (p = 0.0476; p = 0.0397). Adiponectin increased (p = 0.0000) in TRF while total leptin decreased (p = 0.0001), although not when adjusted for fat mass. Triiodothyronine decreased in TRF, but no significant changes were detected in thyroid-stimulating hormone, total cholesterol, high-density lipoprotein, low-density lipoprotein, or triglycerides. Resting energy expenditure was unchanged, but a significant decrease in respiratory ratio was observed in the TRF group. Conclusions Our results suggest that an intermittent fasting program in which all calories are consumed in an 8-h window each day, in conjunction with resistance training, could improve some health-related biomarkers, decrease fat mass, and maintain muscle mass in resistance-trained males.
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Skeletal muscle is critical for human health. Protein feeding, alongside resistance exercise, is a potent stimulus for muscle protein synthesis (MPS) and is a key factor that regulates skeletal muscle mass (SMM). The main purpose of this narrative review was to evaluate the latest evidence for optimising the amino acid or protein source, dose, timing, pattern and macronutrient coingestion for increasing or preserving SMM in healthy young and healthy older adults. We used a systematic search strategy of PubMed and Web of Science to retrieve all articles related to this review objective. In summary, our findings support the notion that protein guidelines for increasing or preserving SMM are more complex than simply recommending a total daily amount of protein. Instead, multifactorial interactions between protein source, dose, timing, pattern and macronutrient coingestion, alongside exercise, influence the stimulation of MPS, and thus should be considered in the context of protein recommendations for regulating SMM. To conclude, on the basis of currently available scientific literature, protein recommendations for optimising SMM should be tailored to the population or context of interest, with consideration given to age and resting/post resistance exercise conditions.
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