BUILD MUSCLE - IDEA Health and Fitness Associationfact, a 2010 article in ACSM’s Current Sports...
Transcript of BUILD MUSCLE - IDEA Health and Fitness Associationfact, a 2010 article in ACSM’s Current Sports...
BUILD MUSCLEEnhancing Resistance Training Results WithProtein/Carbohydrate Supplementation
by Wayne L. Westcott, Ph.D., CSCS and Rita La Rosa Loud, B.S.
LEARNING OBJECTIVES
• To realize that following a strength training session muscle protein
breakdown exceeds muscle protein synthesis, resulting in several
hours of net negative protein balance.
• To recognize that ingesting supplemental protein before and/or after
a resistance workout is essential for attaining a net positive protein
balance that enhances the potential for muscle development.
• To review research-based information and recommendations
for effective pretraining/posttraining protein/carbohydrate
supplementation.
Key words:Strength Training, Muscle Development, Muscle Hypertrophy,Protein Intake, Nutritional Supplementation
There presently exists a disconcerting
irony between the health risks associated
with sedentary lifestyles and the small
percentage of American adults who meet the
minimal physical activity standards established
by the American College of Sports Medicine and
the American Heart Association in 2007 (30
minutes of moderate-intensity physical activity
5 or more days a week or 20 minutes of vig-
orous physical activity 3 days a week) (1).
Recent research on the topic reveals that only
3.5% of our adult population attains this
relatively low level of regular physical activity
(25). There seems to be an even greater
disconnection between the well-documented
health benefits of resistance exercise and the
lack of adult participation in strength training. In
fact, a 2010 article in ACSM’s Current Sports
Medicine Reports presented sufficient research
evidence on the health-related outcomes of
resistance training for the authors to recommend
a public health mandate for resistance training
(19). A 2012 review article by Wescott con-
cluded that standard resistance exercise is
effective in reversing muscle loss, recharging
resting metabolism, reducing body fat, facil-
itating physical function, resisting diabetes,
improving cardiovascular health, increasing
bone mineral density, enhancing mental health,
and reversing specific aging factors (27). A more
complete list of resistance training benefits is
presented in Table 1.
In inactive adults, muscle mass decreases by
3% to 8%per decade after age 30 years (8) and by
5% to 10% per decade after age 50 years (15),
averaging about 1 lb of muscle loss per year
after the fifth decade of life (17). Reduced
muscle mass is largely responsible for reduced
resting metabolism (18), which is typically
accompanied by increased fat accumulation (32).
Fortunately, resistance exercise has been
shown to reverse muscle loss in adults of all ages
(27), averaging approximately 1 lb per month
increase in lean weight during the first several
months of strength training (4,22,29,30). The
importance of muscle remodeling and devel-
opment has spawned numerous resistance ex-
ercise programs and strength training protocols
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for young, middle-aged, and older adults. In addition to
experimenting with various training methods, several studies
have examined the effects of preexercise/postexercise protein/
carbohydrate consumption on muscle building and related
resistance training outcomes.
PRERESISTANCE/POSTRESISTANCE EXERCISEPROTEIN SUPPLEMENTATION
Protein is an essential nutrient that comprises approximately 22%
of muscle tissue, with water contributing most of the remaining
78%. Although it is easy to assume that almost all Americans eat
sufficient protein, about one quarter of 2,600 men and women
aged 65 to 85 years studied in Maryland were consuming in-
adequate amounts of protein (4). The Recommended Dietary
Allowance (RDA) for adults of all ages is 0.36 g of protein per
pound of body weight or about 55 g of protein per day for a
person who weighs 150 lbs. People older than 50 years who
perform resistance exercise need at least 25% more protein than
the RDA level to maintain their muscle mass and 50% more
protein than the RDA level to increase their muscle tissue (4). As
the amount of protein that can be consumed at one time without
exceeding the anabolic maximum is not yet established, it is
recommended that protein intake be distributed throughout the
day (e.g., breakfast, lunch, dinner, and postexercise snack) rather
than at a single protein-rich meal.
Based on numerous study findings, it would seem that the besttime to ingest extra protein is just before or just after a strengthtraining session because doing so significantly enhances muscledevelopment (2,6,7,13,20,21). The muscle-building effects wereperhaps best demonstrated in a study conducted by Paul Cribb,Ph.D., and Alan Hayes, Ph.D., from Victoria University(Australia) in 2006 (5). Seventeen fit young men (mean age,22 years) performed the strength training programs 4 days aweek for a period of 10 weeks. The resistance training consistedof high-intensity workouts using mostly compound exercisesperformed with free weights in a three-phase periodized protocol(70% to 75% 1 RM, 80% to 85% 1 RM, 90% to 95% 1 RM).All of the study participants consumed similar amounts ofsupplemental protein/carbohydrate twice each day on workoutdays only. Half of the subjects took the supplement immediatelybefore and after each strength training session. The other halftook the supplement in the morning and the evening, at least5 hours from the time of the workout. All of the participantswere prescribed 1 g of the supplement for every kilogram ofbodyweight, so a 100-kg (220-lb) male would ingest 100 g ofsupplement twice each training day. The 100 g of supplementcontained 40 g of protein, 43 g of carbohydrate, and 7 g ofcreatine monohydrate.
After 10 weeks of training, the study participants who took theprotein/carbohydrate supplement preworkout/postworkout gainedsignificantly more lean weight than those who ingested theprotein/carbohydrate supplement morning and evening (+2.8 kgvs. 1.5 kg). The preworkout/postworkout supplement group alsodemonstrated significantly greater increases in bench pressstrength (+12.2 kg vs. 9.0 kg) and squat strength (+20.4 kg vs.16.1 kg) than themorning/evening supplement group. In addition,the preworkout/postworkout supplement subjects experiencedsignificantly greater increases in type IIa muscle fiber cross-sectional area, type IIx muscle fiber cross-sectional area, andcontractile protein content than did the morning/evening sup-plement group. Based on their findings, the authors concluded thatsupplement timing represents a simple but effective strategy toenhance the positive physiological adaptations that are associatedwith resistance training. The authors further suggested that thisstrategy should benefit most healthy adults who perform resistanceexercise.
Other investigators (29) decided to test this hypothesis with
previously untrained middle-aged and older adults (52 women
and men aged 39 to 82 years) who completed a 36-week research
program in 1 of 3 study groups. The control group did not
exercise or take supplemental nutrition. The exercise-only group
performed about 25 minutes of strength training (12 standard
resistance machines; 1 set of 8 to 12 repetitions each) and about
25 minutes of aerobic activity (recumbent cycling). The exercise
plus supplement group performed the same exercise program and
TABLE 1: Research-supported Health Benefitsof Resistance Training*Body composition
Increased lean weight (++)
Increased resting energy expenditure (++)
Decreased fat weight (+)
Physical discomfort
Reduced low back pain (+)
Reduced arthritic pain (+)
Diabetes
Increased insulin sensitivity (+)
Improved glucose control (+)
Cardiovascular health
Reduced resting blood pressure (++)
Improved blood lipid profiles (+)
Musculoskeletal health
Increased bone mineral density (++)
Reversed aging factors in skeletal muscle (+)
Mental health
Improved cognitive ability (+)
Enhanced self-esteem (++)
Activities of daily living
Increased functional independence (++)
Enhanced movement control (+)
* Relative strength of resistance training effect: (+) moderate effect; (++)high effect.
VOL. 17/ NO. 2 ACSM’s HEALTH & FITNESS JOURNALA 11
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consumed a protein/carbohydrate shake immediately after each
training session. The supplemental shake provided 24 g of protein
and 36 g of carbohydrate. Only the exercise plus supplement
group attained a significant increase in lean weight (50.3Y52.7 kg).
Based on these findings, it would seem that ingesting a protein/
carbohydrate supplement immediately after strength training
sessions enhances muscle development in middle-aged and
older adults.
In addition to the positive results observed in youngmen (5) and
middle-aged and older adults (29), studies have demonstrated that
posttraining protein/carbohydrate supplementation can enhance
the desired effects of resistance exercise in young women (13)
and elderly men (7). According to John Ivy, Ph.D., and Lisa
Ferguson, M.S., from the University of Texas, (12) postexercise
protein/carbohydrate supplementation is an effective means of
restoring muscle glycogen, repairing muscle damage, attenuating
protein degradation, and initiating protein synthesis.
PROTEIN PLUS CARBOHYDRATE OR PROTEIN ALONEMany of the studies on resistance training supplementation have
used a combination of protein and carbohydrate (5Y7,13,29).
However, protein alone has been shown effective for increasing
muscle fiber size (2), and some studies have indicated that
adding carbohydrate to protein does not increase postexercise
muscle protein synthesis (14,24). In contrast, a review by
Jay Hoffman, Ph.D., concluded that ‘‘the combination of
carbohydrate with protein or amino acids in a supplement
may contribute to a more effective protein uptake and enhanced
synthesis rate of muscle protein’’ (11). The authors of another
research review article concluded that ‘‘Carbohydrates play a
limited role in protein synthesis I(but) are vital to replenish
glycogen stores diminished from prolonged or high-intensity
exercise’’ (21).
Researchers from the University of Texas have proposed that
resistance exercise adaptations may be optimized by taking
appropriate posttraining protein/carbohydrate supplementation
(12). Based on their interpretation of the research, they
recommend a supplement that provides 0.5 to 0.6 g of protein
plus 1.0 to 1.2 g of carbohydrate per kilogram of bodyweight.
As an example, they suggest that a person weighing 70 kg
(154 lbs) should ingest a posttraining supplement that contains
35 to 42 g of protein and 70 to 84 g of carbohydrate.
COMMERCIAL SUPPLEMENTS OR FOOD SOURCESMany of the preexercise/postexercise supplement studies have
used commercial products to provide various combinations of
protein and carbohydrate sources. However, other research has
been conducted with readily available food such as whole milk,
fat-free milk, and whole eggs. Research with men (10) and women
(13) has demonstrated greater lean weight gain and greater fat
weight loss with postexercise fat-free milk compared with those
with a carbohydrate supplement. A similar study (31) compared
skim milk with soy protein for promoting net muscle protein
balance after resistance training. The results indicated that milk-
based proteins promote muscle protein accretion better than soy-
based proteins when ingested after resistance exercise. Another
study (6) compared the effects of fat-free milk and whole milk
taken 1 hour after resistance exercise on net muscle protein
synthesis. When the quantities ingested were the same (237 g),
whole milk was more effective than fat-free milk. However,
when the calories ingested were the same (requiring 393 g of fat-
free milk and 237 g of whole milk), there were no significant
differences between fat-free milk and whole milk supple-
mentation. In his research review, the findings on postexercise
milk supplementation led Dr. Hoffman to conclude that ‘‘a food
source such as milk appears to be suitable for ingestion during
recovery from resistance exercise and may be a cheaper and
effective alternative to protein supplements’’ (11).
Another study (16) examined the effects of ingesting different
amounts of whole egg protein on muscle protein synthesis. The
study participants ingested 0, 5, 10, 20, or 40 g of whole egg
protein after lower body strength training sessions. Higher doses
of protein produced correspondingly higher rates of muscle
protein synthesis through the 20-g supplement. The 40-g dose
did not generate more muscle protein synthesis, indicating that
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Protein Supplements and Resistance Training
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
20 g of whole egg protein may represent an optimal amount of
this postexercise supplement.
PROTEIN INTAKE AND PROTEIN TIMINGWith the exception of older adults, most Americans attain
adequate amounts of protein on a daily basis. However, re-
searchers (33) have suggested that the quantity, quality, and
timing of protein consumption are all important factors in muscle
development. Progressive resistance exercise provides the
stimulus for muscle development. However, the tissue micro-
trauma resulting from a resistance training session requires suf-
ficient protein to sustain the muscle-building processes that lead
to increased strength and size (hypertrophy). Basically, muscle
hypertrophy is dependent on a positive protein balance such that
muscle protein synthesis exceeds muscle protein breakdown.
Although resistance exercise increases the rate of muscle protein
synthesis, it also increases the rate of muscle protein breakdown,
resulting in a net negative protein balance for several hours after
the training session (3). Of course, it is beneficial to promote a
net positive protein balance as much of the time as possible. To
experience a net positive protein balance after resistance exercise,
it is necessary to consume supplemental protein in close prox-
imity to the training session (preworkout/postworkout). In their
review article, Chris Poole, M.Sc., and colleagues (21) stated that
‘‘It is necessary for individuals who seek to gain lean muscle
mass to induce a positive protein turnover as often as possible. It
has been confirmed that protein and/or amino acid ingestion is
required to reach a positive protein/nitrogen balance.’’ Based on
the research reviewed, these authors presented four key findings.
First, resistance exercise increases both muscle protein synthesis
and muscle protein breakdown. Second, the increase in muscle
protein breakdown exceeds the rate of muscle protein synthesis.
Third, consumption of dietary protein and/or amino acids after
strength training sessions augments a net positive protein balance
and enhances the potential for muscle hypertrophy over time.
Fourth, ingestion of dietary protein and/or amino acids im-
mediately after resistance training is more effective than post-
poned supplementation for enabling muscle hypertrophy.
Research also has shown that ingesting supplemental protein
before a resistance training session elicits a significantly greater
increase in resting energy expenditure 24 hours after the workout
compared with that after ingesting supplemental carbohydrate (9).
Therefore, it would seem that consuming supplemental protein,
or protein/carbohydrate, in close time proximity to resistance
exercise sessions may provide dual benefits of enhanced muscle
hypertrophy and increased resting energy expenditure. This may
be one reason why some studies have shown both greater muscle
gain and greater fat loss for subjects ingesting supplemental
protein, or protein/carbohydrate, at the time of their resistance
training sessions (10,13,28).
SUMMARYAs reported in a previous issue of ACSM’s Health & Fitness
JournalA (26), research clearly reveals that resistance exercise is
an effective means for rebuilding muscle, recharging meta-
bolism, and reducing fat in previously inactive adults and older
adults. The studies addressed in this article indicate that these
training outcomes may be enhanced by ingesting supplemental
protein, or protein and carbohydrate, near the time of the
exercise session (just before, just after, or both). Based on these
research findings, it would seem that pretraining/posttraining
protein/carbohydrate supplementation can induce significantly
greater increases in lean weight and resting energy expenditure
and significantly greater decreases in fat weight than those after
resistance exercise without supplementation. Although many
studies have incorporated commercial protein/carbohydrate
products, other studies have demonstrated significant body
composition improvement from ingesting milk after the strength
TABLE 2: Recommended Grams ofPretraining/Posttraining Protein and CarbohydrateSupplementation for Selected Body Weights
Body Weight,kg (lbs)
ProteinSupplement, g
CarbohydrateSupplement, g
50 (110) 18Y22 28Y32
60 (132) 22Y26 34Y38
70 (154) 26Y30 40Y44
80 (176) 30Y34 46Y50
90 (198) 34Y38 52Y56
100 (220) 38Y42 58Y62
VOL. 17/ NO. 2 ACSM’s HEALTH & FITNESS JOURNALA 13
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
training sessions. Some experts have recommended that pre-
training/posttraining supplements contain at least 0.5 g of protein
and 1.0 g of carbohydrate per kg of body weight for optimum
results (~35 g of protein and 70 g of carbohydrate for a 70-kg
individual). However, studies have shown excellent responses to
smaller supplement amounts (~24 g of protein and 36 g of
carbohydrate) for subjects averaging 70 kg of body weight.
Other research has demonstrated net muscle protein synthesis
from postexercise servings of milk that contained about 8 g of
protein and 12 g of carbohydrate. The available evidence
indicates that desired resistance training results, such as muscle
development, strength gain, and fat loss, may be enhanced by
consuming supplemental protein/carbohydrate in close time
proximity to the workout session. Based on the research results
reviewed in this article, general guidelines for pretraining/
posttraining protein and carbohydrate supplementation for exer-
cisers of selected body weights are presented in Table 2.
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Disclosure: The authors declare no conflict of interest and do
not have any financial disclosures.
14 ACSM’s HEALTH & FITNESS JOURNALA | www.acsm-healthfitness.org VOL. 17/ NO. 2
Protein Supplements and Resistance Training
Copyright © 2013 American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
Wayne L. Westcott, Ph.D., CSCS, directs the
exercise science programs and the fitness
research programs at Quincy College in
Quincy, Massachusetts. His research interests
include the variables, acute responses, and
chronic adaptations associated with re-
sistance exercise. He writes the Health &
Fitness Column for ACSM’s Certified News.
Rita La Rosa Loud, B.S., teaches exercise
science and coordinates fitness research
programs at Quincy College in Quincy,
Massachusetts. She is an active member of
the New England Chapter of the American
College of Sports Medicine.
CONDENSED VERSION AND BOTTOM LINE
Inactive adults lose muscle mass at the rate of 3% to 8%per decade, resulting in reduced resting metabolism andincreased fat accumulation. Progressive resistance exerciseprovides the stimulus for strength development, butmuscle hypertrophy requires a net positive protein balance.An effective means for attaining posttraining net positiveprotein balance is supplemental protein (~10Y40 g) con-sumed in close time proximity (e1 hour) of the resistanceworkout. Several studies have shown that pretraining/posttraining protein/carbohydrate ingestion enhancesmuscle development, strength gain, and fat loss in menand women of all ages.
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