Amino Acid Supplements and Recovery from High-Intensity Resistance Training

Abstract

The purpose of this study was to investigate whether short-term amino acid supplementation could maintain a short-term net anabolic hormonal profile and decrease muscle cell damage during a period of high-intensity resistance training (overreaching), thereby enhancing recovery and decreasing the risk of injury and illness. Eight previously resistance trained males were randomly assigned to either a high branched chain amino acids (BCAA) or placebo group. Subjects consumed the supplement for 3 weeks before commencing a fourth week of supplementation with concomitant high-intensity total-body resistance training (overreaching) (3 x 6-8 repetitions maximum, 8 exercises). Blood was drawn prior to and after supplementation, then again after 2 and 4 days of training. Serum was analyzed for testosterone, cortisol, and creatine kinase. Serum testosterone levels were significantly higher (p < 0.001), and cortisol and creatine kinase levels were significantly lower (p < 0.001, and p = 0.004, respectively) in the BCAA group during and following resistance training. These findings suggest that short-term amino acid supplementation, which is high in BCAA, may produce a net anabolic hormonal profile while attenuating training-induced increases in muscle tissue damage. Athletes' nutrient intake, which periodically increases amino acid intake to reflect the increased need for recovery during periods of overreaching, may increase subsequent competitive performance while decreasing the risk of injury or illness.

Full text

AMINO ACID SUPPLEMENTS AND RECOVERY FROM
HIGH-INTENSITY RESISTANCE TRAINING
CARWYN P.M. SHARP
1
AND DAVID R. PEARSON
2
1
Department of Health and Human Performance, College of Charleston, Charleston, South Carolina;
and
2
Strength Research Laboratory, Ball State University, Muncie, IN
ABSTRACT
Sharp, CPM and Pearson, DR. Amino acid supplements and
recovery from high-intensity training. J Strength Cond Res
24(4): 1125–1130, 2010—The purpose of this study was to
investigate whether short-term amino acid supplementation
could maintain a short-term net anabolic hormonal profile and
decrease muscle cell damage during a period of high-intensity
resistance training (overreaching), thereby enhancing recovery
and decreasing the risk of injury and illness. Eight previously
resistance trained males were randomly assigned to either
a high branched chain amino acids (BCAA) or placebo group.
Subjects consumed the supplement for 3 weeks before
commencing a fourth week of supplementation with concom-
itant high-intensity total-body resistance training (overreaching)
(3 36–8 repetitions maximum, 8 exercises). Blood was drawn
prior to and after supplementation, then again after 2 and 4 days
of training. Serum was analyzed for testosterone, cortisol, and
creatine kinase. Serum testosterone levels were significantly
higher (p,0.001), and cortisol and creatine kinase levels were
significantly lower (p,0.001, and p= 0.004, respectively) in
the BCAA group during and following resistance training.
These findings suggest that short-term amino acid supplemen-
tation, which is high in BCAA, may produce a net anabolic
hormonal profile while attenuating training-induced increases in
muscle tissue damage. Athletes’ nutrient intake, which
periodically increases amino acid intake to reflect the increased
need for recovery during periods of overreaching, may increase
subsequent competitive performance while decreasing the risk
of injury or illness.
KEY WORDS overreaching, testosterone, cortisol, muscle
damage, BCAA
INTRODUCTION
Physiological adaptations to training are not linear
over time. Subsequently, short-term periods of
greater than normal increases in training volume
and/or intensity (overreaching) with ensuing
tapering periods are often incorporated into an athlete’s
training program to induce increases in performance (9,10).
However, designing and executing an optimum overreaching
program are complex and delicate. The coach must increase
the training stimulus beyond previous levels to induce an
enhanced adaptation but must not overload the athlete too
greatly, otherwise it can lead to illness, injury, and decreased
performance at a crucial period in the athlete’s competition
cycle. Similarly, an overreaching phase should be intention-
ally short in duration to minimize the risk of overtraining or
injury, yet paradoxically this is often the impetus for coaches
to excessively increase intensity. To attenuate these risks and
maximize the desired performance rebound of overreaching,
enhanced recovery methods such as nutritional supplemen-
tation may be pivotal.
Nutritional support for resistance training is essential
during all phases of training. Prior research has shown that
resistance training alone, while it increases skeletal muscle
protein synthesis (MPS), also results in an increase in protein
breakdown (4,19). Although the net effect is an increase
in protein synthesis, skeletal muscle remains in an overall
catabolic state in the absence of adequate nutritional inter-
vention (5,19). The ingestion or infusion of amino acids in
conjunction with an acute bout of resistance training has
been shown by numerous studies to significantly increase
protein synthesis and yield a net anabolic state (5,7,22).
However, the mechanism(s) by which this occurs remains
elusive. Limited research has also examined the potential of
amino acid supplementation to enhance recovery during
periods of overreaching (15,20) and other physically stressful
periods of training commonly experienced by athletes.
It has been shown that fluctuations in endogenous
hormone levels are strongly correlated to both short- and
long-term adaptations from exercise training and reflect
both the catabolic and anabolic physiological state (1,12)
during stress and recovery periods of training. The resistance
exercise-induced hormonal response to acute resistance
exercise in men is well demonstrated and includes an increase
Address correspondence to David Pearson, dpearson@bsu.edu.
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in serum cortisol (C); an initial decrease in testosterone (T)
(14); and a decrease in the testosterone:cortisol ratio (TC), an
index of overall anabolism/catabolism (3).
Thus, the purpose of this study was to examine the net
hormonal effect of amino acid supplementation on the
overreaching resistance training–induced hormonal stress
response. We hypothesized that amino acid supplementation
would enhance protein synthesis, thereby enhancing skeletal
muscle repair and thus reducing plasma creatine kinase (CK)
levels. It was further hypothesized that this reduction in
muscle damage would reduce the hormonal stress response to
training, which would be determined by evaluating plasma
cortisol levels. It was also speculated that reduced skeletal
muscle damage would also allow for sustained high-intensity
training, thereby eliciting greater T release. Thus, it was
generally hypothesized that amino acid supplementation
during overreaching would result in a net anabolic hormonal
profile as a response to reduced
skeletal muscle damage or en-
hanced recovery.
METHODS
Experimental Approach to the
Problem
This investigation involveda bal-
anced, cross-over, placebo-con-
trolled, double-blind, repeated-
measures design, shown sche-
matically in Figure 1. Subjects
acted as their own control.
Subjects were randomly as-
signed to 1 of 2 treatment
groups: branched chain amino
acids (BCAA) or placebo (P).
The amino acid composition of
the supplement Nutri-Build II (per 12 capsules) consists of the
following: L-Glutamine, 2000 mgs; L-leucine, 1800 mgs; L-
isoleucine, 750 mgs; and L-valine, 750 mgs. The BCAA group
consumed 6 g (12 capsules, which is the manufacturer’s
recommended daily dose) of Nutri-Build II (Nutrient
Technology, Inc.) per day, whereas P consumed 12 capsules
of lactose (virtually identical in size, shape, and color). Subjects
consumed 6 capsules in the morning and 6 capsules in the
evening with meals. Each treatment was consumed for 3
weeks (Day 0 to 21) followed by a fourth week of concurrent
supplementation and resistance exercise (Day 22 to 28). This
was followed by a 5-week wash-out period with no
supplementation or resistance training, then a subsequent 4-
week supplementation period consuming the alternative
treatment.
Neither subjects nor trainers were aware which treatment
was consumed. All subjects were instructed to maintain their
normal daily activity levels
throughout the duration of the
13-week study period. Subjects
completed a 7-day dietary recall
before each supplementation
period and during the final
supplementation period to de-
termine their nutritional status
prior to supplementation. Sub-
jects with a dietary protein
intake in excess of the recom-
mended daily allowance (0.8
g/kg/day) were excluded from
the study.
Two weeks prior to consum-
ing any treatment, subjects’
maximum strength (1 repetition
maximum, or 1RM) was as-
sessed (Cybex, Ronkonkona,
New York). Strength measures
Figure 1. Schematic representation of crossover experimental design for branched-chain amino acid (BCAA) and
placebo (P) supplementation and resistance training.
Figure 2. Mean serum cortisol levels (6SE) during the final 7 days of 28 days of supplementation with either
placebo or a branched chain amino acid (BCAA)–rich supplement. Blood was obtained 12 hours following the first
2 consecutive days of intense resistance training (Day 24) and 12 hours (Day 27) and 36 hours (Day 28) following
the final training session. Resistance training occurred on days 22, 24, 26, and 27. *p,0.05 versus baseline
(Day 0); n=8.
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were completed for leg press, leg curl, leg extension, chest
press, military press, latissimus pulldown, dumbbell curl, and
triceps pushdown following National Strength and Condi-
tioning Association testing recommendations (2).
Subjects
Ten healthy, recreationally active males were recruited from
a university population, and 8 subjects completed the study
(1 withdrew because of illness, and 1 withdrew because of
injury not related to the study) (mean 6SE; age 22.9 62y;
weight 77.9 63.6 kg; height 177.1 61.8 cm). All subjects
completed a medical history and activity questionnaire prior
to initiation of the study. All subjects had a minimum of
1 year previous resistance training experience but had not
participated in resistance train-
ing in the 6 months prior to
commencement of the study.
Approval for conducting the
study was obtained from the
Ball State University Institu-
tional Review Board, and each
subject was informed of the
benefits and risks of the in-
vestigation and subsequently
signed an approved consent
form outlining the risks associ-
ated with the experiment prior
to participation. In addition,
none of the subjects were
taking any medications, nutri-
tional supplements, or anabolic
drugs that would confound the
results of this study.
Procedures
Resistance Training. Training included 4 supervised sessions
between days 22 and 28 of supplementation (Monday,
Tuesday, Thursday, Friday), each consisting of 5 minutes of
passive stretching followed by three sets of 6–8 repetitions at
80% of 1RM of each of the exercises outlined previously.
A 60-second passive rest was observed between sets and
exercises. Subjects were instructed not to cool down or
engage in any heat, cold, or massage treatments for the
duration of the study.
Blood Collection and Analysis. Five antecubital venous blood
draws were obtained following an overnight 12-hour fast
during each 4-week supplementation period (Figure 1).
Samples were taken 2 days
prior to and 3 weeks after
supplementation and again
within an hour after 2 and 4
days of training. The final
sample was obtained 36 hours
after the last training session.
Blood samples were allowed to
coagulate at room temperature
then centrifuged, and the serum
is frozen at –80°C until analysis.
Cortisol and testosterone con-
centrations were determined in
duplicate from thawed serum
using a solid phase
125
I radioim-
munoassay kits (DSL-2100 and
DSL-4000, respectively, Diag-
nostic Systems Laboratories,
Inc, Webster, Texas). Creatine
kinase levels were determined in
duplicate using an enzymatic
Figure 3. Serum cortisol percent change from baseline (area under the curve [AUC]) during 28 days of
supplementation with either placebo or a branched chain amino acid (BCAA)–rich supplement and 7 days
(4 sessions) of concomitant high-intensity total-body resistance training (overreaching) (3 36–8 repetitions
maximum [RM], 8 exercises). Blood was obtained at baseline (day 0), 12 hours following the first 2 consecutive
days of intense resistance training, and 12 hours (Day 27) and 36 hours (Day 28) following the final training session.
*p,0.05 versus placebo; n= 8. Data presented are means 6SE.
Figure 4. Serum testosterone concentration percent change from baseline (area under the curve [AUC]) during 28
days of supplementation with either placebo or a branched chain amino acid (BCAA)–rich supplement and 7 days
(4 sessions) of concomitant high-intensity total-body resistance training (overreaching) (3 36–8 repetitions
maximum [RM], 8 exercises). Blood was obtained at baseline (day 0), 12 hours following the first 2 consecutive
days of intense resistance training, and 12 hours (Day 27) and 36 hours (Day 28) following the final training session.
*p,0.05 versus placebo; n= 8. Data presented are means 6SE.
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assay (Procedure No. 47-UV, Sigma Diagnostic, St. Louis,
Missouri) and spectrophotometry (Spectronic 601, Milton
Roy Company, Rochester, New York).
Statistical Analyses
A 2-way repeated measures analysis of variance (ANOVA)
was used to determine differences (p-value ,0.05) between
groups (P versus BCAA) over time for each variable: C, T,
T:C ratio, and CK. Subsequent differences were determined
using a Tukey post-hoc test when appropriate.
Area under the curve (AUC) was utilized to compare
the effect of treatment over the entire treatment and
training period. AUC was calculated as AUC =
S[b(c+a)/2, where b is the time in days between the two
data points (c and a) and Sis the
sum of each AUC for all sub-
jects. Student’s t-test was used
to assess significance between
treatments (p#0.05).
RESULTS
No significant change in height
or weight of any subject
was observed over the course
of the study. No significant
difference in workload during
each training week was ob-
served for any subject.
Serum cortisol concentrations,
as a percent change from base-
line, were significantly lower
for BCAA compared to P at 2
(p=0.011)and4daysoftraining
(p= 0.005) and 36 hours
after the last bout of training
(p= 0.022) (Figure 2). Total area
under the curve (AUC) for
serum cortisol compared to
baseline was significantly lower
(p,0.001) for BCAA (Figure 3).
Total serum testosterone levels,
measured as AUC, were signif-
icantly greater (p,0.001) with
BCAA supplementation com-
paredtoP(Figure4).
The net hormonal anabolic
effect of supplementation, mea-
sured as the TC ratio, was also
significantly greater (p,0.001)
for BCAA supplementation
compared to P (Figure 5).
Total CK levels were signifi-
cantly lower (p= 0.004) with
BCAA supplementation versus
P (Figure 6).
DISCUSSION
The major findings of this study are (a) that an amino acid
supplement high in BCAA is capable of significantly
decreasing the elevated cortisol response of overreaching
resistance training; (b) testosterone levels may be significantly
increased during overreaching training if accompanied by
BCAA supplementation; and (c) markers of skeletal muscle
damage (CK) in response to chronic high-intensity resistance
training can be significantly decreased with concomitant
BCAA ingestion in previously resistance trained men.
Effective and efficient recovery protocols are critical for
optimal training-induced adaptations and subsequently
achieving enhanced performance-related goals. This is
Figure 5. Serum testosterone: cortisol ratio percent change from baseline (area under the curve [AUC]) during 28
days of supplementation with either placebo or a branched chain amino acid (BCAA)–rich supplement and 7 days
(4 sessions) of concomitant high-intensity total-body resistance training (overreaching) (3 36–8 repetitions
maximum [RM], 8 exercises). Blood was obtained at baseline (day 0), 12 hours following the first 2 consecutive
days of intense resistance training, and 12 hours (Day 27) and 36 hours (Day 28) following the final training session.
*p,0.05 versus placebo; n= 8. Data presented are means 6SE.
Figure 6. Mean serum creatine kinase levels (area under the curve [AUC]) during 28 days of supplementation with
either placebo or a branched chain amino acid (BCAA)–rich supplement and 7 days (4 sessions) of concomitant
high-intensity total-body resistance training (overreaching) (3 36–8 repetitions maximum [RM], 8 exercises). Blood
was obtained at baseline (day 0), 12 hours following the first 2 consecutive days of intense resistance training, and
12 hours (Day 27) and 36 hours (Day 28) following the final training session. *p,0.05 versus placebo; n= 8. Data
presented are means 6SE.
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particularly true of athletes who utilize the rebound enhanced
performance effect of overreaching (9), which occurs only
with adequate recovery.
The results of the present study indicate that an amino acid
supplement high in BCAA exerts an anticatabolic hormonal
effect by significantly decreasing serum cortisol levels in
response to resistance training overreaching. Bird et al. (6)
previously reported in untrained males that essential amino
acid ingestion during an acute bout of resistance exercise
resulted in no significant increase in cortisol compared to
baseline. Thus, our findings support those of previous inves-
tigations that amino acid ingestion is capable of attenuating
exercise-induced increases in cortisol. The implications for
those athletes who engage in overreaching prior to competi-
tion is a reduced risk of opportunistic infections such as upper
respiratory tract infections and increased potential for
maximizing the rebound effect associated with overreaching.
Our results support earlier findings, which indicate that amino
acid supplementation may enhance recovery from overreaching
by reducing skeletal muscle breakdown, indicated by significant
decreases in serum CK levels following exercise (8).
An interesting finding of the present study was that the
results outlined herein may be achieved with low relative and
absolute amino acid supplementation. The amount of BCAA
administered in this study was in accordance with the
manufacturers recommended dosage, which was lower
in absolute and relative terms than that used in other studies
in this area that have shown statistically significant improve-
ments (8,21). Insufficient plasma availability of the BCAA (a
combination of low dosage and splanchnic and gastrointes-
tinal use) may dampen their effects (16). In absolute terms,
recent research indicates that a minimum of 12 g of BCAA per
day (8) is required to elicit an ergogenic effect; however, the
literature supports the use of up to 40 g (21) as a bolus
ingestion postexercise. The current study provided 718 mg
each of valine and isoleucine and 1,442 mg of leucine (i.e., total
of 2.878 g) per day. This is only 24% of that used by Coombes
and McNaughton (8) and a mere 7% used by Tipton and
colleagues (21).
More important, in relative amounts, the current study also
seems to have provided much less amino acids than the
literature suggests, even with the addition of the subject’s
normal daily protein intake. Data from Meguid and cow-
orkers’ (16) investigation illustrate that leucine intake should
be a minimum of 20 mg/kg per day to maintain a positive
leucine balance (take in more than is oxidized). Therefore, it
seems that 20 mg of leucine per kilogram of body weight per
day is an advisable minimum for a normal adult population to
meet their daily needs. The current study used a total of 1,442
mg of leucine per day, which represents an intake of $20
mg/kg per day for only 1 subject. Although this is not
indicative of the total daily intake, to meet amino acid and
energy demands of exercise stress, the amount of amino acids
required for additional protein synthesis for tissue repair and
energy oxidation is necessarily greater. Following a high-
intensity training program (6 days per week) over 5 weeks in
10 previously trained sprinters and jumpers, basal fasting
levels of leucine decreased by 20%, isoleucine by 21%, and
valine by 18% (17). During this study by Mero and colleagues
(17), total serum amino acids decreased by 19% despite
a daily protein intake of 1.26 g/kg per day, which is above the
recommended dietary intake of 0.8 g/kg per day. These
observations concur with Hood and Terjung’s (13) review of
literature, which suggests an increased leucine consumption
in excess of 45 mg/kg per day for regularly active individuals.
Golgan’s (11) more extensive review-based estimate of
a leucine intake of 60 mg/kg per day, valine 50, and
isoleucine 20, for those people engaged in prolonged or
intense training may be more accurate. In the present study,
dietary analysis showed that no subjects were consuming
more than 0.7 g/kg per day of protein during the course of
the study. It is likely, then, that for these virtually novice
lifters, the commencement of resistance training would have
increased their amino acid demands higher than that of
normal individuals. As such, even with the addition of their
normal dietary protein intake to that supplemented, the
subjects in the present study may not have received adequate
BCAA to promote an increase serum BCAA concentration
required to elicit an ergogenic effect.
It is encouraging, however, that in light of the limited
intake of BCAA in this study, relative to other noted studies
that have found significant effects, the consistently observed
trends may imply that small doses of BCAA, such as that
consumed in this study, may provide sufficient BCAA
availability to reduce skeletal muscle cell damage, increase
testosterone, and decrease cortisol. The limited number of
subjects in this study negated the ability to analyze the data
according to mass. Larger sample size is consistently cited in
statistical literature as reducing variability and producing
more meaningful and accurate results.
PRACTICAL APPLICATIONS
The goal of BCAA supplementation is to increase amino acid
availability, thereby increasing substrate and energy avail-
ability for MPS and recovery and decreasing the catabolic and
increasing the anabolic hormonal profile. The consumption
of supplements high in BCAA by individuals and teams that
have athletes ranging in mass and metabolism is likely to yield
variability in results, based on mass and individual physio-
logical differences (e.g., BCAA oxidation and skeletal muscle
uptake) because heavier subjects may need to consume larger
quantities of the BCAA to produce both a more anabolic
hormonal profile and greater muscle membrane integrity.
In conjunction, consultation with a qualified nutritional expert
and the manufacturer is advised to determine the appropriate
amount of supplement to be consumed to ensure adequate
presentation to the skeletal muscle and other tissues because
heavier subjects may need to consume larger quantities of
the BCAA to produce both a more anabolic hormonal profile
and greater muscle membrane integrity.
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BCAA supplementation has been demonstrated to increase
plasma and muscular BCAA concentrations, thereby in-
creasing substrate availability for protein synthesis and energy
production to support protein manufacture. An increase in
amino acid transport postresistance training with a concom-
itant increase in plasma and muscle substrate availability may
increase protein synthesis. In conjunction, if MPS increases
postexercise, the opportunity to exacerbate protein repair and
adaptation is maximized with optimum substrate and energy
availability.
Tipton and colleagues (21) showed oral ingestion of
essential amino acids (including the BCAA) resulted in net
MPS, and, in conjunction with resistance exercise, an even
greater increase in MPS has been shown (18). Thus, sufficient
availability of amino acids following exercise appears
necessary for maximizing increases in skeletal muscle protein
synthesis following an acute bout of resistance exercise.
ACKNOWLEDGMENTS
This research was funded by the Office of Academic Research
and Sponsored Programs Research Grant, Ball State
University, Muncie, Indiana, and Nutrient Technologies,
Inc., Oklahoma City, Oklahoma. The results of this study do
not constitute endorsement of this product by the authors or
the National Strength and Conditioning Association.
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