Ingesting a preworkout supplement containing

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N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
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Ingesting a preworkout supplement containing
caffeine, creatine, β-alanine, amino acids, and B
vitamins for 28 days is both safe and efficacious in
recreationally active men☆
Kristina L. Kendall a,⁎, Jordan R. Moonb, c, Ciaran M. Fairmana, Brandon D. Spradleyb,
Chih-Yin Taib, c, Paul H. Falcone c, Laura R. Carsonc, Matt M. Mosmanc, Jordan M. Joy c,
Michael P. Kimc, Eric R. Serrano c, Enrico N. Esposito b, d
a Department of Health and Kinesiology, Georgia Southern University, Statesboro, GA
b Department of Sports Exercise Science, United States Sports Academy, Daphne, AL
c Sports Science Institute, MusclePharm, Corp, Denver, CO
d Department of Human Performance & Exercise Science, University of Mobile, Mobile, AL
A R T I C L E I N F O
Abbreviations: 1RM, one-repetition maxim
BCAA, branched chain amino acids; BP, blood
oxygen consumption per unit time; VO2ma
consumption per unit time at which ventilat
☆ JM, PF, CT, LC, MK, MM, JJ, and ES are cu
research was conducted at the US Sports Ac
authors have no financial interests concerni
⁎ Corresponding author. PO Box 8076, Georgia
E-mail address: kkendall@georgiasouther
http://dx.doi.org/10.1016/j.nutres.2014.04.003
0271-5317/© 2014 Elsevier Inc. All rights rese
Please cite this article as: Kendall KL, et a
acids, and B vitamins for 28 days is both
A B S T R A C T
Article history:
Received 27 November 2013
Revised 21 February 2014
Accepted 8 April 2014
The purpose of this study was to determine the safety and efficacy of consuming a
preworkout supplement (SUP) containing caffeine, creatine, β-alanine, amino acids, and B
vitamins for 28 days. We hypothesized that little to no changes in kidney and liver clinical
blood markers or resting heart rate and blood pressure (BP) would be observed. In addition,
we hypothesized that body composition and performance would improve in recreationally
active males after 28 days of supplementation. In a double-blind, placebo-controlled study,
participants were randomly assigned to ingest one scoop of either the SUP or placebo every
day for 28 days, either 20minutes before exercise or ad libitum on nonexercise days. Resting
heart rate and BP, body composition, and fasting blood samples were collected before and
after supplementation. Aerobic capacity as well as muscular strength and endurance were
also measured. Significant (P < .05) main effects for time were observed for resting heart rate
(presupplementation, 67.59 ± 7.90 beats perminute; postsupplementation, 66.18 ± 7.63 beats
per minute), systolic BP (presupplementation, 122.41 ± 11.25 mm Hg; postsupplementation,
118.35 ± 11.58 mm Hg), blood urea nitrogen (presupplementation, 13.12 ± 2.55 mg/dL;
postsupplementation, 15.24 ± 4.47 mg/dL), aspartate aminotransferase (presupplementation,
34.29 ± 16.48 IU/L; postsupplementation, 24.76 ± 4.71 IU/L), and alanine aminotransferase
(presupplementation, 32.76 ± 19.72 IU/L; postsupplementation, 24.88 ± 9.68 IU/L). Significant
main effects for time were observed for body fat percentage (presupplementation, 15.55% ±
5.79%; postsupplementation, 14.21% ± 5.38%; P = .004) and fat-freemass (presupplementation,
Keywords:
Human
Amino acids
Exercise
Nutrition
Supplement
um; %fat, percent fat; ALT, alanine aminotransferase; AST, aspartate aminotransferase;
pressure; BUN, blood urea nitrogen; FFM, fat-free mass; PL, placebo; SUP, supplement; VO2,
x, maximal oxygen consumption; VT, ventilatory threshold; VT%, percentage of oxygen
ory threshold occurred.
rrently employees of the funding source, MusclePharm Corporation. However, the current
ademy by authors who at the time were not MusclePharm employees, and the remaining
ng the outcome of this investigation.
Southern University, Statesboro, GA 30468. Tel.: +1 912 478 8013.
n.edu (K.L. Kendall).
rved.
l, Ingesting a preworkout supplement containing caffeine, creatine, β-alanine, amino
safe a..., Nutr Res (2014), http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://dx.doi.org/10.1016/j.nutres.2014.04.003
mailto:kkendall@georgiasouthern.edu
http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://www.sciencedirect.com/science/journal/02715317
http://dx.doi.org/10.1016/j.nutres.2014.04.003
2 N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
Please cite this article as: Kendall KL, et a
acids, and B vitamins for 28 days is both
70.80±9.21kg;postsupplementation, 71.98± 9.27kg;P= .006).A significantdecrease inmaximal
oxygen consumption (presupplementation, 47.28 ± 2.69 mL/kg per minute;
postsupplementation, 45.60 ± 2.81 mL/kg per minute) and a significant increase in
percentage of oxygen consumption per unit time at which ventilatory threshold occurred
(presupplementation, 64.38%±6.63%;postsupplementation, 70.63%±6.39%) and legpress one-
repetition maximum (presupplementation, 218.75 ± 38.43 kg; postsupplementation, 228.75 ±
44.79 kg) were observed in the SUP only. No adverse effects were noted for renal and hepatic
clinical blood markers, resting heart rate, or BP. Supplements containing similar ingredients
and doses should be safe for ingestion periods lasting up to 28 days in healthy, recreationally
trained, college-aged men.
© 2014 Elsevier Inc. All rights reserved.
1. Introduction
Preworkout supplementation has become widely popular
among recreational and competitive athletes. Majority of
users believe that supplementationwill enhance focus, reaction
time, strength and power, whereas delaying fatigue, likely due
to the combination of caffeine, creatine, and β-alanine that are
commonly found in preworkout supplements (SUPs) [1-3].
Recently, a study exploring sports-relatedperformance changes
after the acute ingestion of a preworkout SUP containing
caffeine, creatine, B vitamins, amino acids, and β-alanine was
published by our laboratories [4]. Acute improvements in
muscular endurance and choice reaction time were likely
influenced by the primary ingredient caffeine, which has been
shown to improve various aspects of human performance [5].
Using similar ingredients, Gonzalez et al [6] demonstrated that
acute ingestion of a preworkout SUP significantly increased
training volumeaswell as peakandmeanpower during a single
resistance-based workout.
Although results from current research suggest an overall
improvement in performance after a single serving, there is
no preexisting evidence that supplementation lasting 28 days
with a multi-ingredient product containing all of the afore-
mentioned ingredients is safe and efficacious. In fact,
mainstream media reports have linked creatine and caffeine
supplementation with potential renal and hepatic problems
as well as dehydration. However, scientific evidence does
not support these conclusions [7-10]. Several longitudinal
studies have attested to the safety of chronic creatine
supplementation [11]. Furthermore, both acute and chronic
creatine supplementation have been shown to lower mea-
sures of body fat and improve maximal lower and upper body
strength and power [12-15]. Although high doses of caffeine
have been shown to increase resting heart rate and blood
pressure (BP) acutely [16,17], there are limited data examining
adverse effects after caffeine consumption on renal and
hepatic measures. Given the observed benefits seen with
caffeine consumption (ie, decreased perception of pain and
effort, resulting in improved performance [5,18]), additional
research is warranted examining continued use of caffeine and
potential side effects.
Additional ingredients commonly found in preworkout
SUPs include B vitamins and amino acids. Vitamin B6 has been
shown to have a vital role in metabolic pathways required for
exercise, whereas vitamin B12 assists with DNA synthesis [18].
Moreover, branched chain amino acids (BCAAs) have been
l, Ingesting a preworkou
safe a..., Nutr Res (201
shown to delay fatigue by decreasing the productionof tryptophan during prolonged physical activity [19] as
well as increase protein synthesis and reduce protein
degradation [20]. It remains unclear whether these changes
occur during resistance training, suggesting further research
is needed.
Therefore, as a follow-up to our original acute investi-
gation, we sought to determine the safety and efficacy of
consuming a preworkout SUP containing caffeine, creatine,
B vitamins, amino acids, and β-alanine for 28 days. Because
of the moderate doses used and previous scientific re-
search, we hypothesized that little to no changes in kidney
and liver clinical blood markers or resting heart rate and BP
would be observed. Furthermore, we hypothesized that
body composition and performance would improve after
supplementation in recreationally active males after 28
days of supplementation.
2. Methods and materials
2.1. Participants
Seventeen recreationally trained males participated in the
investigation (mean ± SD; age, 21 ± 4 years; height, 181 ± 8 cm;
weight, 85.69 ± 16.31 kg; and percent fat [%fat], 15.55 ± 5.91).
The investigation was approved by an institutional review
board for use of human participants, and all participants
signed an informed consent before the investigation. All
participants met the necessary inclusion requirements as
assessed by health history and exercise questionnaires.
Participants were required to have been free of any
nutritional SUPs or ergogenic aids for at least 8 weeks
preceding the study and were required to refrain from using
any additional SUPs during the course of the investigation.
In addition, all participants regularly engaged in physical
activity as assessed by an exercise questionnaire. Daily
activity levels before initiation of the study indicated that
participants regularly engaged in exercise activity on a
consistent basis (workouts per week, 4.3 ± 1.3 days; workout
duration per day, 1.7 ± 0.6 hours; cardio training per day, 1.0 ±
0.6 hours; and resistance training per day, 0.8 ± 0.4 hours).
Participants also reported participation in one or more of
the following sport activities: running, swimming, cycling,
tennis, baseball, basketball, football, lacrosse, rugby,
and soccer.
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3N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
2.2. Study design
In a double-blind, placebo (PL)-controlled study, 17 recrea-
tionally trained men were randomly assigned to either the PL
(n = 8; age, 22 ± 4.8 years; height, 179.0 ± 9.5 cm; weight: 92.2 ±
15.4 kg; %fat, 18.3% ± 6.3%; and fat-free mass [FFM], 74.7 ± 8.9
kg) or SUP (n = 9; age, 20.0 ± 1.2 years; height, 181.0 ± 5.0 cm;
weight, 78.0 ± 13.1 kg; %fat, 13.1% ± 4.2%; and FFM, 67.3 ± 8.5 kg)
group. All pretesting subject characteristics were not
significantly different between the PL and SUP groups
(P > .06). Participants ingested one full scoop (46 g) every
day for at least 28 days either 20 minutes before they
exercised or ad libitumonnonexercise days. All participants
were required to take the full serving in one sitting on both
exercise and nonexercise days. The SUP, marketed as
Assault, (Denver, CO, USA) contained BCAAs (6 g), creatine
(5 g), β-alanine (4 g), citrulline malate (1.5 g), and caffeine
(300mg). The PLwas flavoredmaltodextrin, similar in color and
taste to the SUP formulation. Participants recorded the date and
time the SUP was taken on a spreadsheet that was located on
the SUP jug (in place of a label) and returned all remaining
product upon completion of the study.
In addition, participants were required to maintain their
current diet throughout the duration of the study and record
all physical activity in an exercise log. Two-day food logs,
analyzed before the start of the investigation, indicated
that participants consumed no caffeine to moderate
amounts of caffeine in their normal diet with no heavy
caffeine users identified. Participants consuming more
than 500 mg of caffeine daily were excluded from the
study. Participants were told to maintain their current
caffeine intake throughout the duration of the study.
Participants reported to all testing sessions in a fasted
state (12 hours with ad libitum water) after a 48-hour
period of abstinence from strenuous exercise. Resting heart
rate and BP was taken using an automated BP cuff (Omron
BP785; Omron Healthcare, Palatine, IL, USA). The average
of 3 tests with 60 seconds between tests was recorded
and used for analysis. Body composition assessments
were made after resting heart rate and BP measurements
using Lange skinfold calipers (Ann Arbor, MI, USA). Percent
fat was calculated using the 2C model of Brozek et al [21]
from body density estimated using the Jackson and Pollock
3-site skinfold equation using the chest, abdominal, and
thigh skinfold measurements [22]. Reliability results in 14
college-aged men and women resulted in Intraclass
Correlation (ICC) more than 0.97 and SEMs of 0.67% and
0.71 kg for both %fat and FFM, respectively.
Before supplementation, whole blood and serum
samples were collected at local diagnostic laboratories
(Laboratory Corporation of America, Fairhope, Alabama,
USA) 48 hours before or after body composition assess-
ments. Postblood samples were taken 1 day after ceasing
supplementation at the same time of day as presupple-
mentation blood draws. After collection, all samples were
assayed for glucose, creatinine, blood urea nitrogen (BUN),
BUN/creatinine ratio, sodium, potassium, alanine amino-
transferase (ALT), and aspartate aminotransferase (AST) by
an external diagnostic laboratory (Laboratory Corporation
of America, Birmingham, Alabama, USA).
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
2.3. Performance measurements
Amaximal graded exercise test was used for the determination
of aerobic capacity (maximal oxygen consumption [VO2max])
and one-repetition maximum (1RM) tests for bench and leg
press aswell as repetitions to failure at 75% of 1RMwere used to
detect changes in muscular strength and endurance.
All VO2max tests were performed on a calibrated treadmill
(Desmo; Woodway, Waukesha, WI, USA) and measured by
indirect calorimetry using a metabolic cart (True One 2300;
Parvomedics, Sandy, UT, USA). Testing began with a 3-minute
warm-up stage at 5.15 km per hour, whereas the grade
remained at 0% throughout testing. After the protocol of
Peake et al [23], velocity increased to 10 km per hour for the
next stage, then increased 2 km per hour for every 2 minutes
up to 16 km per hour, followed by 1 km per hour increments
per minute up to 24 km per hour. Maximal oxygen consump-
tion was confirmed if at least 2 of the following criteria were
met: (a) plateau in heart rate (HR) or HR values within 10% of
the age-predicted heart rate maximum (HRmax), (b) plateau in
oxygen consumption per unit time (V̇O2 ) (defined by an
increase of ≤150 mL min−1), and (c) respiratory exchange ratio
value greater than 1.15 [24]. Reliability results in 8 men
resulted in ICCs more than 0.98 and SEMs of 0.10 L per minute
and 1.03 mL/kg per minute both absolute VO2max and relative
VO2max, respectively. Ventilatory threshold (VT) was analyzed
by using the metabolic cart software and confirmed by visually
identifying a slope change in ventilation rate. The percentage of
VO2 at which VT occurred was termed VT%.
One-repetition maximum bench press and leg press
were used to determine the maximum amount of weight a
participant could lift one time for each exercise. Following
National Strength and Conditioning Association guidelines for
1RM testing [25], participants performed one warm-up set for
bench and leg press (approximately 50% of estimated 1RM)
and rested for 2 minutes between attempts. Resistance was
increased until the participant failed to complete a repetition;
subjects performed no more than 5 attempts. Maximum
strength for benchand leg press exercises was measured
using plate-loaded isolateral bench and leg press (Hammer
Strength, Cincinnati, OH, USA). Seat height for bench and leg
press was adjusted for each subject and remained consistent
throughout the course of the study. A repetition was recorded
when participants lowered the weight in an eccentric
contraction and then pushed the weight in a concentric
contraction with full joint extension, ensuring the weights
made contact with the back bumper pads after eccentric
movement. After 1RM testing, 75% of each participant’s 1RM
was calculated, and repetitions to fatiguewere assessed and
recorded at respective weight resistance on subsequent
testing visits. The weight for posttesting repetitions to
fatigue was based on posttest 1RM values. Reliability results
for 75% 1RM using 11 men resulted in ICCs of 0.71 and 0.69
and SEMs of 1.4 reps and 2.3 reps for bench press and leg
press, respectively.
2.4. Statistical analyses
Differences in renal and hepatic function, along with HR, BP,
body composition, and performance measures between
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4 N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
pretests andposttestsand theSUPswereanalyzedusinga repeated-
measures analysis of variance (time [presupplementation-
postsupplementation] × drink [SUP vs PL]). Significant
interactions between time and SUP were analyzed using post
hoc dependent t tests. Significant main effects for time and for
SUP were analyzed using Bonferroni post hoc tests to account
for multiple comparisons by maintaining familywise error
rates. A P < .05 was considered significant for this investigation.
All analysis of variance assumptions were met, and analyses
were performed using the computer program SPSS (PASW
Statistics 20.0.0; IBM Corporation, Armonk, NY, USA). Partial η
squared (ηp2) and observed power were calculated for all
significant interactions. Data are presented as mean ± SD.
3. Results
No significant differences were observed between groups
for time (days) between pretesting and posttesting (SUP, 33 ± 4;
PL, 31 ± 4; P = .45), SUP compliance (96.1% ± 6.5%; PL, 95.5% ±
7.0%; P = .87), training days (SUP, 23 ± 7; PL, 21 ± 6; P = .43), or for
Table 1 – Clinical health and blood markers presupplementatio
Variable Treatment
Resting heart rate (beats per minute) PL
SUP
Total
Resting systolic BP (mm Hg) PL
SUP
Total
Resting diastolic BP (mm Hg) PL
SUP
Total
Fasting glucose (mg/dL) PL
SUP
Total
BUN (mg/dL) PL
SUP
Total
Creatinine (mg/dL) PL
SUP
Total
BUN/creatinine PL
SUP
Total
Sodium (mmol/L) PL
SUP
Total
Potassium (mmol/L) PL
SUP
Total
AST (IU/L) PL
SUP
Total
ALT (IU/L) PL
SUP
Total
PL = (n = 8).
SUP = (n = 9).
All data are reported as means ± SD.
a Significant main effect for time; P < .05.
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
training time (hour:minute) per day (SUP, 1:26 ± 0:20; PL, 1:10 ±
0:17; P = .09). Clinical safety and blood results are presented in
Table 1. Significant main effects for time were observed for
resting systolic BP, BUN, AST, and ALT.
Significantmain effects for time for %fat (presupplementa-
tion, 15.55 ± 5.79; postsupplementation, 14.21 ± 5.38; P = .004)
and FFM (presupplementation, 70.80 ± 9.21 kg; postsupple-
mentation, 71.98 ± 9.27 kg; P = .006) indicated a decrease in
body fat and an increase in FFM for both the PL and SUP groups
from pretesting to posttesting. No significant time by SUP
interactions were observed for %fat or FFM (P = .56). However,
2-tailed t tests comparing pretesting to posttesting indicated
significant decreases in body fat for both PL (−1.26 ± 1.35 %fat;
P = .017) and SUP (−1.42 ± 1.84 %fat; P = .025) groups with a
significant increase in FFM associatedwith the SUP group only
(SUP, 1.47 ± 0.97 kg; P < .001; PL, 0.86 ± 1.91 kg; P = .12). Relative
VO2max significantly decreased in the SUP group (presupple-
mentation, 47.28 ± 2.69 mL/kg per minute; postsupplementa-
tion, 45.60 ± 2.81 mL/kg per minute; ηp2 = 0.269; observed
power = 0.593), whereas VT% (presupplementation, 64.38% ±
6.63%; postsupplementation, 70.63% ± 6.39%; ηp2 = 0.457;
n and postsupplementation
Presupplementation Postsupplementation
67.22 ± 8.41 65.78 ± 8.20
68.00 ± 7.84 66.63 ± 7.48
67.59 ± 7.90 66.18 ± 7.63
124.44 ± 10.28 117.67 ± 11.01
120.13 ± 12.53 119.13 ± 12.91
122.41 ± 11.25 118.35 ± 11.58 a
73.00 ± 8.96 69.78 ± 6.69
72.88 ± 7.66 72.75 ± 9.35
72.94 ± 8.11 71.18 ± 7.93
85.78 ± 6.91 82.89 ± 8.37
89.38 ± 3.96 87.00 ± 8.55
87.47 ± 5.84 84.82 ± 8.46
13.00 ± 2.35 15.11 ± 4.68
13.25 ± 2.92 15.38 ± 4.53
13.12 ± 2.55 15.24 ± 4.47†
0.98 ± 0.12 0.97 ± 0.13
1.01 ± 0.10 1.11 ± 0.12
1.00 ± 0.11 1.03 ± 0.14
13.39 ± 2.90 15.69 ± 4.61
13.08 ± 2.51 13.91 ± 3.60
13.24 ± 2.64 14.85 ± 4.14
140.22 ± 2.59 140.11 ± 1.69
139.88 ± 1.55 140.75 ± 1.91
140.06 ± 2.11 140.41 ± 1.77
4.38 ± 0.34 4.23 ± 0.27
4.54 ± 0.18 4.76 ± 0.99
4.45 ± 0.28 4.48 ± 0.73
37.22 ± 20.68 24.22 ± 4.63
31.00 ± 10.42 25.38 ± 5.04
34.29 ± 16.48 24.76 ± 4.71 a
39.22 ± 22.54 27.44 ± 10.54
25.50 ± 13.94 22.00 ± 8.32
32.76 ± 19.72 24.88 ± 9.68 a
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5N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
observed power = 0.913) and 1RM leg press (presupplementa-
tion, 218.75 ± 38.43 kg; postsupplementation, 228.75 ± 44.79 kg;
ηp2 = 0.234; observed power = 0.517) significantly increased in
the SUP group only. No changes were observed for absolute
VO2max, 1RM bench press, or repetitions to failure for either
leg press or bench press (P > .05). Performance results are
presented in Table 2, and individual response graphs for the
variables with significant interactions are displayed in Figs. 1
to 3. No adverse reactions to taking the SUP were reported.
4. Discussion
Findings from the present study support our hypothesis
that consuming the preworkout SUP Assault for 28 days
would not negatively alter renal and hepatic clinical blood
markers, resting heart rate, or resting BP. The safety and
efficacy of isolated supplementation with creatine [26,27],
caffeine [28-30], and amino acids [31-33] on performance have
beenwell investigated.More recently, however, researchers have
begun to examine the effects ofmulti-ingredient SUPs on clinical
safety markers and performance. The use of creatine, caffeine,
and β-alanine in combinatory blends has previously been shown
to increase strength and FFM, whereas reporting no adverse
effects [34-36]. In agreement with past literature [7,8], our results
support the safety and efficacy of 28 days of multi-ingredient
supplementation in healthy college men. Supplementation with
approximately 300mg of caffeine daily did not alter resting heart
Table 2 – Performance data presupplementation and postsuppl
Variable Treatment
VO2max (L/min) PL
SUP
Total
VO2max (mL/kg per minute) PL
SUP
Total
VT (VO2 L/min) PL
SUP
Total
VT% (% of VO2max) PL
SUP
Total
Leg press 1RM (kg) PL
SUP
Total
Bench press 1RM (kg) PL
SUP
Total
Leg press, 75%; 1RM, repetitions to failure PL
SUP
Total
Bench press, 75%; 1RM, repetitions to failure PL
SUP
Total
PL = (n = 8).
SUP = (n = 9).
All data are reported as means ± SD.
a Significant difference from pretesting to posttesting; P < .05.
b Significant interaction between time and SUP; P < .05.
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
rate or BP. In addition, consuming 5 g of creatine per day for
4 weeks did not negatively impact liver or kidney function.
Although resting systolic BP, BUN, AST, and ALT decreased from
pretesting to posttesting in both groups, all values remained
within reference range and trended [37-39]. Furthermore,
the decreasein the aforementioned variables indicates an
improvement, suggesting that the physical activity performed
in the current investigation helped improve cardiovascular, liver,
and kidney functions independent of the SUP taken.
In the current study, improvements in body composition
were seen from pretesting to posttesting in both groups,
suggesting that there was a training effect but with no
observed additional benefit from the SUP. These findings
are consistent with previous literature suggesting that body
composition can be improved exclusive of supplementation
[18]. Interestingly, participants in the SUP group saw an
increase in FFM, with a concurrent increase in leg press 1RM
and VT%. Although relative VO2max decreased from pretesting
to posttesting in the SUP group, absolute VO2max did not
change, suggesting that the increase in FFM may have been
the reason for the decrease in relative VO2max. Thus, we
partially accept our hypothesis that body composition and
performance improvements would be seen in recreationally
trained men after 28 days of supplementation with Assault.
As is common with SUPs composed of multiple ingredi-
ents, it is difficult to decipher which ingredient is responsible
for improvements in performance. The synergistic effects
of common ingredients (caffeine, creatine, β-alanine, BCAA, etc)
ementation
Presupplementation Postsupplementation
4.14 ± 0.56 4.19 ± 0.63
3.62 ± 0.58 3.51 ± 0.49
3.90 ± 0.61 3.87 ± 0.66
44.88 ± 5.21 45.43 ± 5.93
47.28 ± 2.69 45.60 ± 2.81 a,b
46.01 ± 4.27 54.51 ± 4.59
3.11 ± 0.39 3.09 ± 0.39
2.59 ± 0.50 2.70 ± 0.43 a
2.87 ± 0.51 2.91 ± 0.44
71.11 ± 4.34 70.22 ± 3.87
64.38 ± 6.63 70.63±6.39 a,b
67.94 ± 6.38 70.41 ± 5.04
223.33 ± 33.91 216.67 ± 29.16
218.75 ± 38.43 228.75 ± 44.79 a,b
221.18 ± 35.02 222.35 ± 36.58
100.00 ± 16.01 101.94 ± 16.67
94.69 ± 23.85 96.88 ± 16.89
97.50 ± 19.61 99.56 ± 16.45
9.2 ± 3.6 11.3 ± 4.7
12.6 ± 2.5 10.6 ± 2.8
10.8 ± 3.5 11.0 ± 3.8
10.1 ± 2.3 9.3 ± 1.9
11.1 ± 2.5 10.8 ± 2.2
10.6 ± 2.4 10.0 ± 2.1
t supplement containing caffeine, creatine, β-alanine, amino
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-6
-4
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2
4
6
Baseline Δ
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 (
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-6
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Baseline Δ
PL SUP
Fig. 1 – Individual response graphs for changes in relative VO2max for PL (n = 8) and SUP (n = 9) after 28 days of supplementation.
Dashed line represents themean change score. Maximal oxygen consumption (milliters per kilogram perminute) significantly
decreased in the SUP group only (P < .05).
6 N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
inmulti-ingredient SUPs have been researched and established
[34,40,41]. Thus, we hypothesize that the caffeine and creatine
played a primary role in performance improvements.
Caffeine, the primary active ingredient found in Assault, is a
mild stimulant that affects the central nervous system and has
the potential to influence human neuromuscular performance.
In addition, caffeine has the ability to improve strength, which
has been attributed to enhancedmotor unit recruitment during
maximal voluntary contraction [42] or potentially enhancing
Ca2+ release for contraction [43]. Creatine supplementation has
repeatedly been shown to improve strength and anaerobic
power via its ability to restore adenosine triphosphate during
high-intensity exercise [44,45]. Several studies support the
ergogenic effects of creatine supplementation during activities
like resistance training, suggesting that itmay enhance training
volume and intensity, leading to greater strength gains [46].
Thus, it is likely that combination of caffeine and creatine in
this product, in conjunction with training, was responsible for
-10
-5
0
5
10
15
20
Baseline Δ
%
 V
T
-1
-
1
1
2
PL
Fig. 2 – Individual response graphs for changes in VT% for PL (n =
line represents themean change score. Percentage of oxygen cons
significantly increased in the SUP group only (P < .05).
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
improvements in lower body strength and VT% seen in our
study. Although the ergogenic benefits of β-alanine and
BCAAs have been documented [47-49], based on previous
research, we do not feel that supplementation with the
aforementioned ingredients were primary contributors to
performance changes seen in the current study, possibly due
to the lower dosage used. More so, it is difficult to conclude if
the improvements in lower body strength or VT% were the
result of B vitamin supplementation.
A limitation that the authors acknowledge is that
participants in the study did not undergo a training protocol
designed by the researchers. Their levels of physical activity
were instead monitored via a questionnaire. Despite both PL
and SUP groups attaining similar duration and frequency
of exercise, we were not able to control for type or intensity
of exercise or training volume. However, participants were
informed and encouraged to maintain their current levels of
activity based on their initial recall questionnaire. Although
0
5
0
5
0
5
0
Baseline Δ
SUP
8) and SUP (n = 9) after 28 days of supplementation. Dashed
umption per unit time at which ventilatory threshold occurred
t supplement containing caffeine, creatine, β-alanine, amino
4), http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://dx.doi.org/10.1016/j.nutres.2014.04.003
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
Baseline Δ
L
eg
 P
re
ss
 1
 R
M
 (
kg
)
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
35
Baseline Δ
PL SUP
Fig. 3 – Individual response graphs for changes in 1RM leg press for PL (n = 8) and SUP (n = 9) after 28 days of supplementation.
Dashed line represents the mean change score. Only the SUP group observed a significant increase in leg press 1RM after
supplementation (P < .05).
7N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
FFM increased from pretesting to posttesting, with a concom-
itant decrease in training time, the authors hypothesize
that an increase in exercise intensity led to the increase
in FFM. Future research should control for volume and
intensity to support the SUP’s effects on body composition
and performance. Furthermore, the primary purpose of
this study was to assess the safety of supplementation.
Measures of performance and body composition were a
secondary analysis. Further investigation on the effects of this
SUP on performance and/or training (volume, intensity, etc)
is warranted.
The overall findings of this investigation indicate
that ingesting 2 servings (one scoop) of the SUP Assault daily
for 28 days may aid in improvements in VT% and lower body
strength. More so, the dose and frequency of supplementation
used in the current investigation appear to be safe for healthy
college-aged men. More research is needed to determine the
performance benefits of long-term ingestion with concurrent
resistance training using similar products as well as the
safety of using ingestion periods lasting longer than 28 days.
However, researchers should feel confident regarding the safety
and efficacy of investigations up to 28 days using similar doses
of SUPs containing caffeine, B vitamins, amino acids, creatine,
and β-alanine in this population.
Acknowledgment
We thank all of the men who participated and MusclePharm,
Corp. for supplying the product and funding the investigation.
Wealso thankKristyCrowleyandGeff Purdy for their assistance
with study design and data collection.
R E F E R E N C E S
[1] Krumbach CJ, Ellis DR, Driskell JA. A report of vitamin and
mineral supplement use among university athletes in a
division I institution. Int J Sport Nutr 1999;9:416–25.
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
[2] Morrison LJ, Gizis F, Shorter B. Prevalent use of dietary
supplements amongpeople who exercise at a commercial
gym. Int J Sport Nutr Exerc 2004;14:481–92.
[3] Kraemer WJ, Volek JS. Creatine supplementation—its role in
human performance. Clin Sports Med 1999;18:651.
[4] Spradley BD, Crowley KR, Tai CY, Kendall KL, Fukuda DH,
Esposito EN, et al. Ingesting a pre-workout supplement
containing caffeine, B-vitamins, amino acids, creatine, and
beta-alanine before exercise delays fatigue while improving
reaction time and muscular endurance. Nutr Metab 2012;9.
[5] Doherty M, Smith PM. Effects of caffeine ingestion on exercise
testing: ameta-analysis. Int J Sport Nutr Exerc 2004;14:626–46.
[6] Gonzalez AM, Walsh AL, Ratamess NA, Kang J, Hoffman JR.
Effect of a pre-workout energy supplement on acute
multi-joint resistance exercise. J Sports Sci Med 2011;10:261–6.
[7] Buford TW, Kreider RB, Stout JR, Greenwood M, Campbell B,
Spano M, et al. International Society of Sports Nutrition
position stand: creatine supplementation and exercise. J Int
Soc Sport Nutr 2007;4.
[8] Goldstein ER, Ziegenfuss T, Kalman D, Kreider R, Campbell B,
Wilborn C, et al. International society of sports nutrition
position stand: caffeine and performance. J Int Soc Sport Nutr
2010;7.
[9] Pline KA, Smith CL. The effect of creatine intake on renal
function. Ann Pharmacother 2005;39:1093–6.
[10] Poortmans JR, Francaux M. Adverse effects of creatine
supplementation—fact or fiction? Sports Med
2000;30:155–70.
[11] Kreider RB, Melton C, Rasmussen CJ, GreenwoodM, Lancaster
S, Cantler EC, et al. Long-term creatine supplementation does
not significantly affect clinical markers of health in athletes.
Mol Cell Biochem 2003;244:95–104.
[12] Pearson DR, Hamby DG, Russel W, Harris T. Long-term effects
of creatine monohydrate on strength and power. J Strength
Cond Res 1999;13:187–92.
[13] Izquierdo M, Ibanez J, Gonzalez-Badillo JJ, Gorostiaga EM.
Effects of creatine supplementation on muscle power,
endurance, and sprint performance. Med Sci Sports Exerc
2002;34:332–43.
[14] van Loon LJC, Oosterlaar AM, Hartgens F, Hesselink MKC,
Snow RJ, Wagenmakers AJM. Effects of creatine loading and
prolonged creatine supplementation on body composition,
fuel selection, sprint and endurance performance in humans.
Clin Sci 2003;104:153–62.
[15] Zuniga JM, Housh TJ, Camic CL, Hendrix CR, Mielke M,
Johnson GO, et al. The effects of creatine monohydrate
t supplement containing caffeine, creatine, β-alanine, amino
4), http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0005
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0005
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0005
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0010
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0010
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0010
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0200
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0200
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0205
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0205
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0205
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0205
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0205
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0015
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0015
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0020
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0020
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0020
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0210
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0210
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0210
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0210
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0215
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0215
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0215
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0215
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0025
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0025
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0030
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0030
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0030
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0035
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0035
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0035
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0035
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0040
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0040
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0040
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0045
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0045
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0045
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0045
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0050
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0050
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0050
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0050
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0050
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0055
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0055
http://dx.doi.org/10.1016/j.nutres.2014.04.003
8 N U T R I T I O N R E S E A R C H X X ( 2 0 1 4 ) X X X – X X X
loading on anaerobic performance and one-repetition
maximum strength. J Strength Cond Res 2012;26:1651–6.
[16] Astorino TA, Rohmann RL, Firth K. Effect of caffeine ingestion
on one-repetition maximum muscular strength. Eur J Appl
Physiol 2008;102:127–32.
[17] Sokmen B, Armstrong LE, Kraemer WJ, Casa DJ, Dias JC,
Judelson DA, et al. Caffeine use in sports: considerations for
the athlete. J Strength Cond Res 2008;22:978–86.
[18] Woolf K, Manore MM. B-vitamins and exercise: does exercise
alter requirements? Int J Sport Nutr Exerc 2006;16:453–84.
[19] Fernstrom JD. Branched-chain amino acids and
brain function. J Nutr 2005;135:1539S–46S.
[20] Blomstrand E, Eliasson J, Karlsson HKR, Kohnke R.
Branched-chain amino acids activate key enzymes in protein
synthesis after physical exercise. J Nutr 2006;136:269S–73S.
[21] Brozek J, Anderson JT, Keys A, Grande F. Densitometric
analysis of body composition revision of some quantitative
assumptions. Ann N Y Acad Sci 1963;110:113.
[22] Jackson AS, Pollock ML. Practical assessment of body-
composition. Phys Sportsmed 1985;13:76.
[23] Peake J, Wilson G, Hordern M, Suzuki K, Yamaya K, Nosaka K,
et al. Changes in neutrophil surface receptor expression,
degranulation, and respiratory burst activity after
moderate- and high-intensity exercise. J Appl Physiol 2004;97
(1985):612–8.
[24] Day JR, Rossiter HB, Coats EM, Skasick A, Whipp BJ. The
maximally attainable VO2 during exercise in humans: the
peak vs. maximum issue. J Appl Physiol 2003;95(1985):1901–7.
[25] Harman E, Garhammer J. Administration, scoring, and
interpretation of selected tests. In: Baechle T, Earle R, editors.
Essentials of strength training and conditioning. 3rd ed.
Champaign, IL: Human Kinetics; 2008. p. 249–54.
[26] Jagim AR, Oliver JM, Sanchez A, Galvan E, Fluckey J, Riechman
S, et al. A buffered form of creatine does not promote greater
changes in muscle creatine content, body composition,
or training adaptations than creatine monohydrate.
J Int Soc Sport Nutr 2012;9:43.
[27] Hickner RC, Dyck DJ, Sklar J, Hatley H, Byrd P. Effect of 28 days
of creatine ingestion onmusclemetabolism and performance
of a simulated cycling road race. J Int Soc Sport Nutr 2010;7:26.
[28] Eudy AE, Gordon LL, Hockaday BC, Lee DA, Lee V, Luu D, et al.
Efficacy and safety of ingredients found in preworkout
supplements. Am J Health Syst Pharm 2013;70:577–88.
[29] Skinner TL, Jenkins DG, Coombes JS, Taaffe DR, Leveritt MD.
Dose response of caffeine on 2000-m rowing performance.
Med Sci Sports Exerc 2010;42:571–6.
[30] Astorino TA, Cottrell T, Lozano AT, Aburto-Pratt K, Duhon J.
Increases in cycling performance in response to caffeine
ingestion are repeatable. Nutr Res 2012;32:78–84.[31] Kerksick CM, Rasmussen CJ, Lancaster SL, Magu B, Smith P,
Melton C, et al. The effects of protein and amino acid
supplementation on performance and training adaptations
during ten weeks of resistance training. J Strength Cond Res
2006;20:643–53.
[32] Herda AA, Herda TJ, Costa PB, Ryan ED, Stout JR, Cramer JT.
Muscle performance, size, and safety responses after eight
weeks of resistance training and protein supplementation: a
randomized, double-blinded, placebo-controlled clinical trial.
J Strength Cond Res 2013;27:3091–100.
[33] Ratamess NA, Kraemer WJ, Volek JS, Rubin MR, Gomez AL,
French DN, et al. The effects of amino acid supplementation
on muscular performance during resistance training
overreaching. J Strength Cond Res 2003;17:250–8.
Please cite this article as: Kendall KL, et al, Ingesting a preworkou
acids, and B vitamins for 28 days is both safe a..., Nutr Res (201
[34] Ormsbee MJ, Thomas DD, Mandler WK, Ward EG, Kinsey AW,
Panton LB, et al. The effects of pre- and post-exercise
consumption of multi-ingredient performance supplements
on cardiovascular health and body fat in trainedmen after six
weeks of resistance training: a stratified, randomized,
double-blind study. Nutr Metab 2013;10:39.
[35] Shelmadine B, Cooke M, Buford T, Hudson G, Redd L,
Leutholtz B, et al. Effects of 28 days of resistance exercise and
consuming a commercially available pre-workout
supplement, NO-Shotgun(R), on body composition, muscle
strength and mass, markers of satellite cell activation, and
clinical safetymarkers inmales. J Int Soc Sport Nutr 2009;6:16.
[36] Schmitz SM, Hofheins JE, Lemieux R. Nine weeks of
supplementation with a multi-nutrient product augments
gains in lean mass, strength, and muscular performance in
resistance trained men. J Int Soc Sport Nutr 2010;7:40.
[37] M’Kada H, Munteanu M, Perazzo H, Ngo Y, Ramanujam N,
Imbert-Bismut F, et al. What are the best reference values for
a normal serum alanine transaminase activity (ALT)? Impact
on the presumed prevalence of drug induced liver injury
(DILI). Regul Toxicol Pharmacol 2011;60:290–5.
[38] Hosten AO. BUN and creatinine. In: Walker HK, Hall WD,
Hurst JW, editors. Clinical methods: the history, physical, and
laboratory examinations3rd ed. ; 1990 [Boston].
[39] Frese EM, Fick A, Sadowsky HS. Blood pressure measurement
guidelines for physical therapists. Cardiopulm Phys Ther J
2011;22:5–12.
[40] Fukuda DH, Smith AE, Kendall KL, Stout JR. The possible
combinatory effects of acute consumption of caffeine,
creatine, and amino acids on the improvement of anaerobic
running performance in humans. Nutr Res 2010;30:607–14.
[41] Lee CL, Lin JC, Cheng CF. Effect of caffeine ingestion after
creatine supplementation on intermittent high-intensity
sprint performance. Eur J Appl Physiol 2011;111:1669–77.
[42] Warren GL, Park ND, Maresca RD, Mckibans KI,
Millard-Stafford ML. Effect of caffeine ingestion
on muscular strength and endurance: a meta-analysis.
Med Sci Sports Exerc 2010;42:1375–87.
[43] Tarnopolsky MA. Effect of caffeine on the neuromuscular
system—potential as an ergogenic aid. Appl Physiol Nutr
Metab 2008;33:1284–9.
[44] Volek JS, KraemerWJ, Bush JA, Boetes M, Incledon T, Clark KL,
et al. Creatine supplementation enhances muscular
performance during high-intensity resistance exercise.
J Am Diet Assoc 1997;97:765–70.
[45] Greenhaff PL, Bodin K, Soderlund K, Hultman E.
Effect of oral creatine supplementation on skeletal-muscle
phosphocreatine resynthesis. Am J Physiol 1994;266:E725–30.
[46] Hoffman J, Ratamess N, Kang J, Mangine G, Faigenbaum A,
Stout J. Effect of creatine and beta-alanine supplementation
on performance and endocrine responses in strength/power
athletes. Int J Sport Nutr Exerc Metab 2006;16:430–46.
[47] Stout JR, Cramer JT, Zoeller RF, Torok D, Costa P, Hoffman JR,
et al. Effects of beta-alanine supplementation on the onset of
neuromuscular fatigue and ventilatory threshold in women.
Amino Acids 2007;32:381–6.
[48] Nosaka K, Sacco P, Mawatari K. Effects of amino acid
supplementation onmuscle soreness and damage. Int J Sport
Nutr Exerc 2006;16:620–35.
[49] Shimomura Y, Murakami T, Nakai N, Nagasaki M, Harris RA.
Exercise promotes BCAA catabolism: effects of BCAA
supplementation on skeletal muscle during exercise.
J Nutr 2004;134:1583S–7S.
t supplement containing caffeine, creatine, β-alanine, amino
4), http://dx.doi.org/10.1016/j.nutres.2014.04.003
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0055
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0055
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0060
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0060
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0060
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0065
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0065
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0065
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0070
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0070
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0075
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0075
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0080
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0080
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0080
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0220
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0220
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0220
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0225
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0225
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0230
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0230
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0230
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0230
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0230
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0235
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0235
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0235
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0240
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0240
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0240
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0240
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0085
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0085
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0085
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0085
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0085
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0090
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0090
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0090
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0095
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0095
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0095
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0100
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0100
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0100
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0105
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0105
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0105
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0110
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0110
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0110
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http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0125http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0125
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http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0125
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0130
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0135
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0135
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0135
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0135
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0140
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0140
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0140
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0140
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0140
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0245
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0245
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0245
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0145
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0145
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0145
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0150
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0150
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0150
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0150
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0155
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0155
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0155
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0160
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0160
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0160
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0160
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0165
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0165
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0165
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0170
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0170
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0170
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0170
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0175
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0175
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0175
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0180
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0180
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0180
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0180
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0185
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0185
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0185
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0185
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0190
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0190
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0190
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0195
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0195
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0195
http://refhub.elsevier.com/S0271-5317(14)00058-X/rf0195
http://dx.doi.org/10.1016/j.nutres.2014.04.003
	Ingesting a preworkout supplement containing caffeine, creatine, β-alanine, amino acids, and B vitamins for 28 days is both...
	1. Introduction
	2. Methods and materials
	2.1. Participants
	2.2. Study design
	2.3. Performance measurements
	2.4. Statistical analyses
	3. Results
	4. Discussion
	Acknowledgment
	References