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14
www.IJSNEM-Journal.com
ORIGINAL RESEARCH
Quesnele and Wong are with the Division of Clinical Studies,
Laframboise the Division of Sports Sciences, and Kim the Dept.
of Clinical Education and Patient Care, Canadian Memorial
Chiropractic College, Toronto, Canada. Wells is with the Dept.
of Exercise Science, University of Toronto, Canada.
The Effects of Beta-Alanine Supplementation on
Performance: A Systematic Review of the Literature
Jairus J. Quesnele, Michelle A. Laframboise, Jessica J. Wong,
Peter Kim, and Greg D. Wells
Purpose: To critically review the methodological quality and synthesize information from systematic reviews
and high quality studies on the effects of beta alanine (BA) on exercise and athletic performance. Methods:
A search strategy was developed in accordance with the standards for the reporting of scientic literature via
systematic reviews. Five databases were thoroughly searched from inception to November 2012. Inclusion
criteria were English language, human studies, used BA to increase exercise or athletic performance, system-
atic reviews or randomized controlled trials and were published in a peer-reviewed journal. Included studies
were systematically graded for their methodological quality by rotating pairs of reviewers and the results
were qualitatively synthesized. Results: One systematic review and 19 randomized trials were included in
this review. There is one systematic review with several methodological weaknesses that limit the condence
in its results. There are moderate to high quality studies that appear to support that BA may increase power
output and working capacity, decrease the feeling of fatigue and exhaustion, and have of positive effect on
body composition and carnosine content. The reporting of side effects from BA supplementation in the athletic
population was generally under-reported. Conclusions: There appears to be some evidence from this review
that supplementation with BA may increase athletic performance. However, there is insufcient evidence
examining the safety of BA supplementation and its side effects. It is therefore recommended to err on the
side of caution in using BA as an ergogenic aid until there is sufcient evidence conrming its safety.
Keywords: athletic, exercise, ergogenic, aerobic, anaerobic
Muscular fatigue is a multifactorial phenomenon
occurring with high-intensity exercise that is not com-
pletely understood (Artioli et al., 2010; Derave et al.,
2010). However, it has been established that acute
high intensity anaerobic physical activity results in a
decrease in adenosine triphosphate (ATP) molecules,
creatine phosphate stores, and glycolytic substrates that
are needed for energy metabolism in the muscle cell.
High intensity exercise can also lead to an increase in
intracellular metabolites such as adenosine diphosphate,
inorganic phosphate, hydrogen ions, and lactate (Artioli et
al., 2010). This breakdown of energy stores and increase
in intracellular metabolites may be among the causative
factors that lead to muscle fatigue during short-term
high-intensity exercise (Allen et al., 1995; Derave et al.,
2010). Early fatigue is of signicant importance to the
athlete as it may impair performance through decreased
force generation and muscular capacity.
Some athletes have considered using beta alanine
(BA) supplementation to augment fatigue threshold and
improve performance. BA, a precursor of carnosine, has
been shown to increase intracellular levels of carnosine
(Harris et al., 2006; Derave et al., 2007; Baguet et al.,
2010a, 2010b) and reduce acidosis during high-intensity
exercise. This indicates that carnosine may act as a physi-
ologically meaningful physiochemical buffer (Baguet et
al., 2010b). In normal conditions, rate of BA production
is relatively low and serum BA concentration is unde-
tectable. If there is an increase in BA to a detectable
level in the bloodstream, there may also be a subsequent
increase in carnosine in the muscle. This increase has
been considered as enhancing blood buffering capac-
ity and decreasing neuromuscular fatigue (Artioli et
al., 2010; Harris et al., 2006; Kern & Robinson, 2011;
Stout et al., 2007). Thus, the rationale of supplementing
with BA as an ergogenic aid has often been described to
increase athletic performance (Allen et al., 1995; Artioli
et al., 2010; Derave et al., 2007, 2010; Harris et al., 2006;
Hill et al., 2007; Hobson et al., 2012; Stout et al., 2007).
Currently there are several randomized controlled
trials (RCTs) and reviews published that examine the
effects of BA supplementation on exercise performance.
However, a well-controlled critical assessment of the lit-
erature examining the effects of beta alanine on exercise
performance is needed. The purpose of this systematic
review is to critically review the methodological qual-
ity of the literature on BA and its effects on exercise
International Journal of Sport Nutrition and Exercise Metabolism, 2014, 24, 14 -27
http://dx.doi.org/10.1123/ijsnem.2013-0007
© 2014 Human Kinetics, Inc.
A Systematic Review of the Literature 15
or athletic performance and to qualitatively synthesize
information from systematic reviews and high quality
studies. The aim is to inform others on the effectiveness
and safety of BA supplementation for enhancing exercise
performance using the best available evidence.
Method
Search Strategy
A search strategy was developed in accordance with the
standards for the reporting of scientic literature via
systematic reviews. The STARLITE (STAndards for
Reporting LITErature searches) proposal and mnemonic
was used to outline the characteristics of the search,
demonstrate sound search methodology, and support the
consensus for standards for reporting literature searches.
Five electronic databases were searched (MEDLINE,
CINAHL, SPORTDiscus, Rehabilitation & Sports
Medicine Source and the Cochrane Central Register of
Controlled Trials (CENTRAL; The Cochrane Library))
from inception until November 2012. The search strategy
combined terms relevant to beta alanine supplementation
for exercise performance, including subject headings
specic to each database and free text words.
Study Selection
Only systematic reviews with or without meta-analysis
and RCTs were included in this review because they
theoretically provide the highest level of evidence for
this research question (Merlin, Weston, & Tooher, 2009).
Selection criteria for all relevant articles were as follows:
1) English language; 2) Human studies; 3) Beta alanine
supplementation used to increase exercise or athletic
performance (performance included measures of power,
strength, endurance, fatigue, metabolic measures and
sport specic measures); 4) Systematic review with or
without meta-analysis or randomized controlled trial
(RCT; with no supplementation group); and 5) Published
in a peer-reviewed journal.
Studies that examined the effects of multiple per-
formance enhancing substances or supplements were
excluded if they did not perform a stratied analysis for the
beta alanine supplement only. Literature reviews that used
narrative and/or nonsystematic methods were excluded.
One author (JQ) screened titles and abstracts of
identied citations and retrieved the full text publication
of articles that were judged potentially eligible. A second
author (ML) independently reviewed all relevant studies
and determined the eligibility of the studies by reviewing
the methods section of the potentially eligible studies. Stud-
ies were deemed eligible if they pertained to beta alanine
supplementation for athletic performance. Any disagree-
ments were resolved by discussion to reach consensus.
Data Collection and Analysis
Rotating pairs of reviewers independently performed
a critical review for potential sources of bias in study
methodology. Relevant systematic reviews were criti-
cally appraised using Assessing the Methodological
Quality of Systematic Reviews (AMSTAR) checklist
for systematic reviews (Shea et al., 2007; Table 1). Sys-
tematic reviews were critically reviewed to determine if
they had important methodological weakness limiting
condence in their results. Presence of fatal aws (i.e.,
inadequate search strategy, inadequate critical appraisal
or inadequate consideration of scientic quality when
formulating recommendations) was judged to render the
review scientically inadmissible. Systematic reviews
deemed scientically admissible (i.e., without any fatal
aws) were to be included in the qualitative synthesis.
RCTs were critically appraised using the Physiother-
apy Evidence Database (PEDro) rating scale for RCTs.
The PEDro scale was used to assess the internal validity of
the eligible trials. Minor modications were made to two
criteria on the instrument: 1) “therapists” were changed
to “administrator of supplement/placebo” when assessing
blinding; and 2) “prognostic indicators” was expanded
to include the health, functional and training status of
subjects when assessing similarity at baseline. The PEDro
criteria has demonstrated fair to good reliability for rating
quality of RCTs (Maher, Sherrington, Herbert, Moseley,
& Elkins, 2003). Studies were reviewed and scored on
the a priori criteria used to rank research to determine
the quality of each publication.
A grading system was used to grade the strength
of the evidence from RCTs. Studies with a score of 7
and above were deemed as high quality according to the
PEDro scale. Studies scoring 5 or 6 were considered to
be moderate quality and those studies scoring less than
5 were deemed as poor quality. In an effort to simplify
the interpretation of the results, the authors used the
aforementioned descriptive terms of quality assessment.
Similar descriptive classications of the PEDro scale have
been previously used in other reviews (Silva et al., 2012;
Teasell et al., 2007).
The preferred reporting items for systematic reviews
and meta-analyses (PRISMA) statement will be used for
reporting this systematic review (Moher et al., 2009).
Individual RCT demographics including inclusion and
exclusion criteria, cointerventions, primary outcome,
gender, age of participants, and duration of treatment
dose for each group are summarized in Table 2.
Results
Search Results
Figure 1 outlined the search process and ow of this
review. One systematic review (Hobson et al., 2012; Table
1) and nineteen RCTs were included (Table 2). The search
combining MeSH, search terms and limiters yielded 77
studies, which included 25 duplicates. Fifty-two articles’
titles and abstracts were screened for eligibility. There
were 38 potentially relevant trials that were retrieved in
full text. Nineteen of these full text articles were deemed
ineligible: three studies had inadequate randomization
16 Quesnele et al.
(Kendrick et al., 2008; Sale et al., 2011; Sweeney, Wright,
Brice, & Doberstein, 2010) and two failed to stratify for
BA supplementation (Hoffman et al., 2006; Spradley
et al., 2012). Twelve were nonsystematic or narrative
reviews (Artioli et al., 2010; Campbell et al., 2010;
Castell et al., 2010; Culbertson et al., 2010; Deldicque
& Francaux, 2008; Derave et al., 2010; Hoffman et al.,
2012; Sale et al., 2010; Stellingwerff et al., 2007; Stout,
2005; Tipton et al., 2007; Wilson et al., 2010), one was a
thesis (Jagim, 2010), and one was a medical grand rounds
(Messinger-Rapport, 2010). No unpublished preliminary
studies were included in this review.
Methodological Quality of Systematic
Reviews
One systematic review (Hobson et al., 2012) was relevant
for critical appraisal. Table 1 depicts the AMSTAR rating
of the included systematic review. The systematic review
had several methodological weaknesses: 1) no critical
appraisal of relevant studies to assess risk of bias (fatal
aw); 2) no consideration of scientic quality when
formulating recommendations (fatal aw); 3) inadequate
consideration for study similarities when pooling results;
and 4) inadequate assessment of publication bias. This
systematic review was deemed scientically inadmis-
sible as per a priori criteria and was not included in our
analysis.
Characteristics of RCTs
The sample sizes in the included studies ranged from 8
to 55. Details of the studies’ characteristics and interven-
tions are provided in Table 2. All studies reported mean
ages ranging from 18.4 to 85.3 and participants were
overwhelmingly male. There were two studies which
exclusively included female participants (Stout et al.,
2007; Walter et al., 2010), three studies that included
17–20 female subjects (Chung et al., 2012; Smith-Ryan
et al., 2012; Stout et al., 2008) and another study which
included one female participant (Baguet et al., 2010a).
The participants ranged from elite level athletics to
recreational level and the elderly. Rowers were studied
in one trial (Baguet et al., 2010a), football players and
wrestlers in two trials (Hoffman et al., 2008a; Kern &
Robinson, 2011), track-and-eld athletes in one trial
Figure 1 — Literature search ow.
A Systematic Review of the Literature 17
Table 1 AMSTAR Ratings of Systematic Reviews
AMSTAR Criteria Hobson et al., 2012
1. Was a priori design provided? Yes
2. Was there duplicate study selection and data extraction? Yes
3. Was a comprehensive literature search performed? Yes
4. Was the status of publication (i.e., gray literature) used as an inclusion criterion? No
5. Was a list of studies (included and excluded) provided? Yes
6. Were the characteristics of the included studies provided? Yes
7. Was the scientic quality of the included studies assessed and documented? No
8. Was the scientic quality of the included studies used appropriately in formulating conclusions? No
9. Were the methods used to combine the ndings of studies appropriate? No
10. Was the likelihood of publication bias assessed? No
11. Was the conict of interest included? Yes
TOTAL 6/11
(Derave et al., 2007), cyclists in one trial (Van Thienen
et al., 2009), “experienced resistance-trained” in one trial
(Hoffman et al., 2008b) and elite swimmers in another
trial (Chung et al., 2012). All other studies examined
participants who were minimally active to recreationally
active. All studies included a placebo group, which was
most often a dextrose lled capsule or packet, and were
similar to the BA capsules or packets. Only four trials
had an additional control or comparative group, which
included a no supplement and exercise training group
(Walter et al., 2010), another supplement or combination
of two supplements group (Stout et al., 2006; Zoeller et
al., 2007), or a group that was not described (Smith et
al., 2009a).
Methodological quality of RCTs
Table 3 depicts the quality score of each of the included
studies. The PEDro criteria was used to adequately
evaluate the internal validity and statistical rigor of all 19
RCTs and allowed for greater objectivity in the results.
All RCTs reviewed scored moderate to high, with scores
of 5 or higher. Four studies scored 6, six studies scored
7 and eight studies scored 8 out of 10, while Stout et
al. (2006) was the only study to score 5. A total of 14
studies had a methodological quality score of 7 or more.
Only two trials reported allocation concealment. Only six
trials reported adequate baseline comparability (Baguet
et al., 2010a; Chung et al., 2012; del Favero et al., 2012;
Jordan et al., 2010; Van Thienen et al., 2009; Walter et
al., 2010), whereas eight studies did not report adequate
follow-up (Chung et al., 2012; Hoffman et al., 2008a;
Kern & Robinson, 2011; Smith et al., 2009a; Stout et al.,
2006, 2007, 2008; Zoeller et al., 2007).
Almost all of the trials did not report blinding of
the assessor; however, Baguet et al. (2010b), Stout et
al. (2007), and Zoeller et al. (2007) did. Many of the
studies included stated that the trial was double blinded
in the methodology but did not explicitly state whether
the assessor was blinded or if the clinician administering
the treatment was blinded. All other categories within
the PEDro criteria were well described and reect the
high scores given.
Treatment Dose
All of the studies reported the dosage of BA; however,
there was large variability in the amount of BA given per
dose, total grams per day, and duration of supplementa-
tion. The total BA per day ranged from 2.0 g per day to 6.4
g per day. Many of the studies used an incremental dosage
strategy, whereby there were smaller dosages given
early in the intervention period and larger dosages given
late in the intervention period. The intervention period
ranged from 4 weeks to 13 weeks. The BA supplement
was commonly given as either a capsule or powder form.
However, there were several studies that used BA supple-
ments containing other potential ergogenic aids. Specic
brands of BA supplements were used which include
N-Acetylcysteine, alpha-lipoic acid, and vitamin E within
the supplement itself and thus may represent potential
cointerventions. Both Jordan et al. (2010) and Kern and
Robinson (2011) reported using BA supplements which
contained the aforementioned other ingredients, albeit,
in relatively small amounts. Furthermore, more than half
of the studies used a generic brand name BA supplement
and explicit reporting about the ingredients contained
within this BA supplement was not well documented. In
addition, the BA supplement prescribed in many of the
trials also contained dextrose or a sugar derivative, which
may also have contributed to the studies’ results (Smith et
al., 2009a, 2009b; Stout et al., 2006; Walter et al., 2010;
18
Table 2 Characteristics of RCTs and Intervention Details
First author,
year N, sex, sport
Mean age
(range or ±
SD
) Group (s) Beta-Alanine dose
Outcome
Measure
Training; Testing
protocol Follow-up
Other
Intervention
Baguet et al.,
2010a
17 male and 1
female, elite
rowers
23.2 (± 4.4) 1. BA grp 5.0 g/day (7 wks) muscle carnosine
content, LT, sprint
time
rowing training;
2000 m ergometer
test
7 weeks rowing training
2. Placebo grp
Baguet et al.,
2010b
14 male, physical
education students
21.9 (± 1.5) 1. BA grp 4.8 g/day (4 wks) VT, VO
2peak
, pH,
LT, bicarbonate,
base excess
NR; 6 min cycling
exercise
4 weeks normal physical
activity
2. Placebo grp
Chung et al.,
2012
34 male, 26
female, elite/sub-
elite swimmers
BA 22.6 (± 2.8) 1. BA grp 4.8 g/day (10 weeks) Swim perfor-
mance, pH, bicar-
bonate, lactate
performance times
of 50 m sprints,
middle distance
and distance groups
combined and fol-
lowing competition
10 weeks none
PL 21.0 (± 2.4) 2. Placebo grp
del Favero et
al., 2012
8 males, 10
females, physi-
cally inactive
adults
BA 65 (± 4) 1. BA grp 3.2 g/day (12 weeks) muscle carnosine,
physical capacity
tests, muscle func-
tion tests, QALY,
blood and urinary
tests
none; incremental
test on treadmill,
time-stands, timed-
up-and-go tests
12 weeks dextrose
PL 64 (± 7) 2. Placebo grp
Derave et al.,
2007
15 male, track-
and-eld
18.4 (± 1.5) 1. BA grp 2.4 g/day (d 1–4) 3.6 g/
day (d 5–9) 4.8 g/day (d
10–4wk)
calf muscle car-
nosine content,
sprint time
isokinetic and iso-
metric dynamometer
testing, 400m sprint
4 weeks track-and-eld
training
2. Placebo grp
Hill et al.,
2007
25 male, physi-
cally active
BA 25.4 (± 2.1)
PL 29.2 (± 6.9)
1. BA grp 4.0 g/day (wk 1) 4.8 g/
day (wk 2) 5.6 g/day
(wk 3) 6.4 g/day (wk
4–10)
TWD, maximum
power, muscle
biopsies, caron-
sine content
cycle capacity test 10 weeks maintained
similar physical
activity
2. Placebo grp
Hoffman et
al., 2008
8 male, experi-
enced resistance-
trained
19.7 (± 1.7) 1. BA grp 4.8 g/day (two 4 week
sessions)
growth hormone,
testesterone, cor-
tisol
1RM, 6 sets of 12
reps squats at 70%
1RM
12 weeks resistance train-
ing program
2. Placebo grp
Hoffman et
al., 2008
26 male, college
football
19.7 (± 1.6) 1. BA grp 3× 1.5 g/day (3wks
before season + 9 days
preseason
power and total
work, sprint time,
questionnaires-
intensity, soreness
resistance training;
wingate, 3 line drills
30 days practice training
2. Placebo grp
Jordan et al.,
2010
17 male, recre-
ationally active
24.9 (± 5.1) 1. BA grp 6.0 g/day (28 days) %HRmax,
%VO
2max
@
OBLAVO
2max,
Body mass
incremental tread-
mill running pro-
tocol
28 days 600 mg N-Ace-
tylcysteine, 2.7
mg alpha-lipoic
acid, 45 IU Vita-
min E
2. Placebo grp
19
First author,
year N, sex, sport
Mean age
(range or ±
SD
) Group (s) Beta-Alanine dose
Outcome
Measure
Training; Testing
protocol Follow-up
Other
Intervention
Kern et al.,
2011
37 male college
football (FB),
wrester (WR)
FB (18.6 ± 1.5)
WR (19.9 ± 1.9)
1. BA grp 2× 2.0 g/day (wk 1–8) 300 yd shuttle
time, 90 °FAH
time
HIIT, FAH and
shuttle time
8 weeks resistance train-
ing and prac-
tice, N-Acetyl
L-Cysteine,
Alpha-Lipoic-
Acid
2. Placebo grp
Smith et al.,
2009
46 male, recre-
ationally active
22.2 (± 3.3) 1. BA grp 1.5 g 4×/day (wk 1–3)
1.5 g 2×/day (wk 4–6)
EMG
FT
, EEA, HIIT 4 × 2 min
bouts on cycle
ergometer
6 weeks dextrose
2. Placebo grp
3. Control grp
Smith et al.,
2009
46 male, recre-
ationally active
22.2 (± 2.7) 1. BA grp 1.5 g 4×/day (0–21), 3.0
g 2×/day(22–42)
VO
2peak
, VO
2TTE
VT, TWD, body
mass
HIIT; cycle ergom-
eter
6 weeks dextrose, HIIT
2. Placebo grp
Smith-Ryan
et al., 2012
50 (26 men, 24
women) recre-
ationally active
men: 22.0 (±
2.7); women:
21.7 (± 2.1)
1. BA grp 2× 800 mg 3×/day
(0–28)
high-intensity run-
ning performance,
peak velocity
a graded exercise
test on a treadmill
28 days none
2. Placebo grp
Stout et al.,
2007
22 female 27.4 (±6.1) 1. BA grp 3.2 g/day (wk 1) 6.4 g/
day (wk 2–4)
PWC
FT
, VT,
VO
2max
, TTE,
body mass
incremental cycle
ergometry
28 days none
2. Placebo grp
Stout et al.,
2006
51 male 24.5 (± 5.3) 1. Placebo grp 1.6 g 4×/day, for 6 days,
then 2×/day for 22 days
PWC
FT
continuous incre-
mental cycle
ergometry
28 days dextrose
2. Cr grp
3. BA grp
4. BACr grp
Stout et al.,
2008
26 elderly (9
males, 17 females)
BA 72.1 (±
10.6); PL 73.4
(± 11.9)
1. BA grp 2.4 g/day (90 days) PWC
FT
discontinuous cycle
ergometry
90 days none
2. Placebo grp
Van Thienen
et al., 2009
17 male, mod-well
trained cyclists
24.9 (18–30) 1. BA grp 2.0 g/day (wk 1–2); 3.0
g/day (wk 3–4); 4.0 g/
day (wk 5–8)
Power, LT, pH
values
simulated bike race
-ergometer
8 weeks none
2. Placebo grp
Walter et al.,
2010
44 female, recre-
ationally active
21.8 (NR) 1. BA grp 1.5 g 4×/day (0–4wk),
1.5 g 2×/day(5–8)
VO
2peak
, VTw,
body composition
HIIT; cycle ergom-
eter
8 weeks dextrose
2. Placebo grp
3. Control grp
Zoeller et al.,
2007
55 male 24.5 (±5.3) 1. Placebo grp 1.6 g 6×/day, for 6 days,
then 2×/day for 22 days
VO
2peak
, VT, LT,
TTE
cycle ergometer 4 weeks dextrose
2. Cr grp
3. BA grp
4. BACr grp
NR: not reported; BA: beta alanine; VO
2
: oxygen utilitzation; VT: ventilatory threshold, VTw: workload at which VT occurred; PWC
FT
: physical working capacity at fatigue threshold; TWD: total work done; LT:
lactate threshold, TTE: time to exhaustion; Cr: crreatine; HIIT: high intensity interval training; EMG
FT
: electromyographic fatigue threshold; EEA: efciency of electrial activity; FAH: exed arm hang, QALY:
Quality of Life.
20
Table 3 The Methodological Quality of the Included RCTs
PEDro Scale
items
Baguet et al., 2010a
Baguet et al., 2010b
Chung et al. 2012
del Favero et al. 2012
Derave et al., 2007
Hill et al., 2007
Hoffman et al., 2008
Hoffman et al., 2008
Jordan et al., 2010
Kern & Robinson, 2011
Smith et al., 2009a
Smith et al., 2009b
Smith-Ryan et al., 2012
Stout et al., 2006
Stout et al., 2007
Stout et al., 2008
Van Thienen et al., 2009
Walter et al., 2010
Zoeller et al., 2007
1. random
allocation
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2. concealed
allocation
0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0
3. baseline
comparability
0 1 1 1 0 0 0 0 1 0 0 0 0 0 0 0 1 1 0
4. blind sub-
ject
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
5. blind clini-
cian
1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
6. blind asses-
sor
0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1
7. adequate
follow-up
1 1 0 1 1 1 1 0 1 0 0 1 1 0 0 0 1 1 0
8. “inten-
tion to treat”
analysis
1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1
9. between-
group analysis
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
10. point
estimates and
variability
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Total 7 8 8 8 7 8 7 6 8 6 6 7 8 5 7 6 8 8 7
Note. Each satised item contributes 1 point to the total PEDro score (range 0–10 points)
A Systematic Review of the Literature 21
Zoeller et al., 2007). It was also very common among the
included studies to have had an exercise training program
prescribed or maintained during the intervention period.
Outcome Measures
There were a variety of outcomes used to assess athletic
and exercise performance. Largely the outcome measures
used depended on whether the study examined aerobic or
anaerobic tness. There were concrete measures of tness
and athletic performance which included specic time
trials, VO2max, ventilator threshold (VT), lactate thresh-
old (LT), power output and less concrete or indirect mea-
sures of performance such as muscle caronsine levels and
body composition. In addition, several studies included
rates of perceived exertion, fatigue and time to exhaustion
as other measures of cardiorespiratory tness (Smith et
al., 2009b; Stout et al., 2007; Zoeller et al., 2007). For the
purposes of this review the outcomes were grouped into
four general categories: endurance and aerobic measures,
strength, anaerobic measures and workload, sport specic
measures, and metabolic and other measures.
The Effect of Beta-Alanine
Supplementation on Aerobic Oxidative
Metabolism
The effect of beta alanine on aerobic tness and capacity
were assessed in nine studies (Baguet et al., 2010; Baguet
et al., 2010b; Jordan et al., 2010; Kern & Robinson, 2011;
Smith et al., 2009b; Stout et al., 2007; Van Thienen et
al., 2009; Walter et al., 2010; Zoeller et al., 2007). The
most common measures of endurance and aerobic capac-
ity included, but were not limited to, VO2, VT, LT, and
other measures of acidosis and cardiorespiratory tness.
Of the six studies which examined the effects of BA on
VO2, (Baguet, Koppo, et al., 2010; Jordan et al., 2010;
Smith et al., 2009a; Stout et al., 2007; Walter et al., 2010;
Zoeller et al., 2007) only Smith et al. (2009b) found
signicant increases in VO2peak and VO2tte for the BA
group compared with placebo after a second three-week
supplementation period. Walter et al. (2010) found sig-
nicant increases in VO2peak during each training ses-
sion in both the BA and placebo groups at 4 and 8 weeks
but they did not nd any change for the control group.
Three studies (Baguet et al., 2010b; Stout et al., 2007;
Zoeller et al., 2007) found no signicant differences in
VO2 measures. For both groups Baguet, Koppo, et al.
(2010) found no signicant differences in submaximal
VO2 throughout exercise before or after supplementa-
tion. Stout et al. (2007) found no signicant differences
in maximal oxygen consumption, VO2max, between BA
and PL and Zoeller et al. (2007) also found no signicant
differences in VO2peak between BA and PL. Interestingly,
Jordan et al. (2010) found a reduction in aerobic capacity
as evidenced by a decrease in VO2max values in the BA
group compared with no change in the placebo group.
Six studies examined the effects of BA on ventilation
(VE) and VT (Baguet et al., 2010b; Smith et al., 2009b;
Smith-Ryan et al., 2012; Stout et al., 2007; Walter et al.,
2010; Zoeller et al., 2007). Stout et al. (2007) demon-
strated increases in VT by 13.9% in the BA group versus
no change observed in the placebo group. Smith, Walter
et al. (2009) observed no signicant differences among
the improvements in VT between groups. There were
nonsignicant improvements from pre to mid VT for
both the placebo and BA groups (Smith, Walter, et al.,
2009). There were no signicant changes between BA
and placebo in studies by Zoeller et al. (2007), Smith-
Ryan et al. (2012) and Baguet, Koppo, et al. (2010) for
VT. However, the lack of effect in the Smith-Ryan et al.
(2012) study could be attributed to the large rest time (15
min) that may have allowed the metabolites to disperse
between running bouts.
There were eight studies which examined measures
of blood lactate measures following treatment inventions
with BA (Baguet et al., 2010a, 2010b; Chung et al., 2012;
Jordan et al., 2010; Kern & Robinson, 2011; Smith-Ryan
et al., 2012; Van Thienen et al., 2009; Zoeller et al.,
2007). Both Jordan et al. (2010) and Kern and Robinson
(2011) demonstrated improvements in lactate measures
following BA supplementation. In studies that measured
blood lactate parameters during predominantly aerobic
exercise, mixed results were observed. Jordan et al., 2010
demonstrated that the onset of blood lactate accumulation
occurred at a higher % of heart rate and % of VO2max
in the BA group compared with the placebo group fol-
lowing 28 days of BA supplementation. However, there
were no signicant changes in maximal lactate measures
as reported by Baguet et al. (2010a) following a 2000 m
rowing trial which lasted approximately 6 min and 30 s
or Baguet et al. (2010b) 6-min cycling trial. Further, no
signicant differences between BA or placebo groups
were noted in the Van Thienen et al. (2009), Zoeller et al.
(2007) or Smith-Ryan et al. (2012) papers. In a study that
evaluated lactate measures on exercise more associated
with anaerobic capacity Kern and Robinson (2011) found
no change between BA and placebo in both football play-
ers and wrestlers following a 300-yard shuttle or exed-
arm-hang time. Conversely, Chung et al. did not report
substantial effects of BA supplementation on pre- versus
postswimming race blood pH or bicarbonate levels despite
most competitive swimming races relying signicantly
on anaerobic energy metabolism (Chung et al., 2012).
The Effect of Beta-Alanine on Strength,
Anaerobic Capacity and Workload
The most common measures of strength and anaerobic
capacity included, but were not limited to, power output,
torque, physical working capacity at fatigue threshold
(PWCFT), total work done (TWD), power output at LT,
and sprint time trials. Eight trials examined the effects
of BA supplementation on power and TWD and one
study examined the effects of BA supplementation on
knee torque. Hill et al. (2007) examined 4 weeks of
BA supplementation in physically active men on power
output. They found a signicant increase in total work
22 Quesnele et al.
done (TWD) by 13% with a further 3.2% increase at
the 10-week point whereas TWD remained unchanged
at 4 and 10 weeks in the control group. In addition, in
the Hoffman, Ratamess, Ross, et al. (2008) study, there
was greater mean power in the BA group versus placebo
following 4 weeks for supplementation. In another trial
by Hoffman et al. (2008a), 26 football players were
administered either BA or placebo and were tested using
anaerobic line drills and a Wingate test. Their results
indicated no signicant difference between mean and
peak power or total work. In a study conducted by Smith
et al. (2009b) there were also signicant differences in
TWD after 3 weeks of training and supplementing in the
BA and placebo groups, however, there was no signi-
cant difference between groups. The physical working
capacity at fatigue threshold was examined in three stud-
ies which demonstrated a 12.6–28.6% increase for BA
versus no changes in the placebo group indicating that BA
delays onset of neuromuscular fatigue at submaximum
workloads (Stout et al., 2006; Stout et al., 2007; Stout
et al., 2008). Walter et al. (2010) observed increases in
workload at which VT occurred (VTw) for all groups
at weeks four and eight. In addition, Van Thienen et al.
(2009) found similar mean power output between placebo
and BA, however, during the nal sprint after the time
trial, BA on average signicantly increased both peak
power output by 11.4% and mean power output by 5.0%
during a 30 s sprint compared with placebo. Smith-Ryan
et al. (2012) found no signicant treatments effects on
anaerobic running capacity and critical sprint velocity
after subjects performed a series of runs while using BA.
The Effect of Beta-Alanine on Sport
Specific Measures
Three studies reported time trials as indicators of per-
formance enhancement with the treatment intervention.
Baguet, Bourgois et al. (2010) examined rowing time
trials and muscle carnosine content with BA supplemen-
tation and demonstrated nonsignicant improvements
(p = .07) in BA group by 2.7 s (± 4.8s) compared with
placebo. Hoffman, Ratamess, Faigenbaum, et al. (2008)
examined training volume and fatigue rates in line drills,
intense cycling and resistance exercises and there were
no differences in fatigue rate in line drills but a trend (p
= .07) was observed for a lower fatigue rate for BA in
the bench press exercise and a trend for greater training
volume for all resistance exercise sessions. Derave et al.
(2007) also studied 400-m sprint times as a measure of
performance and did not nd signicant differences in
the BA group. Chung et al. (2012) found greater improve-
ment in training performance after eight weeks, though
this effect was not maintained after 10 weeks.
The Effect of Beta-Alanine on Metabolic
and Other Measures
Changes to body composition was reported in seven trials
(Hill et al., 2007; Jordan et al., 2010; Kern & Robinson,
2011; Smith et al., 2009b; Stout et al., 2007; Van Thienen
et al., 2009; Walter et al., 2010). Measures of body com-
position and lean mass included skin-caliper method,
physician scales, or air displacement plesmythography.
There were no changes in body composition reported
in three trials (Hill et al., 2007; Stout et al., 2007; Van
Thienen et al., 2009) while four trials revealed changes
in body composition, with increasing lean mass most
common in the BA group compared with the placebo
group (Jordan et al., 2010; Kern & Robinson, 2011;
Smith et al., 2009b; Walter et al., 2010). In another study,
Hoffman et al. (2008b) examined the hormonal response
to BA supplementation measuring growth hormone,
testosterone and cortisol concentrations and found no sig-
nicant differences between the BA and placebo groups.
In addition, muscle carnosine content was examined in
three studies using proton magnetic resonance spectros-
copy and one study using muscle biopsy HPLC method
following supplementation regimes of BA (Baguet et al.,
2010a; Del Favero et al. (2012) Derave et al., 2007; Hill
et al., 2007). Baguet et al. (2010a) demonstrated signi-
cant (p = .042) positive correlations (r = .498) between
muscle carnosine concentrations and incremental rowing
speeds and performance on a 2000 m simulated race.
Derave et al. (2007) demonstrated BA supplementation
signicantly increased muscle carnosine concentrations
in the soleus (+47%) and gastrocnemius (+37%) com-
pared with placebo. del Favero et al. (2012) also found
a signicant increase in muscle carnosine content in the
BA group (+85.4%) compared with placebo (+7.2%).
Hill et al. (2007) also demonstrated increases in muscle
carnosine following BA supplementation at four weeks
(+58.8%) and at 10 weeks (80.1%).
Eight studies included feelings of fatigue and time
to exhaustion as a measure of cardiorespiratory tness.
Five studies reported the time to exhaustion (del Favero
et al., 2012; Smith et al., 2009b; Smith-Ryan et al., 2012;
Stout et al., 2007; Zoeller et al., 2007). del Favero et al.,
(2012) had time to exhaustion (TTE) as a measure of
exercise tolerance (using the difference between ven-
tilatory anaerobic threshold and VO2peak set at 75%)
and found TTE signicantly improved in the BA group
versus placebo group. One other study dened time to
exhaustion by the time (in seconds) that the subject could
maintain a cadence rate of 60 rpm and was only dened
within the VO2 (Smith, Walter, et al., 2009). The two
other studies did not dene time to exhaustion but it was
measured during a graded exercise protocol and reported
in seconds (Stout et al., 2007; Zoeller et al., 2007). Stout
et al. (2007) found a 2.5% increase (improvement) in
time to exhaustion during maximal cycling ergometry
performance versus no changes in the placebo group.
Smith-Ryan et al. (2012) found no TTE effects that were
evident for bouts at 90–110% PV lasting 1.95–5.06 min.
In addition, Zoeller et al. (2007) found no signicant
differences between BA and placebo for TTE following
28 days of supplementation on cycle ergometry testing.
Three studies also reported on fatigue following the
exercise protocols. Derave et al. (2007) reported fatigue
A Systematic Review of the Literature 23
as measured by exhaustive dynamic knee contractions
but did not dene what constituted fatigue. While Hoff-
man, Ratamess, Faigenbaum, et al. (2008) dened rate of
fatigue as the drop in power from peak power to lowest
power and sprint times (best time/worst time). Subjects
were also asked to rate their feelings of fatigue using a
7-point scale. Jordan et al. (2010) assessed overall body
rating of perceived exertion using a 6–20 numeric scale.
Two studies (Derave et al., 2007; Hoffman, Ratamess,
Faigenbaum, et al., 2008) indicated a signicantly lower
subjective fatigue level for BA compared with placebo.
Adverse Events
Adverse events were generally poorly reported. Seven of
the nineteen studies reported on adverse events following
BA supplementation. Derave et al. (2007), del Favero
et al. (2012) and Van Thienen et al. (2009) reported no
adverse events, while other studies reported mild pares-
thesia and/or infrequent mild transient symptoms such as
tingling in hands and ngers (Chung et al., 2012; Hill et
al., 2007; Jordan et al., 2010; Smith-Ryan et al., 2012).
Discussion
As the popularity of BA supplementation increases, the
need for high quality reviews on the topic is paramount.
There is currently one systematic review with meta-
analysis on this topic (Hobson et al., 2012); however, the
review did not evaluate the methodological quality of the
included studies when formulating their results, leading
to low condence in their ndings. Previous literature
has demonstrated that combining ndings from studies
without considering their methodological quality can
lead to bias (Egger et al., 2002; Schultz et al., 1995). In
light of this, this body of literature is lacking a critical
assessment of studies to draw appropriate conclusions on
BA. Our critical assessment of methodological quality
and synthesis of information from high quality studies
addresses this important knowledge gap to guide the use
of BA for performance.
Overall, nine studies examined the effect of beta
alanine on endurance and aerobic capacity. Only one
high quality trial, Smith, Walter, et al. (2009), found
signicant increases in VO2peak and VO2tte favoring
the BA group compared with placebo. Another study of
high methodological quality, Walter et al. (2010), found
signicant increases in VO2peak for both the BA and
PL groups but did not nd any differences between BA
and PL. The ndings of these studies suggest a potential
treatment effect of the exercise program used during the
study period rather than the BA supplementation. Further-
more, in a high quality study, Jordan et al. (2010) found
a decrease in VO2max in the BA group compared with
PL group. Overall, there is one moderate and two high
quality studies yielding inconsistent results for the effect
of beta alanine on VO2. It appears that BA alone does
not affect VO2peak, but may improve it when combined
with exercise training. Simply put, it appears that BA
may augment the training induced effect on VO2peak.
Likewise, there are high methodological studies
yielding inconsistent evidence for the effect of beta ala-
nine on ventilation and ventilatory threshold (Baguet et
al., 2010b; Smith et al., 2009b; Stout et al., 2007; Walter
et al., 2010; Zoeller et al., 2007). Signicant improve-
ments in lactate measures following BA supplementation
were also noted in two moderate to high quality studies
(Jordan et al., 2010; Kern & Robinson, 2011). While
no signicant changes in lactate measures between BA
and PL groups were noted in six other high quality trials
(Baguet, Bourgois, et al., 2010; Baguet, Koppo, et al.,
2010; Chung et al., 2012; Smith-Ryan et al., 2012; Van
Thienen et al., 2009; Zoeller et al., 2007), thus there is
also inconsistent evidence demonstrating an improvement
in lactate measures following BA supplementation. Based
on inconsistent results across the included studies, the
overall conclusion regarding the effect of beta alanine on
endurance and aerobic capacity is inconclusive.
Ten studies examined the effects of BA on strength,
anaerobic capacity and workload. In one moderate qual-
ity trial (Hoffman, Ratamess, Faigenbaum, et al., 2008)
and two high quality trials (Hoffman et al., 2008a; Van
Thienen et al., 2009) there were signicant increases
in TWD and mean power for the BA group compared
with placebo. In another high quality study (Smith et
al., 2009b) there were signicant differences in TWD
between BA and PL groups, however, there were no
signicant between group differences. Whereas another
moderate quality trial examining power and TWD (Hoff-
man et al., 2008a) and a high quality trial (Smith-Ryan
et al., 2012) examining critical velocity and anaerobic
capacity found no signicant differences between placebo
or BA groups. Physical working capacity and fatigue
threshold were examined in three moderate-to-high
quality trials (Stout et al., 2006, 2007, 2008). These three
studies demonstrated an increase in fatigue threshold
for BA versus placebo group indicating that BA may
delay the onset of neuromuscular fatigue. Overall, there
is moderate to high quality evidence to suggest that BA
supplementation may increase TWD, power output,
physical working capacity, and fatigue threshold.
The effect of beta alanine on sport specic measures
was examined in several trials. In one high quality study,
2000-m rowing time trials improved in the BA group
compared with placebo, with the placebo group demon-
strating decreases in rowing time trials compared with
baseline following a 7 week intervention period (Baguet,
Bourgois, et al., 2010). Greater improvement in training
performance after 4 weeks was found in another high
quality trial, though this effect was not maintained after
10 weeks and should be considered in light of substantial
baseline differences between the two groups (Chung et
al., 2012). While another high quality trial demonstrated
no signicant differences in 400 sprint times between
BA and PL groups (Derave et al., 2007). Overall, three
high quality studies examining time trials yielded incon-
sistent results for the treatment effect of BA compared
24 Quesnele et al.
with placebo on rowing, swimming and running sprint
times.
There were also many studies which aimed to iden-
tify other treatment effects of BA supplementation on
athletes. Factors such as fatigue rates and exhaustion were
found to improve in four moderate-to-high quality trials
for the BA group compared with placebo (del Favero et
al., 2012; Derave et al., 2007; Hoffman et al., 2008a; Stout
et al., 2007). Among seven trials, which included body
composition as a part of their analysis, four moderate-to-
high quality trials revealed changes in body composition,
with increasing lean mass being the most common in the
BA group compared with placebo (Jordan et al., 2010;
Kern & Robinson, 2011; Smith et al., 2009b; Walter et
al., 2010). These studies indicate an association of BA
supplementation having a positive effect on body com-
position; however, it is difcult to ascertain whether this
effect is due to other factors such as exercising training
effect. Muscle content was examined in four high quality
studies which demonstrated increased muscle carnosine
concentrations in the BA supplementation group with
subsequent performance enhancement compared with
the placebo group (Baguet et al., 2010a; del Favero et al.,
2012; Derave et al., 2007; Hill et al., 2007).
The dosage strategies used within the studies varied
considerably. In general, an incremental dosage strategy
was most often used. Smaller dosages were given early
in the intervention period and larger dosages given later.
Employing an incremental strategy of BA ranging from
3.0 to 6.0 g per day may be benecial; however, there
were large discrepancies between the studies in terms of
frequency, duration, and amount of BA used. Based on
this heterogeneity, interpreting the results for optimal
dosage strategy is difcult and thus specic recommen-
dations in this review cannot be made.
Our systematic review found that beta alanine pro-
vided improvements in many performance domains and
exercise measures. However, there were many inconsis-
tencies within our included studies for endurance and
aerobic measures and sport specic measures. Thus, cau-
tion should be applied when conferring the widespread
treatment effects of BA on exercise performance as a
whole. As reported by Hobson et al. (2012), and also
demonstrated in our review, is the lack of reporting of
adverse events in the BA supplementation trials. Only
three trials reported that there were no adverse events
observed (del Favero et al., 2012; Derave et al., 2007;
Van Thienen et al., 2009) while four studies reported
that the adverse events were mild and transient in nature,
which included paresthesias (Chung et al., 2012; Hill et
al., 2007; Jordan et al., 2010, Smith-Ryan et al. 2012).
The under-reporting of BA supplementation adverse
events within the included studies is problematic. There
may have been side effects experienced that were of
mild nature and thus not reported by the subjects if not
explicitly asked. Further, because of the under-reporting
of adverse events the possibility of those subjects who
were lost to follow-up having left the study because of
an adverse event is possible. The under-reporting of
adverse events in the included studies makes conclu-
sions pertaining to side effects and adverse events with
BA supplementation in this population largely unknown.
Recent work by Harris et al. 2006 and Décombaz, Beau-
mont, Vuichoud, Bouisset, & Stellingwerff, 2012 help
to elucidate the potential adverse effects of BA supple-
mentation. Harris et al. (2006) did not nd any adverse
effects, except for mild ushing in 4 participants receiving
BA and one receiving the placebo, of a frequently used
supplementation protocol (4 weeks, 4 doses of 800mg/
day), on blood biochemical and hematological markers.
Further, Decombaz et al. (2012) thoroughly investigated
the sensory side-effects of acute ingestion of both pure
and slow-release beta-alanine (1.6g). Their ndings
also indicate that when the suggested doses and time are
respected, beta-alanine supplementation seems to be safe.
Limitations
This review has some possible limitations including
those within the included RCTs themselves. Although
the PEDro scales takes into consideration many critical
methodological factors such as randomization, blinding,
and follow-up, it can be argued that the scale removes
analytical subjectivity, and thus may over-estimate the
actual quality of the study. It may also be argued that
in ergogenic supplement trials, the PEDro scale may
not be ideal to adequately account for methodological
issues unique to these types of trials. These methodologi-
cal issues include, compliance with supplement dosing
strategy, dietary reporting of participants or specic
detail regarding training status of the participant, which
also contribute as limitations to our review. Although
the authors did not nd any critical aws within the 19
included RCTs there were some general concerns. First,
very few studies reported adequate baseline comparability
on the most important prognostic indicators or reported
adequate allocation concealment. There were also many
studies with inadequate follow-up or reporting of follow-
up. Furthermore, all studies did include placebo as a con-
trol group; however, few studies included an additional
control group, which did not receive the exercise protocol.
Thus, the distinction between the treatment effects of
exercise training on performance cannot be clearly made
and presents itself as a major limitation to the studies
included in this review. There appears to be a positive
mechanistic correlation between BA supplementation,
an increase in muscle carnosine content and enhanced
performance. Ideally muscle carnosine would have been
studied in all studies to determine efcacy for perfor-
mance enhancement; however, only four trials directly
measured this effect in our review and thus serves as a
limitation to the review. In addition, reporting adequate
baseline comparability and evaluating the potential
treatment effects of other potentially active ingredients,
such as Alpha-Lipoic-Acid and Vitamin E was not well
accounted for, as such, the possibility remains that these
other active ingredients may have contributed to the
A Systematic Review of the Literature 25
results of the studies and thus serve as confounders in
our review. Another limitation was that the sample sizes
of most studies were quite small and thus potentially
represents underpowered results. These methodologi-
cal limitations increase the risk of bias and thus make
interpretation of studies results difcult.
The primary limitation among the included studies
was the lack of homogeneity of the study designs. There
were large differences in study samples, dose strategies,
exercise interventions, outcome measures, and treatment
protocols making it difcult to draw rm conclusions
regarding the effect of BA on performance. Another pos-
sible limitation in this review is the language bias as we
only permitted articles published in the English language.
Furthermore, only randomized trials were included in
this review, which excludes potential results regarding
the effectiveness of BA from nonrandomized but well-
controlled cohort studies. The sample was overwhelm-
ingly male and thus interpretation of the results regarding
the effect of beta alanine on both genders is limited.
Research Priorities
Future research should be directed to delineate the opti-
mal dose strategy for subgroups of athletes including
gender differences and body type. Future research should
also aim to further examine the generalizability of BA on
different age groups including adolescents and children as
well as the older athletes. The safety prole of BA appears
to be satisfactory; however, there were insufcient studies
that measured adverse events and thus true representa-
tion of the safety of BA supplementation in the athletic
population cannot be determined. Safety and analysis
of adverse events should be included in future work as
a specic aim to help substantiate and protect the public
who may use this supplement. Further, this review was
not able to precisely establish the effects of pure BA on
performance, as some studies included other potentially
active ingredients and/or additives in relatively small
amounts to their beta alanine supplements. In addition,
more than half of the studies used a generic brand name
BA supplement and did not explicitly state whether this
supplement had potentially active ingredients within the
BA formula. This is a limitation of the included studies
and future studies should consider removing active ingre-
dients from the beta alanine supplements or including
similar ingredients into the placebo. This would allow
for the effects of pure beta alanine to be better assessed.
Future research should emphasize high methodologi-
cal rigor to minimize sources of bias and increase our con-
dence in the results. In RCTs, this emphasis should be
placed on adequate baseline comparability, reporting of
allocation concealment, adequate follow-up and sample
sizes that reach statistical power. Future systematic
reviews in this area should conduct appropriate critical
appraisal of relevant studies and consider scientic qual-
ity when formulating recommendations. This ensures that
conclusions are based on studies of low risks of bias and
adequate scientic validity only.
Conclusion
Team doctors, therapists, and healthcare professionals
need to raise their awareness of the use of beta alanine
as an ergogenic substance. Currently, there appears to
be some evidence from this review that supplementation
with BA may increase athletic performance. Specically,
there appears to be moderate to high quality that BA
supplementation may increase TWD and power output.
There is also moderate to high quality evidence indicat-
ing that BA supplementation may decrease subjective
feelings of fatigue and perceived exhaustion. Moderate
to high quality research also indicates a positive effect of
BA on body composition and muscle carnosine content.
Given these ndings, there may be a benecial role of
implementing BA supplementation among select athletes
who are closely followed by team doctors or health care
professionals. There are currently no long-term trials
examining the extended use of BA supplementation in
athletic populations. Therefore, one should err on the side
of caution in using BA as an ergogenic aid until there is
sufcient evidence conrming its safety.
Acknowledgments
We would like to sincerely thank Anne Taylor-Vaisey for her
assistance in the study’s search strategy. The authors have no
conicts of interest to declare.
References
Allen, D.G., Lännergren, J., & Westerblad, H. (1995).
Muscle cell function during prolonged activity: cellular
mechanisms of fatigue. Experimental Physiology, 80(4),
497–527 Retrieved from http://www.ncbi.nlm.nih.gov/
pubmed/7576593. PubMed
Artioli, G.G., Gualano, B., Smith, A., Stout, J., & Lancha, A.H.
(2010). Role of B-Alanine Supplementation on Muscle
Carnosine and Exericse Performance. Sports Medicine
(Auckland, N.Z.), 75, 1162–1173.
Baguet, A., Bourgois, J., Vanhee, L., Achten, E., & Derave, W.
(2010a). Important role of muscle carnosine in rowing
performance. Journal of Applied Physiology (Bethesda,
Md. : 1985), 109(4), 1096–1101.
Baguet, A., Koppo, K., Pottier, A., & Derave, W. (2010b). Beta-
alanine supplementation reduces acidosis but not oxygen
uptake response during high-intensity cycling exercise.
European Journal of Applied Physiology, 108(3), 495–503.
PubMed doi:10.1007/s00421-009-1225-0
Campbell, B.I., Wilborn, C.D., & La Bounty, P.M. (2010).
Supplements for strength-power athletes. Strength and
Conditioning Journal, 32(1), 93–100 (Allen Press)
Retrieved from http://search.ebscohost.com/login.aspx?
direct=true&db=rzh&AN=2010558717&site=ehost-live.
doi:10.1519/SSC.0b013e3181c212b9
Castell, L.M., Burke, L.M., Stear, S.J., McNaughton, L.R., &
Harris, R.C. (2010). BJSM reviews: A-Z of nutritional
supplements: dietary supplements, sports nutrition foods
and ergogenic aids for health and performance Part 5.
26 Quesnele et al.
British Journal of Sports Medicine, 44(1), 77–78. PubMed
doi:10.1136/bjsm.2009.069989
Chung, W., Shaw, G., Anderson, M.E., Pyne, D.B., Saunders,
P.U., Bishop, D.J., & Burke, L.M. (2012). Effect of 10
week beta-alanine supplementation on competition and
training performance in elite swimmers. Nutrients, 4,
1441–1453. PubMed doi:10.3390/nu4101441
Culbertson, J.Y., Kreider, R.B., Greenwood, M., & Cooke, M.
(2010). Effects of beta-alanine on muscle carnosine and
exercise performance: a review of the current literature.
Nutrients, 2(1), 75–98. PubMed doi:10.3390/nu2010075
Décombaz, J., Beaumont, M., Vuichoud, J., Bouisset, F., & Stel-
lingwerff, T. (2012). Effect of slow-release b-alanine tab-
lets on absorption kinetics and paresthesia. Amino Acids,
43(1), 67–76. PubMed doi:10.1007/s00726-011-1169-7
Deldicque, L., & Francaux, M. (2008). Functional food for
exercise performance: fact or foe? Current Opinion in
Clinical Nutrition and Metabolic Care, 11(6), 774–781
Retrieved from http://search.ebscohost.com/login.aspx?
direct=true&db=mnh&AN=18827583&site=ehost-live.
PubMed doi:10.1097/MCO.0b013e3283139489
del Favero, S., Roschel, H., Solis, M.Y., Hayashi, A.P., Artioli,
G.G., Otaduy, M.C., . . . Gualano, B. (2012). Beta-alanine
(Carnosyn) supplementation in elderly subjects (60-80
years): effects on muscle carnosine content and physical
capacity. Amino Acids, 43, 49–56. PubMed doi:10.1007/
s00726-011-1190-x
Derave, W., Everaert, I., Beeckman, S., & Baguet, A. (2010).
Muscle Carnosine Metabolism and b-Alanine Supple-
mentation in Relation to Exercise and Training. Sports
Medicine (Auckland, N.Z.), 40(3), 247–263. PubMed
doi:10.2165/11530310-000000000-00000
Derave, W., Ozdemir, M. S., Harris, R. C., Pottier, A., Reyn-
goudt, H., Koppo, K., …Achten, E. (2007). beta-Alanine
supplementation augments muscle carnosine content and
attenuates fatigue during repeated isokinetic contraction
bouts in trained sprinters. Journal of Applied Physiology
(Bethesda, Md. : 1985), 103(5), 1736-1743.
Egger, M., Ebrahim, S., & Smith, G.D. (2002). Where now for
meta-analysis? International Journal of Epidemiology, 31,
1–5. PubMed doi:10.1093/ije/31.1.1
Harris, R. C., Tallon, M. J., Dunnett, M., Boobis, L., Coakley,
J., Kim, H.J. …Wise, J.A. (2006). The absorption of orally
supplied beta-alanine and its effect on muscle carnosine
synthesis in human vastus lateralis. Amino Acids, 30(3),
279–289. PubMed doi:10.1007/s00726-006-0299-9
Hill, C.A., Harris, R.C., Kim, H.J., Harris, B.D., Sale, C.,
Boobis, L.H., . . . Wise, J.A. (2007). Inuence of beta-
alanine supplementation on skeletal muscle carnosine
concentrations and high intensity cycling capacity. Amino
Acids, 32(2), 225–233. PubMed doi:10.1007/s00726-
006-0364-4
Hobson, R.M., Saunders, B., Ball, G., Harris, R.C., & Sale, C.
(2012). Effects of b-alanine supplementation on exercise
performance : a meta-analysis. Amino Acids, 43(1), 25–37.
PubMed doi:10.1007/s00726-011-1200-z
Hoffman, J.R., Emerson, N.S., & Stout, J.R. (2012). β-Alanine
supplementation. Current Sports Medicine Reports, 11(4),
189–195.
Hoffman, J.R., Ratamess, N.A., Faigenbaum, A.D., Ross, R.,
Kang, J., Stout, J.R., & Wise, J.A. (2008a). Short-duration
beta-alanine supplementation increases training volume
and reduces subjective feelings of fatigue in college foot-
ball players. Nutrition Research (New York, N.Y.), 28(1),
31–35. PubMed doi:10.1016/j.nutres.2007.11.004
Hoffman, J., Ratamess, N.A., Ross, R., Kang, J., Magrelli,
J., Neese, K., & Wise, J.A. (2008b). Beta-alanine and
the hormonal response to exercise. International Jour-
nal of Sports Medicine, 29(12), 952–958. PubMed
doi:10.1055/s-2008-1038678
Jagim, A. (2010). Effects of Beta-Alanine Supplementation on
Sprint Endurance. Unpublished master’s thesis. University
of Wisconsin-La Crosse, United States of America.
Hoffman, J., Ratamess, N., Kang, J., Mangine, G., Faigen-
baum, A., & Stout, J. (2006). Effect of creatine and beta-
alanine supplementation on performance and endocrine
responses in strength/power athletes. International Jour-
nal of Sport Nutrition and Exercise Metabolism, 16(4),
430–446 Retrieved from http://www.ncbi.nlm.nih.gov/
pubmed/17136944. PubMed
Jordan, T., Lukaszuk, J., Misic, M., & Umoren, J. (2010). Effect
of beta-alanine supplementation on the onset of blood
lactate accumulation (OBLA) during treadmill running:
Pre/post 2 treatment experimental design. Journal of the
International Society of Sports Nutrition, 7, 20. PubMed
doi:10.1186/1550-2783-7-20
Kendrick, I. P., Harris, R. C., Kim, H. J., Kim, C. K., Dang,
V. H., Lam, T.Q.,…. Wise, J.A. (2008). The effects of 10
weeks of resistance training combined with beta-alanine
supplementation on whole body strength, force production,
muscular endurance and body composition. Amino Acids,
34(4), 547–554. PubMed doi:10.1007/s00726-007-0008-3
Kern, B.D., & Robinson, T. (2011). Effects of B-Alanine
Supplementation on Performance and Body Composition
in Collegiate Wrestlers and Football Players. Journal of
Strength and Conditioning Research, 25(7), 1804–1815.
PubMed doi:10.1519/JSC.0b013e3181e741cf
Maher, C.G., Sherrington, C., Herbert, R.D., Moseley, A.M., &
Elkins, M. (2003). Reliability of the PEDro scale for rating
quality of randomized controlled trials. Physical Therapy,
83(8), 713–721 Retrieved from http://www.ncbi.nlm.nih.
gov/pubmed/12882612. PubMed
Merlin, T., Weston, A., & Tooher, R. (2009). Extending an
evidence hierarchy to include topics other than treatment :
revising the Australian ’ levels of evidence ‘. BMC Medical
Research Methodology, 9, 34. PubMed
Messinger-Rapport, B. (2010). What’s new in treating older
adults? Cleveland Clinic Journal of Medicine, 77(11),
770–790.
Moher, D., Liberati, A., Tetzlaff, J., & Altman, D.G. (2009). Pre-
ferred Reporting Items for Systematic Reviews and Meta-
Analyses: The PRISMA Statement. Annals of Internal
Medicine, 151(4), 264–269. PubMed doi:10.7326/0003-
4819-151-4-200908180-00135
Sale, C., Saunders, B., & Harris, R.C. (2010). Effect of beta-ala-
nine supplementation on muscle carnosine concentrations
and exercise performance. Amino Acids, 39(2), 321–333.
PubMed doi:10.1007/s00726-009-0443-4
A Systematic Review of the Literature 27
Sale, C., Saunders, B., Hudson, S., Wise, J.A., Harris, R.C., &
Sunderland, C.D. (2011). Effect of β-alanine plus sodium
bicarbonate on high-intensity cycling capacity. Medicine
and Science in Sports and Exercise, 43(10), 1972–1978.
PubMed
Schulz, K.F., Chalmers, I., Hayes, R.J., & Altman, D.G.
(1995). Empirical evidence of bias. Dimensions of meth-
odological quality associated with estimates of treatment
effects in controlled trials. Journal of the American
Medical Association, 273, 408–412. PubMed doi:10.1001/
jama.1995.03520290060030
Shea, B.J., Grimshaw, J.M., Wells, G.A., Boers, M., Andersson,
N., Hamel, C., . . . Bouter, L.M. (2007). Development of
AMSTAR: a measurement tool to assess the methodologi-
cal quality of systematic reviews. BMC Medical Research
Methodology, 7, 10. PubMed doi:10.1186/1471-2288-7-10
Silva, A., Serrão, P.R.M.S., Driusso, P., & Mattiello, S.M.
(2012). The effects of therapeutic exercise on the balance
of women with knee osteoarthritis: a systematic review.
Revista Brasileira de Fisioterapia (São Carlos (São Paulo,
Brazil)), 16(1), 1-9. Retrieved from http://www.ncbi.nlm.
nih.gov/pubmed/22441221
Smith, A.E., Moon, J.R., Kendall, K.L., Graef, J.L., Lockwood,
C.M., Walter, A.A., . . . Stout, J.R. (2009a). The effects of
beta-alanine supplementation and high-intensity interval
training on neuromuscular fatigue and muscle function.
European Journal of Applied Physiology, 105(3), 357–363.
PubMed doi:10.1007/s00421-008-0911-7
Smith, A.E., Walter, A.A., Graef, J.L., Kendall, K.L., Moon,
J.R., Lockwood, C.M., . . . Stout, J.R. (2009b). Effects
of beta-alanine supplementation and high-intensity
interval training on endurance performance and body
composition in men: A double-blind trial. Journal of the
International Society of Sports Nutrition, 6, 5. PubMed
doi:10.1186/1550-2783-6-5
Smith-Ryan, A.E., Fukuda, D.H., Stout, J.R., & Kendall, K.L.
(2012). High-velocity intermittent running: effects of
beta-alanine supplementation. Journal of Strength and
Conditioning Research, 26(10), 2798–2805. PubMed
doi:10.1519/JSC.0b013e318267922b
Spradley, B.D., Crowley, K.R., Tai, C-Y., Kendall, K.L., Fukuda,
D.H., Esposito, E.N., . . .. Moon, J.R. (2012). 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. Nutrition & Metabolism, 9, 28. PubMed
Stellingwerff, T., Boit, M.K., & Res, P.T. (2007). Nutritional
strategies to optimize training and racing in middle-
distance athletes. Journal of Sports Sciences, 25(Suppl.
1), S17–S28. PubMed doi:10.1080/02640410701607213
Stout, J.R., Graves, B.S., Smith, A.E., Hartman, M.J., Cramer,
J.T., Beck, T.W., & Harris, R.C. (2008). The effect of
beta-alanine supplementation on neuromuscular fatigue in
elderly (55-92 years): A double-blind randomized study.
Journal of the International Society of Sports Nutrition,
5, 21. PubMed doi:10.1186/1550-2783-5-21
Stout, J.R., Cramer, J.T., Zoeller, R.F., Torok, D., Costa, P.,
Hoffman, J.R., . . . O’Kroy, J. (2007). Effects of beta-
alanine supplementation on the onset of neuromuscular
fatigue and ventilatory threshold in women. Amino Acids,
32(3), 381–386. PubMed doi:10.1007/s00726-006-0474-z
Stout, Jeffrey R. (n.d.). Beta-Alanine : The new kid on the
ergogenic block. Strength and Conditioning Journal,
27(6), 90–91.
Stout, J.R., Cramer, J.T., Mielke, M., O’Kroy, J., Torok, D.J.,
& Zoeller, R.F. (2006). Effects of Twenty-Eight Days of
Beta-Alanine and Creatine Monohydrate Supplementa-
tion on the Physical Working Capacity at Neuromuscular
Fatigue Threshold. Journal of Strength and Conditioning
Research, 20(4), 928–931. PubMed
Sweeney, K.M., Wright, G.A., Glenn Brice, A., & Doberstein,
S.T. (2010). The effect of b-Alanine supplementation on
power performance during repeated sprint activity. Journal
of Strength and Conditioning Research, 24(1), 79–87.
PubMed doi:10.1519/JSC.0b013e3181c63bd5
Teasell, R., Bayona, N., Marshall, S., Cullen, N., Bayley, M.,
Chundamala, J., … Tu, L. (2007). A systematic review
of the rehabilitation of moderate to severe acquired brain
injuries. Brain Injury: [BI], 21(2), 107-112.
Tipton, K. D., Jeukendrup, A. E., & Hespel, P. (2007). Nutrition
for the sprinter. Journal of sports sciences, 25 Suppl. 1,
S5–15. doi:101080/02640410701607205
Van Thienen, R., Van Proeyen, K., Vanden Eynde, B., Puype,
J., Lefere, T., & Hespel, P. (2009). Beta-alanine improves
sprint performance in endurance cycling. Medicine and
Science in Sports and Exercise, 41(4), 898–903. PubMed
doi:10.1249/MSS.0b013e31818db708
Walter, A.A., Smith, A.E., Kendall., K.L., Stout, J.R., Cramer,
J.T. (2010). Six weeks of high-intensity interval training
with and without beta-alanine supplementation for improv-
ing cardiovascular tness in women. Journal of Strength
and Conditioning Research, 24(5), 1199–1207. PubMed
doi:10.1519/JSC.0b013e3181d82f8b
Wilson, J.M., Wilson, G.J., Zourdos, M.C., Smith, A.E., &
Stout, J.R. (2010). Beta-alanine supplementation improves
aerobic and anaerobic indices of performance. Strength
and Conditioning Journal, 32(1), 71–78 (Allen Press)
Retrieved from http://search.ebscohost.com/login.aspx?
direct=true&db=rzh&AN=2010558714&site=ehost-live.
doi:10.1519/SSC.0b013e3181c20875
Zoeller, R.F., Stout, J.R., O’Kroy, J.A., Torok, D.J., & Mielke,
M. (2007). Effects of 28 days of beta-alanine and cre-
atine monohydrate supplementation on aerobic power,
ventilatory and lactate thresholds, and time to exhaustion.
Amino Acids, 33(3), 505–510. PubMed doi:10.1007/
s00726-006-0399-6
