Effects of β-alanine supplementation during a 5-week strength training program: a randomized, controlled study

Abstract

Background:
β-Alanine (BA) is a non-essential amino acid that has been shown to enhance exercise performance. The purpose of this investigation was to determine if BA supplementation improved the adaptive response to five weeks of a resistance training program.

Methods:
Thirty healthy, strength-trained individuals were randomly assigned to the experimental groups placebo (PLA) or BA. Over 5 weeks of strength training, subjects in BA took 6.4 g/day of BA as 8 × 800 mg doses each at least 1.5 h apart. The training program consisted of 3 sessions per week in which three different leg exercises were conducted as a circuit (back squat, barbell step ups and loaded jumping lunges). The program started with 3 sets of 40 s of work per exercise and rest periods between sets of 120 s in the first week. This training volume was then gradually built up to 5 sets of 20 s work/60 s rest in the fifth week. The work load during the program was set by one of the authors according to the individual's perceived effort the previous week. The variables measured were average velocity, peak velocity, average power, peak power, and load in kg in a back squat, incremental load, one-repetition maximum (1RM) test. In addition, during the rest period, jump ability (jump height and power) was assessed on a force platform. To compare data, a general linear model with repeated measures two-way analysis of variance was used.

Results:
Significantly greater training improvements were observed in the BA group versus PLA group (p = 0.045) in the variables average power at 1RM (BA: 42.65%, 95% CI, 432.33, 522.52 VS. PLA: 21.07%, 95% CI, 384.77, 482.19) and average power at maximum power output (p = 0.037) (BA: 20.17%, 95% CI, 637.82, 751.90 VS. PLA; 10.74%, 95% CI, 628.31, 751.53). The pre- to post training average power gain produced at 1RM in BA could be explained by a greater maximal strength gain, or load lifted at 1RM (p = 0.014) (24 kg, 95% CI, 19.45, 28.41 VS. 16 kg, 95% CI, 10.58, 20.25) and in the number of sets executed (p = 0.025) in the incremental load test (BA: 2.79 sets, 95% CI, 2.08, 3.49 VS. PLA: 1.58 sets, 95% CI, 0.82, 2.34).

Conclusions:
β-Alanine supplementation was effective at increasing power output when lifting loads equivalent to the individual's maximal strength or when working at maximum power output. The improvement observed at 1RM was explained by a greater load lifted, or strength gain, in response to training in the participants who took this supplement.

Full text

R E S E A R C H A R T I C L E Open Access
Effects of β-alanine supplementation
during a 5-week strength training program:
a randomized, controlled study
José Luis Maté-Muñoz
1*
, Juan H. Lougedo
1
, Manuel V. Garnacho-Castaño
2
, Pablo Veiga-Herreros
3
,
María del Carmen Lozano-Estevan
4
, Pablo García-Fernández
5
, Fernando de Jesús
6
, Jesús Guodemar-Pérez
7
,
Alejandro F. San Juan
8
and Raúl Domínguez
9
Abstract
Background: β-Alanine (BA) is a non-essential amino acid that has been shown to enhance exercise performance.
The purpose of this investigation was to determine if BA supplementation improved the adaptive response to five
weeks of a resistance training program.
Methods: Thirty healthy, strength-trained individuals were randomly assigned to the experimental groups placebo
(PLA) or BA. Over 5 weeks of strength training, subjects in BA took 6.4 g/day of BA as 8 × 800 mg doses each at
least 1.5 h apart. The training program consisted of 3 sessions per week in which three different leg exercises were
conducted as a circuit (back squat, barbell step ups and loaded jumping lunges). The program started with 3 sets
of 40 s of work per exercise and rest periods between sets of 120 s in the first week. This training volume was then
gradually built up to 5 sets of 20 s work/60 s rest in the fifth week. The work load during the program was set by
one of the authors according to the individual’s perceived effort the previous week. The variables measured were
average velocity, peak velocity, average power, peak power, and load in kg in a back squat, incremental load,
one-repetition maximum (1RM) test. In addition, during the rest period, jump ability (jump height and power) was
assessed on a force platform. To compare data, a general linear model with repeated measures two-way analysis of
variance was used.
Results: Significantly greater training improvements were observed in the BA group versus PLA group (p= 0.045) in
the variables average power at 1RM (BA: 42.65%, 95% CI, 432.33, 522.52 VS. PLA: 21.07%, 95% CI, 384.77, 482.19) and
average power at maximum power output (p= 0.037) (BA: 20.17%, 95% CI, 637.82, 751.90 VS. PLA; 10.74%, 95% CI,
628.31, 751.53). The pre- to post training average power gain produced at 1RM in BA could be explained by a
greater maximal strength gain, or load lifted at 1RM (p= 0.014) (24 kg, 95% CI, 19.45, 28.41 VS. 16 kg, 95% CI, 10.58,
20.25) and in the number of sets executed (p= 0.025) in the incremental load test (BA: 2.79 sets, 95% CI, 2.08, 3.49
VS. PLA: 1.58 sets, 95% CI, 0.82, 2.34).
(Continued on next page)
* Correspondence: jmatmuo@uax.es
José Luis Maté-Muñoz and Juan H. Lougedo contributed equally for the
senior authorship
Alejandro F. San Juan and Raúl Domínguez contributed equally to this work
1
Department of Physical Activity and Sport Sciences, Faculty of Health
Sciences, Alfonso X El Sabio University, Avda, Universidad 1, Building C, 3rd
floor, Office C-A15, Villanueva de la Cañada, 28691 Madrid, Spain
Full list of author information is available at the end of the article
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition
(2018) 15:19
https://doi.org/10.1186/s12970-018-0224-0

(Continued from previous page)
Conclusions: β-Alanine supplementation was effective at increasing power output when lifting loads equivalent to
the individual’s maximal strength or when working at maximum power output. The improvement observed at 1RM
was explained by a greater load lifted, or strength gain, in response to training in the participants who took this
supplement.
Keywords: β-alanine, One-repetition maximum test, Exercise program, Average power, Jump height
Background
β-Alanine (BA) is a non-essential amino acid synthesized
in the liver [1]. It is also found naturally ocurring in ani-
mal products such as pork, chicken or red meat [2]. The
dietary supplement classification system of the Austra-
lian Institute of Sport (AIS) describes BA as a class A
supplement based on the level of evidence shown for its
beneficial effects on sport performance [3].
The effect of BA on performance has been attributed to
its capacity to increase carnosine synthesis. Carnosine is a
dipeptide composed of the amino acids BA and L-histidine
[4]. As the organism is incapable of directly absorbing car-
nosine [1] and as it known that, unlike L-histidine, BA is
able to increase muscular carnosine reserves [5], its inges-
tion is considered the limiting factor for muscular carno-
sine synthesis [4,6]. In effect, the intake of 4.8–6.4 g/day of
BA over a period of 5–6 weeks has been noted to increase
muscular carnosine concentrations [7,8].
As the major intracellular buffering protein [9], the main
function of carnosine is pH regulation [10]. Carnosine pro-
motes the sensitivity of muscle fibers to calcium [11,12],
enhancing muscle excitation-contraction [11,13,14]. These
effects have determined that BA supplementation improves
performance at exercise efforts of duration 6 to 60 s
[15–17]. In these short, high-intensity exercise move-
ments, glycolytic energy metabolism prevails over the
high energy phosphagen system and over oxidative
phosphorylation [18].
Among the different studies that have examined the
effects of BA supplementation, only a few have focused
on its impacts on resistance exercises [19,20]. Thus,
Outlaw et al. (2016) [20] found that supplementation
gave rise to a larger number of leg press repetitions exe-
cuted with a load equivalent to 65% of the individual’s
one-repetition maximum (1RM). Hoffman et al. (2006)
[19] noted that the intake of both BA and creatine im-
proved the load lifted in a 1RM squat test.
Although BA supplementation may help increase the
1RM [19] and the maximum number of repetitions con-
ducted at a submaximal load [20], no study has yet ex-
amined the effects of supplementation on power output
in resistance training. Power is related to force and vel-
ocity. As muscular power production is one of the main
determinants of sport performance [21,22], several stud-
ies have assessed the effects of caffeine supplements on
power output in resistance exercises such as back squat
(BS) [23,24], detecting an ergogenic effect on power
production.
Another important factor to consider in sports train-
ing is the quantification of fatigue, defined as an incap-
acity of the neuromuscular system to maintain a given
power level [25]. The countermovement jump (CMJ) is
a movement that reflects the contractile and neuromus-
cular control properties of the whole locomotor system
[26]. Thus, monitoring jump height loss during an exer-
cise session has been used as an indicator of muscular
fatigue. Several studies have confirmed a loss of CMJ
height during various resistance training exercises [27–33].
However,sofarnostudyhasmonitoredCMJjumpheight
while conducting a 1RM test or the effects of BA supple-
mentationonthisindicatoroffatigue.
Given the scarce investigations exploring the influence
of BA on performance in resistance exercises [19,20],
the aim of the present study was to examine the effects
of BA supplementation during a 5-week resistance train-
ing program. The primary outcome for the study was
power output in a BS incremental load test. Secondary
outcomes were kilograms lifted and lifting velocity dur-
ing the test. As tertiary outcomes, we also examined the
jump height and average power losses produced after ex-
ercise in a CMJ test. We hypothesized that BA supple-
mentation would improve power output, kilograms lifted
and movement velocity during the incremental BS test,
and reduce jump height and average power lossess in
the CMJ test produced in response to the BS test.
Methods
Experimental design
Participants undertook a 5-week resistance training pro-
gram during which half the subjects took BA supple-
ments according to whether they were assigned to a
placebo group (PLA) or BA group. Before and after the
training program, all participants performed a BS incre-
mental load test at the laboratory under the same con-
trolled environmental conditions. During the rest
periods of this test, CMJ ability was monitored. The rest
period from the pre-training BS test to the start of the
training program was 72 h. Similarly, the rest period be-
tween the end of the training program and the post-BS
test was also 72 h (Fig. 1).
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 2 of 12

Subjects
Thirty young, healthy, resistance-trained men were en-
rolled in the study. All subjects were students of the
Physical activity and Sport Sciences degree course at the
Universidad Alfonso X El Sabio (Madrid, Spain). Exclu-
sion criteria were: age younger than 18 or older than
25 years; 2) being an elite athlete; 3) having consumed
any substance that could affect hormone levels or sport
performance in the previous 3 months such as nutrition
complements or steroids; 4) having consumed any nar-
cotic and/or psychotropic agents, drugs or stimulants
during the test or supplementation period; 5) any cardio-
vascular, metabolic, neurologic, pulmonary or orthopedic
disorder that could limit performance in the different
tests; 6) having less than 6 months of experience with
BS training; 7) or less than 12 months of experience
with resistance training; or 8) having a BS 1RM lower
than 90 kg.
Subjects were randomly assigned to the two experi-
mental groups: individuals in one group (n= 15) took
BA and those in the control group (n = 15) were given
placebo supplements (PLA) during the 5 weeks of train-
ing. Each day, it was ensured that each subject took the
required supplement dose and attended the training ses-
sions. At the end of the study, data were eliminated for
subjects not completing all laboratory testing sessions, at
least 85% of the training sessions, and/or missing
three days or more of supplements. According to
these criteria, the final study population was com-
prised of 26 subjects (age = 21.85 ± 1.6 years; weight =
80.27 ± 6.9 kg; height = 179.62 ± 6.1 cm; body mass
index = 24.85 ± 1.8 kg·m
2–1
):14inBAand12inPLA.
At the study outset, participants were informed of the
study protocol, schedule and nature of the exercises and
tests to be performed before signing an informed con-
sent form. The study protocol adhered to the tenets of
the declaration of Helsinki and was approved by the
Ethics Committee of the Universidad Alfonso X El Sabio.
Supplementation with β-alanine
The authors packaged and prepared the capsules con-
taining the supplement or placebo. The capsules used
were no. 1 opaque red (Guinama S.L.U, 0044634, La
Pobla de Valbona, Spain) of capacity 0.50 mL/capsule
corresponding to 400 mg of BA [34]. For the encapsula-
tion process, we followed the normalized working proce-
dures, “Procedimientos Normalizados de Trabajo (PNT)”
described for this purpose in the Formulario Nacional
Español. The filling equipment used was a manual semi-
automatic Carsunorm 2000 system (Miranda de Ebro,
Spain).
Based on the doses used in other studies [35,36], sub-
jects assigned to the BA group were administered a daily
β-alanine dose of 6.4 g taken as 8 capsules containing
800 mg at least 1.5 h apart and no longer than 3 h apart.
The reason for the 8 daily capsules was to avoid the
main side effect of paresthesia [4]. Paresthesia is a mild
sensation of prickling, numbness or burning in the skin
that appears when doses of BA greater than 10 mg/kg
are taken [10] and resolves 1 h after intake [10]. Subjects
in PLA took the same number of daily capsules contain-
ing sucrose. Only one of the authors was responsible for
supplying the participants with the corresponding bot-
tles of capsules. All subjects visited the research labora-
tory weekly to collect their supplement (BA or PLA) for
that week. During each of the 5 weeks of the training
program, the authors ensured each participant took their
supplements and also guided each training session.
Training program
The 5-week training program was the same for the two
groups BA and PLA. Three sessions were conducted per
week (15 sessions in total) of around 35–60 min. Each
day a register was taken and any participant missing
more than 2 sessions (ie, around 15%) was excluded. In
each session, after a 15 min warm up, three leg exercises
were alternated as a circuit: back squat, barbell step ups
and loaded jumping lunges (Table 1). Subjects per-
formed a given number of repetitions of each exercise
according to the allocated work time. In the first week,
work time was 40 s per exercise and this was reduced by
5 s each week until a work time of 20 s (Table 2). Partic-
ipants indicated their subjective exertion using the Borg
scale of rating of perceived exertion (RPE) (CR-10) when
completing each set of exercises and at the end of the
session [37].
Load increases were guided by an observer during the
program according to the perceived exertion of the pre-
vious week. In the first week, the load selected for the
Fig. 1 Study design
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 3 of 12

BS was 60% of 1RM obtained in the incremental load
test before the start of the training program. In contrast,
for the barbell step ups and loaded jumping lunges, the
load was adjusted by each individual by targeting an RPE
of 5–6 to complete 40 s of each exercise, thus maintain-
ing around 50–60% of maximal intensity. Therefore,
from the second week onwards: when RPE was 1 point
below or above the target, the training load was in-
creased or reduced respectively by 5% (kg) in each exer-
cise; when between 1 and 2.5 points below or above the
target, the load was adjusted by 10% (kg); and when 2.5
points above or below the target, the load was adjusted
by 15%–20% [38,39].
To increase the training volume, rest periods between
exercises were reduced by 15 s per week from an initial
120 s to 60 s in the fifth week (Table 2). Rest periods be-
tween exercise sets were initially 2 min and then re-
duced by 15 s weekly until 1 min (Table 2). The
numbers of exercise sets executed were 3 sets in week 1,
4 sets in weeks 2 and 3, and 5 sets in weeks 4 and 5.
Pre- and post-training test
Warm up
For the pre- and post-training incremental load/CMJ
test, subjects first undertook a general warm up followed
by a specific warm up. The session commenced with
10 min of light to moderate trotting, 5 min of joint
movement and ballistic stretching, and 1 set of 5 BS rep-
etitions with a 20 kg load. During this set, subjects were
instructed to increase execution velocity, targeting a
Table 2 Training prescription week by week
Week 1 Week 2 Week 3 Week 4 Week 5
Working time (s) 40 s 35 s 30 s 25 s 20 s
Rest between exercises (s) 120 s 105 s 90 s 75 s 60 s
Rest between sets (s) 120 s 105 s 90 s 75 s 60 s
Number of sets 3 4 4 5 5
BS workload 60% 1RM based on RPE based on RPE based on RPE based on RPE
SU workload free based on RPE based on RPE based on RPE based on RPE
LJL workload free based on RPE based on RPE based on RPE based on RPE
BS back squat, SU barbell step up, LJL loaded jumping lunge, 1RM one-repetition maximum, RPE rating of perceived exertion, sseconds
Table 1 Exercises prescribed in the resistance training program
RESISTANCE TRAINING PROGRAM
3 days a week × 5 weeks
1 Back squat
2 Barbell step up
3 Loaded jumping lunge
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 4 of 12

velocity close to their maximum velocity in the final
repetition. After 30 s of rest, subjects executed 3 con-
secutive CMJ at submaximal intensity. After 1 min of
rest, subjects completed 1 set of 2 BS repetitions with
2 s of rest between repetitions, lifting a 30 kg load at
maximum velocity of displacement for optimal muscle
activation. After 30 s, subjects executed 2 CMJ at max-
imal intensity with 10 s of rest between jumps.
Back squat incremental load test
Three minutes after the warm-up, subjects started the
incremental load BS test with an initial load of 30 kg.
This load was increased in each set by 15 kg until aver-
age bar displacement velocity measured by a linear pos-
ition transducer was under 0.7 m/s. Loads were then
increased gradually in 1–5 kg steps until the 1RM was
accurately determined. When mean velocities were
above 0.7 m/s, subjects undertook 2 BS repetitions with
a rest period between sets of 3 min. For lower velocities,
only one repetition per set was executed with 5 min of
rest.
The variables recorded in this session were average
velocity (AV), peak velocity (PV), average power (AP),
peak power (PP) and the load in kg lifted in the incre-
mental BS 1RM test in which power output is at its
maximum (Pmax) as follows [40]:
Velocity (m·s
−1
) = vertical movement of the bar (m) x
time (s
−1
).
Acceleration (m·s
−2
) = vertical bar velocity (m·s
−1
)x
time (s
−1
).
Force (N) = system mass (kg) × vertical acceleration of
the bar (m·s
−2
) + acceleration due to gravity (m·s
−2
).
Power (W) = vertical force (N) × vertical bar velocity
(m·s
−1
). Power was calculated based on barbell velocity and
not velocity of the centre of mass of the system [41,42].
Back squat technique
For the BS, the subject stands with feet shoulder-width
apart and the barbell placed on top of the shoulder
blades with hands clutching the barbell, and then flexes
the knees to 120° followed by their extension to the ori-
ginal standing position. Maximal strength, or 1RM, was
defined as the maximum load the individual was able to
lift with the appropriate exercise action [43].
The test was performed in a multipower, bar-guiding
system Smith machine (Matrix, Chácara Alvorada,
Brazil) using 20, 10, 5, 2.5 and 1.25 kg discs (Matrix). In
this set up, both ends of the barbell are fixed allowing
only vertical movement of the bar.
To estimate the execution velocity of each repetition
in the incremental load test, we used a linear displace-
ment system (Tendo Weight-lifting Analyzer System,
Trencin, Slovak Republic). The cable was attached to
one end of the bar to avoid hindering the BS movement.
This system allows for measurement of the vertical dis-
placement of the the bar according to the exercise
movement and using the system’s software (Tendo
Weightlifting analyzer 3.6.15), the device provides bar
velocities (average and peak) and powers (average and
peak) in the incremental load test [40].
Jump ability and muscular fatigue
At the start of the rest period for each set of the BS in-
cremental load test, jump capacity was measured in 2
CMJs with 30 s of rest between one jump and the next.
The variables jump height, power and take off velocity
were measured using a Kistler Quattro Jump contact
platform (Kistler Instruments, Winterthur, Switzerland).
The CMJ test commences with the subject standing with
the legs extended and arms on hips. The subject initiates
the jump by bending the knees to ~ 90
0
(eccentric
action) and immediately and synchronously then starts
to extend the knees (concentric action) in an explosive
movement to attain the maximum height possible.
During the jump, the knees should be fully extended and
contact with the ground is first made with the toes.
Subjects were instructed to keep their hands on the hips
during the jump and to avoid any sideways or backward/
forward movements.
Statistical analysis
The effects of BA supplementation on the power output,
kilograms lifted and movement velocity in response to
the 5 weeks of training were assessed through a general
linear model with repeated measures two-way analysis of
variance as the Levene’s test revealed the homogeneity
of variances of the initial variables and the Shapiro
Wilk’s test confirmed their normal distribution. We thus
considered an inter-subject factor (PLA, BA) and an
intra-subject factor (pre-training, post-training) along
with the effects of their interaction.
Although the general linear model with two-way ana-
lysis of variance revealed no significant differences be-
tween pre-training values for the two study groups, we
performed a covariance analysis through a univariate
procedure, in which the pre-training values were used as
covariates to confirm that the differences observed in
the general linear model were not due to differences in
pre-training values betwee the PLA and BA groups.
To support the results of the previous analyses, we
assessed the effect size of the kilograms lifted and num-
ber of sets accomplished. The effect size indicating the
difference between means of the dependent variables
was calculated using the formula: effect size = post –
pre. For this analysis we also used a univariate general
linear model.
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 5 of 12

In addition, the pre- and posttraining power and vel-
ocity data recorded at different work intensities in the
BS incremental load test were compared through linear
or polynomic regression models. We also determined
through linear regression, the variables determining
jump ability (jump height, average power and take off
velocity) for different relative workloads in the BS incre-
mental load test.
In all tests, effect size (ES) and statistical power (SP)
were calculated. The general linear model procedure
generates an effect size, known as partial eta squared,
categorized as small = 0.01, medium =0.06, large = 0.14
[44]. All data are provided as their means, standard devi-
ation, and 95% confidence intervals (CI) when data are
provided as percentages. Percentage improvements were
calculated using the equation ([post - pre]/pre X 100).
Significance was set at p< 0.05. All statistical tests were
performed using the software package SSPS version 21.0
(SPSS, Chicago, Ill).
Results
Incremental BS test
Significantly greater pre-post training (time factor)
improvements (p< 0.001); were detected in the kilo-
grams lifted at Pmax (F= 72.425; ES = 0.751; SP = 1.000):
15.95% in the PLA group (95% CI, 90.90, 106.52) and
20.17% in the BA group (95% CI, 92.16, 106.62). How-
ever, no significant effects (p= 0.356) on this variable
were observed of the interaction time xgroup (F= 0.888;
ES = 0.036; SP = 0.148) (Table 3) (Additional file 1). Once
analysis of covariance had ruled out an effect of the pre-
training variables acting as covariate of the kilograms
lifted at Pmax, no significant differences (2.36%, p=0.371)
were observed between the two groups (PLA: 95% CI,
99.99, 111.11; BA: 95% CI, 103.74, 114.04) (F= 0.832;
ES = 0.035; SP = 0.141) (Additional file 2).
For the variable AP at Pmax, significant effects (p< 0.001)
were noted of time (PLA: 10.74%, 95% CI, 628.31, 751.53;
BA: 20.17%, 95% CI, 637.82, 751.90) (F= 60.61; ES = 0.716;
SP = 1.000) and of time xgroup (F= 5.034; p= 0.034;
ES = 0.173; SP = 0.577) (Table 3)(Additionalfile1).
When we assessed the covariables, significant differ-
ences between groups (4.61%, p=0.037) were confirmed
for this variable (PLA: 95% CI, 681.18, 750.46; BA: 95%
CI, 734.38, 798.50) (F=4.893; ES =0.175; SP =0.563)
(Additional file 2).
In addition, for PP at Pmax, significant differences
(p< 0.001) were also detected in the factor time (F=
47.54; ES =0.665;SP = 1.000). Improvements were 12.06%
(95% CI, 1351.76, 1611.24) and 18.83% (95% CI, 1420.88,
1661.12) for the PLA and BA groups respectively, with no
effects of time xgroup (F= 2.361; p= 0.137; ES = 0.090;
SP = 0.314) (Table 3)(Additionalfile1).
When we examined factors related to the partici-
pants’1RM, some significant effects were observed. For
the variable kilograms lifted at 1RM differences were
significant (p< 0.001) for both time (PLA: 12.44%, 95%
CI, 121.16, 142.09; BA: 19.21%, 95% CI, 126.85, 146.22)
(F= 151.764; ES = 0.863; SP = 1.000) and time xgroup
(F= 7.103; p=0.014; ES = 0.228; SP = 0.725) (Table 3)
(Additional file 1). Analysis of covariance confirmed
these significant differences between groups (54.42%,
p= 0.005) eliminating the effect of the covariate pre-
training (PLA: 95% CI, 135.40, 143.82; BA: 95% CI,
144.37, 152.16) (F= 9.737; ES = 0.297; SP = 0.848)
(Additional file 2).
For AP at 1RM, the time factor had a significant effect
(p< 0.001) (PLA: 21.07%, 95% CI, 384.77, 482.19; BA:
42.65%, 95% CI, 432.33, 522.52) (F= 36.862; ES =0.606;
SP = 1.000) while the impact of time xgroup approached
significance (p=0.056; F=4.049; ES =0.144; SP =0.489)
(Table 3) (Additional file 1). However, by adjusting pre-
training levels through analysis of covariance, significant
differences (102.42%, p=0.045)wereindeedconfirmed
for AP at 1RM between groups (PLA: 95% CI, 416.26,
535.20; BA: 95% CI, 503.85, 613.97) (F=4.507;ES =0.164;
SP = 0.529). (Additional file 2).
Significant pre-posttraining differences (p<0.001) were
also observed in two last variables related to power, PP at
1RM (PLA: 26.56%, 95% CI, 1136.50, 1490.42; BA: 23.89%,
95% CI, 1265.38, 1593.05) (F= 32.797; ES =0.577; SP =
1.000) and mean AP (PLA: 16.25%, 95% CI, 502.80, 593.04;
BA: 19.12%, 95% CI, 521.51, 605.06) (F= 100.680; ES =
0.808; SP = 1.000). However, no significant effects on
these variables of time xgroup were noted (F=0.085;p=
0.774; ES = 0.004; SP = 0.059; F= 0.791; p= 0.383; ES =
0.032; SP = 0.137, respectively) (Table 3)(Additional
file 1). Using as covariates in the univariate ananlysis
of variance the pre-training variables, we confirmed
the lack of significant differences between BA and PLA
for PP at 1RM (−10.50%, p= 0.359, PLA: 95% CI, 1359.53,
1628.13; BA: 95% CI, 1452.75, 1701.25) and mean AP
(17.66%, p= 0.314, PLA: 95% CI, 566.31, 618.08; BA:
95% CI, 585.80, 633.72) (Additional file 2).
No significant effects were recorded on the variables
related to velocity of movement (AV at Pmax, PV at
Pmax and peak velocity at 1RM) of either time or group
(Table 3) (Additional file 1).
For mean AV, significant differences (p= 0.005) were
observed according to time (PLA: 95% CI, 0.67, 0.71; BA:
95% CI, 0.67, 0.71) (F= 9.529; ES =0.284; SP = 0.842), with
similar improvements observed in PLA and BA (4.75%,
4.45%, respectively) (Table 3)(Additionalfile1).
The following tables (Tables 4and 5) provide mean
pre-post training improvements for BA versus PLA in
the number of sets accomplished (p= 0.025; 95% CI,
0.82, 2.35, BA: 95% CI, 2.08, 3.49) and number of
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 6 of 12

Table 3 Effects of the 5-week resistance training program in the PLA and BA groups
Variable Group Pre (mean ± SD ± CI) Post (mean ± SD ± CI) Post-Pre(u) Post-Pre (%) CI (95%) pfor Group pfor Time pfor GroupXTime
Kg at 1RM (kg) PLA 123.92 ± 18.02 (112.38–135.45) 139.33 ± 15.13 (129.45–149.22) 15.41 12.44% 121.16–142.09 0.484 < 0.001* 0.014*
BA 124.57 ± 20.42 (113.89–135.25) 148.50 ± 17.73 (139.35–157.65) 23.93 19.21% 126.85–146.22
AV at 1RM (m·s
−1
) PLA 0.325 ± 0.073 (0.29–0.36) 0.370 ± 0.125 (0.29–0.45) 0.045 12.16% 0.31–0.39 0.328 0.023* 0.354
BA 0.324 ± 0.049 (0.29–0.36) 0.426 ± 0.137 (0.35–0.50) 0.102 31.57% 0.34–0.41
PV at 1RM (m·s
−1
) PLA 0.844 ± 0.222 (0.71–0.8) 0.951 ± 0.203 (0.86–1.05) 0.107 12.7% 0.80–1.00 0.802 0.044* 0.626
BA 0.881 ± 0.224 (0.76–1.00) 0.947 ± 0.113 (0.86–1.04) 0.066 7.49% 0.82–1.01
AP at 1RM (W) PLA 392.16 ± 87.69 (342.70–441.63) 474.8 ± 104.58 (409.99–539.61) 82.64 21.07% 384.77–482.19 0.185 < 0.001* 0.056
BA 395.14 ± 78.86 (349.35–440.94) 559.70 ± 112.20 (499.71–619.70) 164.56 41.65% 432.33–522.52
PP at 1RM (W) PLA 1159.5 ± 338.91 (939.31–1379.69) 1467.42 ± 334.48 (1297.52–1637.31) 307.92 26.56% 1136.50–1490.42 0.332 < 0.001* 0.774
BA 1258.79 ± 393.66 (1054.92–1462.64) 1599.64 ± 235.49 (1442.35–1756.94) 300.85 23.89% 1265.38–1593.05
Kg at Pmax (kg) PLA 91.42 ± 15.73 (83.02–99.81) 106.00 ± 12.43 (97.71–114.28) 14.58 15.95% 90.90–106.52 0.896 < 0.001* 0.356
BA 90.29 ± 12.53 (82.51–98.06) 108.50 ± 15.03 (100.83–116.17) 18.21 20.17% 92.16–106.62
AV at Pmax (m·s
−1
) PLA 0.735 ± 0.096 (0.69–0.78) 0.698 ± 0.072 (0.66–0.74) −0.037 −5.03% 0.68–0.75 0.861 0.373 0.226
BA 0.710 ± 0.054 (0.67–0.75) 0.716 ± 0.055 (0.68–0.75) 0.006 0.85% 0.68–0.74
PV at Pmax (m·s
−1
) PLA 1.289 ± 0.122 (1.22–1.36) 1.246 ± 0.088 (1.19–1.30) −0.043 −3.34% 1.22–1.32 0.497 0.323 0.354
BA 1.291 ± 0.102 (1.23–1.35) 1.289 ± 0.086 (1.24–1.34) −0.002 −0.15% 1.25–1.34
AP at Pmax (W) PLA 654.75 ± 113.98 (586.27–723.23) 725.08 ± 106.84 (664.74–785.43) 70.33 10.74% 628.31–751.53 0.904 < 0.001* 0.034*
BA 631.21 ± 115.73 (567.82–694.61) 758.50 ± 96.33 (702.63–814.37) 127.29 20.17% 637.82–751.90
PP at Pmax (W) PLA 1397.25 ± 245.66 (1242.88–1551.62) 1565.75 ± 146.17 (1445.86–1685.63) 168.5 12.06% 1351.76–1611.24 0.494 < 0.001* 0.137
BA 1408.43 ± 269.93 (1265.51–1551.34) 1673.57 ± 238.06 (1562.58–1784.57) 265.14 18.83% 1420.88–1661.12
Mean AV (m·s
−1
) PLA 0.673 ± 0.046 (0.65–0.70) 0.705 ± 0.058 (0.68–0.73) 0.032 4.75% 0.67–0.71 0.988 < 0.005* 0.905
BA 0.674 ± 0.049 (0.65–0.70) 0.704 ± 0.033 (0.68–0.73) 0.050 5.05% 0.68–0.71
Mean AP (W) PLA 506.73 ± 68.56 (458.34–555.21) 589.07 ± 73.10 (543.27–634.87) 82.34 16.25% 502.80–593.04 0.611 < 0.001* 0.383
BA 514.13 ± 90.68 (469.29–558.97) 612.44 ± 79.92 (570.04–654.84) 98.31 19.12% 521.51–605.06
PLA Placebo, BA β-alanine supplementation, Pmax Maximun power, AP Average power, PP Peak power, AV average velocity, PV Peak velocity, 1RM one-repetition maximun, kg Kilogram, WWatts, m·s
−1
m·second, * =
Significant difference (p< 0.05). Data expressed as mean ± standard deviation (SD), ± 95% confidence intervals (CI)
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 7 of 12

kilograms lifted (p= 0.014; 95% CI, 10.58, 20.25, BA: 95%
CI, 19.45, 28.41) in the 1RM test (Additional file 3).
Regression lines for AV recorded in PLA and BA pre-
and post-training in the BS incremental load test were
similar. This indicates that both 5 weeks of training and
supplementation with BA did not modify the relation-
ship between AV and relative work intensity. In contrast,
the mean tendency for AP was higher in the BA group
than PLA group after training, while means before train-
ing failed to vary between the groups, suggesting a bene-
ficial effect of BA supplementation plus training on the
BS incremental load test (Fig. 2).
Regression lines for the variables recorded in the CMJ
test, jump height and AP indicated no significant
impacts of supplementation during training on these
variables (Fig. 3).
Discussion
In relation to our first hypothesis, the main finding of
the present study was a significant improvement pro-
duced in AP at 1RM in response to a 5 week training
program in the group of subjects who took 6.4 g/day of
BA throughout the course of training. This improved
average power was attributed to a greater accomplished
training load and more kilograms lifted in the BA group,
with no differences recorded between groups in move-
ment velocity, thus confirming our second working hy-
pothesis. In response to the third hypothesis, scarce
differences between groups were observed in the height
and AP values recorded in the CMJ tests despite more
kilograms lifted (BA =24 kg, PLA =16 kg) and more sets
executed (BA = 2.79 sets, PLA = 1.58 sets) in the incre-
mental BS test after 5 weeks of training in the BA group.
Significant improvements in the kilograms lifted at
1RM in response to the training intervention, were 12.
44% (16 kg) for PLA and 19.21% (24 kg) for BA. Similar
strength gains (9.3 ± 6.7%) to those observed in our PLA
group have been reported in response to a 6-week
training intervention in 56 participants in an incremen-
tal load test of similar characteristics [45]. In contrast, a
greater improvement was observed here in the subjects
in our BA supplement group (19.21%) than the gains
reported by others [45].
Similar supplementation effects on strength gains have
been reported by Hoffman et al. (2006) [19] who ob-
served that both supplementation with creatine and with
creatine plus BA was effective at significantly increasing
the BS 1RM load (25 kg) over the increase produced
with placebo (5 kg) in response to 10 weeks of strength
training. A novel finding of our study was that subjects
taking BA supplements, besides improving their 1RM,
were able to execute significantly more sets in the incre-
mental load test compared to the subjects receiving
placebo (2.79 VS. 1.58 sets) (Table 4).
The increase produced in the number of sets completed
in the BA group may be related to the pH regulation cap-
acity of BA [46]. This supplement could have had only an
indirect ergogenic effect due to the scarce contribution of
glycolytic energy metabolism in the incremental exercise
used in our study. In other words, the lifts in the test were
classed as explosive actions in which energy is mainly pro-
vided by the high-energy phosphagen system [18]. Further,
the rest periods used in this test were sufficient to replen-
ish the used phosphocreatine reserves, as its resynthesis
involves a rapid first stage resulting in the recovery of up
to 70% of stores, followed by a second stage extend-
ing into minutes 3–5 when reserves have completely
recovered [47].
For the half squat, it has been shown that the lactate
threshold is reached at work intensities approaching 25%
of 1RM [38,48]. Above this threshold, a glycolytic type
metabolism starts to predominate [49]. Thus, the most
used energy metabolism during the 5-week training
period tested here was glycolytic. Besides their intensity,
the duration of the exercise sets (20–40 s) performed
here suggests that a lowered pH could limit performance
Table 5 Mean improvements in the number of kilograms lifted in the pre- versus post-training BS incremental test at 1RM
Kilograms Kg Post –Kg Pre CI (95%) F/ SP
Pre Post
Placebo 123.92 ± 18.02 139.33 ± 15.13 15.41 ± 5.82
a
10.58–20.25 7.103/ 0.725
β-Alanine 124.57 ± 20.42 148.50 ± 17.73 23.92 ± 9.64 19.45–28.41
a
significant difference between groups (p< 0.05); SP statistical power, CI confidence interval
Table 4 Mean improvements in the number of sets executed in the pre- versus post-training BS incremental test at 1RM
Number of repetitions Sets Post–Sets Pre CI (95%) F/ SP
Pre Post
Placebo 9.83 ± 1.80 11.41 ± 1.50 1.58 ± 1.44
a
0.82–2.35 5.709/ 0.630
β-Alanine 10.07 ± 2.26 12.85 ± 1.74 2.79 ± 1.12 2.08–3.49
a
significant difference between groups (p< 0.05); SP statistical power, CI confidence interval
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 8 of 12

during training sessions. In effect, in a recent study it
was noted that BA supplementation improves the num-
ber of repetitions performed lifting a load equivalent to
65% of 1RM [20]. These findings indicate that the sup-
plement increases the training session work load [20]
and support the results of Hoffman et al. (2006) [19],
who observed that BA plus creatine supplementation
improved training volume in a strength training program
compared to placebo or creatine alone. Thus, the mech-
anism for this ergogenic effect would involve executing a
greater training volume in each pre-post session or im-
proved adaptive responses to the program in the subjects
who took BA. This could be observed in the incremental
BS test at 1RM, whereby significant improvements were
recorded not only in the number of sets undertaken by
subjects in the BA group compared to PLA group (2.79
VS. 1.58 sets), but also in the load improvement pre-
minus post-training (24 VS. 16 kg) (Table 4).
Muscle power is one of the major determinants of
sport performance, and high power levels are required in
numerous sport modalities [21,22]. A common target
for athletes is to apply maximum power levels to a given
work load. Our results suggest a significantly greater im-
pact on AP at 1RM (p= 0.045, 41.70% VS. 21.10%) of
BA supplementation than of PLA, possibly explained by
the significant improvement recorded in the kilograms
lifted at 1RM (p= 0.005, 19.21% VS. 12.44%). However,
although the gain produced in AP at Pmax was also sig-
nificantly greater in BA than PLA (p= 0.037, 20.17% VS.
10.74%), the improvement in the number of kg lifted at
Pmax was not significant (p= 0.371, 20.17% VS. 15.95%).
These beneficial impacts of supplementation with BA on
AP are consistent with observations related to caffeine
supplementation [23,24].
Del Coso et al. (2012) [23] reported that supple-
mentation with a single dose of 3 mg·kg
−1
of
caffeine was effective at improving average power
during an incremental BS test in which loads were
increased from 10% to 100% 1RM in steps of 10%
1RM in moderately strength-trained subjects. These
findings were confirmed in highly trained subjects in
which this same dose of caffeine improved AP levels
when lifting loads of 25%, 50% and 75% of 1RM,
while higher supplement doses (6 and 9 mg·kg
−1
)
improved AP levels at loads of 25%, 50%, 75% and
90% of 1RM [24]. In both studies, average velocity
also increased with each work load [23,24]. Thus,
caffeine supplementation improved AP performance,
likely because of the recruitment of more motor
units [50].
Fig. 2 aAverage velocity β-alanine VS. placebo-Pretest; bAverage velocity β-alanine VS. placebo-Posttest; cAverage power β-alanine VS.
placebo-Pretest; dAverage power β-alanine VS. placebo-Posttest
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 9 of 12

In contrast with the beneficial effects of caffeine on
power output in parallel with barbell displacement vel-
ocity, BA supplementation seems to increase power
through an increased training volume without affecting
the relationship between intensity and velocity. This may
be observed in Table 3and Fig. 2, in which none of the
velocity variables differed significantly between the two
groups (p> 0.05 for AV at Pmax, AV at 1RM, and mean
AV). Accordingly, this could indicate different mecha-
nisms underlying the impacts of caffeine and BA on
power production. Further work is needed to examine
the possibility of a synergistic effect of both supplements
in athletes following strength programs targeted at
improving power output.
Sodium bicarbonate has also been tested in athletes as
the main acid-base regulator and described as superior
even to carnosine, which may reduce H
+
produced
through glycolytic pathway activation during high-
intensity exercise by up to 62% [51]. The goal of sodium
bicarbonate supplementation is to increase plasma bicar-
bonate levels and thus increase alkaline capacity before
an exercise effort with a high anaerobic glycolysis contri-
bution [52]. Given the high glycolytic component of
strength training sessions, Carr et al. (2013) [53]
administered 300 mg·kg
−1
of sodium bicarbonate to a
group of athletes conducting a typical training session
targeting muscle hypertrophy (4 sets of 10–12
maximum repetitions in 3 lower limb exercises). Results
indicated that sodium bicarbonate supplementation
enabled the execution of a greater training volume. In a
second study, it was also observed that sodium
bicarbonate supplementation (300 mg·kg
−1
)was
effective at increasing the training volume in strength
training sessions as a higher number of repetitions were
accomplished in three sets using a load equivalent to
80% of 1RM [54].
These results as well as prior investigations suggest
that combining BA and sodium bicarbonate has a syner-
gistic effect that is not observed with each supplement
alone. Further, this suggests that sodium bicarbonate
might potentiate the effects of BA by increasing training
volume and thus promote further adaptations with
regards to strength training [17].
In the present study, we also assessed muscular fatigue
through performance in a CMJ. No prior work has
tested jump ability at the end of each set of an incre-
mental strength test despite being a common laboratory
test [27–33]. However, no appreciable pre-posttraining
Fig. 3 aJump height β-alanine VS. placebo-Pretest; bJump height β-alanine VS. placebo-Posttest; cAverage power β-alanine VS. placebo-Pretest;
dAverage power β-alanine VS. placebo-Posttest
Maté-Muñoz et al. Journal of the International Society of Sports Nutrition (2018) 15:19 Page 10 of 12

differences were detected between our BA and PLA
groups. Hence, jump height and average power values
recorded in the CMJ test were similar in both groups
despite more kilograms lifted (24 kg VS. 16 kg) and
more sets accomplished (2.79 sets VS. 1.58 sets) in the
BA supplementation group after 5 weeks of training.
Limitations
The main limitation of our study was its small sample size
(n= 26). Four of the subjects enrolled did not fulfil the in-
clusion requirements as the supplementation and training
protocols had to be strictly adhered to. This included a
need for 8 doses of 800 mg of supplement (1.5 to 3 h
apart) to be taken daily to avoid paresthesia and only two
training sessions in the 5 weeks could be missed. The final
26 participants were sufficiently disciplined to complete
these requirements of the study design.
Future lines of research
Based on our findings, future studies should examine the
effects of taking both BA and sodium bicarbonate supple-
ments during a strength training program. Further, owing
to the effects of BA on work load giving rise to increased
power output and to the known benefits of caffeine in im-
proving load displacement velocity in strength training ex-
ercises, possible interactions or synergistic effects of
caffeine and BA will also need to be explored.
Conclusions
Five weeks of supplementation with 6.4 g/day of β-
alanine compared with placebo during strength training
led to increases in: 1) power output for loads equivalent
to 1RM; 2) kilograms lifted at 1RM; 3) power output
gains at maximum power; 4) the number of sets exe-
cuted; and 5) the pre-post gain in kilograms lifted at
1RM in an incremental load test.
The ergogenic effects of β-alanine supplementation on
power generation were the result of an increased work
load. No effects of supplementation were produced on
velocity of movement variables or on CMJ test perform-
ance (jump height and power).
Additional files
Additional file 1: General linear model with repeated measures two-way
analysis of variance. (PDF 661 kb)
Additional file 2: Covariance analysis throught a univariate procedure.
(PDF 261 kb)
Additional file 3: Univariate general linear model. (PDF 169 kb)
Abbreviations
1RM: One-repetition maximum; AP: Average power; AV: Average velocity;
BA: β-alanine; BS: Back squat; CMJ: Countermovement jump; ES: Effect size;
PLA: Placebo; Pmax: Maximum power; PP: Peak power; PV: Peak velocity;
RPE: Scale of rating of perceived exertion; SP: Statistical power
Availability of data and materials
Supporting information is included in this manuscript.
Authors’contributions
JLM-M, RD conceived and designed the study; JLM-M, RD, JHL, AFS-J, PG-F, FDJ,
JG-P, and PV-H perform the exercises test; MCL-E, FD-J and PV-H perform the
packaged and prepared the capsules containing the supplement or placebo;
JHL, AFS-J, PG-F and MVG-C, carry out program training; JLM-M, RD, JHL, realize
data curation; JLM-M, writing the original manuscript; MVG-C, FDJ, and JG-P
translated the manuscript into English; RD, JLM-M, RD, JHL, AFS-J, PG-F, FDJ,
MCL-E, JG-P, PV-H and MVG-C edited and revised manuscript; JLM-M, RD, JHL,
AFS-J, PG-F, FDJ, MCL-E, JG-P, PV-H and MVG-C approved the final version of
the manuscript.
Ethics approval and consent to participate
The study was approved by the Ethical Committee of the University Alfonso
X el Sabio on December 15, 2014.
Competing interests
The authors declare that they have no competing interests.
Publisher’sNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1
Department of Physical Activity and Sport Sciences, Faculty of Health
Sciences, Alfonso X El Sabio University, Avda, Universidad 1, Building C, 3rd
floor, Office C-A15, Villanueva de la Cañada, 28691 Madrid, Spain.
2
Department of Physical Activity and Sport Sciences, TecnoCampus, College
of Health Sciences, Pompeu Fabra University, Ernest Lluch, 32 (Porta
Laietana), 08302 Mataró-Barcelona, Spain.
3
Department of Pharmacy, Faculty
of Health Sciences, Alfonso X El Sabio University, Avda, Universidad 1,
Building C, 3rd floor, Office C-A04, Villanueva de la Cañada, 28691 Madrid,
Spain.
4
Department of Pharmacy, Faculty of Health Sciences, Alfonso X El
Sabio University, Avda, Universidad 1, Building D, 3rd floor, Office D-342,
Villanueva de la Cañada, 28691 Madrid, Spain.
5
Department of Physiotherapy,
Faculty of Health Sciences, Alfonso X El Sabio University, Avda, Universidad,
1, Building C, 3rd floor, Office C-H05, Villanueva de la Cañada, 28691 Madrid,
Spain.
6
Department of Pharmacy, Faculty of Health Sciences, Alfonso X El
Sabio University, Avda, Universidad 1, Building D, 3rd floor, Office D-348,
Villanueva de la Cañada, 28691 Madrid, Spain.
7
Department of Physiotherapy,
Faculty of Health Sciences, Camilo José Cela University, Urb, Villafranca del
Castillo, Calle Castillo de Alarcón, 49, Villanueva de la Cañada, 28692 Madrid,
Spain.
8
Department of Health and Human Performance. Faculty of Physical
Activity and Sport Sciences, Polytechnic University, Social Building, 2nd floor,
Office 205, Madrid, Spain.
9
Department of Physical Activity and Sport
Sciences, Faculty of Health Sciences, Alfonso X El Sabio University, Avda,
Universidad 1, Building C, 3rd floor, Office C-A12, Villanueva de la Cañada,
28691 Madrid, Spain.
Received: 28 September 2017 Accepted: 19 April 2018
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