R E S E A R C H A R T I C L E Open Access
Effects of placebo on bench throw
performance of Paralympic weightlifting
athletes: a pilot study
Gustavo De Conti Teixeira Costa
, Luan Galvão
, Martim Bottaro
, João Felipe Mota
Gustavo Duarte Pimentel
and Paulo Gentil
Background: The aim of the present study was to analyse the effects of placebo on bench throw performance in
Paralympic weightlifting athletes.
Methods: The study involved four Paralympic weightlifting male athletes (age: 40.25 ± 9.91 years, weight:
60.5 ± 8.29 kg, height: 1.60 ± 0.15 m) that visited the laboratory in three occasions, separated by 72 h. In the
first session, the athletes were tested for bench press one repetition maximum (1RM). The other two sessions were
performed in a randomized counter-balanced order and involved bench throw tests performed either after taking
placebo while being informed that the capsule contained caffeine or without taking any substance (control). The
bench throw tests were performed with loads corresponding to 50, 60, 70 and 80% of the bench press 1RM.
Results: According to the results, mean velocity (Δ: 0.08 m/s, ES 0.36, p< 0.05) and mean propulsive velocity
(Δ:0.11m/s,ES0.49,p< 0.05) at 50% of 1RM were significantly higher during placebo than control (p<0.05).
However, there were no difference between control and placebo for 60, 70 and 80% of 1RM (p>0.05).
Conclusion: Our results suggest that placebo intake, when the athletes were informed they were taking caffeine,
might be an efficient strategy to improve the performance of explosive movements in Paralympic weightlifting
athletes when using low-loads. This brings the possibility of using placebo in order to increase performance, which
might reduce the risks associated with ergogenic aids, such as side-effects and positive doping testing.
Keywords: Nutritional supplements, Sports performance, Psyching up
The intake of nutritional supplements are a common
practice among physical activity practitioners and
athletes; however, few actually have scientific evidence
for their efficacy . Among them, caffeine is one of the
most consumed substances by athletes  and is consid-
ered to positively impact physical performance . In
this regard, previous studies suggested that caffeine may
be ergogenic, sparing muscle glycogen improving pain
tolerance, reducing rate of perceived exertion, increase
maximum voluntary contraction, strength and power in
high-intensity activities besides of stimulating central
nervous system [4–10]. However, there are specific
controversies about its effects, mainly when the studies
compared the acute effects of caffeine vs placebo intake
showed inconsistent conclusions [11–17].
While genetic factors might explain a large portion of
the variance associated with the caffeine effects such as
pain tolerance, anxiogenic and alert effects [18–20],
there are important psychological responses to ingesting
a substance that should be considered. The placebo
effect  can influence the physiological aspects to
physical exercise performance 
one of the all factors
that might influence the effects of caffeine is the placebo
effect . In agreement with this, Saunders et al. 
found an improvement in the cycling time to exhaustion
in trained cyclists who ingested placebo believing to
have ingested caffeine. Similarly, in a previous study,
* Correspondence: firstname.lastname@example.org
Faculdade de Educação Física e Dança, Universidade Federal de Goiás,
Full list of author information is available at the end of the article
© The Author(s). 2019 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.
Costa et al. Journal of the International Society of Sports Nutrition (2019) 16:9
Beedie et al.  reported that when competitive male
cyclists ingested placebo believing to have ingested caf-
feine there were increases in aerobic power at VO2max
test and 10-km time trials, with no difference in oxygen
uptake, heart rate, and blood lactate. Such placebo ef-
fects do not rule out a true effect of caffeine supplemen-
tation. Although these studies suggested that aerobic
performance improves following placebo intake when in-
dividuals believed that they are ingesting caffeine, we are
not aware of studies that measured the placebo effect in
powerlifting. Moreover, Paralympic athletes have been
shown to have psychological particularities that might
make them especially vulnerable to the placebo effect,
such as, concerns about having to perform consistently
well throughout training and difficulties in coping with
negative results . Therefore, it seems important to
perform specific studies in these group despite the diffi-
culty to select subjects with these characteristics.
The analysis of the placebo effect might be of great
practical importance since it could provide an alternative
for improving performance through the intake of an
inert substance, with no risk of testing positive for dop-
ing or adverse effects, either due to the direct use of pro-
hibited substances, or by the possible contamination of
nutritional supplements [10,26–30]. Based on this, the
present study aimed to evaluate if muscle performance
during explosive movements would change in Paralympic
weightlifting athletes after the intake of placebo when the
participants were informed that they were taking caffeine.
Materials and methods
Four Paralympic weightlifting male athletes were
recruited to participate in this study (age: 40.25 ± 9.91 y,
weight: 60.5 ± 8.29 kg, height: 1.60 ± 0.15 m). One had
dwarfism, one myelomeningocele and hydrocephalus
and two poliomyelitis. Athletes trained regularly five
times a week aiming to compete, and all had previous
experience with caffeine use, but have not taken any
caffeine supplements in the previous six months. Two
athletes had won medals in at least two phases on the
national circuit. They were only allowed to participate if
they had no orthopaedic or cardiometabolic problems
that could be aggravated by the study protocol, as
attested by a physician. This study was approved by
Federal University of Goias committee (2.058.322) and
all the participants signed a written informed consent
form before participation (Table 1).
The study is a randomized, double-blind, crossover
study. The athletes attended the laboratory three times,
with an interval of 72 h between visits. During the first
visit, they were submitted to the one repetition
maximum test (1RM) in the bench press, as previously
recommended . The second and third visits involved
the bench throw tests. The athletes were randomly
assigned to ingest a capsule of placebo or no capsule on
the second and third visits, in a cross-over design.
During the placebo situations, the athletes received one
capsule containing maize starch one-hour prior the test
and were informed that it contained 6 mg.kg-1 caffeine.
The athletes were oriented to avoid caffeine containing
beverages and foods one week prior to the beginning of
Muscular performance was measured in the bench
throw, using an isoinertial indicator (T-Force, Dynamic
Measurement System; Ergotech Consulting S.L., Murcia,
Spain). The exercise was performed on a smith machine
and the athletes were instructed to perform three repeti-
tions with maximum intended velocity in all repetitions.
The tests were performed with 50, 60, 70 and 80% of
1RM, with 5 min of rest between each load condition.
The movement started with elbows fully extended and
then the bar was get down until touching the sternum.
A linear position transducer was attached to the bar.
The bar position data were sampled at 1000 Hz using a
computer, as recommended by the manufacturer. The
finite differentiation technique was used to calculate the
velocity and acceleration of the bar, presenting an
associated error of < 0.25%, while the displacement was
accurate to ±0.5 mm .
Data were analysed using the Statistical Package of
Social Science software (SPSS 20.0, Chicago, IL, USA).
Factorial ANOVA with a within-within design was used
to compare the performance between placebo vs control
situation at different loads. When necessary multiple
comparisons were used as post hoc. Data were consid-
ered statistically significant when p< 0.05. Effect size
(ES) of the mean differences was determined using
Cohen’s d. The magnitude of the ES was determined by
Hopkin’s scale as follows: < 0.1 (trivial), 0.1–0.3 (small),
0.3–0.5 (moderate), 0.5–0.7 (large), 0.7–0.9 (very large)
and > 0.9 (perfect) .
Table 1 Characteristics of the participants
Mean Minimum Maximum
Age (years) 40.25 ± 9.91 26 54
Weight (kg) 60.6 ± 8.36 49.0 71.2
Height (m) 1.61 ± 0.16 1.36 1.78
Body mass index (kg/m
) 23.83 ± 4.48 19.38 30.82
1 repetition maximum load (kg) 69 ± 19.46 40 92
Costa et al. Journal of the International Society of Sports Nutrition (2019) 16:9 Page 2 of 6
Tabl e 2shows the results relative to the absolute velocity
values as a function of the load lifted. Although the mean
velocity to peak and peak velocity were not different be-
tween situations, the mean velocity at 50% RM was signifi-
cantly higher in placebo vs control (Δ: 0.08 m/s), with
moderate effect size (0.36; p< 0.05). Similarly, mean
propulsive velocity at 50% RM was significantly higher in
placebo vs. control (Δ: 0.11 m/s) with moderate effect size
(0.49; p< 0.05) as shown in Fig. 1.
To the best of our knowledge, this was the first study to
analyse the placebo effects of caffeine on bench throw
performance of Paralympic weightlifting athletes. Accord-
ing to the results, the ingestion of placebo significantly
increases mean velocity and mean propulsive velocity at
50% of 1RM. These findings may be particularly interest-
ing, since this intensity is in the recommend range for
maximum power output in the bench throw .
Moreover, considering that the tests involved highly trained
athletes, the differences might be relevant to training and
competition. It is important to note that, whilst they did
not reach significance, the differences with higher loads oc-
curred in the opposite direction, with a trend for a detri-
mental effect with placebo. The reason for this is not
known, but there are two hypotheses to consider. First, the
tests were incremental, so it might be possible that the
higher performance in the earlier sets with lower loads lead
to fatigue in the later sets, performed with higher loads.
Second, when the load increased and becomes more chal-
lenging, the participants might have expected to have an
improved performance perform. However, since there was
not physiologic enhancement due to the supplementation,
a negative psychological influence might have occurred.
Although the deception used in the present study is
not common in scientific literature, it is closer to what
happens in real world, where many athletes take nutri-
tional supplements believing on a true physiological
effect, which might affect the results . Besides that,
uptake placebo was able to improve performance on
bench throw with no reports of adverse effects already
shown to caffeine supplementation before . In this
regard, Hurst et al. suggested that the intention to im-
prove performance by the athletes when taking placebo
can make a difference in the final performance; there-
fore, in order to take full advantage of this intervention,
the athletes should believe in the benefits of the ingested
Whilst many athletes believe that nutritional supple-
ments are related to performance enhancements 
most do not obtain adequate information and do not
even know the active ingredients or mechanism of
action of the substances used [36–42]. Therefore,
supplements use seems to rely more on beliefs than on
scientific evidence. Considering our findings that an
inert substance might increase performance when
athletes were deceived to believe it was an ergogenic aid;
this might help to explain the divergence that often
occurs between anecdotal and scientific evidence. On
the other hand, this study had the focus only in placebo
effect and a third group of caffeine was not used aiming
to compare three groups.
Regarding the possible explanation for the placebo
effect, Beedie et al. divided it in four categories: pain
reduction, belief-behaviour relation, attentional changes
and arousal changes. Within these mechanisms, the
improvements found in our study can be explained by
attentional and arousal changes . Besides that, caf-
feine intake also increasing pain tolerance , however,
this probably did not happen in this study due to short
duration with just three repetitions of exercise per-
formed. The placebo effect might be associated with
self-directed cognitive strategies and preparatory arousal
(i.e. including imagery and attentional focus), which has
been shown to enhance force production [44,45].
The major limitation of the present study is the low
number of participants. However, due to the characteristics
Table 2 Comparison between the placebo and control group on velocity of displacement of the bar in bench press
Variable 50% 1RM ES 60% 1RM ES 70% 1RM ES 80% 1RM ES
Mean velocity (m/s) Control 0.76 ± 0.08 0.36* 0.70 ± 0.07 0.19 0.61 ± 0.10 0.26 0.47 ± 0.10 0.31
Placebo 0.84 ± 0.12 0.74 ± 0.12 0.56 ± 0.08 0.41 ± 0.08
Mean velocity to peak (m/s) Control 0.79 ± 0.09 0.33 0.72 ± 0.07 0.18 0.61 ± 0.11 0.19 0.48 ± 0.10 0.31
Placebo 0.87 ± 0.13 0.76 ± 0.13 0.57 ± 0.09 0.42 ± 0.08
Mean propulsive velocity (m/s) Control 0.81 ± 0.09 0.46* 0.74 ± 0.09 0.19 0.63 ± 0.12 0.27 0.48 ± 0.10 0.36
Placebo 0.92 ± 0.12 0.79 ± 0.15 0.57 ± 0.09 0.41 ± 0.08
Peak velocity (m/s) Control 1.16 ± 0.11 0.37 1.06 ± 0.13 0.14 0.91 ± 0.19 0.27 0.72 ± 0.19 0.32
Placebo 1.27 ± 0.16 1.11 ± 0.21 0.82 ± 0.11 0.61 ± 0.12
ES effect size, RM Repetition Maximum
*significant difference between placebo and control (p< 0,05)
Costa et al. Journal of the International Society of Sports Nutrition (2019) 16:9 Page 3 of 6
of the participants, it would be difficult to obtain a higher
sample size. It would also be interesting to have a third
situation, with caffeine use. Future research should be con-
ducted on a higher number of athletes, including Paralym-
pic athletes with different limitations. Moreover, it would
be valuable to assess the long-term effects of placebo, in
order to test if the regular increase in performance over
training sessions might bring long-term benefits.
Our results suggest that placebo intake, when the
athletes believe they are taking caffeine, might be an
efficient strategy to improve performance in the bench
throw test in Paralympic weightlifting athletes under
low-loads. This brings the possibility of using placebo in
order to increase performance in plyometric and speed
exercises, reducing the side effects and risks associated
with the use of ergogenic aids. Additionally, it would be
ideal that nutritional strategy was investigated with high
loads before using it in practice. Finally, it might be
suggested that part of the conflict that usually exists be-
tween anecdotal reports and scientific evidence about
nutritional supplementation can be associated to the
psychological effects of ingesting a supplement.
Authors would like to thank to subjects that participated of this study for
their commitment and effort.
This research received no grant.
Availability of data and materials
The datasets used and analyzed during the current study are available from
the corresponding author on reasonable request.
GC participated in the study design, collected data, interpreted the data, and
wrote the article. GC, LG, MB, JFM, GDP, and PG participated in the study
design, and wrote the manuscript. All authors read and approved the final
Ethics approval and consent to participate
Participation in the study was voluntary, with written consent being
obtained from each subject before the initiation of data collection. This
study was conducted after review and approval by the Federal University of
Goias committee. Committee’s reference number: 2.058.322.
Consent for publication
All the study participants gave their consent to publish the research findings.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Faculdade de Educação Física e Dança, Universidade Federal de Goiás,
Faculdade de Educação Física, Universidade de Brasília, Distrito
Federal, Brasília, Brazil.
Faculdade de Nutrição, Universidade Federal de
Goiás, Goiás, Brazil.
Fig. 1 Mean propulsive velocity (m/s)
Costa et al. Journal of the International Society of Sports Nutrition (2019) 16:9 Page 4 of 6
Received: 13 July 2018 Accepted: 12 February 2019
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