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Journal of Physical Education and Sport
®
(JPES), 17(4), Art 280, pp. 2495 - 2501, 2017
online ISSN: 2247 - 806X; p-ISSN: 2247 – 8051; ISSN - L = 2247 - 8051 © JPES
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Corresponding Author: GIANPIERO GRECO, E-mail: gianpiero.greco@uniba.it
Original Article
Negative effects of smartphone use on physical and technical performance of
young footballers
GIANPIERO GRECO
1
, ROBERTO TAMBOLINI
2
, PASQUALE AMBRUOSI
3
, FRANCESCO FISCHETTI
4
1,2,3,4
Department of Basic Medical Sciences, Neuroscience and Sense Organs, School of Medicine, University of
Bari, ITALY
Published online: December 30, 2017
(Accepted for publication December 02, 2017
DOI:10.7752/jpes.2017.04280
Abstract:
Mobile devices (i.e., smartphones and tablets) have acquired important functions in both interpersonal
and individual spheres. For this reason, they can cause a true dependence for the young people. The purpose of
this study was to assess the effects of prolonged use of smartphones on physical and technical performance of
young footballers. In total, 16 young male footballers (15.0 ± 1.1 years) were randomly assigned to two studies,
Study 1 (S1, n=8) or Study 2 (S2, n=8), in which the Yo-Yo Intermittent Recovery Test level 1 and the
Loughborough Soccer Passing Test were performed, respectively. The soccer-specific physical and technical
performance was assessed for S1 and S2. In both studies, the participants underwent to mental fatigue through
the use of smartphones (Brain It On App) for 30 minutes, and to the control condition (normal activities) after at
least 48 hours. S1 performed shorter running distances in the state of mental fatigue than under the control
condition (∆ -10.56%; p = 0.046; d = 0.82). In addition, mental fatigue significantly increased the performance
time in S2 compared with the control condition (∆ +15.7%; p = 0.003; d = 1.64). Our findings suggest that
prolonged use of smartphones, which causes mental fatigue, can reduce the physical and technical performance
of young footballers. Therefore, it is necessary to educate to the conscientious use of technology.
Key words: mental fatigue; cognitive task; physical education; technology.
Introduction
Mobile devices, such as smartphones and tablets, are a filter through which the reality and interpersonal
relations are enjoyed. These devices have acquired important functions in both interpersonal and individual
spheres. Because these objects are status symbols that are strongly tied to fashion, they can cause a true
dependence for the adolescents. In Italy, 17 % of young people cannot stop using smartphones and social
networks, 25 % are always online, 45 % are connected several times a day, 78 % chat continuously on
WhatsApp and 21 % are afflicted by vamping, which means that they wake up during the night to check
messages on their cellphones (Safer Internet Day, 2016). Besides, the brightness of devices can delay sleep of
those who use them for a long time before sleeping (Figueiro, Wood, Guilty, and Plitnick, 2012). In the field of
physical education, the use of these devices to play, for example, videogames has often been viewed with
skepticism and has been traditionally associated with several risks to physical and mental health (Funk &
Buchman, 1995). When significant effort is focused on cognitive exercise, there is a possibility of mental fatigue
(Kaplan, 2001). Recent studies have demonstrated that mental tasks that involve cognitive control can lead to the
reduction of systemic glucose. This indicates that a significant mental effort can produce a state of tiredness that
can influence performance (Gailliot & Baumeister, 2007).
Previous studies, which observed the effects of mental fatigue on physical performance, demonstrated
that prolonged periods of cognitive activity induce mental fatigue, which is a psychological state that is
characterized by tiredness and lack of energy (Boksem, Meijman, & Lorist, 2006; Marcora, Staiano, & Manning,
2009). Besides, it has been suggested that mental fatigue can negatively impact on explosive strength, maximum
muscular contraction, power and anaerobic work capacities (Ferraz et al., 2011; Martin, Thompson, Keegan,
Ball, & Rattray, 2015; Pageaux, Marcora, & Lepers, 2013; Rampinini, Impellizzeri, Chestnut, Coutts, & Wisloff,
2009; Smith, Marcora, & Coutts, 2015). Furthermore, mental fatigue affects performance during constant weight
resistance testing (Marcora et al., 2009). Team sports are characterized by very important cognitive requests that
force athletes to maintain concentration for prolonged periods of time and to take swift and accurate decisions in
a highly dynamic environment (Montgomery et al., 2008; Tavares, Smith, & Driller, 2017; Walsh, 2014). In fact,
the study by Smith et al. (2016b) indicated that mental fatigue induced by a cognitive task of 30 minutes
increased decision-making time and reduced accuracy of tired players compared with a control group during
game situations that were created during Small Sided Games. Additional studies highlighted a decrease in terms
of quantity and quality of technical performance due to mental fatigue, which was verified by the competition
progress (Carling & Dupont, 2011; Rampinini et al., 2008, 2009).
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The studies highlighted that the condition of mental fatigue is induced by long and intense cognitive
tasks, which lead to an objective feeling of tiredness and lack of energy. To identify the standardized conditions
of mental fatigue, cognitive tasks are provided using a personal computer. These tasks include Psychomotor
Vigilance Task (Loh, Lamond, Dorrian, Roach, & Dawson, 2004), Ax-Continuous Performance Task (Smith et
al., 2015), and Stroop Color Task (Smith et al., 2016a). While trying to clarify neurological mechanisms that are
at the base of the relation between mental fatigue, perception of fatigue and performance, it is still necessary to
take into account real habits of athletes during pre-competition or pre-training. In fact, even if the athletes can
devote themselves to mentally hard tasks before a game, it is improbable that before the competition they
perform a similar cognitive task, for example “Stroop color”. Therefore, the present social habits of prolonged
use of smartphone or tablet should have been identified. In this respect, there are no studies in the literature that
evaluate the effects of these electronic devices, and little is known about the fatigue that they can induce in
young footballers. Thus, the present research aims to investigate the effect of prolonged use of smartphones on
the physical and technical performance of young footballers. It was hypothesized that the prolonged device
utilization during pre-competition induces mental fatigue, which limits both the physical performance and
technique.
Material and methods
Participants
Sixteen young healthy male footballers (15.0 ± 1.1 years old; height 1.71 ± 0.1 m; weight 61.4 ± 8.2 kg;
BMI 20.9 ± kg/m2) participated voluntarily in this study. The participants were recruited from the youth sector
of the ASD Nick Calcio Bari in April 2017, and subsequently they were assigned randomly to two groups. One
group participated in Study 1 (n=8), and another group participated in Study 2 (n=8). Randomization was
achieved using a software that is available online (www.randomization.com). All of the participants and their
parents received complete information about the experiment and gave their agreement. The ethical principles
based on the declaration of Helsinki were respected in the research. The study was conducted in May 2017.
Procedures
A cross-over design in which the same group was subjected to the experimental condition and control
condition was used for both studies. Each group was subjected to the condition of “mental fatigue” and to the
condition of “control”, separated by a minimum of 48 h. The sessions of control and mental fatigue were
performed in a randomized and counterbalanced order generated by online software (randomization.com).
Before starting the study, the subjects were informed about the evaluations and procedures. The players did not
perform any activities during 48 hours before the evaluation sessions. The participants completed all testing
sessions at the same time of day (within 1 h), starting at 15:30. Besides, all of the measurements were carried out
by the same person who has a degree in motor sciences, and standardized test protocols were used under his
supervision. This research was planned to estimate whether the use of smartphones for 30 minutes with a free
application named “Brain It On” was able to cause any possible performance decrease during the evaluation of
physical (study 1: Yo-Yo Intermittent Recovery Test level 1) and technique (study 2: Loughborough Soccer
Passing Test) performance of young footballers.
Performance testing
Yo-Yo Intermittent Recovery Test level 1 (Yo-Yo IR1). It is a valid and reliable test of physical
performance for football players (Bangsbo, Iaia, & Krustrup, 2008; Krustrup et al., 2003). It is an evolution of
the Lèger test (20-m shuttle run test), and this test was proposed to make the execution protocol closer to a real
football competition, inserting a pause of 10 seconds after each shuttle (2 × 20 m) (Figure 1)
Fig. 1 - Schematic representation of the run used to make the Yo-Yo Intermittent Recovery Test level 1.
The test consists of running 20 m with a progressively increasing speed and with intervals of 10 seconds
of active and continuous recovery up to the time when the players are able to hold the rhythm with a speed
dictated by an acoustic signal. The distance completed up to that moment is noted in the final test. The test is
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preceded by a short warm-up. The test starts at 10 km/h. The rhythm and the increase of the speed of the run are
regulated using an audio signal. It is a maximal intermittent test with a change of the running direction, and it
can be given to many players at the same time. It has high reliability and allows to make a detailed analysis of
physical abilities of athletes in intermittent sports. During the test, the aerobic intensity approaches maximum
values, and the anaerobic energy system is kept very busy (Krustrup et al., 2003). The Yo-Yo Intermittent
Recovery tests provide a simple and valid way for obtaining important information about the ability of an
individual to repeatedly carry out intense exercises and to examine changes in the performance (Bangsbo et al.,
2008). In addition, the tests show their validity for elite football players (Fanchini, 2015), and they are reliable
for evaluating performance of young footballers (Póvoas et al., 2016). At the end, Yo-Yo IR1 shows a strong
correlation between the obtained result and athletic performance.
Loughborough Soccer Passing Test (LSPT). To evaluate the specific technical performance in football
and to quantify the skill of footballers to make short passes, the first version of LSPT test was used, which was
developed and validated by Wings et al. (2003). The schematic representation of the run used in the test is shown
in figure 2.
Fig. 2 - Schematic representation of the run used for the Loughborough Soccer Passing Test.
The test consists of the execution of 16 passages clockwise that are made within a run as fast and exact
as possible. Four targets with a dimension of 30 × 60 cm (two yellow and two blue targets) and one target with a
dimension of 30 × 10 cm (purple) were positioned on a wooden target (30 × 250 cm). The subjects start with the
ball in the central box and, after the signal of the operator, they must lead the ball to the passing area, make the
pass towards the target A, retake the control of the ball, return with the ball to the central box and then move in
the direction of the target B using the same approach. Then, before making the next passage in the passing area,
the ball must be led to the central box. According to the errors made by the athletes, the following penalties are
provided:
- + 5 s to completely miss a target or to hit a wrong target with the ball;
- + 3 s to hit the wooden target but miss the colored targets (for example, to hit a corner of the wooden
target);
- + 2 s to hit a yellow target;
- + 1 s to hit a blue target;
- + 2 s to make the passage to the outside of the passing area;
- + 2 s if the ball touches a cone;
- +1 s for each second over 43 ", which is a pre-established time to complete the test.
For each passage that perfectly strikes the purple target, 1 second from the total time is taken away.
There are three performance indices:
1) required total time to complete 16 passages and to return to the central box (LSPT time);
2) accumulated penalties (LSPT penalties);
3) sum of these first two indices as an indicator of total performance (LSPT total).
Experimental conditions
Condition of mental fatigue. The participants drew figures on the smartphone screen to solve puzzles,
which were proposed by free application “Brain It On”, with the fastest solution to advance to the next level. To
increase the motivation for the activity, a competitive environment was created. Therefore, the participants
challenged each other to complete successfully as many levels as possible within 30 minutes. The participants
from both groups completed the task in the same room under the supervision of the same researcher.
Condition of control. The participants carried out their usual activities before the training.
Study 1
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During the first meeting, standardized instructions were supplied to the participants to be memorized
and to use the Borg scale for the subjective perception of the exertion CR10 (RPE) (Borg, 1998). The
participants had an opportunity to learn the Yo-Yo IR1 (Bangsbo et al., 2008), and they were instructed to avoid
vigorous activities the day before the next visit and to consume a light meal 2 hours before the test. The respect
for these instructions was estimated using a pre-test checklist on arrival. Still, the respect for these instructions
was not evaluated using objective measures. The RPE values were recorded at the end of each Yo-Yo IR1 level
and also at the point of exhaustion (10 minutes prior to the end of the test). For both conditions, the participants
were asked to perform the test to exhaustion. Besides, no motivational intervention was supplied beforehand or
during the Yo-Yo IR1. During the “control” session and during the “mental fatigue” session, the participants had
2 minutes of warm up before the test.
Study 2
The participants were familiarized with LSPT twice (Ali et al., 2003). They were given the same pre-
test instructions as the study 1 participants, and the conformity was ensured via a pre-test checklist at the
moment of arrival for the test sessions. The control and mental fatigue sessions in study 2 followed the same
procedures as in study 1 up to the warm up phase. For Study 2, 2 minutes of warm up with a ball with elements
of passage, dribbling and ball control were carried out. After the warm up, the participants completed the
technical test. No motivational intervention was made before or during the tests of specific football skills.
Statistical analysis
All data are presented as mean ± SD and statistically analyzed using the software SAS JMP version
13.2 (Cary, NC, USA). To compare between the two conditions to which the groups were subjected, one-tailed
Student’s t-test for the dependent samples was used. Besides, to estimate the scientific magnitude of the
differences within the groups, the effect size d was calculated using the formula of Dunlap, Curtain, Vaslow and
Burke (1996) and interpreted according to Cohen (1988), with the values of 0.20, 0.50 and 0.80, which indicate a
small, medium and large effect size. The statistical significance was set at p<0.05.
Results
Study 1
Yo-Yo Intermittent Recovery Test level 1. Figure 3 shows the mean distance completed during the Yo-
Yo IR1 test. The participants completed shorter distances under the condition of mental fatigue compared with
the control condition (1610 ± 135 m vs. 1780 ± 249 m; ∆ -10.56%; t = -1.95; p = 0.0460; d = 0.82).
Fig. 3 - Effect of mental fatigue during the Yo-Yo Intermittent Recovery Test level 1. The data are shown as
mean ± SD. The difference is statistically significant (p < 0,05).
Subjective perception of the exertion. Statistically significant differences were not observed (p > 0.05)
with regard to the subjective perception of the exertion using the Borg CR10 scale between the condition of
mental fatigue (RPE = 7.9 ± 0.35) and of the control (RPE = 7.1 ± 1); for both conditions, perception of the
exertion at the end of the test was very strong.
Study 2
Loughborough Soccer Passing Test. The ability of making passes was affected by the mental fatigue.
The score, statistical differences and their scientific magnitude are shown in table 1.
Table 1 – Effects of the mental fatigue on the soccer-specific technical performance evaluated using the
Loughborough Soccer Passing Test.
LSPT CONTROL MENTAL FATIGUE p d
Original time (s) 40.1 ± 3.4 42 ± 3 0.0221 0.57
Penalty time (s) 2.9 ± 2.2 9 ± 4,5 0.0105 1.11
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A statistically significant difference was found between the two conditions in “Performance Time” (∆
+15.7%; t = - 3.89; p = 0.0030; d = 1.64) (Figure 4). The “Penalty Time” was significantly greater for the mental
fatigue condition compared with the control condition (t = - 2.96; p = 0.0105; d = 1.11). This indicated that the
participants were less accurate under the mental fatigue condition.
Fig. 4 – Effect of the mental fatigue on “Performance time” during the Loughborough Soccer Passing Test. The
data are shown as mean ± SD. The difference is statistically significant (p<0.05).
Discussion and conclusions
The purpose of the present research was to investigate the effects of the prolonged use of smartphones
on the physical and technical performance of young footballers. The results confirmed our hypotheses.
Specifically, the participants completed shorter distances during the intermittent run that simulates the
requirement of a team sport, such as football, made more mistakes during the passes, and control of the ball was
less accurate after being mentally fatigued.
In the first study, Yo-Yo Intermittent Recovery Test level 1 was used, and the evident result is the
decrease of physical performance of the footballers, following the inducing fatigue, in accordance with previous
studies (Ferraz et al., 2011; Martin et al., 2015; Pageaux et al., 2013; Rampinini et al., 2009; Smith et al., 2015).
In fact, the prolonged use of a smartphone probably induced a mental fatigue, reducing the completed distance to
170-m, with an individual mean decrease of 10.56 %. This confirms that the reduction of physical performance,
which happened in the present research, is similar to that induced via the Stroop Color test used by Smith et al.
(2016a), which recorded 207 meters of the distance completed, with an individual mean decrease of 16.3 %.
Then, it is possible to state that mental fatigue modifies the intermittent exercise in the test that simulates the
requirements of a team sport, as asserted by Smith et al. (2015), and, probably, it can significantly affect high-
intensity running performance during a game (Krustrup et al., 2003).
Although the perception increase of the exertion is mostly responsible for the negative effects of mental
fatigue on effort tolerance (Pageaux et al., 2013; Smith et al., 2016a), in this study, the condition of mental
fatigue has not determined a greater subjective perception of the exertion using the Borg CR10 scale, in
disagreement with the results of the study by Smith et al. (2016a). Nevertheless, the participants stopped earlier
compared with the control condition and completed smaller total distance, as in the studies by Smith et al. (2015,
2016).
The purpose of the second study was to analyze the technique of execution of the fundamental football
movements using the Loughborough Soccer Passing Test. The results confirmed that the prolonged use of
smartphones causes mental fatigue and may increase the number of passages and ball controlling errors, which
can reduce the quality and quantity of the technical performance, as it happens at the end of a football match
(Rampinini et al., 2009). Besides, the results of the present study agree with some studies that evaluated the
effects of mental fatigue on the technical performance of footballers using different protocols (Rampinini et al.,
2008; Smith et al., 2016a). In addition, the results agree with studies from other fields of research, which
highlighted an increase in errors due to the mental fatigue during cognitive tasks and driving tasks (Boksem et
al., 2005; Gailliot & Baumeister, 2007; Kaplan, 2001; Lal & Craig, 2001).
The present research shows some limitations, which should be considered during the interpretation of
the results. In fact, due to the reduced sample size, the results of the study should be interpreted with caution.
Besides, during the first study, physiological parameters were not measured, such as cardiac frequency, hematic
lactate, and arterial pressure, which could have supplied additional evidence about the effects of prolonged use
of smartphones and the induced mental fatigue.
However, this is the first study that examined the influence of prolonged use of smartphones, via a
“game application”, on the physical and technical performance of young footballers. The real need to identify
Performance time (s) 43 ± 2.2 51 ± 6 0.0030 1.64
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common and habitual pre-competition activities that can induce mental fatigue, allowed to develop research
using a widely used electronic device instead of a cognitive task, such as the Stroop color, which simulates an
unrealistic pre-competition tasks. In the future, it will be interesting to verify the effects in other sports and, if
possible, to compare the effects caused by a smartphone or a tablet with the laboratory cognitive tests. Finally,
our findings confirm that the sustained mental effort, as when a smartphone is used for playing, can induce
mental fatigue and limit performance. Thus, it is evident that present social need is to educate the youth to use
technology conscientiously.
Authors’ contribution
Gianpiero Greco contributed to research conception and design, data analysis and interpretation, writing and
critical review of the manuscript. Roberto Tambolini contributed to research design, data acquisition and
interpretation. Pasquale Ambruosi contributed to research design and data interpretation. Francesco Fischetti
coordinated the study and contributed to research design and critical review of the manuscript. All authors have
read and approved the final manuscript.
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