International  Journal  of
Environmental Research
and Public Health
Article
Speed, Change of Direction Speed and Reactive Agility in
Adolescent Soccer Players: Age Related Differences
Slobodan Andraši´c 1
, Marko Guši´c 2
, Mima Stankovi´c 3
, Draženka Maˇcak 2
, Asim Bradi´c 4, Goran Sporiš 4
and Nebojša Trajkovi´c 3,*


Citation: Andraši´c, S.; Guši´c, M.;
Stankovi´c, M.; Maˇcak, D.; Bradi´c, A.;
Sporiš, G.; Trajkovi´c, N. Speed,
Change of Direction Speed and
Reactive Agility in Adolescent Soccer
Players: Age Related Differences. Int.
J. Environ. Res. Public Health 2021, 18,
5883. https://doi.org/10.3390/
ijerph18115883
Academic Editors: Caio Victor Sousa
and Samuel da Silva Aguiar
Received: 31 March 2021
Accepted: 27 May 2021
Published: 30 May 2021
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4.0/).
1
Faculty of Economics, University of Novi Sad, 24000 Subotica, Serbia; andrasicslobodan@yahoo.com
2
Faculty of Sport and Physical Education, University of Novi Sad, 21000 Novi Sad, Serbia;
gusicmarko@yahoo.com (M.G.); macak.md@yahoo.com (D.M.)
3
Faculty of Sport and Physical Education, University of Niš, 18000 Niš, Serbia; mima.stankovic974@gmail.com
4
Faculty of Kinesiology, University of Zagreb, 10000 Zagreb, Croatia; asim.bradic@kif.unizg.hr (A.B.);
goran.sporis@kif.unizg.hr (G.S.)
*
Correspondence: nele_trajce@yahoo.com
Abstract: There are a plethora of studies investigating agility in soccer; however, studies have rarely
presented the reaction time in differentiating age groups in adolescent soccer players. We investigated
age differences in reactive agility, speed, and change of direction speed (CODs), in a group of highly
trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14–19 years)
were recruited. The players were grouped based on their age to under 15 (U15; n = 27), under 17
(U17; n = 25), and under 19 (U19; n = 23) players. Players were tested for 5 m, 10 m, and 20 m sprint,
CODs speed test, Illinois test, and reactive agility test (total and reaction time). Only the reactive
agility test with a live tester (RAT live) and RAT live reaction time (RAT live RT) distinguished U19
from both groups, U17 (RAT live, p < 0.01; RAT RT live, p < 0.01) and U15 (RAT live, p < 0.01; RAT
RT live, p < 0.01). Groups did not have different times for 5 m sprint, RAT light and RAT RT light,
F = 0.472, 2.691, 1.023, respectively, p > 0.05. Moreover, a signiﬁcantly slower average performance of
sprint 20, CODs left and right, and Illinois was also observed in U15 as compared to U17 and U19
(p < 0.05). We can conclude that results in agility tests that include live testers can be a signiﬁcant
factor that differentiates between adolescent soccer players considering their age.
Keywords: agility; differences; youth; performance; football
1. Introduction
The demands of modern soccer have changed signiﬁcantly and increased in recent
years. Nowadays, players are required to have more power and to cover greater distances,
with more frequent changes in intensity [1–3]. Most high-intensity activities (sprints)
take place during decisive moments, such as tackling, offensive and defensive actions,
as well as goal-scoring opportunities [4–7]. As soccer is considered to be a sport that
requires that attackers evade their opponents’ pressures or tackles, and defenders reduce
space on the ﬁeld in order to limit attacking movements or potentially achieve a turnover,
having good change of direction speed (CODs) and agility is beneﬁcial [8]. In the last few
decades, change of direction speed and reactive agility were considered to be the same
skill [9]. However, nowadays, pre-planned agility may be deﬁned as sprints with change
of direction, while the reactive agility (RA) is classiﬁed as sprints with directional changes
in response to a stimulus [10,11]. Therefore, RA is based on greater levels of motor control,
when compared to pre-planned CODs [12].
Reactive agility and CODs are one of the most important skills required for soccer
success [13]. Moreover, reactive agility tests (RATs) are able to differentiate the key per-
formance indicators presented as the skill levels among soccer players [14]. On the other
side, there are still some doubts about the test design and type of stimulus presented in
Int. J. Environ. Res. Public Health 2021, 18, 5883. https://doi.org/10.3390/ijerph18115883
https://www.mdpi.com/journal/ijerph
Int. J. Environ. Res. Public Health 2021, 18, 5883
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the existing literature regarding reactive agility tests. In addition, most of the studies only
measured total times instead of reaction times. As RATs are designed to evaluate both
physical, and technical and cognitive abilities, there is an absolute need to further examine
reactive agility assessment in soccer [15].
Some research shows that older adolescent players tend to complete the RATs quicker
than younger players due to their higher ﬁtness level, CODs, and anticipatory skill, which
makes them play on a much higher level [13]. Several studies investigated the perceptual
abilities of higher-level players, and it was shown that there are fundamental perceptual
and cognitive differences between them and lower-level players [16–18]. Additionally,
Tretloci et al. [19] showed that ﬁeld-based tests including vertical jumps, change of direction
speed, and reactive agility can differentiate between under 16 elite and sub-elite soccer
players. This was conﬁrmed by Trajkovic et al. [20], showing that the skilled players
performed better in reactive agility tests, speed, and CODs compared to amateur players.
Moreover, the authors stated that reactive agility tests with live opponent stimuli can
be a signiﬁcant factor that differentiates between adolescent soccer players considering
their level.
At this point, there are studies that determine the difference in physical performance
between levels of play. However, there are not many studies that show the difference
between age groups in CODs and RA [13,21]. Additionally, the categories used in those
studies do not match the categories used here.
Moreover, according to the authors’ knowledge, there are no studies that compare
light and live stimulus in RATs in soccer players to assess whether these approaches
differentiate between different age groups. Therefore, the purpose of this study was to
determine possible age-related differences in speed, CODs and reactive agility in a group
of trained adolescent soccer players.
2. Materials and Methods
2.1. Subjects
A priori, the G*power 3.1 power analysis software was used to determine that the
required sample size is n = 72 given the critical F(69) = 3.13, eta2 = 0.13 p = 0.05, 1 − β = 0.8,
and number of groups = 3. A total of 75 adolescent male soccer players (aged 14–19 years),
who participate at the highest level of competition in Serbia at their age, were recruited
for this research (Table 1). The players were grouped based on their age to under 15 (U15;
n = 27), under 17 (U17; n = 25), and under 19 (U19; n = 23) players. Only ﬁeld players
were tested, with goalkeepers excluded. Written informed consent was obtained from the
players and their parents. Moreover, the ethics board of the Faculty of Sport and Physical
Education provided the approval of the research experiment (Ethical Board Approval No:
2019/31). Players were recruited if they had at least 5 years of experience in playing soccer;
had a general training history (more than three times per week) in the previous 12 months;
were currently training for soccer (more than 7 h per week); and did not have existing
medical conditions that would compromise study participation.
Table 1. Physical characteristics for U15 (n = 25), U17 (n = 27), and U19 (n = 23).
U15
U17
U19
Age
14.7 ± 0.6
16.2 ± 0.7
18.8 ± 0.7
Height
178.06 ± 5.82
180.49 ± 6.56
179.12 ± 5.45
Weight
69.06 ± 10.82
72.89 ± 8.48
70.70 ± 8.22
Experience (years)
5.1 ± 2.7
6.5 ± 2.9
7.3 ± 1.4
Training (min·week-1)
447 ± 126
475 ± 167
487 ± 130
U15—younger than 15 years; U17—younger than 17 years; U19—younger than 19 years; min·week—minutes
per week.
Int. J. Environ. Res. Public Health 2021, 18, 5883
3 of 7
2.2. Procedure
Testing was conducted at the beginning of the annual training season to limit differ-
ences in training status between players. All players followed a similar training program
under the supervision of their respective coaches. All performance tests were conducted
on the same day. Test sessions were undertaken between 09:00 and 13:00 h following at
least 8 h of sleep and 48 h of rest. All performance tests were performed on an outdoor
facility with artiﬁcial grass in favorable weather conditions (no wind or rain). Before
testing, a 20 min standardized warm-up was conducted, which consisted of low-intensity
running, acceleration runs, skipping and hopping exercises. Players were familiar with all
test procedures.
Height and weight measurements were taken in the morning. Height was measured
with a ﬁxed stadiometer (+0.1 cm, Holtain Ltd., Crosswell, UK), and body mass with a
digital balance (+0.1 kg, ADE Electronic Column Scales, Hamburg, Germany). The same
researcher conducted all the measurements.
Running speed. The running speed of players was determined using the time to 5, 10
and 20 m using infrared timing gates, 20-m sprint effort with photocell gates (Microgate,
Polifemo Radio Light, Bolzano, Italy) placed 0.4 m above the ground, with an accuracy of
0.001 s. The timer was automatically activated as participants crossed the ﬁrst gate at the
starting line with split times at 5 m and 10 m. Players were instructed to run as quickly
as possible over the 20-m distance from a standing start (crouched start positioned 0.5 m
behind the timing lights). Acceleration was evaluated using the time to cover the ﬁrst 5 m
of the 20-m test. Participants performed two trials with at least 3 min of rest between them.
The best performance of the two tests was used for analysis.
Change of direction speed test (CODs). The pre-planned agility test [22] is used to
evaluate CODs. Participants were asked to sprint as fast as possible for 5 m through a
triggered timing gate (start gate), make a 45◦ cut and sprint 5 m to the left and right through
a target gate. In this test, participants knew the cut direction. Running time was recorded
using photocell gates (Microgate, Polifemo Radio Light, Bolzano, Italy) placed 0.4 m above
the ground, with an accuracy of 0.001 s at the start and ﬁnish gates. The best time of three
attempts on the left and right side was considered for further analysis.
The reactive agility test (RAT) was performed according to the protocol described
previously by Chaouachi et al. [23]. In the current study, the RAT involved a decision-
making element provided by a live tester (RAT live) acting as an opponent and light stimuli
used instead of testers (RAT light). During RAT live, the tester had 4 options for each
condition: preplanned and randomly ordered (i.e., 8 trials). All these conditions were
provided to each player in 2 series (5–8 min between sets rest) in a random order. Players
were instructed to recognize the cues as soon as possible. Running time was recorded
using photocell gates (Microgate, Polifemo Radio Light, Bolzano, Italy) placed 0.4 m above
the ground, with an accuracy of 0.001 s. Total time (RAT TT live) and reaction time (RAT
RT live) were recorded for each trial, and the best performance was considered for the
analysis. The same conditions were used for RAT light, but this time the Witty SEM lights
were used instead the testers. When the participants pass the ﬁrst gate, the signal shows
right or left direction. The participants must react to the visual signal, change direction
and pass the third gate. Similar to RAT live, the total time (RAT TT light) and response
movement time (RAT RT light) were recorded for each trial, and the best performance was
taken for analysis.
Illinois agility test: The length of the ﬁeld is 10 m, while the width (distance between
the start and ﬁnish points) is 5 m. Four cones were placed in the center of the testing area
at a distance of 3.3 m from one another. Four cones were used to mark the start, ﬁnish
and two turning points. The subjects started the test lying face down, with their hands at
shoulder level. The trial started on the “go” command, and the subjects began to run as
fast as possible. The trial was completed when the players crossed the ﬁnish line without
having knocked any cones over. Best time out of three trials was used for analysis [24].
Int. J. Environ. Res. Public Health 2021, 18, 5883
4 of 7
2.3. Statistical Analysis
The analysis of the data obtained from the study was performed by SPSS software,
version 23.0 (SPSS Inc., Chicago, IL, USA). Data are reported as mean ± SD unless otherwise
stated. The Kolmogorov–Smirnov test was conducted to verify if all data met the normality
test assumption. Test–retest reliability was assessed for all tests using a one-way intra-class
correlation coefﬁcient (ICC) based on average measurements (ICC 1,k).
All analyses of variance (ANOVA) were performed on log-transformed data; for the
sake of clarity, however, they are reported non-transformed. Age-based comparisons of
study outcomes were made with one-way ANOVA (U15, U17, and U19). When ANOVA
showed a signiﬁcant group effect, between group differences were allocated by using post
hoc Bonferroni tests. Eta squared (η2) is reported as a measure of effect size and deﬁned as
small (0.01), medium (0.06), and large (0.14) according to Cohen. The level of signiﬁcance
was set at p < 0.05.
3. Results
3.1. Sample Characteristics
Table 1 shows the physical characteristics of the players according to age group.
Height and weight were similar across the groups (p > 0.05); therefore, adjustments were
not performed.
3.2. Study Outcomes in Relation to the Age Group of Soccer Players
On average, the U15 needed signiﬁcantly more time than U19 to perform all tests,
except sprint 5 m (p = 0.63), RAT light (p = 0.08), and RAT RT light (p = 0.37), which were
similar across the age groups. A signiﬁcantly slower average performance of sprint 20,
CODs left and right, and Illinois was also observed in U15 as compared to U17 and U19.
However, the U17 had a signiﬁcantly slower mean performance only of RAT live and RAT
RT live than the U19. Visit Table 2 for detailed results from a one-way analysis of variance.
Table 2. Times for 5 m, 10 m sprint, and 20 m sprint, and agility performance for the U15 (n = 25),
U17 (n = 27), and U19 (n = 23) soccer players.
Outcomes
U15
U17
U19
A One-Way ANOVA
F(1, 144)
η2
Sprint 5 m
1.16 ± 0.23
1.13 ± 0.19
1.11 ± 0.12
0.47
0.02
Sprint 10 m
1.93 ± 0.13 a
1.85 ± 0.18
1.83 ± 0.11
3.28 *
0.09
Sprint 20 m
3.38 ± 0.23 b
3.18 ± 0.27
3.16 ± 0.31
5.17 **
0.16
CODs left
2.25 ± 0.15 b
2.15 ± 0.17
2.12 ± 0.21
3.61 *
0.07
CODs right
2.27 ± 0.14 b
2.16 ± 0.19
2.13 ± 0.16
4.87 **
0.11
Illinois
15.82 ± 0.76 b
15.24 ± 0.53
14.93 ± 0.58
12.47 **
0.25
RAT light
2.69 ± 0.13
2.61 ± 0.16
2.60 ± 0.19
2.69
0.07
RAT live
2.58 ± 0.10
2.58 ± 0.11
2.48 ± 0.06 c
8.99 **
0.20
RAT RT light
1.44 ± 0.16
1.41 ± 0.16
1.38 ± 0.11
1.02
0.03
RAT RT live
1.49 ± 0.08
1.38 ± 0.10
1.31 ± 0.14 c
16.27 **
0.31
Values are mean ± SD. U15—younger than 15 years; U17—younger than 17 years; U19—younger than 19 years;
CODs left—change of direction left; CODs right—change of direction right; RAT light—reactive agility test with
witty SEM visual signals; RAT RT light—reaction time during RAT live; RAT live—reactive agility test with testers;
RAT RT light—reaction time during RAT light; * signiﬁcant age group effect at p ≤ 0.05; ** signiﬁcant age group
effect at p ≤ 0.01; a U15 and U19 signiﬁcantly different at p ≤ 0.05; b U15 signiﬁcantly different at p ≤ 0.05; c U19
signiﬁcantly different at p ≤ 0.05.
4. Discussion
The present study aimed to determine the difference in several performance indica-
tors relevant for soccer performance in adolescent players of different age groups. The
main ﬁnding of this study was that the reactive agility test with live testers was able to
differentiate U19 players from other age groups. Moreover, the U15 group showed slower
average performance in sprint 20, CODs left and right, and Illinois compared to U17 and
Int. J. Environ. Res. Public Health 2021, 18, 5883
5 of 7
U19. A possible explanation for these results could be found in the fact that modern soccer
training, with frequent changes in tactics based on the characteristics of the opponent, has
led to increased adaptability of player roles, especially in young players [9]. Moreover, it is
not so uncommon in youth training to change a player’s position in response to different
game situations, developing a large range of technical solutions useful for their future
soccer-playing career [25].
In the literature, sprinting ability over short (5 m) and longer distances (20 m) is
considered to require separate and speciﬁc biomechanical and neuromuscular qualities
and, therefore, training techniques [26]. When considering the U15, U17, and U19 players,
we found a difference between groups for 10 m and 20 m distance, which is in line with the
abovementioned fact. The current ﬁndings [14] show that there is no difference between
U17 and U19 for 20 m sprints which is, as well, presented in this study. In addition, we
found that U15 players had worse results than U17 and U19 players. Generally, most
studies that investigated age difference came to the conclusion that older age groups had
better results than younger groups [14,27]. These differences could be associated with the
maturity stage of players, which can affect U15 sprint performance more [28] compared to
U17 and U19. Moreover, post-pubertal players have accelerated gains in strength supported
by rapid gains in muscle mass [29], which may also contribute to the mentioned differences.
Our ﬁndings suggest that U19 and U17 players, who performed with similar results,
were statistically signiﬁcantly better at CODs left, CODs right and the Illinois test than U15
players. These results are similar to the ones found by [9], where U16 and U18 players
gave better results in the Illinois modiﬁed test. Additionally, their study showed that there
was no difference in the CODs left and CODs right test between U16 and U18 players,
but there were differences found between U14 players and the aforementioned groups.
A possible reason for non-existent differences between U19 and U17 players is that the
greatest individual differences in biological maturation were found in players 11–16 years
old [30]. Contrary to this study [14], Poljskic et al. concluded that U19 players were
signiﬁcantly better that U17 players. Taking everything into account, the superiority of
U19 players in agility performances may be observed as a direct consequence of their long
involvement in systematic soccer training and higher performance level due to the CODs.
Our results show that U19 players scored better in the RAT live test than U15 and U17
players. Additionally, we found that U19 players had better results than U15 and U17 in
reaction time with live stimuli. Therefore, in the current study, RATs clearly discriminated
U19 players from U15 and U17. A possible reason could be found in better anticipatory
skills in older adolescent players who have more games and experience behind them. They
have better ability to recognize relevant cues of testers, as previously demonstrated for
team sport athletes [31,32]. Our results are similar to Fiorilli et al. [13], where U16 and U18
players made better results than U14 in the reactive agility test. Moreover, Poljskic et al. [14]
showed that U19 players had better results than U17 in RAG (reactive agility) test. On
the other hand, there is a study that found no signiﬁcant difference between juniors (<18)
and seniors (>18) in speciﬁc reactive agility tests [33]. However, reactive agility is being
developed until the late adolescent age, when it can reach its peak, which could be the
reason for the discrepancy in the results.
It has been stated recently that intervention programs may have to be different for
different age stages [34]. According to our results, we could speculate that modern training
is similar for all age categories in adolescent soccer players. Nowadays, the training
contains sport-speciﬁc stimuli rather than generic and high-intensity training for physical
skills. Soccer players, who have anticipatory expertise and make decisions much faster, are
able to recognize and react promptly to a stimulus. Younger players with less experience
may need more time to respond to a stimulus before having the proper reaction in the
shortest time possible in order to avoid being executed by the opponent.
The main limitation of this study is that the attribution of physical ability could be to
talent or previous training. In our study, the players were interviewed about their current
training load (weekly time) and previous experience (years engaged in soccer). Moreover,
Int. J. Environ. Res. Public Health 2021, 18, 5883
6 of 7
they were from the same squad, with the same programs conducted in all categories.
Therefore, we could speculate if different approaches to training could contribute to differ-
ences in other variables. Future studies should examine players from different teams and
academies. Moreover, the maturity level was not introduced and taken into account due
to the fact that the majority of studies have focused largely on players 11–16 years of age,
where individual differences in biological maturation are perhaps the greatest. Another
limitation is the possibility of the circadian rhythm’s inﬂuence on performance [35] due to
the time the testing was conducted (9:00 to 13:00 h).
5. Conclusions
Reactive agility and COD speed are key skills required for soccer success, based on
greater levels of motor control. We found that the reactive agility test with a live tester
can be a signiﬁcant factor that differentiates between older and younger adolescent soccer
players. Moreover, our ﬁndings prove that ﬁeld-based tests including speed, change of
direction speed, and reactive agility are sufﬁciently sensitive to differentiate between a
group of adolescent soccer players. Further studies are needed to conﬁrm these results.
Author Contributions: Conceptualization, S.A. and N.T.; methodology, M.G.; software, D.M.; vali-
dation, S.A. and N.T.; formal analysis, D.M.; investigation, S.A.; resources, G.S.; data curation, S.A.,
M.G. and N.T.; writing—original draft preparation, S.A., M.S., and N.T.; writing—review and editing,
N.T. and D.M.; visualization, A.B. and M.S.; supervision, N.T.; project administration, S.A.; funding
acquisition, G.S. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: The study was conducted according to the guidelines of the
Declaration of Helsinki, and approved by the Institutional Review Board of the Faculty of Sport and
Physical Education, University of Novi Sad (Ref. No. 30-08-01/2018).
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.
Data Availability Statement: The data presented in this study are available on request from the
corresponding author. The data are not publicly available because they contain information that
could compromise the privacy of research participants.
Conﬂicts of Interest: The authors declare no conﬂict of interest.
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Speed, Change of Direction Speed and Reactive Agility in Adolescent Soccer Players: Age Related Differences.
Andrašić, Slobodan,Gušić, Marko,Stanković, Mima,Mačak, Draženka,Bradić, Asim,Sporiš, Goran,Trajković, Nebojša