sensors
Article
Physical Demands of U10 Players in a 7-a-Side Soccer
Tournament Depending on the Playing Position and
Level of Opponents in Consecutive Matches Using
Global Positioning Systems (GPS)
Antonio Hernandez-Martin 1
, Javier Sanchez-Sanchez 2,*
, Jose Luis Felipe 2
,
Samuel Manzano-Carrasco 1
, Carlos Majano 1
, Leonor Gallardo 1
and
Jorge Garcia-Unanue 1
1
IGOID Research Group, Physical Activity and Sport Sciences Department, University of Castilla-La Mancha,
45071 Toledo, Spain; Antonio.HMartinSan@uclm.es (A.H.-M.); samuel.Manzano@uclm.es (S.M.-C.);
carlos.majanoldm@gmail.com (C.M.); leonor.gallardo@uclm.es (L.G.); jorge.garciaunanue@uclm.es (J.G.-U.)
2
School of Sport Sciences, Universidad Europea de Madrid, 28670 Villaviciosa de Odón, Spain;
joseluis.felipe@universidadeuropea.es
*
Correspondence: javier.sanchez2@universidadeuropea.es
Received: 19 November 2020; Accepted: 4 December 2020; Published: 6 December 2020


Abstract: The aim of this study was to analyse the physical demands of U10 players in a 7-a-side-soccer
tournament based on the playing positions in 6 consecutive matches by global positioning systems
(GPS). Variables of total distance, relative distance in diﬀerent speed zones, maximum speed,
time interval between accelerations, maximum speed acceleration, maximum acceleration, acceleration
distance and the number of high-intensity accelerations were analysed. Diﬀerences between playing
positions were found in the total distance covered by the midﬁelders. They covered higher total
distances than the defenders (+1167 m; 95% CI: 411 to 1922 m; eﬀect size (ES) = 1.41; p < 0.05) and
forwards (+1388 m; CI 95%: 712 a 2063 m; TE = 0.85; p < 0.05). The total covered distance increased in
the ﬁnal rounds with respect to the group stage (p < 0.05; ES: 0.44 to 1.62), and high-intensity actions,
such as the number of accelerations, were greater in the ﬁnal rounds compared to the group stage
(p < 0.05; ES: 0.44 to 1.62). The physical performance of young football players in a tournament
with consecutive matches on a 40 × 62 m football ﬁeld on the same day is inﬂuenced by the playing
position and dependent on the level diﬀerence between opponents.
Keywords: tracking system; U10 soccer tournament; load; match analysis; players positions
1. Introduction
Football requires high-intensity actions such as jumps, changes of direction, accelerations,
decelerations and shots, interspersed with short recovery periods [1–3]. Physical demands such as
aerobic and anaerobic endurance, agility or speed [3] and physiological demands such as heart rate,
blood lactate concentration or RPE [4] and inter-limb strength asymmetry [5] present a critical inﬂuence
in the performance of football players.
Over recent years, scientiﬁc literature has focused on the movement patterns and physiological
requirements of football players (both adults and youths) [6–8]. Meanwhile, it has been argued that
players in the developmental stages (i.e. under U13), should not be considered as miniature adults [9]
and therefore, speciﬁc football training programmes should be developed in these stages. For this
reason, 7-a-side football emerged in Spain [as well as 8-a-side football in other countries, such as the
United Kingdom], is practised during grassroot stages and is well regulated by the Royal Spanish
Sensors 2020, 20, 6968; doi:10.3390/s20236968
www.mdpi.com/journal/sensors
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Football Federation with the purpose of promoting the progression of learning and improving physical
and tactical skills in young football players, such as reducing the size of the pitch [10]. This kind of
football practice adapted to the movement patterns and physiological demands on young football
players positively aﬀects the development of young football players [4]. On the other hand, it is
important to know the physical demands in a 7-a-side football game to prepare adequate training
programmes for football players in their growing and developmental stage [2].
In light of this, global positioning systems (GPS) and accelerometers have been used to describe
the physical profile of the football players in terms of distance and speed variables during friendly
matches[11–13], officialmatches[14]andtoquantifythephysicalperformanceineliteyouthplayers[15–17].
In addition, previous research on adult players indicates that a player’s position can inﬂuence
their physical demands [14] or the degree of fatigue during a match [18]. However, there is little
scientiﬁc evidence that has used GPS to analyse the physical demands during a U10-category 7-a-side
football tournament.
Modern elite football currently involves a large number of tournaments and matches throughout
the season, and it is not unusual for a team to play two or more matches in a very short period of
time [19]. Similarly, in grassroots football, there are many tournaments where usually 6 or more 7-a-side
matches are played in the same day. There are reasons to believe that too many games may lead to a lack
of motivation, concentration and more incremental fatigue, which can aﬀect coordination, leading to
worse performance and an increased risk of injury [20]. However, there is not enough research on
this topic. Therefore, the aim of this study was to analyse the physical demands in a 7-a-side-soccer
tournament based on the playing positions and level of opponents in consecutive matches.
2. Materials and Methods
2.1. Experimental Approach to the Problem
This study was designed to describe and compare distances and movement patterns (measured by
GPS) of U10 7-a-side football players during a tournament of 6 games played in less than 24 h with a
1-hour break between match 1 (T1) and match 2 (T2), 40 min between T2 and match 3 (T3), 2 h and
30 min between T3 and the quarter-ﬁnal match (TQ), 1 h and 35 min between TQ and the semi-ﬁnal
match (TS) and 55 min between TS and the ﬁnal match (TF). One half of 20 min was played in T1, T2,
T3, TQ and TS and one half of 30 min was played in the TF. The tournament was played on the football
ﬁeld of the size 40 × 62 m.
2.2. Sample
Six games of a 7-a-side soccer tournament in the central region of Spain played by a U10 amateur
soccer team [age = 10.2 ± 0.6 years; height = 136.5 ± 7.4 cm; body mass = 33.2 ± 6.13 kg] were analysed
using a GPS with sampling rates of 15 Hz (GPSport, Canberra, Australia). The analysed matches
correspond to the analysis of the players with more than 10 min played per match for the same team,
with a total of 48 observations of 8 players. There was no limit to the number of substitutions according
to the 7-a-side football regulations (the goalkeeper was excluded) from the tournament held on April
20th of the 2018/2019 season. The outﬁeld players were divided into forwards (FWs), midﬁelders (MFs)
and defenders (DFs). All subjects (and their parents or guardians) were carefully informed about the
study procedures and about the possible risks and beneﬁts associated with participating in the study,
and a signed informed consent was obtained before participating in any procedure related to the study.
The Clinical Research Ethics Committee of the Castilla-La Mancha Health Service [Spain] approved
this study based on the latest version of the Declaration of Helsinki (Ref.: 489/24022020).
2.3. Equipment
Position-tracking system (Figure 1). Global positioning systems (GPS) provide data on the location
and time of satellite tracking devices and have previously been used in various investigations [21–24].
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At least four satellites orbiting the Earth are required to determine the GPS position trigonometrically
and the GPS devices receive information that determines the signal traﬃc. Together with the addition
of triaxial accelerometers, magnetometers and gyroscopes, the data are more accurate. Depending on
the location and environmental obstruction, the signal quality may change. GPS devices (15 Hz, Spi Pro
X, GPSports, Canberra, Australia) have demonstrated better validity and reliability values than their
1 HZ and 5 HZ predecessors and similar values with 10 Hz [25]. The 15 Hz GPS has proven to be
reliable during speciﬁc football movements [26]. The GPS devices were installed and placed in a
custom-made child’s vest, located at the back of the torso and well-adjusted to the body.
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trigonometrically and the GPS devices receive information that determines the signal traffic. Together 
with the addition of triaxial accelerometers, magnetometers and gyroscopes, the data are more 
accurate. Depending on the location and environmental obstruction, the signal quality may change. 
GPS devices (15 Hz, Spi Pro X, GPSports, Canberra, Australia) have demonstrated better validity and 
reliability values than their 1 HZ and 5 HZ predecessors and similar values with 10 Hz [25]. The 15 
Hz GPS has proven to be reliable during specific football movements [26]. The GPS devices were 
installed and placed in a custom-made child’s vest, located at the back of the torso and well-adjusted 
to the body.  
 
Figure 1. Process of capturing the signal and transmitting the global positioning system (GPS) 
tracking devices. 
2.4. Procedures 
Body mass and height measurements were completed during the last week before the 
tournament. Body mass was determined using the DXA (Hologic Series Discovery QDR, Software 
Physician’s Viewer, APEX System Software Version 3.1.2. Bedford, MA, US) following the protocols 
described in previous research [27]; height (cm) was measured with a scientific height rod (Seca 214, 
Hamburg, Germany). Before the warm-up (20 min) and before each game, a GPS unit (15 Hz, Spi Pro 
X, GPSports, Canberra, Australia) was attached to each player’s torso, following the protocols 
described by Sanchez-Sanchez [28].  
A total of six matches were analysed in this study, all of them completed on the same day (20 
April 2019, in the central region of Spain). Before the first match, players had rested for <24 h since 
their last training session or game. The tournament was played on the football field (40 × 62 m) of the 
organising club, including a group stage with three matches (T1, at 9:10 h: final score 5-0; T2, at 10:30: 
final score 3-0; T3, at 11:30: final score 2-0); a second-round quarter-final game (TQ at 14:20: final score 
3-0); the semi-final (TS, at 16:15: final score 2-0); and the final (TF, at 17:30: final score 0-1). One half 
of 20 min (T1, T2, T3, TQ and TS) and one half of 20 min plus 10 min additional time were played in 
the TF. Given the U10 7-a-side football rules (regulated by the Royal Spanish Football Federation), 
there were unlimited substitutions. The study required football players to complete ≥10 min / game 
during each match of the tournament to be included in the research. 
2.5. Data Processing 
The GPS software (Team AMS R1 2019.1 software, GPSports, Canberra, Australia) provided 
information about the total distance (TD) covered during the game and the percentages of distance 
covered in each one of the six locomotor categories with speed ranges. All players participated in a 
10 m sprint test with a 5 m split time and the results were used to calculate speed zones for each 
player [29]: standing (zone (Z)1: 0–2 km·h−1); walking (Z2: 2–4 km·h−1); easy running (Z3: 4.1–7 km·h−1); 
fast running (Z4: 7.1–13.0 km·h−1); high-speed running (Z5: 13.1–17 km·h−1); sprinting (Z6: ≥17.1 
Figure 1.
Process of capturing the signal and transmitting the global positioning system (GPS)
tracking devices.
2.4. Procedures
Body mass and height measurements were completed during the last week before the tournament.
Body mass was determined using the DXA (Hologic Series Discovery QDR, Software Physician’s
Viewer, APEX System Software Version 3.1.2. Bedford, MA, US) following the protocols described
in previous research [27]; height (cm) was measured with a scientiﬁc height rod (Seca 214, Hamburg,
Germany). Before the warm-up (20 min) and before each game, a GPS unit (15 Hz, Spi Pro X,
GPSports, Canberra, Australia) was attached to each player’s torso, following the protocols described
by Sanchez-Sanchez [28].
A total of six matches were analysed in this study, all of them completed on the same day (20 April
2019, in the central region of Spain). Before the ﬁrst match, players had rested for <24 h since their
last training session or game. The tournament was played on the football ﬁeld (40 × 62 m) of the
organising club, including a group stage with three matches (T1, at 9:10 h: ﬁnal score 5-0; T2, at 10:30:
ﬁnal score 3-0; T3, at 11:30: ﬁnal score 2-0); a second-round quarter-ﬁnal game (TQ at 14:20: ﬁnal score
3-0); the semi-ﬁnal (TS, at 16:15: ﬁnal score 2-0); and the ﬁnal (TF, at 17:30: ﬁnal score 0-1). One half
of 20 min (T1, T2, T3, TQ and TS) and one half of 20 min plus 10 min additional time were played
in the TF. Given the U10 7-a-side football rules (regulated by the Royal Spanish Football Federation),
there were unlimited substitutions. The study required football players to complete ≥10 min/game
during each match of the tournament to be included in the research.
2.5. Data Processing
The GPS software (Team AMS R1 2019.1 software, GPSports, Canberra, Australia) provided
information about the total distance (TD) covered during the game and the percentages of distance
covered in each one of the six locomotor categories with speed ranges. All players participated in a 10 m
sprint test with a 5 m split time and the results were used to calculate speed zones for each player [29]:
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standing (zone (Z)1: 0–2 km·h−1); walking (Z2: 2–4 km·h−1); easy running (Z3: 4.1–7 km·h−1); fast running
(Z4: 7.1–13.0 km·h−1); high-speed running (Z5: 13.1–17 km·h−1); sprinting (Z6: ≥17.1 km·h−1). The GPS
software also provided information about the number and average distance of the sprints. Sprint time
(s) is the average time that athletes’ speed is above 17.1 km·h−1 and sprint distance (m) is the distance
covered with a speed above 17.1 km·h−1. In the same way, the GPS devices registered the maximum
acceleration peaks and the number of accelerations of the players in different ranges of intensity.
During actual match play, this study’s players showed maximal accelerations in the range of 2.7 and
3.0 m·s−2. As a consequence of this, and due to the classification proposed by Osgnach [30], we assumed
2.5 m·s−2, as variable high-intensity accelerations are the accelerations made in the maximum intensity
zone (ACCMAX). Also, using the data obtained from the Team AMS software, the average maximum
speed of each acceleration (VmaxACC; km·h−1) was calculated, together with the average values of the
time interval between accelerations (IACC; s), the average distance travelled in each acceleration greater
than 2.5 m·s−2 (TDACC; m) and the number of high-intensity accelerations (n) in each of the matches to
facilitate the comparison of results.
2.6. Statistical Analysis
Data encoding and data processing were carried out using the SPSS 25.0 statistical package
(SPSS Inc., Chicago, IL, USA). The normality of the variables has been analysed with the Shapiro–Wilk
test. After a descriptive analysis (means and standard deviations), a comparison test was performed
by the analysis of variance (ANOVA) in order to compare the physical performance variables between
the three positions, and the repeated measures analysis of variance (repeated measures ANOVA) to
compare the physical performance variables between the six matches. A Bonferroni post hoc test
was used for pairwise comparisons in the ANOVA test and DMS test for repeated measures ANOVA.
Eﬀect size (ES; Cohen’s d) was included and evaluated as follows: 0–0.2 = trivial; 0.2−0.5 = small;
0.5−0.8 = moderate; and >0.8 high. The statistical signiﬁcance criterion was established at p < 0.05.
3. Results
Table 1 shows the results obtained from the GPS according to the playing position. Midﬁelders had
signiﬁcantly higher values than defenders in TD, Z4, Z5, Z6, ACCMAX and HI acceleration and
signiﬁcantly lower values in Z2 (p < 0.05; ES: 1.01 to 2.85). In addition, midﬁelders also revealed
signiﬁcantly higher values in TD, Z4, Z5, Z6, VMAX, VMaxACC and HI acceleration and signiﬁcantly
lower values in Z2 and Z3 than the forwards (p < 0.05; ES: 0.85 to 2.41). In Z1, IACC and TDACC no
signiﬁcant diﬀerences were found (p > 0.05).
In the results obtained from the GPS, diﬀerences in the relative distances covered in the matches
were identiﬁed (p < 0.05; Figure 2). The players showed no signiﬁcant diﬀerence in Zone 6. Players in
TQ covered a shorter distance in Zone 5 than in T1 (p < 0.05; ES: 0.93). The results obtained by the
players in the distances covered in Zone 4 showed a greater distance covered in T1 compared to TS
(p < 0.05; ES: 1.04) and in T2 with respect to TQ, TF (p < 0.05; ES: 0.77 to 1.09) being the greater distance
covered in T2 (−8.6%; CI 95%: 3.8 to 13.3%; TE = 1.14; p < 0.05) with respect to TS. The distance travelled
by players in lower speed zones showed greater variability between matches. Players in Zone 3 showed
higher distances in TQ than TS (p < 0.05; ES: 0.43). Furthermore, in T3 they covered signiﬁcantly lower
total distance than in T1, T2, TQ, TS and TF (p < 0.05; ES: 0.85 to 1.65). Players in Zone 2 travelled a
lower distance in T1 than in TQ, TS and TF (p < 0.05; ES: 0.89 to 1.30). Also, in TS and TF the distance
they covered in Zone 2 was greater than in T2 (p < 0.05; ES: 0.73 to 0.93); in addition, in TF the players
travelled more distance in Zone 2 than in TQ (p < 0.05; ES: 0.37). However, no signiﬁcant diﬀerences
were found in the distances covered in Zone 1 by the players in the diﬀerent matches.
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Table 1. Diﬀerences between match positions in load metrics.
Defenders
Midﬁelders
Forwards
TD (m)
1515.78
±
800.94 b
2683.13
±
854.69 c
1294.94
±
783.26
Distance Z1 (%)
1.50
±
0.29
1.56
±
0.36
1.85
±
0.54
Distance Z2 (%)
30.12
±
6.08 b
18.87
±
1.82 c
25.25
±
6.90
Distance Z3 (%)
43.60
±
4.38
39.42
±
3.99 c
43.98
±
5.69
Distance Z4 (%)
18.89
±
6.29 b
30.34
±
2.67 c
23.14
±
7.28
Distance Z5 (%)
4.77
±
2.31 b
7.42
±
2.54 c
4.98
±
3.19
Distance Z6 (%)
1.12
±
0.91 b
2.39
±
1.61 c
0.80
±
0.92
VMAX (km·h−1)
18.57
±
3.39
20.85
±
1.80 c
17.44
±
3.19
IACC (s)
2.66
±
0.89
2.84
±
0.45
2.45
±
0.63
VMaxACC (km·h−1)
14.51
±
2.04
14.60
±
1.26 c
13.10
±
1.53
ACCMAX (m·s−2)
2.71
±
0.11 b
2.88
±
0.15
2.75
±
0.18
TDACC (m)
9.44
±
4.70
10.22
±
2.18
7.91
±
2.98
HI acceleration (n)
3.91
±
2.12 b
12.89
±
5.07 c
3.69
±
2.56
b = significant differences between defenders and midfielders; c = significant differences between midfielders
and forwards; m = metres; % = relative distance percentage; s = seconds; km·h−1 = kilometers per hour;
m·s−2 = metres per second squared; n = number of accelerations; TD = total distance; VMAX = maximun speed;
IACC = time interval between accelerations; VmaxACC = average maximum speed acceleration; MaxACC = maximum
acceleration; TDACC = average distance travelled in acceleration greater than 2.5 m·s−2; HI acceleration = number of
high-intensity accelerations.
Figure 2. Mean and standard deviation of % distance covered in Zone 1 (standing); Zone 2 (walking);
Zone 3 (easy running); Zone 4 (fast running); Zone 5 (high-speed running) and Zone 6 (sprinting) of
each tournament match. Match 1 (T1), match 2 (T2) and match 3 (T3): group stage; TQ = quarter ﬁnal;
TS = semi-ﬁnal and TF = ﬁnal. b = signiﬁcant diﬀerences with T3. c = signiﬁcant diﬀerences with TQ.
d = signiﬁcant diﬀerences with TS. e = signiﬁcant diﬀerences with TF.
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Figure 3 shows the results of the GPS in relation to TD, VMAX, IACC, VMaxACC, ACCMAX, TDACC
and HI acceleration of each match played in the tournament. The players covered a greater total distance
in TF than in T3, TQ and TS. The time interval between accelerations (IACC) was greater for players in TF
than in TQ. Players achieved higher VMaxACC peaks in TF than in T2 and higher HI acceleration than
in T3 and TQ (p < 0.05; ES: 0.44 to 1.62). The players covered a greater total distance in TS than in T3.
Players reached higher VMaxACC peaks in TS than in T2 and showed a higher number of high-intensity
accelerations (HI acceleration) than in T3 (p < 0.05; ES: 0.78 to 1.50). The players covered a greater total
distance in TQ than in T3 (p < 0.05; ES: 0.52). However, the time interval between accelerations (IACC)
was shorter in TQ than in T3, as was the total distance travelled in acceleration p < 0.05; ES: 1.57 to
1.65). The players covered a lower total distance in T3 than T2 and T1, the peaks of VMaxACC were
lower than in T2 and showed a lower number of high-intensity accelerations (HI accelerations) than in
T1 (p < 0.05; ES: 0.74 to 2.01). The players in T2 performed a lower total distance than in T1 (p < 0.05;
ES: 1.59). In VMAX and ACCMAX no significant differences were found.
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TS= semi-final and TF= final. b= significant differences with T3. c= significant differences with TQ. d= 
significant differences with TS. e= significant differences with TF. 
Figure 3 shows the results of the GPS in relation to TD, VMAX, IACC, VMaxACC, ACCMAX, TDACC and 
HI acceleration of each match played in the tournament. The players covered a greater total distance 
in TF than in T3, TQ and TS. The time interval between accelerations (IACC) was greater for players in 
TF than in TQ. Players achieved higher VMaxACC peaks in TF than in T2 and higher HI acceleration 
than in T3 and TQ (p < 0.05; ES: 0.44 to 1.62). The players covered a greater total distance in TS than 
in T3. Players reached higher VMaxACC peaks in TS than in T2 and showed a higher number of high-
intensity accelerations (HI acceleration) than in T3 (p <0.05; ES: 0.78 to 1.50). The players covered a 
greater total distance in TQ than in T3 (p <0.05; ES: 0.52). However, the time interval between 
accelerations (IACC) was shorter in TQ than in T3, as was the total distance travelled in acceleration p 
<0.05; ES: 1.57 to 1.65). The players covered a lower total distance in T3 than T2 and T1, the peaks of 
VMaxACC were lower than in T2 and showed a lower number of high-intensity accelerations 
(HI  
Figure 3. Mean and standard deviation of total distance (TD; m); maximum speed (VMAX; km·h−1);
time interval between accelerations (IACC; s); average maximum speed acceleration (VMaxACC; km·h−1);
maximum acceleration (MaxACC; m·s−2); average distance travelled in acceleration greater than 2.5 m·s−2
(TDACC; m); n of high-intensity accelerations (HI accelerations; n); T1, T2 and T3: group stage;
TQ = quarter final; TS = Semi-final and TF = final. a = significant differences with T2; b = significant
differences with T3; c = differences with TQ; d = significant differences with TS; e = significant differences
with TF.
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4. Discussion
The current study aimed to describe and analyse the physical demands of U10 7-a-side players
during a tournament based on the playing positions in consecutive matches. The main ﬁndings indicated
that in total distance, as high-intensity distance, midﬁelders covered more distance; furthermore,
high-intensity actions were higher in midﬁelders compared to defenders and strikers. These diﬀerences
in the midﬁelders, accumulated in six matches, can become very important in the development of
the diﬀerent phases of the tournament. By exchanging positions, these demands could be equalised.
In addition, the distances covered at high intensity reduced as the tournament progressed; however,
in the ﬁnal rounds the players showed a tendency to increase the total distance and high-intensity
actions compared to the initial matches of the tournament. Thus, these results suggest that physical
demands during a multi-match tournament on the same day inﬂuence a decrease in the performance
of the U10 players.
The U10 players used 15 Hz GPS devices, which showed higher reliability and validity values
than 1 Hz and 5 Hz devices in distance covered at high speed, accelerations and short distances [25].
Previous 15 Hz GPS validation studies recreated football movements and showed a commensurate
degree of accuracy in measuring distance by walking, jogging, running and sprinting linearly
(CV 2.95–3.16%) and curvilinearly (CV −2.20–1.92%) [26]. The 15 Hz GPS devices showed valid results
at the maximum speed reached by the U10 players (< 20 km/h−1), however these devices would not be
valid enough to record maximum speed in adults, as reliability decreases by values > 20 km/h−1 [31].
With regard to accelerations, they oﬀer reliability values (CV < 10%) for accelerations of less than 3 m/s,
which are those recorded by U10 players, while the reliability is lower (CV = 30%) for accelerations
greater than 3 m/s [32].
All of the multi-match tournament analysis data in the current study are novel, as the match
analysis of U10 players has not been previously described. In recent years, physical performance in
football has been studied during training and competition in male participants [33–35]. These studies
have examined diﬀerent physical parameters, such as total distance covered, sprint and high-intensity
movement patterns, patterns which, in central positions, are able to maintain and even increase in three
consecutive matches [36,37]. The literature has shown that these physical demands diﬀer between
playing positions [38]. Thus, attacking and defending positions are characterised by high-intensity
activities, producing the highest sprint distance, and a number of accelerations and decelerations [39,40].
The diﬀerences observed in TD between diﬀerent positions may be explained by the diﬀerent movement
patterns required for each football-speciﬁc position. According to previous studies, [41,42] our results
revealed that MFs produce the highest TD compared to other positions and DFs produce the lowest
TD and high-speed distances. Buchheit et al. [15] observed positional diﬀerences in U13–U18 players
regarding the distance covered during matches, especially in high-intensity actions. Similar results
were also observed [17] in elite youth football players aged 8–18 years. Thus, although our study
allows quantifying by positions, it is important to highlight the frequency of coaches interchanging
players during the diﬀerent multi-match tournaments to improve technical and tactical abilities in
youth football players.
Analysing the results of the distances covered in each zone showed that Zone 3 is where a greater
distance was recorded in consecutive matches by players (35–45%) as has been shown previously
for adult players [39]. Previous studies showed that jogging is the majority movement pattern
in football [29]. Therefore, U10 football players were required to use a longer time performing
lower-intensity exercise to recover the match eﬀort made [29]. Similarly, walking distances were of
signiﬁcantly longer relative distance (30%) in TS than in the other phases of the tournament. Conversely,
medium-intensity running showed less distance covered (20%) by the participants in TF compared to
the other phases. This may be attributed to the physiological demands needed to maintain this kind of
velocity run, as it has been demonstrated that during a 30 s all-out cycle sprint the percentage decline
in power output is lower in children than in adults [43]. If we compare the muscular characteristics
of adults and children, the greater resistance to fatigue shown by children compared to adults could
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be related, since children have less muscle mass, thus generating less absolute power, and they have
lower glycolytic activity and higher muscle oxidative activity [44]. However, the distance covered
at high-intensity running was signiﬁcantly higher in T1 compared to TQ, revealing how players
decrease intensity in actions based on the course of the diﬀerent matches of the tournament as well as
increased fatigue and physical capacity [45]. No signiﬁcant diﬀerences were found in standing and
sprint distances between the diﬀerent rounds of the tournament, despite showing a longer duration in
the ﬁnal match, probably due to contextual variables of the matches. This is an interesting ﬁnding,
as high-intensity and sprint running distance has been described to distinguish the standard of senior
football players [46].
In the present study, U10 7-a-side football players covered approximately between 1200 and
2500 m. However, this total distance drops signiﬁcantly in the last group match, and then again sees an
increase in the progression from this phase to the ﬁnal match. These values are less than those reported
by other studies, where the players of this same category covered a greater distance (4056 m) [29].
This could be explained by the longer duration of the matches and the relaxation; once the team
manages to move from the group stage there is an increase in intensity as the ﬁnal phase is reached.
However, this does not happen in the same way with other variables—for example, VMAX and ACCMAX
remain constant throughout the tournament. This may be due to the energy path required for these
eﬀorts, which depends on the capacity of each player, and so the diﬀerent fatigue-related physiological
mechanism appears to operate in diﬀerent periods of a football game [47]. However, TDACC is greater
in the ﬁrst matches, especially in T3, because the next round of the tournament is at stake. Our results
show that in the ﬁnal rounds of the tournament, the number of accelerations is increased, since the goal
of winning the tournament is about to be achieved. In contrast, the distance covered by accelerating
is less than that found in the group stage, caused mainly by the high physical load and increased
fatigue. The ﬁndings are similar to previous studies [28,48] because in U10 players the contribution
of the anaerobic metabolism is not as developed as in adults [49], which may help immature players
to reduce metabolic stress, but on the other hand may limit their capacity to perform high-intensity
actions, especially when inadequate recovery time is provided [48].
There are some limitations in this study, one of which is that the sample was composed of football
players belonging to the same team, so more studies are needed to conﬁrm the results obtained in this
study, and it would also be interesting to complete the results by analysing more players from several
teams at the same time. Furthermore, the system of play used during matches was not taken into
account, as match training has been shown to have an impact on very high-intensity running activities
with and without the ball in adult players [50], and could also aﬀect the physical performance of the
match analysed in this study. The 7-a-side soccer rule on unlimited substitutions of U10 players is also
a limitation, as it could induce a great variability among U10 players in terms of distance travelled and
acceleration during matches.
5. Conclusions
The present study indicates that the physical performance of U10 football players in a tournament
with diﬀerent matches on the same day is inﬂuenced by the playing position and is dependent on
the level diﬀerence between opponents. Midﬁelders covered more distance in high-intensity zones
(Zone 5 and Zone 6) and performed more high-intensity actions (VMaxACC, MaxACC, TDACC and
HI accelerations) than defenders and forwards. Regarding the level diﬀerence between opponents,
the distances covered at high intensity were reduced as the tournament progressed; however, the total
distance and high-intensity accelerations are higher in the ﬁnal rounds, probably due to the level of the
opponent and the longer duration of the ﬁnal match. The results of the present study oﬀer additional
information to youth football coaches, enabling them to know the physical demands that are required
in each of the matches of a tournament, and thus adjust the load of the players depending on the level
diﬀerence between opponents in order to increase their performance in key matches. Furthermore,
it allows training and load distribution to be designed according to the demands of a congested
Sensors 2020, 20, 6968
9 of 11
schedule, taking into account the possibility of not having a limit on replacements. The results support
new studies related to the performance of players in diﬀerent tournaments of diﬀerent amateur football
categories, an area with great complexities that has not been practically investigated until now.
Author Contributions: Conceptualisation, J.S.-S. and J.G.-U.; data curation, A.H.-M.; formal analysis, J.G.-U. and
C.M.; investigation, S.M.-C., J.L.F., and A.H.-M.; methodology, A.H.-M.; project administration, L.G.; resources,
J.S.-S. and J.L.F.; software, J.G.-U.; supervision, L.G. and J.L.F.; validation, J.G.-U. and J.L.F.; writing–original draft,
A.H.-M. and S.M.-C.; writing–review and editing, L.G., J.S.-S., J.L.F. and J.G.-U. All authors have read and agreed
to the published version of the manuscript.
Funding: No funding has been received for the development of this study.
Acknowledgments: The authors would like to thank the football sport schools for their support and collaboration,
as well as all the football players who contributed in this research. A.H.-M. acknowledges the Spanish Ministry of
Science, Innovation and Universities for funding the development of his PhD (Grant Number: FPU18/03222).
S.M.-C. acknowledges the University of Castilla-La Mancha for funding the development of his PhD (2019/5964).
J.G.-U. acknowledges “Fondo Europeo de Desarrollo Regional, Programa Operativo de la Región de Castilla-La
Mancha” (2018/11744) for funding the development of his research.
Conﬂicts of Interest: The authors declare no conﬂict of interest.
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Physical Demands of U10 Players in a 7-a-Side Soccer Tournament Depending on the Playing Position and Level of Opponents in Consecutive Matches Using Global Positioning Systems (GPS).
Hernandez-Martin, Antonio,Sanchez-Sanchez, Javier,Felipe, Jose Luis,Manzano-Carrasco, Samuel,Majano, Carlos,Gallardo, Leonor,Garcia-Unanue, Jorge