Small-Sided Games Are Not as Effective as Intermittent Running to Stimulate Aerobic Metabolism in Prepubertal Soccer Players

Abstract

Purpose:
The purpose of this study was to investigate the influence of the soccer pitch area during small-sided games (SSG) in prepubertal children on physiological and technical demands, and to compare them, for the physiological demands, to high-intensity interval training (HIIT).

Methods:
Ten young soccer players (13.0 [0.3] y) performed a HIIT and 3 SSG of various field sizes (30 × 20 m, 42 × 38 m, and 51 × 34 m). Each SSG was performed with 5 players per team, during 4 × 4-minutes interspaced with 1 minute of passive recovery in between. HIIT also followed a 4 × 4-minute protocol with running speed set on an individual basis. Heart rate (HR) was continuously monitored during training sessions. For each exercise modality, time spent above 90% of HRmax (T≥90%,HRmax) was calculated, and technical actions were quantified during SSG by video analysis.

Results:
T≥90%,HRmax was similar between the 3 SSG (∼587 [276] s; P > .2) but 24% to 37% lower than during HIIT (826 [140] s, P < .05). Coefficients of variations in T≥90%,HRmax were 2.3 to 3.5 times larger in SSG compared with HIIT. For technical actions, greater number of possessions (21 [6] vs ∼14 [4]), and lower ball touches per possession (2.4 [0.6] vs ∼2.9 [0.6]) were found in the small SSG compared with larger SSG, respectively (P < .05).

Conclusion:
The 3 SSG led to lower acute stimulation of the aerobic metabolism, suggesting a lower potential for chronic aerobic adaptations, compared with HIIT. Moreover, interindividual variability in the physiological response was substantially greater in SSG compared with HIIT, indicating increased heterogeneity among players performing the same training protocol.

Full text

Small-Sided Games Are Not as Effective as Intermittent Running
to Stimulate Aerobic Metabolism in Prepubertal Soccer Players
Anasthase Massamba, Stéphane P. Dufour, Fabrice Favret, and Thomas J. Hureau
Purpose:The purpose of this study was to investigate the influence of the soccer pitch area during small-sided games (SSG) in
prepubertal children on physiological and technical demands, and to compare them, for the physiological demands, to high-
intensity interval training (HIIT). Methods:Ten young soccer players (13.0 [0.3] y) performed a HIIT and 3 SSG of various field
sizes (30 ×20 m, 42 ×38 m, and 51 ×34 m). Each SSG was performed with 5 players per team, during 4 ×4-minutes interspaced
with 1 minute of passive recovery in between. HIIT also followed a 4 ×4-minute protocol with running speed set on an individual
basis. Heart rate (HR) was continuously monitored during training sessions. For each exercise modality, time spent above 90% of
HR
max
(T
≥90%,HRmax
) was calculated, and technical actions were quantified during SSG by video analysis. Results:T
≥90%,HRmax
was similar between the 3 SSG (∼587 [276] s; P>.2) but 24% to 37% lower than during HIIT (826 [140] s, P<.05). Coefficients
of variations in T
≥90%,HRmax
were 2.3 to 3.5 times larger in SSG compared with HIIT. For technical actions, greater number
of possessions (21 [6] vs ∼14 [4]), and lower ball touches per possession (2.4 [0.6] vs ∼2.9 [0.6]) were found in the small SSG
compared with larger SSG, respectively (P<.05). Conclusion:The 3 SSG led to lower acute stimulation of the aerobic
metabolism, suggesting a lower potential for chronic aerobic adaptations, compared with HIIT. Moreover, interindividual
variability in the physiological response was substantially greater in SSG compared with HIIT, indicating increased
heterogeneity among players performing the same training protocol.
Keywords:aerobic capacity, endurance exercise performance, football, high-intensity interval training, young soccer athletes
While soccer performance is multifactorial,
1
suggesting that
time is needed to develop every required technical skill or physical
quality, games frequency rises, leading to reduction in training
sessions (ie, time). In this context, small-sided games (SSG),
characterized by modified games played on reduced pitch areas
and often using adapted rules involving a smaller number of
players compared with traditional games,
2
is an attractive exercise
modality to simultaneously develop endurance capacity and tech-
nical soccer skills.
3
Indeed, as SSG are performed with the ball
and require dribbling, passing, and shooting, they are thought to
stimulate technical aspects.
4,5
In terms of physical demand, SSG
may be an effective training mode to enhance aerobic fitness,
6
which plays a pivotal role in soccer. For example, it was found that
significant improvements in maximal oxygen uptake ( ˙
VO2max) led
to a higher number of sprints per game and a higher distance
covered during competitive match play in elite junior players.
7
Endurance aerobic intensity is often assessed using heart rate
(HR) during training sessions, based on the linear relationship
between HR and ˙
VO2.
8
However, studies investigating the acute
influence of SSG on aerobic fitness often reported the mean HR
throughout the session,
6,9
which does not provide accurate indica-
tions for potential improvements in ˙
VO2max. Instead, the time
spent at or above 90% ˙
VO2max has been identified as a key
indicator for aerobic adaptations,
7,10,11
but is almost absent from
SSG scientific literature with only few exceptions.
2,12
Importantly,
it is possible to observe similar mean HR for 2 training sessions
while the time spent at or above 90% (T
≥90%,HRmax
) would be
drastically different. It is therefore crucial to assess aerobic inten-
sity using the T
≥90%,HRmax
.
During SSG, a wide range of parameters influence the physio-
logical demand, such as the number of players, the rules, or the
pitch area.
2
More specifically, the bigger is the pitch area, the
higher is the aerobic contribution in adult players.
13
However, it
is also important to compare these physiological demands to
high-intensity interval training (HIIT), established as the “gold-
standard,”most effective method to improve aerobic metabolism
(ie, ˙
VO2max).
14
HIIT is characterized by repeated bouts of high-
intensity work performed above the lactate threshold, interspersed
by periods of low-intensity exercise or complete rest.
15
The major
difference between HIIT and SSG in terms of physiological stress
is that HIIT is set on an individual basis (ie, running distance/speed
calculated for each player to reach a targeted HR) while it is not for
SSG, meaning that training intensity is more difficult to control.
Therefore, it would be insightful to investigate both the intensity
and the interindividual variability of the physiological response
when comparing HIIT and SSG.
Previous studies found that SSG HR responses were similar to
HIIT in adults.
16
However, data are missing, using the above-
mentioned methodology, in prepubertal players. While SSG are
already widely utilized in elite soccer academies to develop aerobic
capacity in young players, it is important to emphasize that results
found for adults may not be translated into prepubertal children
characterized by substantial differences in their physiology due to
their immature system.
17
Of note, aerobic metabolism of prepu-
bertal children seems close to well-trained adult endurance athletes
for several aspects,
17
strengthening the idea that they likely need to
be exposed to a high-intensity exercise to get significant ˙
VO2max
improvements. Then, if SSG are often preferred by coaches for the
development of young players because they are undeniably more
Massamba, Dufour, Favret, and Hureau are with the Faculty of Medicine, Mito-
chondria, Oxidative Stress and Muscular Protection Laboratory (EA 3072), and the
Faculty of Sport Sciences, European Center for Education, Research and Innovation
in Exercise Physiology (CEERIPE), University of Strasbourg, Strasbourg, France.
Massamba is with the Racing Club de Strasbourg Alsace, Strasbourg, France.
Hureau (t.hureau@unistra.fr) is corresponding author.
1
International Journal of Sports Physiology and Performance, (Ahead of Print)
https://doi.org/10.1123/ijspp.2019-0966
© 2020 Human Kinetics, Inc. ORIGINAL INVESTIGATION

soccer specific
18
and also more enjoyable by players,
9
it is still
critical to assess their efficacy compared with HIIT to provide
insights for coaches interested in fine-tuning physical/technical
stimuli for their training programs.
The purpose of the present study was to investigate the
influence of the soccer pitch area during SSG in prepubertal
children on physiological and technical demands, and to compare
them, for the physiological demands, to HIIT. We hypothesized
that larger SSG would lead to greater physiological demand
(ie, time spent at high intensity), while reducing technical demand
(ie, less passes, more ball touches per possession), compared with a
smaller SSG, in prepubertal players. Moreover, we hypothesized
that SSG would lead to reduced time spent at high intensity as well
as larger interindividual variability in the HR response compared
with HIIT sessions.
Methods
Participants
Ten boys from the academy of an elite French soccer team took part
in the present study (age 13.0 [0.3] y; height 152 [8] cm; weight 41
[7] kg). Mean age from peak height velocity was calculated (−1.5
[0.6] y) using a validated, noninvasive method based on anthropo-
metric variables to assess player’s maturity.
19
Participants practiced
2 to 3 training sessions per week and played 1 game of 80 minutes
per week on a regular-sized soccer pitch (60 ×100 m) with the rules
of 11-a-side football. Written informed consent was obtained from
each participant prior to the beginning of the study. The study was
approved by the local ethics committee and conducted according to
the Declaration of Helsinki for human experimentation.
Experimental Protocol
Study participation included 5 visits, each separated by 3 to 7 days,
and were performed at the same time on each day. During the first
session, participants performed a maximal incremental test to
determine their individual speed for the subsequent HIIT session.
Then, on 4 different sessions, participants performed 3 SSG with
various pitch areas and 1 HIIT session, following the same exercise
pattern (4 ×4 min interspersed with 1 min of passive recovery).
Maximal Incremental Test
Participants performed the 30-15
IFT
maximal incremental exercise
test
20
on a turf soccer pitch to determine their end-test speed (S
peak
)
and maximal HR (HR
max
). The test (30-s run and 15-s rest) started at
8.0 km·h
−1
and speed was increased by 0.5 km·h
−1
every 45 second.
HR was continuously measured during testing using HR monitors
(Polar Team
2
; Polar Electro Oy, Kempele, Finland). For each
subject, individual HR
max
was collected and 90% and 95% of HR
max
were calculated. ˙
VO2max was estimated using the following
equation
21
:
˙
VO2max mL · min−1·kg
−1=28.3 −2.15 ×G−0.741 ×A−0.0357
×BM þ0.0586 ×A×Speak þ1.03 ×Speak
where G is the gender (female = 2 and male = 1), A is the age (years),
BM is the body mass (in kilogram) of the participant, and S
peak
is the
end-test speed of the 30-15
IFT
maximal incremental test.
Small-Sided Games
The 3 SSG were performed on a natural turf surface with 5 players
per team with small (SSG
Sm
), medium (SSG
Md
), and large (SSG
Lg
)
pitch areas of similar length ×width proportions (Table 1). Com-
pared with SSG
Sm
,
16,22,23
playing area was doubled (SSG
Md
) and
tripled (SSG
Lg
) to presumably promote T
≥90%,HRmax
,
21,23
to give
the opportunity of SSG to reach, or surpass, HIIT intensity. Each
SSG followed the same exercise pattern, with 4 ×4 minute playing
bouts interspersed with 1 minute of passive recovery, for a total
duration of 20 minutes. Players had to stop the ball with their foot
backside to the limits of the pitch to score while the number of ball
touches per possession was free. Several balls were placed all
around the pitch to ensure fast throw-in when the ball went out of
play. Uniform verbal encouragements were given to all participants
by the team’sfitness coach throughout the sessions. Time spent at
high intensity from the HR response were calculated (ie, T
≥90%,
HRmax
and T
≥95%,HRmax
) for each SSG.
Each game has been filmed using a full high-definition camera
(DH-SD22404T-GN; Dahua Technology, Binjiang, China) located
on an extendable mast (height 7.30 m) to assess technical actions
during SSG. Three categories of technical actions were analyzed
for each player, namely number of passes, dribbles, and posses-
sions.
24
Video analysis was conducted using LongoMatch (version
3.1.7; Fluendo SA, Barcelona, Spain).
High-Intensity Interval Training
Similar to SSG, participants performed 4 sets of 4 minutes of exercise
interspersed with 1 minute of passive recovery during the HIIT
session. Each set consisted of 30-second running intervals at 100% of
the participant’s individual S
peak
interspersed with 30 seconds of
passive recovery. Of note, the 30- to 30-second intermittent exercise
has been described as a training modality maximizing the time spent
at high intensity.
25
HIIT was performed in shuttle with one 180°
change of direction. HR was recorded throughout the session.
Statistical Analysis
Normality of all dependent variables and sphericity of variance of
the distribution were assessed using the Kolmogorov–Smirnov test
Table 1 Characteristics of the 3 SSG
Number
of players
Pitch
dimensions, m
Pitch
area, m
2
Work/rest ratio,
min
Number
of sets
Total duration,
min
SSG
Sm
5vs5 30×20 600 4/1 4 20
SSG
Md
5vs5 42×28 1176 4/1 4 20
SSG
Lg
5vs5 51×34 1734 4/1 4 20
Abbreviations: SSG, small-sided games; SSG
Sm
, small SSG; SSG
Md
, medium SSG; SSG
Lg
, large SSG. Note that SSG were matched for length ×width proportions despite
changes in the pitch area.
(Ahead of Print)
2Massamba et al

and the Mauchly test, respectively. A Greenhouse–Geisser correc-
tion was used when sphericity was violated. One-way analysis of
variances were used to test differences between each training
modality (SSG
Sm
, SSG
Md
, SSG
Lg
, and HIIT) in physiological
and technical responses. When a significant difference was identi-
fied, multiple-comparison analysis was performed using Fisher
least significant difference test. Between-subjects coefficients of
variation were calculated for T
≥90%,HRmax
and T
≥95%,HRmax
to
evaluate differences in interindividual variability between training
sessions. Statistical analyses were conducted using Statistica (ver-
sion 8.0; StatSoft Inc, Tulsa, OK). The relationship between S
peak
and T
≥90%,HRmax
, during the 3 SSG were tested by calculating
Pearson correlation coefficients (r
2
). Data presented are expressed
as mean (SD). Statistical significance was set at P<.05.
Results
Maximal Incremental Test
The S
peak
observed at end test was 19.5 (0.8) km·h
−1
, and HR
max
was 202 (4) beats per minute. Estimated ˙
VO2max
21
was 50.0
(0.8) mL·min
−1
·kg
−1
.
Cardiac Responses to SSG and HIIT
Intensity of the Response. As illustrated in Figure 1A,T
≥90%,
HRmax
was 24% to 37% greater in HIIT (826 [140] s) compared with
SSG
Sm
(613 [244] s, P= .02), SSG
Md
(628 [278] s, P= .03), and
SSG
Lg
(519 [307] s, P= .001). T
≥90%,HRmax
was similar between
the 3 SSG. T
≥95%,HRmax
(Figure 1B) was 32% to 61% greater in
HIIT (387 [235] s) compared with SSG
Sm
(150 [159] s, P= .01)
and SSG
Lg
(218 [275] s, P= .04), but not different compared with
SSG
Md
(264 [271] s, P= .13). T
≥95%,HRmax
was similar between the
3 SSG. Average relative intensity was similar between the 3 SSG
(SSG
Sm
, 85% [4%] HR
max
; SSG
Md
, 87% [4%] HR
max
; and SSG
Lg
,
85% [5%] HR
max
). Average relative intensity during HIIT (90%
[3%] HR
max
) was greater than during SSG
Sm
(P= .01) and SSG
Lg
(P= .002), but not different compared with SSG
Md
(P= .13).
Interindividual Variability of the Response. As illustrated in
Figure 1C, coefficients of variations in T
≥90%,HRmax
were 2.3 to
3.5 times larger in SSG compared with HIIT. For T
≥95%,HRmax
(Figure 1D), coefficients of variations were 1.7 to 2.1 times larger
in SSG compared with HIIT. Figure 2illustrates this interindividual
variability in the HR response via the comparison of 2 representa-
tive subjects. While the 2 subjects spent substantial and similar
T
≥90%,HRmax
during HIIT (∼900 s for both; Figure 2D–2H), for
SSG, subject 2 spent 71% to 89% less T
≥90%,HRmax
compared
with subject 1. Therefore, subject 2 spent 77% to 82% less T
≥90%,
HRmax
during SSG compared with HIIT. Importantly, if subject 1
spent substantial T
≥90%,HRmax
during the 3 SSG, T
≥90%,HRmax
was
still 5% to 30% lower than during HIIT. This result is even more
demonstrative for T
≥95%,HRmax
, where subject 2 spent absolutely no
time at or above 95% HR
max
in any SSG (0 s), while subject 1 did
(219 s in SSG
Sm
, 527 s in SSG
Md
, and 572 s in SSG
Lg
). Here again,
for HIIT, the 2 subjects spent similar T
≥95%,HRmax
(524 vs 493 s for
subject 1 vs subject 2, respectively). No correlations were found
between S
peak
and T
≥90%,HRmax
(SSG
Sm
,r
2
= .11, P= .76; SSG
Md
,
r
2
= .34, P= .33; SSG
Lg
,r
2
= .54; P= .11). Moreover, no correla-
tions were found between S
peak
and T
≥95%,HRmax
(SSG
Sm
,r
2
= .18,
P= .22; SSG
Md
,r
2
= .10, P= .37; SSG
Lg
,r
2
= .25; P= .14).
Technical Demand During SSG With Various
Pitch Areas
As shown in Figure 3, number of passes (∼13 [7], P= .16), number
of possessions (∼14 [4], P= .46), and number of ball touches per
possession (∼2.9 [0.6]; P= .73) were similar between SSG
Md
and
SSG
Lg
. However, greater number of possessions (+41% and
+57%, P= .01 and .001) and lower number of ball touches per
possession (−14% and −29%, P= .03 and .01) were found in
SSG
Sm
compared with SSG
Md
and SSG
Lg
, respectively. A 63%
Figure 1 —Time spent above 90% (A) and above 95% (B) of HR
max
during SSG and HIIT and their associated coefficients of variation (C and D).
Data are presented as mean ± SEM. HR
max
indicates maximum heart rate; HIIT, high-intensity interval training; SSG, small-sided games. *P<.05
versus HIIT.
(Ahead of Print)
Small-Sided Games in Prepubertal Players 3

greater number of passes was found in SSG
Sm
compared with
SSG
Lg
(P= .03). No difference was found between the 3 SSG for
the number of dribbles.
Discussion
The aim of the present study was to investigate the influence of the
soccer pitch area during SSG in prepubertal soccer players on
physiological and technical demands. As HIIT is established as the
“gold-standard”method to improve aerobic metabolism,
26
we also
compared acute physiological responses to SSG with those from a
HIIT session. The physiological demand (T
≥90%,HRmax
) was similar
between the 3 SSG modalities while the technical demand was
increased in SSG
Sm
compared with SSG
Md
and SSG
Lg
, as evi-
denced by significant differences in the number of passes and
possessions per session. However, the 3 SSG led to 24% to 37%
reduction in T
≥90%,HRmax
compared with HIIT, indicating a lower
aerobic stimulus (ie, acute response), and suggesting a lower
training effect on endurance capacity (ie, chronic adaptations).
Moreover, interindividual variability in the HR response was 2.3 to
3.5 times greater in SSG compared with HIIT, indicating increased
heterogeneity among players performing the same training protocol.
Together, these findings indicate that HIIT is more effective than
SSG to stimulate aerobic metabolism in prepubertal soccer players
and might be interesting to consider for training sessions where the
primary outcome is the development of endurance capacity.
Implication of the Aerobic Metabolism During SSG
Versus HIIT
In the present study, modifications of the pitch area from 600 to
1734 m
2
led to unchanged physiological demand during SSG in
prepubertal soccer players, based on the T
≥90%,HRmax
or T
≥95%,HRmax
.
This result is supported by a study reporting no change in T
≥90%,
Figure 2 —Heart-rate responses during SSG
Sm
(A and E), SG
Md
(B and F), SSG
Lg
(C and G), and HIIT (D and H), for 2 representative subjects. The 2
subjects spent substantial T
≥90%,HRmax
during HIIT (∼900 s for both). However, for SSG, only subject 1 spent substantial T
≥90%,HRmax
(632–863 s) while
subject 2 did not (69–208 s, ie, 71%–89% less time than during HIIT). A similar observation can be made for the T
≥95%,HRmax
between subjects 1 and 2
(SSG
Sm
, 219 vs 0 s; SSG
Md
, 527 vs 0 s; SSG
Lg
, 572 vs 0 s; HIIT, 524 vs 493 s, respectively). HR
max
indicates maximum heart rate; HIIT, high-intensity
interval training SSG indicates small-sided games; SSG
Sm
, small SSG; SSG
Md
, medium SSG; SSG
Lg
, large SSG.
(Ahead of Print)
4Massamba et al

HRmax
during SSG from different dimensions.
22
However, this study,
also performed in prepubertal players, did not compare SSG with
HIIT, making it difficult to ascertain whether SSG is as effective as
HIIT to stimulate the aerobic metabolism. It is also important to note
that participants spent ≤20% of the training session above 90% of
HR
max
(ie, ≤4.8 min).
22
Moreover, studies investigating the acute
influence of SSG on endurance capacity often reported the mean HR
throughout the session,
13,27
which does not provide accurate indica-
tions for potential improvements in ˙
VO2max.Instead,T
≥90%,HRmax
has
been identified as a key indicator.
7,10
Thepresentstudyrevealedthat
SSG led to significantly lower T
≥90%,HRmax
, whatever the pitch area,
compared with iso-time HIIT, indicating a lower stimulation of the
aerobic metabolism during SSG versus HIIT. This observation is
consistent with others
28
but not all SSG studies
6
investigating its
acute physiological demand in prepubertal children.
It is important to emphasize that this acute study provides direct
evidence of the HR activation, and indirect evidence on the potential
of each training modality to improve endurance capacity following
a training cycle (ie, chronic adaptations). Indeed, training studies
are requisite to directly assess the potential of a training modality to
develop ˙
VO2max. Interestingly, studies that compared chronic effects
on ˙
VO2max of SSG versus HIIT in young soccer players report either
similar
29
or greater
30
improvements for HIIT. Of note, a recent meta-
analysis
31
based on training studies found that HIIT and SSG can
provide similar benefits on endurance and soccer-specific perfor-
mance. However, this conclusion is based on studies performed on
older adolescents (mean age: 16 y old) than the present investigation.
Regardless, it appears that training should include at least 4 sets of
4 minutes each interspersed with 3 minutes of recovery betweensets
to maximize endurance capacity through SSG in young players.
32
Alternatively, it is also possible to prescribe a combination of HIIT
and SSG, which has been found to better develop endurance capacity
than SSG alone in young players.
18
Variability of the Aerobic Metabolism Response
During SSG Versus HIIT
Interindividual variability in the HR response was 2.3 to 3.5 times
greater in SSG compared with HIIT, indicating larger hetero-
geneity among players getting the same training protocol during
SSG compared with HIIT. This result, consistent with a previous
investigation performed in professional adult players,
33
may not be
surprising and is likely explained by the level of control of each
training modality. Indeed, HIIT was individually fine tuned based
on the player’s endurance capacity (ie, run speed set at 100% of
their S
peak
). Conversely, SSG is unpredictable in format and
training intensity is therefore difficult to control.
32
This observation
likely explains why 2 participants can get similar substantial T
≥90%,
HRmax
during HIIT but drastic differences during SSG (Figure 2).
The present investigation also sought to provide insights on the
individual characteristics leading to small T
≥90%,HRmax
during
SSG. We found no correlation between S
peak
and T
≥90%,HRmax
,
indicating that the players with highest endurance capacity did not
get specifically the lowest aerobic stimulus during SSG. While
outside the scope of the present investigation, we can speculate that
factors related to individual technical/tactical skills and displace-
ment efficiency might explain why some players are not getting a
large aerobic stimulus when other teammates are.
34
Further inter-
ventions are needed to test this hypothesis.
Influence of the Pitch Size on the Technical Actions
During SSG
Technical skills are fundamental for children to develop, and the
idea of performing SSG is to stimulate endurance capacity while
also including technical actions. Therefore, while our 3 SSG with
different pitch sizes were similar in terms of physiological demand,
potential differences in the number of technical actions might be
insightful to determine the most interesting modality. Interestingly,
our results showed that SSG
Sm
led to an increase in the number of
passes and possessions, and a reduction in the number of touches
per ball possession compared with SSG
Md
and SSG
Lg
(Figure 3).
This is explained by the higher spatio-temporal pressure during
SSG
Sm
because of the greater players’density
5
and is consistent
with other studies performed on adult players showing greater
technical demand with smaller pitches.
24,35
Therefore, SSG
Sm
might be the most interesting modality to stimulate technical skills
without compromising the physiological demand compared with
SSG
Md
and SSG
Lg
.
In contrast to HIIT, the soccer-specific approach of SSG favors
technical and tactical skills
36
as well as multifaceted physical
actions such as changes of direction or jumps.
37
Moreover, SSG
is more enjoyable than HIIT for young players,
9
which is also a
criterion to consider for coaches when programming training
contents.
Practical Applications
Based on the present investigation, it appears that SSG are not as
efficient as HIIT to stimulate aerobic metabolism in prepubertal
soccer players. Therefore, we would suggest promoting HIIT if the
development of endurance capacity is the primary focus, as the
training intensity is set on an individual basis and therefore easy to
control. In contrast, SSG is unpredictable in format and therefore
difficult to control and might be preferred when the technical
component is important. In this context, we suggest prescribing
SSG with small pitch areas, as they are technically more challeng-
ing for the players and do not compromise the physiological
demand compared with larger SSG. Then, the combination of
both HIIT and SSG in training programs
3
might be a great strategy
for the multifaceted development of the young soccer player.
Regardless, we recommend to coaches to assess the aerobic
Figure 3 —Number of technical actions performed per player during
each of the 3 SSG. Data are presented as mean ± SEM. *P<.05 versus
SSG
Lg
.**P<.05 versus SSG
Md
. SSG indicates small-sided games;
SSGSm, small SSG; SSG
Md
, medium SSG; SSG
Lg
, large SSG.
(Ahead of Print)
Small-Sided Games in Prepubertal Players 5

contribution of their SSG sessions with HR monitors by (1) using
T
≥90%,HRmax
and not only the mean HR, and (2) to analyze and
validate their efficacy on an individual basis due to their large
interindividual variability.
Conclusion
The 3 SSG led to lower acute stimulation of the aerobic metabolism,
suggesting a reduced training effect on the player’s endurance
capacity, compared with HIIT. Moreover, interindividual variability
in the physiological response was substantially greater in SSG
compared with HIIT, indicating increased heterogeneity among
players performing the same training protocol. Based on these
observations, we suggest prescribing HIIT, and not only SSG, in
prepubertal soccer players from elite soccer academies if the primary
focus is the development of endurance capacity ( ˙
VO2max). If the
development of the technical soccer skills is also targeted, we
suggest prescribing SSG with small pitch areas, as they are techni-
cally more challenging for the players without compromising the
physiological demand compared with larger SSG.
Acknowledgments
We acknowledge the valuable assistance of Mr Erwan Pondaven (strength
and conditioning coach) and Mr Samir Guendouz (video analyst) during
the study.
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