Content uploaded by Randall Gutierrez-Vargas
Author content
All content in this area was uploaded by Randall Gutierrez-Vargas on May 17, 2017
Content may be subject to copyright.
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Setiembre-Enero, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
1
DOI: http://dx.doi.org/10.15359/mhs.14-1.1
URL: http://www.una.ac.cr/salud
CORREO: revistamhsalud@una.cr
EFFECTS OF ARTIFICIAL TURF AND NATURAL GRASS
ON PHYSICAL AND TECHNICAL PERFORMANCE OF
PROFESSIONAL SOCCER PLAYERS
EFECTOS DEL CESPED ARTIFICIAL Y LA GRAMA NATURAL
SOBRE EL RENDIMIENTO FÍSICO Y TÉCNICO DE LOS JUGADORES
PROFESIONALES DE FÚTBOL
Juan Carlos Ávalos-Guillén 1,2
Randall Gutiérrez-Vargas (0000-0003-4187-3484) 1,2
Gerardo Araya-Vargas 2
Braulio Sánchez-Ureña(0000-0001-8791-6836) 1,3
Juan Carlos Gutiérrez-Vargas1
Daniel Rojas-Valverde (0000-0002-0717-8827) 1,2
1 Centro de Investigación y Diagnóstico en Salud y Deporte, Escuela Ciencias del
Movimiento Humano y Calidad de Vida, Universidad Nacional
2 Escuela Ciencias del Movimiento Humano y Calidad de Vida, Universidad Nacional,
Costa Rica
3 Programa Ciencias del Ejercicio y la Salud, Escuela Ciencias del Movimiento Humano
y Calidad de Vida, Universidad Nacional, Costa Rica
drojasv@hotmail.com
Abstract
The purpose of this study was to compare the effect of artificial turf (AT) and natural grass (NG)
on the physical and technical performance of professional soccer players. A total of 17 healthy
male soccer players (24.0 ± 4.1 years, height 174 ± 6.1 cm; body weight 73.4 ± 6.3 kg; body fat %
14.2 ± 2.3; VO2max 55.5 ± 5.3 ml/kg/min) from a Costa Rican Professional Soccer League club
were subjected to different tests in both types of surfaces (technical test, agility test, repeated
sprint ability test, and a small-sided game [8 minutes, 32 x 32 meters, 5 vs. 5]). Players were
monitored using a GPS in two sessions, separated by 48 hours, during the club’s pre-season.
There were no significant differences between the two types of surfaces for the technical, agility,
and repeated sprint ability tests. The physiological and kinematic variables analyzed during the
small-sided game presented significant differences in average heart rate (NG = 168.5 ± 8.8, AT =
154.8 ± 11.8, p <.001), maximum heart rate (NG = 183.2 ± 8.3, AT = 175.9 ± 10.4, p =.02), body
load (NG = 34.3 ± 11.2, AT = 30.5 ± 11.4, p =.03), and total impacts (NG = 230.1 ± 89.5, AT =
194. 8 ± 86.4, p=.03). It is concluded that playing on the natural grass surface caused more
impact on physiological and perceived body load in players. In the case of technical variables, it
is concluded that there were no statistically significant differences between the two types of
surfaces (p <0.05).
Keywords: soccer, physical tests, exercise, training.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
2
Resumen
El propósito de este estudio fue comparar el efecto de la superficie artificial (AT) y la natural (NG) sobre
el desempeño físico y técnico de los jugadores profesionales de fútbol. Un total de 17 jugadores de fútbol
en buen estado de salud (24.0 ± 4.1 años, peso 174 ± 6.1 cm; peso corporal 73.4 ± 6.3 kg; porcentaje de
grasa corporal 14.2 ± 2.3; VO2max 55.5 ± 5.3 ml/kg/min) de una liga profesional de fútbol de Costa Rica
realizaron diferentes pruebas en ambas superficies (prueba técnica, agilidad, sprints repetidos y juego en
espacio reducido [8 min, 32x32 m, 5 vs. 5]). Los jugadores se monitorearon con un GPS en dos sesiones,
las cuales estuvieron separadas por 48 horas, durante la pretemporada del club. No se encontraron
diferencias significativas entre ambas superficies de juego en cuanto a desempeño técnico, agilidad y
sprints repetidos. Existieron diferencias significativas en las variables fisiológicas y cinemáticas
analizadas durante el juego en espacio reducido en cuanto a frecuencia cardiaca promedio (NG = 168.5
± 8.8, AT = 154.8 ± 11.8, p <.001), frecuencia cardiaca máxima (NG = 183.2 ± 8.3, AT = 175.9 ± 10.4, p
=.02), carga corporal (NG = 34.3 ± 11.2, AT = 30.5 ± 11.4, p =.03) e impactos totales (NG = 230.1 ±
89.5, AT = 194. 8 ± 86.4, p=.03). Se concluye que practicar en terreno natural ocasiona mayor impacto
en los jugadores en cuanto a la carga corporal y fisiológica. En el caso de las variables técnicas, se
concluye que no hubo diferencias estadísticamente significativas entre los dos tipos de superficies (p
<0.05).
Palabras clave: fútbol, pruebas diagnósticas, ejercicio, entrenamiento.
INTRODUCTION
Soccer has become a phenomenon with a great social impact. According to
Gallardo (2009), over 245 million people play soccer worldwide. Likewise, the
Fédération Internationale de Football Association (FIFA) Big Count for 2006 claimed
that 4% of the World’s population actively participated in this sport. As a response to
this large-scale phenomenon, soccer fields have proliferated during the last decade.
According to Gallardo, Felipe, Burillo, and Gallardo (2010), soccer fields have
become one of the most widely used sports facilities, both for competitive and
recreational purposes (Gallardo, Sánchez, Gallardo, Felipe, and Burillo, 2013).
Developments in the world of soccer such as material resources – specifically
playing surfaces – have evolved through time, depending on aspects such as climate,
use, and/or socioeconomic context. Different types of fields can be currently found,
including natural grass, soil, artificial turf, and even mixed fields (Díez and Burillo,
2012; Sánchez-Sánchez et al., 2016).
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
3
Artificial turf is a surface that is intended to imitate the properties of natural
grass, seeking to solve problems such as maintenance costs and care associated with
natural grass fields. This type of surface has proven to be promising for sports, being
used in diverse sporting disciplines (Gallardo, 2009).
Based on data from the Spanish Soccer Federation, Sanchis, Rosa, and Magraner
(2010) indicated that there has been an enormous increase in the number of soccer fields
with artificial turf, especially due to the technological developments that have taken
place since they were first used. In fact, in 2004 FIFA included artificial turf as a
playing surface in official competitions.
According to Sánchez-Sánchez et al. (2016), in spite of the massive proliferation
of soccer fields, few studies analyze the influence of the different types of playing
surfaces in soccer since there are no tests to make the comparison. Hernández, Romero,
and Vaca (2013) also indicate that, as of yet, there are no specific studies to contribute
in this area.
One of the few investigations available is the one conducted in Spain by Díez
and Burillo (2012). They analyzed three types of surfaces (soil, natural grass and
artificial turf), adapting different types of tests to soccer and found that in agility tests
(“a quality that allows body control in space, with adequate precision and speed”,
Cañizares, 2011, p. 65), significant differences were observed between natural grass
(where lower times were obtained) with respect to the other two types of surfaces.
However, no significant differences were found between natural grass and artificial turf
in the fatigue index. This data suggests that a natural grass surface is more favorable to
physical and technical performance.
A study conducted by Andersson, Ekblom, and Krustrup (2008), which
examined movement patterns, ball skills, and impressions of elite Swedish soccer
players during competitive matches on artificial turf and natural grass indicates that
there were no significant differences between these types of surfaces in terms of overall
distance covered (10.2 km vs. 10.9 km) or high-intensity running (1.86 km vs. 1.87 km).
Players, furthermore, reported a negative impression of ball control and greater physical
effort on artificial turf, as opposed to natural grass. It was concluded that playing pattern
and technique were similar during matches on both artificial turf and natural grass
surfaces.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
4
The studies by Díez and Burillo (2012) and Andersson, Ekblom, and Krustrup
(2008) coincide that there are no significant differences in physical performance and
technique when playing on different types of surfaces and also show that the natural
surface is perceived as more favorable by players.
Given the existing dispute on the effects of artificial turf on soccer players’
performance, the highest governing body of this sport worldwide, FIFA, conducted a
study in 2006 and analyzed two matches of the Union of European Football
Associations (UEFA) (one on artificial turf and the other one on natural grass). The
study concluded that artificial turf did not affect the development of the match, which
showed clear similarities with the match on natural grass. Data suggested that players
on artificial turf controlled the ball more easily, and made a larger amount of effective
passes. Although it would seem that artificial turf improved the development of the
match, this data contrasted with the overall negative perception players have of this type
of surface.
In Costa Rica there has been a proliferation of soccer fields with artificial turf.
According to Jiménez (2009), fields with artificial turf had gained ground rapidly in the
country, with four stadiums using artificial turf at the time of the study and 6 teams in
the process of installing it during the course of the year.
The decision of changing to artificial turf took place without the support of
scientific studies providing adequate criteria to ensure players’ safety and development
of games, in addition to the lack of justification for the financial investments made.
Further investigations should focus more on this issue, since, as previously discussed,
physical and technical performances are not jeopardized, and may even be favored in
some cases, by artificial turf. Given the problems presented, the objective of this study
was to compare the effect of the type of surface, whether artificial or natural, on the
physical and technical performances of professional soccer players.
METHODS
Participants
Seventeen healthy professional male soccer players, with a mean age of 24.0 ±
4.1 years, height of 174 ± 6.1 cm, body weight of 73.4 ± 6.3 kg, body fat of 14.2 ±
2.3%, and VO2 max of 55.5 ± 5.3 ml/kg/min, who trained regularly between 4 and 5 times
a week and were part of a Costa Rican Professional Soccer League.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
5
Ethical Statement
All subjects were informed of the details of the experimental procedures and the
associated risks and discomforts. Each subject gave a written informed consent
previously approved by the Academic Committee of the Sports Science Program from
Universidad Nacional and based on the Declaration of Helsinki regarding biomedical
research involving human subjects (18th Medical Assembly, 1964; revised in 2008 in
Seoul).
Instruments and Materials
Participants were characterized based on measurements of aerobic capacity
using equipment to measure oxygen consumption (VO2max, VO2000, measured using a
MedGrapics® system, Minnesota, United States). Body weight was measured with an
Elite digital scale, Series BC554, Tanita-Ironman®, Illinois, United States, with 0.1 kg
sensitivity. A wall-mounted measuring rod was used to determine height. Body fat
percentage was obtained based on dual absorptiometry using X Rays (General Electric
enCORE 2011®, software version 13.6, Wisconsin, United States).
Technique was measured using the test described by Sans and Frattarola (1999),
which consists of a series of activities involving different basic soccer techniques such
as short pass, wall pass, ball control, long pass, and shot on goal, with scores ranging
from 0 to 50 points, as shown in Figure 1.
Figure 1. Representation of technical test by Sans and Frattarola (1999).
The test described by Sans and Frattarola (1999) was used to measure players’
agility on both surfaces, as indicated on Figure 2. Two sets of photoelectric cells were
employed, as well as a Newtest Powertimer for Throwing Gate test, No. 10700®, (Oulu,
Finland).
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
6
Figure 2. Representation of the agility test by Sans and Frattarola (1999).
The repeated sprint ability (RSA) test described by Díez and Burillo (2012) was
used to measure the fatigue index. Kinovea 0.8.15 software was used to subsequently
measure data obtained from this test, as implemented in sports biomechanical studies.
The technical test is 50 points, in which the higher the score the better the result,
while in the agility test, the lower the time, the better the result. In the case of the RSA
test, which measures the fatigue index of each player, the lower the value, the more
ability the player has to maintain an anaerobic effort.
Small-sided games were also played for 8 minutes, with a pitch size of 736m2
(activity based on Casamichana, Castellano, and Hernández, 2009), in order to analyze
soccer techniques, such as goals, passes, and shots on goal of two teams on both types
of surfaces. Small-sided games simulate, totally or partially, a soccer match, and are
considered a highly valuable strategy to improve soccer players’ performance (Sánchez,
Yagüe, Fernández, and Petisco, 2014). Teams were randomly selected.
Global Positioning System (GPS) tracking from GPSports (SP PRO X II, 15 Hz;
Canberra, Australia) was used to measure physiological variables. Validity and
reliability of the GPS devices with different frequencies have been established by
Edgecomb and Norton (2006) when evaluating different speeds in circuits of different
lengths (r =.998, r=.989. r=.999).
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
7
The results obtained using GPS devices and actual distances measured with a
measuring tape were highly correlated (r= .99). The GPS mean error was 4.8%, which
showed moderate-to-high reliability (according to the study by Edgecomb and Norton,
2006). In addition, Barbero-Álvarez, Coutts, Granda, Barbero-Álvarez and Castagna,
(2010) showed that measurements made with this equipment present a high correlation
between maximum speed values and performance in the repeated sprint ability test (r2=
.87, p< .001; r2= .94, p< .001). This instrument was used to quantify the variables of
distance covered, average speed in meters per minute, average and maximum heart rate,
impacts, accelerations, decelerations and body load.
Each individual’s impacts were analyzed using Team AMS software, which
records the amount and intensity of impacts above a 5 g threshold. These impacts,
called performance stressor impacts, were categorized by Carling, Reilly, and Williams
(2009) as follows: slight impacts (5 – 6 g), collisions and contacts with the field (6 – 6.5
g), moderate-to-strong impacts (6.5 – 7 g), strong impacts (7 – 8 g), very strong impacts
(8 – 10 g), and severe impacts > 10 g).
A SONY high-definition camera, model HDV HDR-FX1E, was used to analyze
technical actions in the small-sided games. A template created by Gutiérrez-Vargas et
al. (2015) was also used to include variables such as number of goals scored, total
passes, successful passes (those reaching the recipient), unsuccessful passes (not
reaching the recipient), total fouls made and received, offsides, corner kicks, counter-
attack moves, total shots on goal, direct shots on goal (aimed at the rival’s goal),
indirect shots on goal (rebounds from the rival’s goal posts), and effective playing time
(time during which the ball was in play). For the purposes of this study, only the
variables of goals scored, positive passes, negative passes, and direct and indirect shots
on goal were considered due to the characteristics of the small-sided games, obtaining
qualitative information about differences in technical actions on the two types of
surfaces for later analysis.
Tests on a natural surface were conducted in a field located in San Antonio de
Belén while tests on artificial turf were on a field in the Central canton of Belén. This
field is designed for high traffic and the surface is 55 mm thick. Turf was installed on
sand and crushed rubber (FIFA 1 star) in 2008, with a use life of approximately 10
years. Both fields meet FIFA’s regulatory measurements and provide appropriate
conditions for playing professional soccer.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
8
Procedures
The present study was conducted at the beginning of the club’s pre-season, in
two sessions with a 48 hr rest in between. In addition, both sessions took place at the
same time (8:00 AM) and players had to wear the same types of shoes and clothing.
The same warm-up exercises were conducted by the club’s physical trainer in
both sessions, followed by 20 minutes of practice to assimilate the technical and agility
tests. The tests were then applied in the following order: 1) technical test, 2) agility test,
and 3) RSA test (which consists of eight 30-meter sprints with 30 seconds of active rest
between each repetition), concluding with a small-sided game (32 x 32 meters), 5
players on each side (the same 10 players in both sessions). This activity provided
kinematic and physiological data measured using GPS; each small-sided game was
recorded for further analysis using the template prepared by Gutiérrez et al. (2015) for
technical actions of each team. The same procedure detailed previously was used in
both sessions, on both natural grass and artificial turf.
Statistical Analysis
Descriptive statistics were used to present the characteristics of the samples and
calculate averages and standard deviations. Data normality was evaluated using the
Shapiro-Wilk test. In addition, the Student’s paired t-test was used to compare
dependent variables based on field surface (natural and artificial). Technical
characteristics of the small-sided game on the different surfaces were also described,
where relative differences were calculated by subtracting the results obtained on the
artificial surface from the results obtained on the natural surface, and then expressed as
a percentage of the result obtained on natural grass ((CA-CN) /CN), using the data
obtained by each team in the template. SPSS (Statistical Package for the Social
Sciences, IBM, SPSS Statistics, V 21.0 Chicago, IL, USA) was used. Significance for
the decision making was p <.05.
RESULTS
Table 1 shows averages obtained during the technical, agility, and RSA tests
conducted in the different fields.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
9
Table 1
Comparison of average values obtained in the technical, agility, and RSA tests on
natural grass and artificial turf
_________ mean ± S.D.__________
Tests_____________Natural grass ____Artificial turf ________Sig._____
Technical test [pts]
12.9 ± 4.6
12.6 ± 2.9
.93
Agility test [s]
6.35 ± 0.13
6.43 ± 0.16
.10
RSA test (fatigue index)
4.74 ± 1.76
4.24 ± 1.62
.92
Note. All averages presented in Table 1 were obtained from n = 17 soccer players evaluated.
Table 1 shows that no statistically significant differences were found in the
results obtained from the technical test (p=.93), the agility test (p=.10), and the fatigue
index (p=.92) evaluated on each type of surface.
Table 2 shows the average values of the physiological and kinematic variables
measured using GPS in an eight-minute small-sided game.
Table 2
Physiological and kinematic variables in an eight-minute small-sided game in two
different types of surfaces
mean ± S.D.
Variables
Natural grass
Synthetic turf
Sig.
Variables
Average HR (heart beat/min)
168.5 ± 8.8
154.8 ± 11.8
<.001**
Maximum HR (heart beat/min)
183.1 ± 8.3
175.9 ± 10.34
.02*
Meters per minute
147.5 ± 9.8
147.2 ± 8.5
.52
Average speed (km/h)
8.9 ± 0.6
8.8 ± 0.5
.96
Total distance (m)
1 000.9 ± 98.8
1002.2 ± 107.8
.20
Distance (m) 0-11 km/h
301.8 ± 83.8
293.1 ± 69.2
.12
Distance (m) 11.1-14 km/h
172 ± 57.1
168.1 ± 10
0.10
Distance (m) 14.1-19 km/h
93 ± 38.8
102.8 ± 37.6
.15
Distance (m) 19.1-23 km/h
23.5 ± 20
24.3 ± 26
.67
Body load (wmu)
34.3 ± 11.2
30.5 ± 11.3
.03*
Magnitude of impact (g-force)
6.1 ± 0.1
6.1 ± 0.2
.61
Total impact
230 ± 89.5
194.8 ± 86.4
.03*
Note. S.D.= Standard deviation, wmu= without measuring unit, *p<.05, **p<.001. All average values
shown in the Table were obtained based on n = 17 soccer players evaluated.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
10
Statistically significant differences were found for average heart rate (p<.001),
maximum heart rate (p=.02), body load (p=.03), and total impacts (p=.03). In all cases,
averages were higher on the natural grass surface. No statistically significant
differences were reported for the other variables (p>0.05).
Table 3 presents differences in technical actions obtained while playing a small-
sided game for 8 minutes in the two different types of surfaces.
Table 3
Values of technical actions obtained during an eight-minute small-sided game in two
different types of surfaces
Natural grass
Artificial turf
% change natural vs.
artificial
Action
Red
team
Yellow
team
Red
team
Yellow
team
Red
team
Yellow
team
+ Passes
38
45
63
55
65.8%
22.2%
- Passes
9
7
6
9
-33.3%
28.6%
Direct shots on goal
7
8
6
4
-14.9%
-50.0%
Indirect shots on goal
0
1
0
1
0
0
Goals scored
4
6
6
3
50.0%
-50.0%
Note. All values shown in Table 3 were obtained from team evaluations.
The percentage of change observed between the types of surfaces describes the
tendencies of change for both types of surfaces, given that both teams improve or
worsen the performance of some of the technical actions; for instance, the red team
reported a 65.8% improvement in positive passes on artificial turf, but at the same time
it showed a 14.9% decrease in direct shots on goal on that surface. The descriptive
information shows that technical actions did not occur with equal frequencies,
suggesting that the pattern of play may be changing and adapting depending on the type
of surface used.
DISCUSSION
This is the first study in the country comparing the effects of artificial and
natural surfaces in Costa Rican soccer players’ physical and technical performance.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
11
As indicated in the introduction, the main motivation for conducting this study
was the proliferation of soccer fields with artificial turf both locally and internationally
and the existing debate about which surface is better and safer. This difference of
opinions is reflected in articles published in the local newspaper La Nación, which
constantly addresses this issue. For instance, in the article entitled “Natural o
artificial?” Díaz (2007) states that natural grass is preferable, but events in Costa Rica
show that it is convenient for soccer to change to artificial turf for economic reasons.
However, as shown in the results of the present study, statements like this lack scientific
foundation. In addition to economic variables (which have not been addressed in this
study), there are physiological and technical variables that are directly related to soccer
players’ performance which must receive more consideration to decide whether to
invest in soccer fields with natural grass or artificial turf.
Anthropometrical data for the participants in this study is similar to the one
presented by Enizeler (2005) in terms of age (24.4 ± 4.1 years old), weight (70.7 ± 3.1
kg), height (176.4 ± 6.2 cm), and body fat percentage (9.3 ± 3.4%). Furthermore,
Sánchez and Salas (2009) reported a mean of 57.7 ± 8.8 ml/kg/min of maximum oxygen
consumption in a sample of 219 Costa Rican first-division players, a value similar to the
one reported in this study (VO2max 55.5 ± 5.3 ml/kg/min). In addition, Clemente and
Muñoz (2011) presented data regarding anthropometric characteristics, years of
experience, and training frequency similar to the one from the participants in this study.
Based on this evidence, it can be concluded that the subjects of this study can be
characterized as high-performance players due to their level of physical abilities and
anthropometric data.
In the case of the results obtained in the technical test, no differences between
the two types of surfaces were reported. It is worth noting that this test has a limitation,
since it is used for soccer schools. Bedoya (2014) mentions that these types of test
batteries have a practical value during the training stages while they are only for
reference during performance. Bedoya (2014) and Díez and Burillo (2012) state that
there are no specific tests for soccer players and insist that the ability of a soccer player
is not objectively measured in the existing tests. In this sense, the results obtained by
this test must be regarded as references, since it is not possible to conclude with
certainty that the surfaces used would have an actual impact on player performance.
The results reported in the agility test indicate that no significant differences
existed between performance on artificial turf and natural grass. In spite of this, the
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
12
results obtained are similar to those of Díez and Burillo (2012) who conducted an
agility test without a ball, and found better times on natural grass than on artificial turf.
Given this result, it may be proposed that the field with natural grass favors
performance in terms of player agility, but since there is no scientific evidence and
significant data to prove this, it cannot be regarded as certain that the type of surface has
an impact on player performance.
The RSA test has been applied in multiple investigations, such as those of Arjol
and Gonzalo (2012), Clemente and Muñoz (2011), and Rodríguez, Sánchez, and Villa
(2014), due to its usefulness in measuring the effects produced by training on players’
anaerobic capacity.
In this study, the results of the RSA test did not show significant differences in
the fatigue index between fields with natural grass and artificial turf surfaces, which
coincides with the findings by Díez and Burillo (2012). According to these findings, the
fatigue index does not vary between the two types of surfaces, showing that anaerobic
capacity was very similar in both cases and that players’ physical performance,
therefore, should be the same whether they play on grass or artificial turf.
With respect to small-sided games, no significant differences were found in the
distances covered with different speeds (0- 11 km/h, 11-14 km/h, 14-19 km/h, 19-23
km/h), total distance covered, and number of impacts on both types of surfaces.
Significant differences were reported in maximum and average heart rates, as well as
between body load and number of total impacts, with playing on natural grass surfaces
producing higher stress values (see Table 2).
These significant differences may be affected by the characteristics inherent in
each of the surfaces used in this study. In the case of a field with an artificial surface, a
study by Gallardo, Felipe, Burillo, and Gallardo (2010) showed that the main advantage
of artificial turf compared to a natural grass surface is its endurance, the uniformity of
the surface, and the good performance it provides, while a natural surface may be
affected by climatic factors and require extensive maintenance. In addition, Báron and
Ferreira (2010) indicated that artificial turf can withstand many hours of use without
suffering significant deterioration, which is not the case with a natural surface, which
requires time to recover.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
13
In addition, Guía FIFA para las superficies artificiales (2011) indicates that a
major characteristic of any surface, either natural or artificial, must be its shock
absorption capacity (defined as “the capacity of a surface to absorb the impact of a
player running on that surface”; own translations). It also indicates that a natural grass
field in ideal conditions has a shock-absorption capacity ranging between 55% and
70%, and that existing artificial turf shows similar values.
Belloch, Soriano, and Figueres (2009) agree that the mechanical behavior of a
field with an artificial turf surface is very similar to the one observed on natural grass
fields. Rozas (2009) mentions that artificial turf surfaces provide impact-absorption and
energy-return and dissipation, which is very similar to natural grass. Rabal and Casajús
(2014) also claim that similar, or even better performance, may be found on artificial
surfaces as opposed to traditional surfaces (soil and natural grass), considering they are
adequately maintained.
This author also found higher osseous mass values in players that competed on
natural grass than in those who competed on artificial turf surfaces, suggesting that this
increase in bone density may be due to the fact that a greater body load and intensity are
present when playing on natural grass. These findings are consistent with those
observed in the present study, in which the values for the amount of impacts and body
loads were significantly greater on natural surfaces than on artificial surfaces.
Athletes’ performance is not only affected by their individual characteristics, but
also by factors such as the ball and, of course, the pavement or playing surface with
which they interact (Báron and Ferreira, 2010). In their study of trainers’ and players’
satisfaction with natural grass and artificial turf soccer fields, Gallardo et al. (2010)
claimed that 72% of the trainers stated that a natural grass surface presents lower burden
risks than a field with artificial turf; in addition, 74% said that shock-absorption of the
impacts is significantly better on a natural grass surface, which contrasts the findings of
this study. However, it should be noted that these are subjective observations and not
opinions based on scientific data.
With respect to the differences found in average and maximum heart rate (see
Table 2), there is no sufficient scientific evidence to explain this result. However, there
may be greater body load when playing on a natural grass surface. It may be suggested
that, given the greater physical burden experienced by the player, there may have a need
for greater physical effort consequently raising the player’s heart rate.Ç
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
14
Regarding the technical actions obtained in the eight-minute small-sided game,
results presented in Table 3 show that different technical actions increased or decreased
between different types of surfaces; for instance, positive passes were more frequent on
synthetic grass, while direct shots on goal were less frequent compared to a natural
grass surface. The variables of indirect shots on goal and goals scored did not show
important variations between the types of playing surfaces studied. Based on the
foregoing, no substantial changes have been found which may suggest important effects
on playing patterns or on team performance, or that may indicate that differences
between surfaces actually influence the differences observed.
Between 2006-2007, FIFA (2007) analyzed 14 soccer games, four played on
artificial turf and 10 on natural grass, and concluded that playing patterns were not
influenced by differences between artificial turf and natural grass surfaces; instead, it
reported clear similarities between patterns of play on the different surfaces. In addition,
no significant differences were found in the frequencies of passes made, passes
received, ball control, and other technical actions studied. This data coincides with the
one reported in this study, in which the analysis of the frequencies of these technical
actions did not show important changes or suggest some variability in performance in
either physical or technical aspects of players, who interact on a natural grass or
artificial turf surface.
CONCLUSION
Based on the results of this study, it may be concluded that playing on natural
surfaces caused greater impact and body load than playing on artificial turf, while in the
case of technical aspects, differences between both types of surfaces did not have an
important effect on technical performance in professional soccer players.
RECOMMENDATIONS AND PRACTICAL APPLICATIONS
Further research should be conducted to analyze body load and impacts when
playing on natural and artificial surfaces with different characteristics and qualities.
Scientific long-term data related to the technical level of Costa Rican soccer players
should be collected from their early youth until they become professional players. The
characteristics and quality of natural grass and artificial turf fields in Costa Rica should
also be analyzed, following the recommendations and applying the tests prepared by
FIFA for certifying soccer fields, as well as to study in more detail if playing patterns
change depending on whether play takes place on natural or artificial surfaces.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
15
References
Arjol, J.L. and Gonzalo, O. (2012). Reflexiones sobre el entrenamiento de la RSA en el
fútbol.. Revista de preparación física en el fútbol, 4 (4), 12-25. Retrieved from
http://futbolpf.com/revista/index.php/fpf/article/view/51
Andersson, H., Ekblom, B., and Krustrup, P. (2008). Elite football on artificial turf
versus natural grass: movement patterns, technical standards, and player
impressions. Journal of sport sciences, 26(2), 113-122.
doi:10.1080/02640410701422076
Barbero-Álvarez, J., Coutts, A., Granda, J., Barbero-Álvarez, V., and Castagna, C.
(2010). The validity and reliability of a global positioning satellite system device
to assess speed and repeated sprint ability (RSA) in athletes. Journal of science
and medicine in sport/ Sport medicine Australia, 13(2), 232-235. doi:
10.1016/j.jsams.2009.02.005.
Báron, J. & Ferreira, M. (2010). Criterios FIFA y propiedades biomecánicas
relacionadas con la performance y epidemiología del deportista en las
superficies de césped artificial. Hacia una superficie deportiva saludable y
segura. [FIFA criteria and biomechanic properties related to performance and
epidemiology of athletes on artificial turf surfaces. Towards a healthy and safe
sport surface]. [PDF Document]. Retrieved from
http://www.munideporte.com/imagenes/documentacion/ficheros/201006081301
42jose_antonio_baron.pdf
Bedoya, M. (2014). Batería de Test aplicados al fútbol (T.A.F). [Slideshare slides].
Retrieved from http://es.slideshare.net/meber21/presentacin1-40276633
Belloch, S., Soriano, P., and Figueres, E. (2009). La epidemiología del fútbol. Una
revisión sistemática. Revista Internacional de Medicina y Ciencias de la
Actividad Física y el Deporte. 10(37), 22-40. Retrieved from
http://cdeporte.rediris.es/revista/ revista37/artfutbol130.htm
Cañizares, J.M. (2011). Fútbol: Fichas para el entrenamiento de la velocidad y
agilidad.. Barcelona: WANCEULEN.
Carling, C., Reilly, T., and Williams, M. (2009). Performance assessment for field
sports. Oxon: Routledge.
Casamichana, D., Castellano, J., and Hernández, A. (2009). Análisis de los diferentes
espacios individuales de interacción y los efectos en las conductas motrices de
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
16
los jugadores: aplicaciones al entrenamiento en fútbol.. Motricidad. European
Journal of Human Movement, X (37), 194-205. doi:
http://dx.doi.org/10.5232/ricyde2014.03702
Castellano, J., Casamichama, D., and Dellal, A. (2013). Influence of game format and
number of players on heart rate responses and physical demands in small-sided
soccer games. Journal of Strength and Conditioning Research, 27(5), 1295-
1303. doi: http://dx.doi.org/10.1519/JSC.0b013e318267a5d1
Clemente, V. and Muñoz, V. (2011). Fatiga del sistema nervioso después de realizar un
test de capacidad de sprint repetidos en jugadores de fútbol profesional. Archivos
de Medicina del Deporte, XXVIII (143), 174-180. Retrieved from
http://archivosdemedicinadeldeporte.com/articulos/upload/Abstract_fatiga_174_
143.pdf
Díaz, L. (November 4, 2007). ¿Natural o Artificial? [Natural or artificial?] La Nación.
Retrieved from
http://wvw.nacion.com/ln_ee/2007/noviembre/04/deportes1303270.html
Díez, Ó. and Burillo, P. (2012). Influence of playing surface in performance of amateur
football players: natural grass, artificial turf and dirt field. AGON International
Journal of Sport Sciences, 2(2), 106-114. Retrieved from
http://agonjournal.com/wp-content/uploads/2012/10/6_D%C3%ADez_
Burillo_106_.pdf
Edgecomb, S.J. and Norton, K.I. (2006). Comparison of global positioning and
computer-based tracking systems for measuring player movement distance
during Australian Football. Journal of science and medicine in sport, 9(1)(2).
25-32. doi: http://dx.doi.org/10.1016/j.jsams.2006.01.003
Enizeler, N. (2005). Heart Rate and Blood Lactate Concentrations as Predictors of
Physiological Load on Elite Soccer Players During Various Soccer Training
Activities. The Journal of Strength and Conditioning Research. 19 (4), 799-804.
Retrieved from http://g-se.com/es/evaluacion-deportiva/articulos/estudio-de-la-
frecuencia-cardiaca-y-las-concentraciones-de-lactato-sanguineo-como-variables-
para-predecir-la-carga-fisiologica-en-jugadores-de-futbol-de-lite-678
Federación Internacional de Fútbol Asociado [FIFA] (International Federation of
Association Football). (2015). Reglamento oficial de fútbol 2015-2016.[PDF
Document]. Retrieved from
http://es.fifa.com/mm/Document/FootballDevelopment/Refereeing/02/36/01/11/
LawsofthegamewebES_Spanish.pdf
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
17
Federación Internacional de Fútbol Asociado [FIFA] (International Federation of
Association Football). (2007). Technical study with ProZone (2006-2007) #2.
[PDF Document]. Retrieved from http://www.fifa.com/mm/document/
afdeveloping/pitchequip/technical_study2_11163.pdf
Federación Internacional de Fútbol Asociado [FIFA] (International Federation of
Association Football). (2006). Gran Censo 2006.. [PDF Document]. Retrieved
from http://es.fifa.com/mm/document/fifafacts/bcoffsurv/smaga_9472.pdf
Federación Internacional de Fútbol Asociado [FIFA]. (International Federation of
Association Football). (2006). Technical study with ProZone (2006). [PDF
Document]. Retrieved from
http://www.fifa.com/mm/document/afdeveloping/pitchequip/case_study_technic
al_analysis_351.pdf
Federación Internacional de Fútbol Asociado [FIFA]. (International Federation of
Association Football). (2011). Guía FIFA para las superficies artificiales.
(FIFA Guide for Artificial Surfaces) [PDF Document]. Retrieved from
http://www.kirolarte.net/adminkirolarte/material/FIFAguidecastellano.pdf.
Felipe, J., Burillo, P., Gallardo, A., and Gallardo, L. (2011). Diagnóstico de la gestión
de los campos de fútbol de césped artificial según los gestores deportivos.
[Diagnostic of management of artificial turf soccer fields according to sports
managers]. Kronos. 10(1), 97-104. Retrieved from
http://www.revistakronos.com/docs/File/kronos/19/Kronos_X_1_11.pdf.
Gallardo, A. (2009). Análisis de la satisfacción de la práctica deportiva en los campos
de fútbol de césped natural y artificial de la Región de Murcia desde el punto de
vista del gestor, entrenador y deportista..(Ph.D. Thesis). Universidad Católica
San Antonio, Murcia, España.
Gallardo, A., Felipe, J.L., Burillo, P., and Gallardo. L. (2010). Satisfacción de
entrenadores y deportistas con los campos de fútbol de césped natural y
artificial. [Satisfaction of trainers and athletes with soccer fields of natural grass
or artificial turf]. Cultura, Ciencia y Deporte, 5(15), 189-199. Retrieved from
http://www.redalyc.org/pdf/1630/163018699006.pdf
Gallardo, L., Sánchez, J., Gallardo, A., Felipe, J.L. & Burillo, P. (2013). Acreditación
de los campos de fútbol de césped artificial: Garantía de éxito - SportTK:
Revista Euroamericana de Ciencias del Deporte. 2. 59-66.
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
18
Gutiérrez-Vargas, R., Rojas-Valverde, D., Jiménez-Madrigal, E., Sánchez-Ureña, B.,
Salas-Cabrera, A., Gutiérrez-Vargas, J.C., and Salazar-Cruz, I. (2015).
Parámetros fisiológicos y técnicos en jugadores jóvenes de fútbol después de
modificar la regla del fuera de juego (regla 11).Kronos, 14(2). Retrieved from
https://g-se.com/es/journals/kronos/articulos/parametros-cinematicos-y-tecnicos-
en-jugadores-jovenes-de-futbol-despues-de-modificar-la-regla-del-fuera-de-
juego-regla-11-1905
Hernández, P., Romero, E., and Vaca, M. (2013). El desarrollo de la técnica del fútbol
en etapa de iniciación en superficies de diversos tipos. [Development of soccer
technique in initial initiation stages on surfaces of different types].
EFDeportes.com, Revista Digital.187, 1-12. Retrieved from
http://www.efdeportes.com/efd187/futbol-en-superficies-de-diversos-tipos.htm
Jiménez, G. (January 18, 2009). La moda sintética invade al futbol costarricense.
[Synthetic fashion invades Costa Rican soccer]. La Nación. Retrieved from
http://wvw.nacion.com/ln_ee/2009/enero/18/ deportes1842899.html
Rabal, J. & Casajús, J. (2014). Influencia de la superficie de juego en la masa ósea de
jóvenes futbolistas. [Influence of playing surface on osseous mass of young
soccer players]. (Graduation thesis). Universidad de Zaragoza, Huesca, Spain.
Retrieved from http://invenio2.unizar.es/record/30901/files/TAZ-TFG-2014-
1514.pdf
Rodríguez, A., Sánchez, J., & Villa, G. (2014). Efectos de 2 tipos de entrenamiento
interválico de alta intensidad en la habilidad para realizar esfuerzos máximos
(RSA), durante una pretemporada de fútbol. [Effects of two types of high-
intensity interval training on the ability to make maximum efforts (RSA), during
a soccer pre-season]. Ciencia, Cultura y Deporte, 9(10), 251-259. doi:
http://dx.doi.org/10.12800/ccd.v9i27.467
Rozas, R. (2009). Proyecto de una multicancha tipo, con terminación de césped
sintético, para la cuidad de Valdivia.. (Graduation thesis). Universidad Austral
de Chile, Valdivia, Chile.
Sánchez-Sánchez, J., García-Unanue, J., Felipe, JL., Jiménez-Reyes, P., Viejo-Romero,
D., Gómez-López, M., Hernando, E., Burillo, P., and Gallardo, L. (2016).
Physical and physiological responses of amateur football players on third
generation artificial turf systems during simulated game situations. J Strength
Cond Res 30(11): 3165-3177
URL www.una.ac.cr/mhsalud J.C Ávalos-Guillén, R. Gutiérrez-Vargas, G.Araya-Vargas, B. Sánchez-Ureña,
J.C Gutiérrez-Vargas y D. Rojas-Valverde
Revista MHSalud® (ISSN: 1659-097X) Vol. 14. No. 1. Febrero-Agosto, 2017
Artículo de la Revista MHSalud de la Universidad Nacional, Costa Rica protegido por Licencia de Costa Rica
Creative Commons Attibution-NonComercial-NoDerivs 3.0 .
Para más información visite www.una.ac.cr/MHSalud
19
Sánchez-Ureña, B. and Salas-Cabrera, J. (2009). Determinación del consumo máximo
de oxígeno del futbolista costarricense de primera división en pretemporada
2008.. Movimiento Humano Salud, 6(2), 1-5. Retrieved from
http://www.redalyc.org/articulo.oa?id=237016584003.
Sánchez, J., Yagüe, J., Fernández, R., and Petisco, C. (2014). Efectos de un
entrenamiento con juegos reducidos sobre la técnica y la condición física de
jóvenes futbolistas.. Internacional Journal of Sport Science. 10(10), 221-234.
doi:http://dx.doi.org/10.5232/ricyde2014.03704
Sanchis, M., Rosa, D., and Magraner, L. (2010). La RFEF pone en marcha un sistema
homologación de campos de césped artificial.. Revista de Biomecánica. 53(15),
15-16, Retrieved from
http://gestion.ibv.org/gestoribv/index.php?option=com_docman&view=downloa
d&alias=390-la-rfef-pone-en-marcha-sistema-homologacion-campos-cesped-
artificial&category_slug=productos&Itemid=142
Sans, Á. and Frattarola, C. (1999). Fútbol: Manual para la organización y el
entrenamiento en las escuelas de fútbol. [Soccer: a manual for soccer school
organization and training]. Barcelona: Paidotribo.
Received Date: September, 26th,2016
Correction Date: February, 25th, 2017.
Acceptance Date: March, 21st,2017.
Publication Date: April, 5th,2017
