Tests específicos para el control de la agilidad en playa joven  
jugadores de voleibol  
Resumen  
El voleibol de playa es un deporte de alta exigencia física, donde la agilidad se convierte en un  
habilidad importante. El objetivo de  este  trabajo fue diseñar pruebas específicas  para el  control  
de la agilidad en jóvenes jugadores de voleibol de playa, en correspondencia con el contexto y  
exigencias del juego. Los estudios sobre este tema son escasos y están dirigidos principalmente a jugadores  
del más alto nivel de competencia,  por lo tanto, es necesario profundizar en este aspecto  y  
especialmente con vistas a la iniciación deportiva. Como la tendencia de los entrenadores ha sido  
extrapolar las pruebas de Voleibol, sin tener  en cuenta las diferencias con  Playa  
Voleibol, la investigación se basó en una metodología descriptiva donde la dinámica de  
el juego fueron considerados. Métodos y técnicas como el análisis y la síntesis,  
análisis documental, taller metodológico, lluvia de ideas y evaluación por  
Para ello se utilizó el criterio de expertos. El resultado de  este  proceso proporcionó  evidencia   específica
contextualizado a las acciones de  los jugadores. La relevancia  de  estas pruebas radica en  el  hecho  
que permiten evaluar el nivel de  desarrollo de la agilidad en  jóvenes de  voleibol   de playa
jugadores, relacionando los diferentes movimientos básicos con las acciones técnico-tácticas del juego.  
Palabras clave: pruebas físicas, agilidad, voleibol de playa, entrenamiento, iniciación.  
Introducción  
El voleibol de playa es un deporte colectivo de red que se juega sobre una superficie muy inestable,  
exigiendo altas exigencias físicas a  sus  practicantes  en acciones explosivas de  corta  
duración. Sus  protagonistas  experimentan grandes esfuerzos físicos  en complejos  técnico-tácticos  
acciones, que se repiten constantemente durante el partido (McLaren et al., 2018).  
Es un juego con mucha variabilidad de acciones y, sobre todo, habilidad en las acciones de defensa de campo,  
donde se realizan movimientos rápidos  con cambios de dirección y  posiciones corporales.  Tal  
circumstances require coaches to plan training sessions that are increasingly tempered to  
the demands of the game (Doeven, Brink, Frencken, & Lemmink, 2017); (Palao, García  
de Alcaraz, Hernández, Valades and Ortega, 2018); (Echeverría, Ortega and Palao, 2020).  
This aspect is currently of vital importance, since it improves the physical condition of  
the players and is essential to successfully resist the demands of the competition  
(Andrade, et. al., 2020). Training planning in team sports has evolved significantly in  
terms of forms of control and variety of methods for working on the physical capacities  
of each sport modality.  
As a significant element, it stands out that, in contrast to traditional and reductionist  
methodologies, a new approach emerges where non-linear pedagogy is appreciated,  
focused on the analysis of the actions and execution patterns of the players at different  
levels of competition (Cantos and Moreno , 2019); (Martin and Camacho, 2021);  
(Haddad, Stylianides, Djaoui, Dellal, and Chamari, 2017).  
The different forms of control of physical capacities during preparation can constitute a  
determining action with a view to guaranteeing the desired performance levels (Alzate,  
Ayala and Melo, 2017); (Martinez, 2017). In this direction, authors such as Romero and  
Becali (2014) affirm that the growing competitive demands in the world of sports force  
scientists in this field to carry out new studies, so that competitors successfully face their  
competitive projection.  
Associated with the above, it is stated that the preparation of beach volleyball players  
requires constant research in the current context, as a fundamental way to obtain reference  
values for training. However, studies on physical abilities in Beach Volleyball have been  
directed fundamentally at the highest competitive level, with little study of the sports  
initiation stage. Research has focused on conditional capacities such as strength, speed  
and resistance (Jiménez, 2019) and less coordination has been studied.  
As beach volleyball demands high physical complexities due to the characteristics of its  
game and the environment where it is developed, more attention should be given to the  
control of complex coordination abilities such as agility. Young, Jones and Montgomery  
(2001) identify two main areas as the most significant and influential factors in agility:  
the speed of changes of direction and the perceptual factors that influence decision  
making, both of which are very present in volleyball actions. beach.  
Movement speed and agility are important skills in this sport, since playing on sand  
influences and makes it difficult for players to act, therefore, the ability to change  
direction quickly can make the difference between winning or losing a point.  
Agility in Beach Volleyball allows players to move quickly and smoothly on the field  
Martínez, 2017). This involves quickly and suddenly speeding up, slowing down, or  
(
changing direction to respond to disparate game situations. There are factors that  
influence agility, such as the speed of changes of direction, the technique of movement  
on the sand, the position adopted by the body at the time of the action and the physical  
peculiarities of each player (Dawes and Roozen, 2017 ); (Jiménez, 2019).  
Despite this being an important physical ability in the game of Beach Volleyball, there  
are hardly any studies to control this ability in sports initiation and that are linked to  
technical-tactical actions.  
The works found on agility control in beach volleyball for the sports initiation stage, focus  
on carrying out tests with resistance limits (Martínez, (2017). To this it can be added that  
regardless of an action of the player with similarity to the action of the game, there is no  
direct link with the technical-tactical actions of the game, remaining only in actions that  
reproduce specific technical gestures of the actions of the players (Portela, Rodríguez and  
Moreno, 2022).  
The limited availability of specific tests for this ability makes coaches extrapolate them  
from Volleyball, without taking into account the differences between these modalities.  
Given this existing limitation in the national and international literature, the objective of  
this work was to design tests for the control of agility in young beach volleyball players,  
in correspondence with the context and the demands of the game.  
Materials and methods  
For the development of the research, we worked with a population made up of 16 coaches  
of the Beach Volleyball pairs participating in the National High Performance Games  
(JENAR) of this sport in Cuba in 2022. As characteristic elements, they all had work  
experience for more than 8 years in the category of basic initiation (pioneer, 11-12 years)  
or school (13-15 years), all Graduates in Physical Culture and ages between 22 and 40  
years. In addition, all the provinces of the country were represented and four of them had  
the status of Master in Sports Training. Similarly, we worked with an intentional sample  
of 10 experts with special characteristics in order to determine the theoretical validity of  
the tests.  
Based on the foregoing, it was assessed that the use of a sufficiently large number of  
expert judges is required for a satisfactory validation of the proposal. In this direction,  
several authors such as Conejero, Prado, Claver, et al., (2018) indicate a minimum of 10.  
Experts were considered to be people who had the following characteristics: more than  
2
0 years of experience in the field of Physical Culture and Sports, with at least 15 years  
of experience as a coach and a minimum of five linked to initiation Beach Volleyball.  
Possess the academic category of Master's in Sports Training or scientific category of  
Doctor in Physical Culture Sciences and have carried out research related to the Theory  
and Methodology of Sports Training, specifically in relation to the preparation of tests.  
Different methods and techniques were used such as: Analysis and synthesis,  
documentary analysis to support the evaluation of physical tests in Beach Volleyball,  
specifically in relation to agility. Such review included scientific articles and specialized  
texts. Brainstorming was used in the design of the test and in order to determine the  
aspects that it should contain. Methodological workshops, used in the process of  
elaboration and theoretical validation of the tests.  
The research went through three phases, the first aimed to develop an evaluative analysis  
of the agility tests carried out by the coaches, who worked with the initiation categories.  
The needs of the coaches were determined from the methodological point of view,  
regarding the evaluation of the development of the agility and movement speed of their  
players. Likewise, a documentary analysis was carried out aimed at analyzing the  
demands of the game, assessing the current trends in Beach Volleyball training and its  
characterizing elements.  
The second phase had the objective of designing tests that would allow evaluating the  
levels of agility in initiation beach volleyball players. To this end, three sessions of  
methodological workshops were held within the framework of the championship with the  
aforementioned coaches, with the use of brainstorming.  
In the first, a specialized conference was held on the development and validation of tests  
in sports games. This action allowed them to increase their level of knowledge on the  
subject. In the second joint workshop with the coaches, there was a debate about their  
needs regarding the control and evaluation of the agility of the players at this level,  
evaluating the criteria of Zatsiorski (1989) and Morales (1995), regarding the elaboration  
of tests.  
In the third workshop, a brainstorming and discussion was developed on the  
characteristics that the tests should have to evaluate the level of agility of the players in  
initiation Beach Volleyball, where the proposal of three tests was finally finalized by  
consensus. In the third phase of the research, a methodological meeting was held with the  
experts to assess the designed tests and establish their theoretical validity.  
In order to obtain expert assessments and seeking a high level of consensus among them,  
this was carried out in a group manner, since all the subjects could be brought together in  
a scientific framework (Escobar and Cuervo, 2008). This action allowed a wide and  
diverse discussion space, based on the needs of the coaches. In this procedure, the  
objective of the tests, their description of the exercise, the necessary means and  
instruments and the standardization criteria were reviewed.  
Results and Discussion  
In the first phase of the research, the main needs of the training process were identified,  
which affects coaches who work in the initiation stage, regarding agility control. The  
interviews carried out with them allowed to verify the lack of theoretical and conceptual  
mastery on the elaboration of agility tests for Beach Volleyball. It was possible to  
appreciate that the tests carried out regarding this capacity are extrapolated from  
Volleyball and without taking into consideration the characteristics of the beach modality.  
In the second phase of the research, after analyzing the previous results, several tests were  
designed to control agility in young beach volleyball players. To this end, two  
methodological workshop sessions were held with the coaches, considering budgets such  
as: the tests must link the speed of the different basic movements of Beach Volleyball in  
the sand, have in turn a link with technical-tactical actions, the logic of the action in game  
and had to assess the level of development of agility in the players.  
As a result of the work sessions with the coaches, three agility tests were obtained, which  
are shown below and which take into consideration several of Zatsiorski's (1989)  
postulates.  
Test 1.  
Test Name: Three (3) Short and Long Side Contacts.  
Objective: To evaluate the level of development reached by the players in agility,  
specifically in lateral movements.  
Test description:  
Short displacements: A ball or marker is placed in the middle of the court and the other  
is placed on the lateral band (figure 1a). The player in defense position, stands behind the  
ball that is in the center of the field. The distance that separates the balls will be 3.5 meters  
for the pioneer category, and 4 meters for the school category.  
Long movements: Two balls are placed on the lateral bands that delimit the width of the  
court (figure 1b). The player stands behind the ball in the center of the court. In the pioneer  
category, the distance that will separate the balls will be 7 meters, which is the width of  
the field, and 8 meters in the school category.  
The player in defense position, at the signal (preferably visual) of the coach, starts from  
the center of the court and will make three contacts as quickly as possible. The time is  
taken from the signal until the player touches the third ball. The test is carried out twice,  
in the first one the displacements are started to the left and in the second one it is started  
to the right. The two times are added and divided by two to finally have the time of  
completion of the test.  
The coach is left with the information on which side each of his players has more  
difficulties, an important aspect that will give him reference values that he must take into  
account in the preparation process.  
Figure 1a. Short side contacts.  
Symbology: Ball.  
Figure 1b. Long side contacts.  
player movements  
Player  
As these movements are fundamental, especially in defense actions, and taking into  
consideration that everything that is done in the preparation of the players must be in  
correspondence with their actions in the game, it is recommended to end the player's  
actions with a Shot on a thrown ball, although this does not count within the time of the  
test and its complexity will depend on the preparation stage.  
Test #2.  
Test name: Three (3) zig-zag contacts to the front (short and long).  
Objective: To evaluate the level of development reached by the players in agility,  
specifically in forward movements.  
Test description:  
Short displacements: The balls or marks are placed as shown in figure 2A. A ball is placed  
towards the center of the court at a distance of 5.33 meters from the final band. Another  
will be placed on the lateral band 2.66 meters from the final band and a third will also be  
placed on the lateral band on the extreme left under the net at the mark that delimits the  
middle of the field. For the pioneer category, as in the special bases for the competition it  
is declared that the dimensions of the field will be two courts of 7 x 7 meters, the ball in  
the center of the court is placed at a distance of 4.66 meters from the final band. Another  
will be placed on the sideline at 2.33 meters from the final touchline and the third will  
also be placed on the sideline at the far left under the net.  
Long displacements: The balls or marks are placed as shown in figure 2B. A ball will be  
placed on the left lateral band at a distance of 2.66 meters from the final band of the field.  
A second ball will be placed on the right lateral band at a distance of 5.33 meters from  
the final band and a third ball that is also placed on the lateral band on the far left under  
the net at the halfway mark.  
For the pioneer category, as in the special bases for the competition, it is declared that the  
dimensions of the field will be two courts of 7 x 7 meters, the balls will be placed, one  
located on the left lateral band at a distance of 2.33 meters from the band end of the land.  
A second ball will be placed on the right sideline at a distance of 4.66 meters from the  
final touchline and a third ball which is also placed on the far left sideline under the net  
at the halfway mark.  
The player is placed adopting the defensive position, in front of the final band and in the  
center of the court (figure 2a and 2b). At the starting signal (preferably visual) you must  
make the three contacts moving as quickly as possible. The time is taken from the starting  
signal until the player touches the third ball. The test is carried out twice, first moving  
from the center of the field to the left and then in the same way, but to the right. The two  
times are added and divided by two to finally have the time of the test.  
Test diagram:  
Arregla este que al copiar quedó así y yo no pude arreglarlo  
Figure 2a. Short front contacts.  
Symbology: Ball.  
Figure 2b. Long front contacts.  
Player player movements  
The coach has the information on the side that each of his players has the most difficulties,  
these will constitute reference values for the planning of the preparation. As these  
displacements end near the net, it is recommended to end the player's actions with a  
blocking action or shot on a thrown ball, although this no longer counts within the time  
of the test. In the same way, the degree of complexity for this action will depend on the  
moment where the preparation stage is carried out.  
Test #3.  
Test name: Three (3) contacts front and back.  
Objective: To evaluate the level of development reached by players in agility, specifically  
in combined forward and backward movements.  
Test description:  
The balls or marks are placed in the middle of the field as shown in figure 3. One located  
5
0 centimeters from the final band of the field, another is placed 4 meters and a third  
under the net in the middle of the field. For the pioneer category, as in the special bases  
for the competition, it is declared that the dimensions of the field will be two courts of 7  
x 7 meters, one will be placed 50 centimeters from the final band of the field, another is  
placed 3.50 meters and a third equally under the net at half court.  
To start the test, the player, adopting the defensive position, stands next to the ball located  
near the final band of the field (figure 3). At the signal (preferably visual) of the coach,  
he must move forward as quickly as possible making a movement to touch the ball that  
is in the middle of the court, he will move backwards until touching the ball from the  
starting point and finally move again forward to touch the ball located in the center of the  
court under the net.  
The time is taken from the starting signal until the third ball is touched. The test will be  
done twice, the two times are added and divided by two to get the time of the test. In this  
test it is important to insist that the movement backwards is lateral and with the eyes  
looking straight ahead.  
Figure # 3. Front and back contacts.  
Symbology:  
Ball.  
Player  
player movements  
As these displacements that make up the test end near the net, it is recommended to  
culminate the player's actions with a blocking execution or shot on a thrown ball, although  
this does not count within the time of the test. The complexity that will be given to this  
action will depend on the moment of the preparation stage.  
Standardization conditions for carrying out the tests:  
The tests will always be carried out after having performed a warm-up. The exercise will  
never be performed after training. The player must have a normal pulse and respiratory  
rate before running the test.  
Evaluators: At least two trainers will participate, for greater ease in their organization and  
veracity in the collection of information.  
Norm for the evaluation of the tests. As the result of the measurements is obtained in  
seconds, and the less time it takes, the better it is. An analysis was carried out in table  
work with the researchers to establish the following evaluation criteria:  
Very good. The value resulting from subtracting the value of the standard  
deviation from the mean.  
Good. values around the mean.  
Regular. The value resulting from adding the value of the standard deviation to  
the mean. A rigid value is not given, but it oscillates around that result.  
Wrong. The result obtained is superior to that qualified as regular.  
As a result of the third phase and after having defined the test proposal, a methodological  
meeting was held in a formal space with the experts, which allowed obtaining the  
theoretical validity of the tests. To this end, a debate and discussion focused on some  
fundamental aspects was carried out, through which they had to issue their assessments  
of the tests.  
Considerations were issued on: if the structure is adequate or not, if they allow to control  
the level of agility development in initiation Beach Volleyball players, if they respond to  
the characteristics of the internal logic of the game at the initiation level and if the design  
is in correspondence with current trends in sports training.  
The decision-making made by the group of experts was achieved by consensus, after an  
extensive process of debate and discussion. As a result of the evaluation, it was obtained  
that 100% of the expert evaluators agreed to affirm that the aforementioned requirements  
are met in the tests. Highlighting as an element of great value and novelty, the linking of  
the actions of the players in the tests with technical-tactical actions of the game depending  
on its logic and the moment of preparation. However, they recommended submitting the  
tests to a more rigorous validation process, also considering reliability and objectivity  
assessments (Zatsiorsky, 1989).  
The objective of this work was to design specific tests for the control of agility in young  
beach volleyball players, in correspondence with the context, the speed of displacement  
and the demands of the internal logic of the game. The research process made it possible  
to demonstrate the need to temper the preparation of the players in the control of  
conditional abilities, to the characteristics of the game action, in this case specifically  
related to agility.  
Due to the above, it became clear the need to contextualize the evaluations of this  
capacity, to the current trends of sports training and to contribute to perfect the contents  
of the Comprehensive Program for the Preparation of the Athlete (PIPD) of the Cuban  
Beach Volleyball.  
It is necessary to understand the need for a new approach, on the control of this capacity  
that is so important in the performance of beach volleyball players today (Jiménez, 2019).  
It implies for the coaches to go beyond the mere formality of placing balls, conditioning  
an area or using a stopwatch to evaluate. The need to go towards a more comprehensive  
conception of physical tests in Beach Volleyball as an essential support of competitive  
dynamics is evident (Dawes and Roozen, 2017).  
The integration of different factors by combining, in each specific agility test, technical-  
tactical and cognitive aspects of the game action, should have significant results with a  
view to greater optimization of training time and the preparation of the players. From the  
above it can be deduced that the tests under these conditions become a dynamic  
component of the sports preparation process. Undoubtedly, players with a high level of  
agility are more accurate when it comes to recognizing and taking advantage of dissimilar  
game situations, which can constitute a competitive advantage over their opponents.  
As a significant element of these tests, the similarity in movement patterns, muscle groups  
and necessary energy systems present in the game action in Beach Volleyball can be  
mentioned, all of which provide information for significant feedback. It is important to  
highlight the fact that the proposed tests have very specific characteristics for beach  
volleyball players in the initiation stage. Its realization contemplates the actions of the  
player in short and long displacements that are basic in the game.  
It will make it easier for coaches to have collected data to compare sports performance,  
assess their preparation plans and track the progress of each player, from one test to the  
next and from one season to the next. More reliable information will be available to set  
precise targets for improving performance. The correct evaluation of the specific demands  
and of the movements involved in it, can provide relevant information in terms of  
perfecting the sports preparation process, such as, for example, the regularity of which  
direction the players are most deficient in collectively and individually.  
Conclusions  
The evaluative analysis carried out about the agility tests carried out by the coaches who  
worked with the initiation categories, demonstrated the need for a change in their  
conception to temper them to the characteristics of the game action with a link to technical  
actions. -tactics, the lack of evidence for their control during the preparation process, as  
well as the tendency to extrapolate them from Volleyball.  
The tests designed have as a novelty the fact of establishing a link between the different  
basic displacements of Beach Volleyball in the sand with technical-tactical actions, based  
on the logic of the action in play and allowing a more precise assessment of the level of  
development of players in agility.  
The experts in its assessment recognize the theoretical validity of the content of the tests,  
pointing out the need to deepen its validation through elements of greater consistency, for  
which it is necessary to continue perfecting its validation process in terms of reliability  
and objectivity.  
References  
Alzate Salazar, D. A., Ayala Zuluaga, C. F., and Melo Betancourth, L. G. (2017). Training  
control components used by school coaches. Physical Education and Science, 19(1),  
e026. https://doi.org/10.24215/23142561e026  
Andrade, A. D., Simim, M., Kassiano, W., Palao, J. M., de Jesus, K., Maia, N.,  
Assumpção, C., and Araripe Medeiros, A. I. (2020). Do differences between the training  
load perceived by elite beach volleyball players and that planned by coaches affect  
neuromuscular  
function?.  
Challenges,  
38,  
632-636.  
https://doi.org/10.47197/challenges.v38i38.77625  
Cantos, J. & Moreno, F. (2019). Nonlinear pedagogy as a method of teaching tactical  
behaviors in team sports, application to rugby. Challenges, 35, 402-406.  
https://www.researchgate.net/publication/332465566_Pedagogia_no_linear_como_meth  
od_of_teaching_tactical_behaviors_in_team_sports  
Conejero, M., Prado, P. L., Claver, F., Jara, J. and Moreno, M. P. (2018). Design and  
validation of an observation instrument for decision-making in volleyball blocking.  
SPORT-TK: Euroamerican Journal of Sports Sciences, 7(1), 63-70.  
https://revistas.um.es/sportk/article/view/321891  
Dawes, J., and Roozen, M. (2017). Development of agility and speed. NSCA. Barcelona.  
Editorial Paidotribo.  
Doeven, S. H., Brink, M. S., Frencken, W. G. P., & Lemmink, K. (2017). Impaired Player-  
Coach Perceptions of Exertion and Recovery During Match Congestion. International  
Journal  
of  
Sports  
Physiology  
and  
Performance,  
12(9),  
1151-1156.  
https://doi:10.1123/ijspp.2016-0363  
Echeverría, C., Ortega, E., and Palao, J. M. (2020). Normative Profile of the Efficacy and  
Way of Execution for the Block in Women’s Volleyball from Under-14 to Elite Levels.  
Mount. J. Sports Sci. Med. 9(1), 1-7. DOI 10.26773/mjssm.200306  
Escobar, J., and Cuervo, A. (2008). Content validity and expert judgment: an approach to  
its  
use.  
Advances  
in  
Measurement,  
6,  
2736.  
http://www.humanas.unal.edu.co/psicometria/files/7113/8574/5708/Articulo3_Juicio_d  
e_expertos_27-36.pdf  
Haddad, M., Stylianides, G., Djaoui, L., Dellal, A., & Chamari, K. (2017). Session-RPE  
Method for Training Load Monitoring: Validity, Ecological Usefulness, and Influencing  
Factors. Frontiers in Neuroscience, 11:612. https://doi:10.3389/fnins.2017.00612  
Jiménez Moya, C.G. (2019). Tests for the control of special resistance in Beach  
Volleyball youth category. (Master's Thesis). Central University "Marta Abreu" of Las  
Villas. Clear Villa.  
Martín Barrero, A., and Camacho Lazarraga, P. (2021). The session structure as an  
element that enhances learning and training in team sports from the perspective of non-  
linear pedagogy. SPORT TK: Euroamerican Journal of Sport Sciences, 10(1), 51-58.  
https://revistas.um.es/sportk/article/view/461661/298481  
Martinez Penton, O. (2017). Specific test for agility control in universal school Beach  
Volleyball players in special preparation. (Diploma Thesis). Central University "Marta  
Abreu" of Las Villas. Clear Villa.  
Morales, A. (1995). Specific tests for the control of the development of the cognitive  
processes of the Cuban school fencer-foil fencer (14-16 years old). (Doctoral thesis not  
published). ISCF. Clear Villa.  
McLaren, S. J., Macpherson, T. W., Coutts, A. J., Hurst, C., Spears, I. R., & Weston, M.  
(2018). The Relationships Between Internal and External Measures of Training Load and  
Intensity in Team Sports: A Meta-Analysis. Sports Medicine, 48(3), 641658,  
https://doi:10.1007/s40279-017-0830-z  
Palao, J. M., García-de-Alcaraz, A., Hernández-Hernández, E. Valades, D. & Ortega-  
Toro, E. (2018). Establishing technical and tactical performance goals for elite male  
volleyball players. Central European Journal of Sport Sciences and Medicine, 21(1), 5-  
1
2. https://wnus.edu.pl/cejssm/pl/issue/757/article/12247/  
Portela Pozo, Y., Rodríguez Stiven, E., and Moreno León, R. A. (2022). Evaluation of  
the development of the vertical jump in university volleyball. EmásF, Digital Magazine  
of  
Physical  
Education.  
77,  
52-64.  
https://emasf.webcindario.com/Evaluacion_del_desarrollo_del_salto_vertical_en_el_vol  
eibol_universitario.pdf  
Romero Esquivel, R. J., and Becali Garrido, A. E. (2014). Sports Training Methodology.  
The Cuban School. Havana: Editorial Sports.  
Young, W. B., McDowell, M. H., & Scarlett, B. J. (2001). Specificity of sprint and agility  
training methods. J.Strength Cond. Res., 15(3), 315-319.  
Zatsiorski, V.M. (1989). Sports Metrology. Moscow: Editorial Planeta.  

Original text