Front. Sports Act. Living Frontiers in Sports and Active Living Front. Sports Act. Living 2624-9367 Frontiers Media S.A. 10.3389/fspor.2023.1308960 Sports and Active Living Original Research Physical fitness in young top level table tennis players: differences between sex, age and playing style Pradas de la FuenteFrancisco 1 Toro-RománVíctor 2 * Ortega-ZayasMiguel Ángel 1 Moreno-AzzeAlejandro 1 ENFYRED Research Group, University of Zaragoza, Huesca, Spain Faculty of Sports Science, University of Extremadura, University Avenue, Cáceres, Spain

Edited by: Jesus Ramón-Llin, University of Valencia, Spain

Reviewed by: Veroljub Stankovic, University of Pristina, Serbia Nicolae Ochiana, University of Bacău, Romania Armando Raimundo, Universidade de Évora, Portugal

 Correspondence: Víctor Toro-Román vtoro@unex.es

Abbreviations TT, table tennis; MIX, mixed style; DEF, defensive style; OFF, offensive style; VO2max, maximum oxygen uptake.

 28112023 2023 51308960 07102023 10112023 © 2023 Pradas de la Fuente, Toro-Román, Ortega-Zayas and Moreno-Azze. 2023Pradas de la Fuente, Toro-Román, Ortega-Zayas and Moreno-Azze

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Understanding the physical fitness of table tennis (TT) players could be interesting in improving the training process and evaluating talent. This study aimed to assess the physical fitness of U14 TT players and differentiate between sex, age and playing style. A total of 352 players (203 males and 149 females) aged between 9 and 13 years participated in the present study. Furthermore, the sample was divided according to playing style: offensive (OFF) and mixed + defensive (M + D). A battery of tests was carried out to assess cardiorespiratory capacity, speed, strength, flexibility and power. Both sexes reported significant differences in cardiorespiratory capacity and speed (p < 0.05). Concerning age, there were substantial differences in cardiorespiratory capacity, speed, strength and power, with older players obtaining better results (p < 0.05). Finally, concerning playing style, differences were reported in cardiorespiratory capacity, higher in OFF style group, and flexibility, higher in the M + D style group. Finally, there were relationships between playing style and cardiorespiratory fitness and flexibility. Physical fitness evolves with increasing age as a function of sex. This is the first study to assess fitness in a large sample of TT players as a function of playing style.

 racket sports youth elite defensive offensive 10/UPB10/10 Consejo Superior de Deportes to Research Project section-at-acceptanceElite Sports and Performance Enhancement Introduction

Table tennis (TT) is a sport where highly complex motor tasks are performed. The efforts made during a game in TT are acyclic, intermittent, of short duration, high intensity, with constant changes of rhythm and direction, where players must continuously react, move and hit a ball that moves at high speed (1, 2). The activity of a TT player is not only determined by the complexity of its technical and tactical actions but also by the cumulative-explosive nature of the physical effort caused by the high precision required by the movements to be executed (2) and the continuous repetitiveness of interactions between the neuromuscular system and the ball as a moving stimulus (3).

At the technical level, the dynamics of TT playing demands are characterized by the continuous and fast execution of different types of strokes and displacements that involve significant physical stress for players. Movements at high velocity and endurance are two critical physical qualities in this sport (4, 5). Short and intense efforts during the game require essential training in reaction speed and anaerobic endurance (5, 6), At the same time, the duration of the matches makes it necessary to maintain an adequate aerobic endurance base (7, 8).

The resistance to be overcome by the upper extremity when impacting on the ball is relatively small (6). However, this type of action involves a significant muscular effort for the lower extremities due to the degree of acceleration and deceleration required to hit each ball in a properly position (9, 10). In this sense, the manifestations of the lower extremities' explosive and reactive strength are considered one of the sport's main physical qualities (11, 12). On the other hand, flexibility in TT performance is of little relevance. However, the range of motion of the lower body is an essential physical aspect because if it is insufficient, there is a reduction of the gestural content and a deterioration of neuromuscular coordination (13).

In terms of tactical skills, TT is a demanding sport as athletes have to plan different and precise technical-tactical actions (14), depending on the style of play and the opponent, making decisions in very short periods of time, also enduring situations of physical fatigue (15). TT players mainly use two styles of play: offensive (OFF) and defensive (DEF) (16). Although less known, there is also a style of play called mixed (MIX), intermediate between the two previous styles. The development of each type of play is directly related to the use of specific materials in the table tennis blades (17).

The OFF style of play is one in which the players are positioned at a very close or far distance from the table, using techniques to initiate the attack, either through lift-type strokes such as flip and topspin or with blocks to accelerate the game's pace (1, 18). On the other hand, the DEF playing style is performed at a medium distance or even far away from the table. In a defensive game, the player tries to nullify the opponent's attacking strokes by defensive techniques (push or chop), producing a recoil effect on the ball. These players tend to slow down the game's speed, lengthening the play and trying to win the point by forcing their opponent to make mistakes (1, 18). Finally, the MIX playing style can be performed very close to the table or at a middle distance. This style of play is very varied and aims to confuse the opponent with different types of slice or lift effects, especially in a defensive phase (1, 18).

In the scientific literature, some studies show differences in the physical load depending on the style of play (19). Differences have been reported in physiological parameters (heart rate and maximum oxygen consumption), the duration of games and matches, and the type and number of total strokes performed (7, 19, 20). However, no research has been found that analyzes and compares the levels of physical fitness as a function of the style of play developed (OFF vs. MIX + DEF), especially in young top level players, and in particular studies that include the female sex. Consequently, the study aimed to analyze the influence of playing styles (OFF vs. MIX + DEF) in young high-level TT players' physical fitness levels according to age and sex.

 Materials and methods Participants

Three hundred fifty-two children aged from 9 to 13 years volunteered to participate in the study (203 males and 149 females). The sample size is larger for a population of 1981 players of U14 categories (based on the number of licenses of the Royal Spanish Table Tennis Federation) for a confidence interval of 95% and a margin of error of 5% (n = 322). The TT players were recruited from the National Sports Technification Program developed by the Royal Spanish Table Tennis Federation. All players were ranked in the top positions of their respective categories and sex. The playing style data were obtained by reviewing the types of racquets and coverings used by the players, in addition to observing the use given by the players during training and competitions. Also, the players and their coaches were asked about the type of game they intended to develop with the playing equipment used.

After an extensive verbal and written explanation of the study, written informed consent was obtained from the parents or legal guardians. The research protocol was reviewed and approved by the Clinical Research Ethics Committee of Aragon (Spain) (code: 19/2010) following the guidelines of the Helsinki Ethical Declaration for research in humans.

For inclusion in the study, participants had to achieve the following criteria: (i) practice only TT as a sport modality; (ii) have at least one year's experience; (iii) be federated; (iv) not having any pathology; (v) not ingest of medication. The playing characteristics of the participants were provided by the coaches of the study participants (Table 1).

General characteristics of the sample.

Variables n %
Sex Male 203 57.6
Female 149 42.4
Playing style Defensive 5 1.4
Mixed 12 3.4
Offensive 335 95.2
Laterality Right-handed 318 90.3
Left-handed 34 9.7
9 32 9.1
10 80 22.7
11 94 26.7
12 109 31.0
13 37 10.5
Procedures

The study was carried out during the summer months, coinciding with the vacation period of the participants. No training was required for a more objective assessment the day before the evaluations.

Before the assessments, participants performed a 10-minute warm-up based on general mobility and jogging. All participants were familiarized with the different tests. The physical fitness assessments were performed in two different phases in the following order: anthropometry, flexion, vertical jump, upper limb strength and running speed. In the second phase, carried out 60 min after the first phase, the test to assess maximum cardiorespiratory capacity was performed.

 Anthropometric

Body weight, height and body mass index (BMI) were evaluated. A scale (Seca 769, Seca, Hamburg, Germany) and a measuring rod (Seca 220, Seca, Hamburg, Germany) were used. All participants were evaluated with as minimal clothing as possible and without footwear.

 Flexibility

The sit-and-reach test was used to measure the range of motion of the lumbar region and the hamstring muscle, according to standardized procedures (21) using the sit-and-reach flexibility tester (Baseline®, New York, USA). From a seated position on the floor with legs fully extended, participants extended the arm along the measurement scale as far as possible without bending the knee, placing one hand on the other with palms down. The best of two repetitions was chosen for further analysis.

 Vertical jump

To evaluate the vertical jump, the squat jump (SJ), counter-movement jump (CMJ) and Abalakov jump (ABK) tests were established (22). A jump mat system (Newtest Powertimer®, Oulu, Finland) was used to measure height and flight time during the jumps. During the test, the guidelines proposed by Bosco et al. (23), were followed.

For the SJ, participants initiated the movement from a squat position (knee angle 90°) and arms resting on the hips. After 2 s of holding the position, a jump was performed without countermovement at maximum intensity. For the CMJ, participants started the execution from an upright position and hands resting on the hips. Subjects performed a knee flexion-extension followed by a jump at maximum possible intensity. For the ABK, participants could propel their arms by swinging.

Recovery was 30 s between jumps. The best jump of three attempts was selected for further analysis.

 Upper limb strength

The handgrip strength and medicine ball throw tests were performed to assess upper body strength.

A Takei 5,101 dynamometer (Takei Instruments Ltd., Tokyo, Japan) was used to determine handgrip strength. Participants completed two maximal voluntary contractions with the dominant and non-dominant hand. At all times, the arm was extended. The grip of the dynamometer was adjusted to the participant's hands. The best of two alternative repetitions was chosen. The asymmetry of grip strength (difference between the dominant and non-dominant hand) was evaluated.

The overhead medicine ball throw tests upper body strength and explosive power, which consists of throwing the ball forward over the head. It consists of performing a quick downward motion, bending the knees and hips, before quickly extending the hips, knees and arms to throw the medicine ball as far as possible. A 3 kg medicine ball was used for both sexes. Two attempts were made, and the most significant distance obtained was chosen for analysis.

 Flying 30 meter sprint test

Flying 30-meter sprint test is a physical test used to measure the maximum sprint speed of an individual. On a 70-meter straight line, the subject sprints to reach the maximum speed upon reaching a photocell located at 20 m and holding it until passing the photocell at the finish line located at 50 m (Newtest Powertimer®, Oulu, Finland). Two attempts were performed with a 2-minute rest between attempts. The best of the two repetitions was chosen.

 Cardiovascular fitness

Cardiovascular fitness was examined by a maximal multistage 20 m shuttle run test (Course Navette Test; CN) (24). Sound signals were emitted from a pre-recorded tape that increased 0.5 km·h−1 each minute from a starting speed of 8.5 km·h−1. When the subject could no longer follow the pace, the last stage number announced was used to estimate the maximal oxygen uptake (VO2max) by formula (24). Distance, periods, and speed were noted.

 Statistical analysis

The data were processed in IBM SPSS 25.0 Statistics (IBM Corp., Armonk, NY, USA) and were expressed as mean ± standard deviation, except for the data on the characteristics of the participants, which were described as frequencies and percentages. The normality of the distribution of the variables was analyzed using the Kolmogorov-Smirnov test and the homogeneity of variances using the Levene test. A two-way ANOVA (sex and age effect) was used to show any differences in the variables studied. The effect size was calculated using partial eta squared. Effect size values were classified as 0.01–0.06 small effect size; 0.06–0.14 moderate effect size; >0.14 large effect size (25). A t-test for independent samples was used to analyze differences between play styles. Finally, Pearson's correlation coefficient r was used to establish relationships between playing style and sex with the physical fitness parameters analyzed. Differences of p < 0.05 were considered statistically significant.

 Results

The data obtained in the present study are presented below. Table 2 shows the anthropometric characteristics. Significant differences were observed in height, weight and BMI (p < 0.05) being higher in older players.

Anthropometric characteristics.

Variables Age (years) Male Female Sex effect Age effect Sex × Age
Height (m) 9 1.39 ± 0.05 1.38 ± 0.06 0.301 <0.001## 0.510
10 1.42 ± 0.07 1.43 ± 0.05
11^^ 1.47 ± 0.06 1.50 ± 0.07
12^^,$$ 1.52 ± 0.06 1.54 ± 0.06
13^^,$$,&& 1.57 ± 0.08 1.56 ± 0.06
Weight (kg) 9 33.61 ± 4.15 34.02 ± 7.87 0.443 <0.001## 0.496
10 37.02 ± 7.10 38.15 ± 6.28
11^^ 41.08 ± 9.04 42.92 ± 8.93
12^^ 44.28 ± 7.72 44.59 ± 6.35
13^^,$$,&& 50.72 ± 9.71 47.00 ± 6.89
BMI (kg/m2) 9 17.26 ± 1.85 17.73 ± 3.68 0.515 0.019## 0.510
10 18.22 ± 2.59 18.57 ± 2.83
11 18.68 ± 3.20 18.81 ± 3.15
12 19.04 ± 2.50 18.62 ± 1.94
13 20.34 ± 2.79 19.13 ± 2.28

p < 0.01 differences vs. 9.

p < 0.01 differences vs. 10.

p < 0.01 differences vs. 11.

Large effect size.

The results related to the upper body strength and flexibility are presented in Table 3. There were significant differences between sexes in medicine ball throwing and flexibility (p < 0.001). On the other hand, with respect to age, there were differences in hand grip and medicine ball throwing, being higher in older players (p < 0.001).

Upper body strength and lower body posterior flexibility.

Variables Age (years) Male Female Sex effect Age effect Sex × Age
HG Dominant (kg) 9 17.78 ± 2.69 15.01 ± 2.27 0.490 <0.001## 0.018##
10 17.03 ± 3.68 17.14 ± 3.18
11^^,$$ 20.27 ± 4.32 18.04 ± 2.38
12 23.84 ± 5.21 23.81 ± 3.65
13 25.48 ± 6.76 24.78 ± 5.13
HG Non-Dominant (kg) 9 16.88 ± 2.51 13.84 ± 2.24 0.181# <0.001## 0.014##
10 15.10 ± 3.14 15.54 ± 3.30
11^^,$$ 17.70 ± 4.48 16.32 ± 2.60
12 21.14 ± 5.46 21.84 ± 5.13
13 24.44 ± 5.43 22.10 ± 3.17
Asymmetry HG (%) 9 3.47 ± 11.71 12.29 ± 4.90
10 9.23 ± 8.62 15.54 ± 9.75 0.312 0.542 0.601
11 8.62 ± 9.38 14.14 ± 4.87
12 9.61 ± 10.65 12.71 ± 9.36
13 10.61 ± 12.47 12.78 ± 10.20
Medicine ball throw (m) 9 3.01 ± 0.39 2.18 ± 0.18 <0.001## <0.001## 0.037##
10 3.20 ± 0.41 2.62 ± 0.52
11^^ 3.64 ± 0.44 3.12 ± 0.46
12^^,$$,&& 4.33 ± 0.84 3.66 ± 0.74
13^^,$$,&&,“” 5.45 ± 1.00 4.42 ± 0.37
Flexibility (cm) 9 16.28 ± 4.19 21.33 ± 8.03 <0.001## 0.121# 0.043##
10 14.18 ± 3.21 21.50 ± 6.27
11 17.10 ± 5.09 23.50 ± 6.03
12 18.84 ± 5.16 23.71 ± 8.44
13 19.67 ± 4.16 20.16 ± 6.43

HG, hand grip.

p < 0.01 differences vs. 9.

p < 0.05 differences vs. 10.

p < 0.05 differences vs. 11.

p < 0.01 differences vs. 12.

Large effect size.

Moderate effect size.

The results related to the vertical jump are presented in Table 4. No significant differences were observed between sexes. However, there were significant differences between the ages of the participants where the jump height was higher with increasing age (p < 0.001).

Vertical jump.

Variables Age (years) Male Female Sex effect Age effect Sex × Age
SJ (cm) 9 17.67 ± 2.41 17.55 ± 3.21 0.434 <0.001## 0.911
10 19.02 ± 3.91 18.53 ± 4.43
11 21.01 ± 4.37 20.15 ± 4.01
12^^,$$ 22.81 ± 4.67 22.52 ± 4.26
13^^,$$ 24.18 ± 4.99 22.59 ± 3.48
CMJ (cm) 9 20.80 ± 2.76 21.66 ± 4.17 0.382 <0.001## 0.932
10 21.64 ± 4.02 20.87 ± 5.09
11 24.29 ± 4.59 23.70 ± 4.20
12^^,$$ 26.07 ± 5.64 25.40 ± 5.04
13^^$$ 27.60 ± 5.38 25.55 ± 3.02
ABK (cm) 9 23.58 ± 3.69 23.13 ± 4.11 0.670 <0.001## 0.714
10 23.80 ± 4.88 23.82 ± 6.58
11 27.48 ± 5.09 27.58 ± 4.72
12^^,$$ 29.79 ± 6.00 28.81 ± 6.07
13^^,$$ 31.66 ± 5.5 29.50 ± 4.75

SJ, squat jump; CMJ, countermovement jump; ABK, abalakov jump.

p < 0.01 differences vs. 9.

p < 0.05 differences vs. 10.

Large effect size.

Table 5 shows the results obtained in velocity and cardiorespiratory test. There were significant differences and large effect sizes between sexes and between ages in all parameters analyzed (p < 0.05).

Cardiorespiratory capacity and speed assessment.

Variables Age (years) Male Female Sex effect Age effect Sex × Age
Periods CN (n) 9 4.21 ± 1.40 3.28 ± 0.84 <0.001## <0.001## 0.516
10 4.93 ± 1.56 3.53 ± 1.09
11^^,$$ 6.35 ± 1.58 4.37 ± 1.25
12^^,$$ 6.19 ± 1.53 4.89 ± 1.56
13^^ 7.00 ± 1.98 5.30 ± 1.29
Speed CN (km/h) 9 10.12 ± 0.69 9.67 ± 0.42 <0.001## <0.001## 0.421
10 10.55 ± 0.79 9.85 ± 0.55
11^^ 11.24 ± 0.81 10.26 ± 0.62
12^^,$$ 11.15 ± 0.77 10.51 ± 0.80
13^^ 11.55 ± 1.02 10.76 ± 0.66
Distance CN (m) 9 658.4 ± 241.8 502.5 ± 139.6 <0.001## <0.001## 0.561
10 812.7 ± 291.1 564.4 ± 191.3
11^^ 1,068.3 ± 311.6 706.0 ± 221.6
12^^,$$ 1,033.4 ± 297.1 798.1 ± 288.8
13^^ 1,178.3 ± 379.5 887.3 ± 246.1
VO2max (mL/min/kg) 9 39.85 ± 4.07 37.23 ± 2.46 <0.001## <0.001## 0.481
10 42.36 ± 4.67 38.28 ± 3.27
11^^ 46.38 ± 4.78 40.67 ± 3.64
12^^,$$ 45.86 ± 4.56 42.12 ± 4.69
13^^ 48.19 ± 6.00 43.62 ± 3.89
Speed 20 + 30 m (s) 9 5.48 ± 0.70 6.14 ± 1.07 0.019## <0.001## 0.463
10 5.60 ± 1.01 5.81 ± 0.99
11 5.03 ± 0.56 5.29 ± 0.65
12^^,$$ 4.85 ± 0.39 5.03 ± 0.31
13^^,$$ 4.53 ± 0.42 4.96 ± 0.39

VO2max, maximal oxygen uptake; CN, course navette.

p < 0.01 differences vs. 9.

p < 0.01 differences vs. 10.

p < 0.01 differences vs. 11.

Large effect size.

Table 6 shows the differences in the physical fitness parameters analyzed previously comparing between playing styles. Differences between playing styles were observed in weight (p = 0.012), CN period (p = 0.017), CN distance (p = 0.033), CN speed (p = 0.033), maximum oxygen consumption (p = 0.033) and flexibility (p < 0.001).

Differences in physical fitness in all participants according to playing style.

Variables Ofensive Mixed-Defensive t p
Height (m) 1.47 ± 0.070 1.51 ± 0.07 1.7 0.09
Weight (kg) 41.05 ± 7.11 46.71 ± 6.08 2.5 0.01
BMI (kg/m2) 18.71 ± 2.19 20.21 ± 1.34 2.3 0.01
Periods CN (n) 5.24 ± 1.73 4.11 ± 1.49 2.3 0.01
Distance CN (m) 861.02 ± 320.51 677.47 ± 270.45 2.1 0.03
Speed CN (km/h) 10.86 ± 0.93 10.17 ± 0.74 2.1 0.03
VO2max (mL/min/kg) 44.1 ± 5.21 40.15 ± 4.38 2.1 0.03
Speed 20 + 30 (s) 5.28 ± 0.71 5.19 ± 0.67 0.2 0.81
HG Dominant (kg) 21.16 ± 5.41 24.08 ± 7.05 1.9 0.05
HG Non-Dominant (kg) 19.07 ± 4.15 20.63 ± 6.12 1.3 0.17
Asymmetry HG (%) 10.87 ± 8.10 13.97 ± 9.67 1.0 0.29
Medicine ball throw (m) 3.85 ± 0.83 3.78 ± 0.97 0.3 0.70
Flexibility (cm) 18.43 ± 4.42 24.20 ± 9.73 3.8 <0.01
SJ (cm) 21.06 ± 4.59 20.87 ± 5.15 0.0 0.99
CMJ (cm) 24.21 ± 6.06 24.17 ± 5.44 0.2 0.84
ABK (cm) 28.01 ± 5.13 26.32 ± 6.83 0.5 0.60

BMI, body mass index; CN, course navette; VO2max, maximal oxygen uptake; HD, hand grip; SJ, squat jump; CMJ, countermovement jump; ABK, abalakov jump.

Table 7 shows the differences in physical fitness parameters as a function of playing style and sex. Regarding playing style, significant differences were observed in BMI (p = 0.025). In relation to sex, no significant differences were reported.

Anthropometry and physical fitness according to sex and playing style.

Style Male Female Sex effect Style effect Style × Age
Height (m) OFF 1.46 ± 0.05 1.45 ± 0.04 0.812 0.710 0.910
MIX + DEF 1.48 ± 0.02 1.47 ± 0.11
Weight (kg) OFF 41.14 ± 8.81 38.61 ± 7.34 0.317 0.081## 0.615
MIX + DEF 49.10 ± 2.12 44.38 ± 7.98
BMI (kg/m2) OFF 19.10 ± 4.12 18.51 ± 3.09 0.276 0.022## 0.498
MIX + DEF 22.26 ± 0.32 20.19 ± 0.82
Periods CN (n) OFF 5.64 ± 1.61 4.21 ± 1.19 0.691 0.114# 0.101#
MIX + DEF 3.50 ± 0.00 4.30 ± 1.30
Distance CN (m) OFF 958.5 ± 351.9 710.5 ± 231.8 0.495 0.131# 0.211
MIX + DEF 608.0 ± 0.0 681.2 ± 199.9
Speed CN (km/h) OFF 11.09 ± 0.61 10.51 ± 0.61 0.412 0.181# 0.191
MIX + DEF 10.0 ± 0.0 10.20 ± 0.57
VO2max (ml/min/kg) OFF 45.12 ± 4.18 41.01 ± 3.91 0.517 0.161# 0.191
MIX + DEF 39.12 ± 0.00 40.29 ± 3.33
Speed 20 + 30 (s) OFF 5.21 ± 0.79 5.45 ± 0.61 0.415 0.463 0.911
MIX + DEF 5.43 ± 0.19 5.63 ± 0.85
HG Dominant (kg) OFF 19.41 ± 4.91 23.36 ± 4.92 0.101# 0.681 0.517
MIX + DEF 20.35 ± 7.42 23.14 ± 6.57
HG Non Dominant (kg) OFF 17.42 ± 4.76 19.99 ± 5.42 0.253 0.955 0.966
MIX + DEF 17.40 ± 5.09 19.78 ± 6.74
Asymmetry HG (%) OFF 8.19 ± 9.11 12.17 ± 7.55 0.321 0.411 0.691
MIX + DEF 13.29 ± 6.61 14.94 ± 11.53
Medicine ball throw (m) OFF 3.91 ± 0.91 3.41 ± 0.95 0.085## 0.714 0.615
MIX + DEF 4.03 ± 0.80 3.26 ± 0.87
Flexibility (cm) OFF 17.15 ± 3.11 20.15 ± 7.18 0.055## 0.796 0.618
MIX + DEF 16.00 ± 1.41 21.50 ± 10.01
SJ (cm) OFF 22.18 ± 5.81 20.81 ± 4.27 0.312 0.219 0.610
MIX + DEF 19.50 ± 0.70 16.76 ± 2.56
CMJ (cm) OFF 24.69 ± 6.94 22.91 ± 6.11 0.415 0.131 0.619
MIX + DEF 21.85 ± 0.49 19.88 ± 3.47
ABK (cm) OFF 28.12 ± 7.49 27.39 ± 6.12 0.421 0.181 0.487
MIX + DEF 25.50 ± 0.70 21.60 ± 4.27

BMI, body mass index; CN, course navette; VO2max, maximal oxygen uptake; HD, hand grip; SJ, squat jump; CMJ, countermovement jump; ABK, abalakov jump; IE, elastic index.

Large effect size.

Moderate effect size.

Finally, Table 8 shows the correlations between physical condition parameters and playing style as a function of sex. There were negative correlations in male players and the CN period (p = 0.045). That is, OFF players performed longer periods in the CN. Regarding female players, there were positive correlations between female players and maximal oxygen consumption (p = 0.037), as well as flexibility (p = 0.030). That is, players with MIX and DEF playing styles obtained higher values of maximal oxygen consumption and flexibility.

Correlations, according to sex, in the parameters of physical fitness and style of play.

Playing style (0 = OFF; 1 = MIX + DEF)
Periods CN (n) Male r −0.144
p 0.043
Female r −0.004
p 0.961
Distance CN (m) Male r −0.110
p 0.117
Female r 0.007
p 0.930
Speed CN (km/h) Male r −0.110
p 0.111
Female r 0.006
p 0.941
VO2max (mL/min/kg) Male r −0.105
p 0.131
Female r 0.005
p 0.961
Speed 20 + 30 (s) Male r 0.042
p 0.541
Female r −0.101
p 0.225
HG Dominant (kg) Male r 0.041
p 0.681
Female r 0.115
p 0.351
HG Non-Dominant (kg) Male r 0.004
p 0.961
Female r 0.099
p 0.411
Medicine ball throw (m) Male r 0.010
p 0.891
Female r 0.712
p 0.128
Flexibility (cm) Male r −0.004
p 0.951
Female r 0.171
p 0.034
SJ (cm) Male r −0.031
p 0.631
Female r 0.041
p 0.591
CMJ (cm) Male r −0.043
p 0.551
Female r 0.072
p 0.381
ABK (cm) Male r −0.034
p 0.612
Female r −0.015
p 0.836

BMI, body mass index; CN, course navette; VO2max, maximal oxygen uptake; HD, hand grip; SJ, squat jump; CMJ, countermovement jump; ABK, abalakov jump.

 Discussion

The objective of the present study was to analyze the differences of sex, age and style of play on the physical fitness of young high-level TT players. The present study reported significant differences between sexes and ages in the physical fitness parameters. In addition, as a novelty of the current investigation, it is shown that there could also be differences in the physical fitness parameters according to the style of play, as well as correlations. However, it should be noted that the participants in each playing style group (OFF and MIX + DEF) were very heterogeneous. The different playing styles result in specific and different spatiotemporal activity patterns in terms of stroke length, stroke speed, tactics, techniques and effects on the ball, as well as using other specific materials on the table tennis blades (rubbers and wood), factors that alter the pattern of playing activity (26). Consequently, the development of one or the other style of play is related to specific physical and physiological demands associated with the performance of more explosive game actions as in the OFF style (27).

The results of the sex differences observed in the current study are similar to those reported by other authors (28–30), who reported that men have higher performance in strength, vertical jump, running speed and aerobic endurance tests. In comparison, women are significantly more flexible than men (31).

The evaluation of physical fitness using test batteries allows monitoring the evolution of the athlete to create individual training programs (6). In TT, high speed, agility, coordination, reaction time, strength and flexibility are fundamental to performing the different techniques and tactics correctly (32, 33). Previous studies have analyzed physical fitness in adult high-level TT players (6, 33) and in children practicing TT (34). However, this is the first study to assess fitness as a function of playing style.

Physical fitness is an essential marker of health and sports performance in youth (35). Proper physical fitness monitoring can be an excellent strategy to promote health and identify young athletic talent for all types of sports (35). It is common practice to analyze the physical profile of young athletes and compare them with adult athletes when aiming to predict potential success (36). However, this type of methodology is strongly rooted in assumptions (35). Adolescence is a dynamic period characterized by the growth and development of different organ systems (e.g., bone tissue, muscle tissue), which rarely progresses at the same time (37). The development of physical fitness in children and the effects of moderating variables, such as age and sex, are well documented (38, 39). Girls have more advanced skeletal and sexual maturity relative to chronological age, entering puberty and reaching peak growth velocity earlier than male (an average of 12 years in female and 14 years in male) (40).

The present study observed age differences in anthropometric parameters (weight, height, and BMI). Previous studies reported that the onset of accelerated height growth is around 10–12 years of age (41). The data on height and weight coincide with other studies performed on soccer (42), padel (43) and TT (33) players. These differences are directly related to sexual dimorphism between males and females (44, 45).

Regarding upper body strength, in the present study, differences between ages were observed in grip strength, being higher in older players. With respect to medicine ball throwing, males threw the ball a longer distance than females. These results coincide with general populations (46), young padel (47) and tennis (48) players. Sex differences in strength could be due to differences in muscle mass. It is well known that males tend to have more lean mass than females, influencing strength levels (49, 50). Sex differences in strength could be due to differences in muscle mass. It is well known that males tend to have more lean mass than females, influencing strength levels (39).

In relation to the flexibility of the lower back and hamstring muscles, the present study reported differences between sexes, with females obtaining higher values. These results coincide with other racket sports, such as padel and tennis (5, 51). The anatomical structure of the hip and pelvis could explain these differences (52), and the greater muscle mass that characterizes the male sex (41, 53). On the other hand, the differences found according to the style of play could be explained by the physical requirements of each style. The OFF style requires greater muscle mass to generate high levels of explosiveness that could be related to lower values in the sit and reach test. In this sense, a lower muscle mass in MIX + DEF players would directly impact higher flexibility values as this style of play requires less power than OFF.

As for the data obtained in the vertical jump, differences between ages were reported, with the height of the jumps being greater as age advanced. Pradas de la Fuente et al. (11), showed similar results in vertical jump performance, where significant differences were found in table tennis players from under 11 years to 17 years of age. Other authors reported similar results in school populations (54). The differences between ages could be related to higher plasma testosterone levels in males (55), as well as the development of muscle mass and anatomical changes in both sexes (38). On the other hand, the sex difference in jumps that involved a countermovement might indicate that males were slightly more effective in using the stretch-shortening cycle (56) and/or involving the hip extensor muscles (57). In the CMJ, men appear to apply greater concentric momentum and, therefore, achieve greater velocity during most of the concentric phase, including the take-off (28). When comparing jump height as a function of gender and playing style, a higher jump height, although not significant, is observed in players who play an OFF game. These data point to a tendency in the OFF style of play from an early age to generate higher levels of strength in the active (impulsive) and reactive (elastic-impulsive) manifestations as has been demonstrated in similar research (6, 58, 59).

Regarding the speed test, differences in displacement time between sexes and age were reported. Previous authors observed similar results in distances of 5 and 10 meters in TT players (33), as well as reaction times and lateral displacement times (6). The differences in times in the tests between sex and age could be related to hormonal characteristics. Higher levels of circulating testosterone, characteristic of men, result in increased muscle weight and more significant muscle cross-sectional area, translating into greater applications of reaction forces, which generates superior running performance for men (60). On the other hand, the differences found in speed as a function of playing style could be explained by the physical requirements of each playing style. The OFF style requires more muscle mass to generate high levels of reactivity and explosiveness as opposed to the more conservative and less powerful MIX + DEF style of play (6, 27).

Finally, concerning the cardiorespiratory capacity, differences were observed between sexes and ages, with greater distance and maximum oxygen consumption (VO2max), estimated in males and at older ages. These data align with those reported Pradas et al. (34), Pradas et al. (43), in TT and padel players. Generally, higher VO2max values have been observed in males (61) and sex differences increase as they progress through adolescence. These could be attributed to males' greater muscle mass and hemoglobin concentration (61). In addition, it could also be explained by a slight increase in body fat in children aged 7–12 years, as well as a reduction in body fat at puberty (62). OFF styles of play, characterized by short and very explosive actions, show lower values of oxygen consumption compared to players who develop MIX or DEF styles of play, characterized by the development of game actions of longer duration and with a higher volume of hits and displacements, requiring a more significant contribution of the aerobic pathway (6, 26).

Concerning the differences found according to playing styles, one of the most exciting findings, considering the results obtained for both sexes, is that those players with a greater body weight tend to develop MIX + DEF playing styles, which require less explosiveness in their playing actions compared to OFF players, who need a more significant development of strength and speed. The MIX − DEF style of play at early ages is an essential technical-tactical resource to improve performance. In young TT players, the MIX − DEF style of play can be linked to different limitations, which can be physical because they have a greater body weight, cognitive because they have not yet consolidated the learning of such vital aspects in this sport as reading and analyzing quickly and effectively the effects produced on the ball; or of a technical-technical-tactical type, by covering one side of the racquet with a defensive covering (e.g., long pimples-out rubber), which prevents the opponent from benefiting from a weakness on one side of the game (1).

According to sex, no significant differences were found, but co-relationships were found. Male players with an OFF style of play were negatively correlated with the CN period (p < 0.05). These results could be explained as a consequence of the needs of the OFF style of play, characterized by the development of short, fast and explosive game actions, where the anaerobic metabolic pathway is essential to obtain optimal performance in this type of players (6, 19).

In the female sex, players who developed a MIX + DEF style of play were correlated with higher values of flexibility (p < 0.05). The MIX + DEF style of play is characterized by the performance of game actions of longer duration but at a slow pace. This type of game, in which low-intensity aerobic actions predominate, produces adaptations in the biotype, particularly in women with MIX − DEF playing styles, characterized by lower power and speed of play, and as a consequence, makes it possible to acquire and maintain higher levels of flexibility (6, 12, 33).

This study also has certain limitations: (i) the rubber materials used in the table tennis blade were not taken into consideration; (ii) the lateral dominance of the players was not considered; (iii) the years of experience not been considered; (iv) this study did not consider biological maturation; and (v) the play style and age groups were very heterogeneous in terms of the number of participants.

 Conclusions

There are differences in physical fitness parameters between playing styles, sex and age. Generally, male and older players perform better in physical fitness tests.

Flexibility and cardiorespiratory capacity are related to playing style and sex. Players practising the MIX − DEF style of play have higher levels of flexibility, while those of the OFF style are characterized by developing a greater aerobic capacity.

The MIX − DEF style of play is developed in both sexes by players who have a greater body weight, so using this style of play could be considered as a technical-tactical resource to improve the performance of young athletes with certain deficiencies such as low physical fitness.

It is necessary to carry out new studies to confirm the results obtained in this study, especially at early ages, since, in some cases, the players have a short sporting experience in table tennis.

The existing differences in the levels of physical fitness could help coaches develop specific training programs according to the style of play of their players and sex.

 Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

 Ethics statement

The studies involving humans were approved by Clinical Research Ethics Committee of Aragon (Spain) (code: 19/2010). The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin.

 Author contributions

FP: Conceptualization, Investigation, Visualization, Writing – original draft, Writing – review & editing. VT-R: Writing – original draft, Writing – review & editing. MO: Data curation, Methodology, Writing – review & editing. AM: Conceptualization, Investigation, Writing – original draft.

 Funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article.

This research was funded by the Consejo Superior de Deportes to Research Project 10/UPB10/10 “TEMENOT. Studying the sport performance of top table tennis players by omputerized notational analysis”. In addition, this publication has been supported by public funds from de Dirección General de Investigación e Innovación del Gobierno de Aragón to the ENFYRED research group.

 Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

 Publisher's note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

 References PradasF. In: de la Fuente FranciscoP, editors. Fundamentos del tenis de mesa: Aplicación al ámbito escolar. Murcia: Editum (2015). Editum. Pradas de la FuenteFSalvá MartínezPGonzález CamposGGonzález JuradoJA. Analysis of performace indicators that define the modern table tennis. J Sport Heal Res (2015) 7(2):149–62. MatytsinOV. The role of personal characteristics of the table tennis player in providing efficiency and stability during competitions. Int J Table Tennis Sci. (1994) 2:55–60. FaberIRElferink-GemserMTOosterveldFGJTwiskJWRNijhuis-Van der SandenMWG. Can an early perceptuo-motor skills assessment predict future performance in youth table tennis players? An observational study (1998–2013). J Sports Sci (2017) 35:593–601.27136184 PradasFSánchez-PayAMuñozDSánchez-AlcarazBJ. Gender differences in physical fitness characteristics in professional padel players. Int J Environ Res Public Health. (2021) 18:5967. 10.3390/ijerph1811596734199473 PradasFToro-RománVde la TorreAMoreno-AzzeAGutiérrez-BetancurJFOrtega-ZayasMÁ. Analysis of specific physical fitness in high-level table tennis players-sex differences. Int J Environ Res Public Health. (2022) 19:5119. 10.3390/ijerph1909511935564512 ZagattoAMMorelEAGobattoCA. Physiological responses and characteristics of table tennis matches determined in official tournaments. J Strength Cond Res. (2010) 24:942–9. 10.1519/JSC.0b013e3181cb700320300034 ZagattoAMde Mello LeiteJVPapotiMBenekeR. Energetics of table tennis and table tennis–specific exercise testing. Int J Sports Physiol Perform. (2016) 11:1012–7. 10.1123/ijspp.2015-074626869146 Le MansecYDorelSHugFJubeauM. Lower limb muscle activity during table tennis strokes. Sport Biomech. (2018) 17:442–52. CastellarCPradasFCarrascoLLa TorreADGonzález-JuradoJA. Analysis of reaction time and lateral displacements in national level table tennis players: are they predictive of sport performance? Int J Perform Anal Sport. (2019) 19:467–77. 10.1080/24748668.2019.1621673 Pradas de la FuenteFCastellarCNicolaeO. Analysis of explosive and elastic-explosive strength of lower limbs in spanish young top-level table tennis players. Gymnasium. (2013) 14:21. Mikel PicabeaJCamaraJYanciJ. Physical fitness analysis in male and female table tennis players and their relationship to competition performance. RICYDE Rev Int Cienc Deporte. (2017) 13:39–51. 10.5232/ricyde2017.04703 MartínezECarrascoLAlcarazPEPradasFCarrilloJP. Perfil antropométrico, somatotipo, composición corporal y dinamometría manual en jóvenes jugadores de alto nivel de tenis de mesa. Act Física y Deport Cienc y Profesión. (2009) 10:53–8. MunivranaGPetrinovićLZKondričM. Structural analysis of technical-tactical elements in table tennis and their role in different playing zones. J Hum Kinet. (2015) 47:197–214. 10.1515/hukin-2015-007626557204 NikolakakisATelopoulosPLanzoniIMMavridisG. Comparison of the service and reception between winning and defeated high-level table tennis athletes. J Hum Sport Exerc. (2023) 18:670–78. GeskeK-MMuellerJRossH. Table tennis tactics: your path to success. Aachen: Meyer & Me. Aachen (2010). MajorZLangRW. Characterization of table tennis racket sandwich rubbers. Science and racket sports III. The proceedings of the eighth international table tennis federation sports science congress and the third world congress of science and racket sports (2005). p. 146–51 Pradas de la FuenteF. Metodología del tenis de mesa: Aproximación multidisciplinar y su didáctica. Sevilla: Wanceulen (2009). MartinCFavier-AmbrosiniBMoussetKBraultSZouhalHPriouxJ. Influence of playing style on the physiological responses of offensive players in table tennis. J Sports Med Phys Fitness. (2015) 55:1517–23.25766049 SperlichBKoehlerKHolmbergH-CZinnerCMesterJ. Table tennis: cardiorespiratory and metabolic analysis of match and exercise in elite junior national players. Int J Sports Physiol Perform. (2011) 6:234–42. 10.1123/ijspp.6.2.23421725108 Castro-PiñeroJChillonPOrtegaFBMontesinosJLSjöströmMRuizJR. Criterion-related validity of sit-and-reach and modified sit-and-reach test for estimating hamstring flexibility in children and adolescents aged 6–17 years. Int J Sports Med. (2009) 30:658–62. 10.1055/s-0029-1224175 Rodríguez-RosellDMora-CustodioRFranco-MárquezFYáñez-GarcíaJMGonzález-BadilloJJ. Traditional vs. sport-specific vertical jump tests: reliability, validity, and relationship with the legs strength and sprint performance in adult and teen soccer and basketball players. J Strength Cond Res. (2017) 31:196–206. 10.1519/JSC.0000000000001476 BoscoCLuhtanenPKomiPV. A simple method for measurement of mechanical power in jumping. Eur J Appl Physiol Occup Physiol. (1983) 50:273–82. 10.1007/BF004221666681758 LegerLAMercierDGadouryCLambertJ. The multistage 20 metre shuttle run test for aerobic fitness. J Sports Sci. (1988) 6:93–101. 10.1080/026404188087298003184250 HopkinsWGMarshallSWBatterhamAMHaninJ. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. (2009) 41:3–12. 10.1249/MSS.0b013e31818cb27819092709 MilioniFLeiteJVdMBenekeRDe PoliRABPapotiMZagattoAM. Table tennis playing styles require specific energy systems demands. PLoS One. (2018) 13:e0199985. 10.1371/journal.pone.019998530020946 Pradas de la FuenteFToro-RománVCastellarCCarrascoL. Analysis of the spatial distribution of the serve and the type of servereturn in elite table tennis. Sex differences. Front Psychol. (2023) 14:1–7. 10.3389/fpsyg.2023.1243135 McMahonJJRejSJEComfortP. Sex differences in countermovement jump phase characteristics. Sports. (2017) 5:8. 10.3390/sports501000829910368 de AraújoMCBaumgartCJansenCTFreiwaldJHoppeMW. Sex differences in physical capacities of German Bundesliga soccer players. J Strength Cond Res. (2020) 34:2329–37. 10.1519/JSC.0000000000002662 HöögSAnderssonEP. Sex and age-group differences in strength, jump, speed, flexibility, and endurance performances of Swedish elite gymnasts competing in TeamGym. Front Sport Act Living. (2021) 3:653503. 10.3389/fspor.2021.653503 BalePMayheJPiperFBallTWillmanMK. Biological and performance variables in relation to age. J Sport Med Phys Fit. (1992) 32:142–8. NikolićIFurjan–MandićGKondričM. The relationship of morphology and motor abilities to specific table tennis tasks in youngsters. Coll Antropol. (2014) 38:241–5. PicabeaJMCámaraJYanciJ. Physical fitness profiling of national category table tennis players: implication for health and performance. Int J Environ Res Public Health. (2021) 18:9362. 10.3390/ijerph1817936234501953 PradasFAraIToroVCourel-IbáñezJ. Benefits of regular table tennis practice in body composition and physical fitness compared to physically active children aged 10–11 years. Int J Environ Res Public Health. (2021) 18:2854. 10.3390/ijerph1806285433799620 Henriques-NetoDHetherington-RauthMMagalhaesJPCorreiaIJudicePBSardinhaLB. Physical fitness tests as an indicator of potential athletes in a large sample of youth. Clin Physiol Funct Imaging. (2022) 42:88–95. 10.1111/cpf.1273534918454 JonesBWeavingDTeeJDarrall-JonesJWeakleyJPhibbsP Bigger, stronger, faster, fitter: the differences in physical qualities of school and academy rugby union players. J Sports Sci. (2018) 36:2399–404. 10.1080/02640414.2018.145858929608414 PattonGCSawyerSMSantelliJSRossDAAfifiRAllenNB Our future: a lancet commission on adolescent health and wellbeing. Lancet. (2016) 387:2423–78. 10.1016/S0140-6736(16)00579-127174304 MalinaRMBielickiT. Retrospective longitudinal growth study of boys and girls active in sport. Acta Paediatr. (1996) 85:570–6. 10.1111/j.1651-2227.1996.tb14089.x8827101 MalinaRMEisenmannJCCummingSPRibeiroBArosoJ. Maturity-associated variation in the growth and functional capacities of youth football (soccer) players 13–15 years. Eur J Appl Physiol. (2004) 91:555–62. 10.1007/s00421-003-0995-z14648128 CummingSPStandageMGillisonFMalinaRM. Sex differences in exercise behavior during adolescence: is biological maturation a confounding factor? J Adolesc Heal. (2008) 42:480–5. 10.1016/j.jadohealth.2007.10.005 MalinaRMBouchardCBar-OrO. Growth, maturation, and physical activity. IL: Human kinetics (2004). ParpaKMichaelidesM. Age-related differences in the anthropometric and physical fitness characteristics of young soccer players: a cross-sectional study. Children. (2022) 9:650. 10.3390/children905065035626827 PradasFToro-RománVOrtega-ZayasMÁMontoya-SuárezDMSánchez-AlcarazBJMuñozD. Physical fitness and upper limb asymmetry in young padel players: differences between genders and categories. Int J Environ Res Public Health. (2022) 19:6461. 10.3390/ijerph1911646135682046 CoxRMCalsbeekR. Sex-specific selection and intraspecific variation in sexual size dimorphism. Evolution (N Y). (2010) 64:798–809. KirchengastS. Gender differences in body composition from childhood to old age: an evolutionary point of view. J Life Sci. (2010) 2:1–10. Gómez-CamposRVidal EspinozaRDe ArrudaMRonqueERVUrra-AlbornozCMinangoJC Relationship between age and handgrip strength: proposal of reference values from infancy to senescence. Front Public Heal. (2023) 10:1072684. 10.3389/fpubh.2022.1072684 Courel-IbáñezJLlorca-MirallesJ. Physical fitness in young padel players: a cross-sectional study. Int J Environ Res Public Health. (2021) 18:2658. 10.3390/ijerph18052658 Fernandez-FernandezJNakamuraFYMoreno-PerezVLopez-ValencianoADel CosoJGallo-SalazarC Age and sex-related upper body performance differences in competitive young tennis players. PLoS One. (2019) 14:e0221761. 10.1371/journal.pone.022176131479492 CummingD. The male reproductive system, exercise, and training. In: FilicoriM, editor. Sports endocrinology. NJ: Springer (2000). p. 119–31. MalinaRMGeithnerCA. Body composition of young athletes. Am J Lifestyle Med. (2011) 5:262–78. 10.1177/1559827610392493 DobosKNovakDBarbarosP. Neuromuscular fitness is associated with success in sport for elite female, but not male tennis players. Int J Environ Res Public Health. (2021) 18:6512. 10.3390/ijerph1812651234204221 Arregui ErañaJAMartínez de HaroV. Current state of the investigations on the flexibility in the adolescence. Rev Int Med Cienc Act Fís Deport (2001) 1:127–35. BredellaMA. Sex differences in body composition. In: Mauvais-JarvisF, editor. Sex and gender factors affecting metabolic homeostasis, diabetes and obesity. NJ: Springer (2017). p. 9–27. GonzálezJLDíazNGarcíaLMoraJCastroJFacioM. Jumping capacity and elasticity index at primary scholar age. Rev Int Med Cienc Act Fís Deport. (2007) 7:359–73. BoscoC. La fuerza muscular: aspectos metodológicos. Barcelona: Inde (2000). ZivGLidorR. Vertical jump in female and male basketball players—a review of observational and experimental studies. J Sci Med Sport. (2010) 13:332–9. 10.1016/j.jsams.2009.02.00919443269 LeesAVanrenterghemJDe ClercqD. The maximal and submaximal vertical jump: implications for strength and conditioning. J Strength Cond Res. (2004) 18:787–91.15574084 PradasFaDe TeresaCVargasM. Evaluation of the isometric maximal force of the superior extremities in high level table tennis players. Sport Sci Res. (2005) 26:86. PradasFGarcía-GiménezAToro-RománVOchianaNCastellarC. Gender differences in neuromuscular, haematological and urinary responses during padel matches. Int J Environ Res Public Health. (2021) 18:5864. 10.3390/ijerph1811586434072562 HerbstKLBhasinS. Testosterone action on skeletal muscle. Curr Opin Clin Nutr Metab Care. (2004) 7:271–7. 10.1097/00075197-200405000-0000615075918 ArmstrongNWelsmanJR. Assessment and interpretation of aerobic fitness in children and adolescents. Exerc Sport Sci Rev. (1994) 22:435–76. 10.1249/00003677-199401000-000167925551 MarkovićLTrbojević JocićJHorvatinMPekasDTrajkovićN. Cardiorespiratory fitness and health-related quality of life in secondary school children aged 14–18 years: a cross-sectional study. Healthcare (MDPI). (2022) 10:660. 10.3390/healthcare10040660