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Tóm tắt nội dung (trích từ tài liệu gốc): IMPACT OF FITNESS CHARACTERISTICS ON TENNIS PERFORMANCE IN ELITE JUNIOR TENNIS PLAYERS ALEXANDER ULBRICHT,1 JAIME FERNANDEZ-FERNANDEZ,2 ALBERTO MENDEZ-VILLANUEVA,3 AND ALEXANDER FERRAUTI1 1Department of Training and Exercise Science, Ruhr-University Bochum, Bochum, Germany; 2Sports Research Centre, Miguel Hernandez University, Elche, Spain; and 3ASPIRE Academy for Sports Excellence, Doha, Qatar Downloaded from https://
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IMPACT OF FITNESS CHARACTERISTICS ON TENNIS
PERFORMANCE IN ELITE JUNIOR TENNIS PLAYERS
ALEXANDER ULBRICHT,1 JAIME FERNANDEZ-FERNANDEZ,2 ALBERTO MENDEZ-VILLANUEVA,3 AND
ALEXANDER FERRAUTI1
1Department of Training and Exercise Science, Ruhr-University Bochum, Bochum, Germany; 2Sports Research Centre, Miguel
Hernandez University, Elche, Spain; and 3ASPIRE Academy for Sports Excellence, Doha, Qatar
Downloaded from https://journals.lww.com/nsca-jscr by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3JhfpBaN+HkwNqxxiNKILwQ+ZhLMJ+u+cGSh7hSxuWUg= on 06/17/2018 ABSTRACT INTRODUCTION
Ulbricht, A, Fernandez-Fernandez, J, Mendez-Villanueva, T he modern game of tennis has evolved from a pri-
A, and Ferrauti, A. Impact of fitness characteristics on tennis mary technical sport with sport-specific technical
performance in elite junior tennis players. J Strength Cond skills being the predominant factors (e.g., racket
Res 30(4): 989�998, 2016--The impact of fitness charac- and ball handling skills and stroke skills, such as
teristics on tennis performance in adolescent players is not service skill), to a more dynamic and explosive sport char-
clearly understood. Therefore, the aim of the present study acterized by higher stroke and serve velocities and requiring
was to test whether physical characteristics are related to notably higher physical demands (11,19). Therefore, it is
players' competitive level (i.e., national youth ranking). A widely accepted that players require higher levels of physical
secondary aim was to compare adolescent tennis players fitness to execute advanced shots and compete effectively
by performance level (i.e., regional selected players and against progressively more elite opponents (11). In this
the national team). A total of 902 male and female junior regard, it has been suggested that tennis players require
players (aged, 11�16 years) in Germany were evaluated a mix of speed, agility, coordination, and power, combined
using a physical testing battery: grip strength; countermove- with medium-to-high aerobic and anaerobic capacity. Thus,
ment jump; 10 and 20-m sprint; tennis-specific sprint; over- successful performance cannot be defined by one predomi-
head, forehand, and backhand medicine ball throws (MBT); nant physical attribute; rather, tennis demands a complex
serve velocity and tennis-specific endurance test (hit interaction of several physical components and metabolic
and turn tennis test). Results showed that serve velocity pathways (11,19).
(r = 20.43 to 0.64 for female subjects []; r = 20.33 to
0.49 for male subjects []) and upper-body power (e.g., Despite recent advances in epidemiologic research on
MBT r = 20.26 to 20.49 ; r = 20.20 to 20.49 ) were tennis injuries (3,30), there is a need for more tennis-
the most correlated predictors of tennis performance specific research because the physical demands related
(i.e., national youth ranking) in both female and male tennis to performance are not clearly understood. Given the
players. Moreover, national selected players showed better considerable high demands of elite tennis and the
performance levels than their regional counterparts, mainly increased participation in competitions from an early
in the most predictive physical characteristics (i.e., serve age (i.e., 12 years and under championships), players are
velocity: effect size [ES], 0.78�1.04 ; ES 0.92�1.02 , selected and trained to cope successfully with physical
MBT: ES, 0.66�0.88 ; ES, 0.67�1.04 ) and specific stress (8). Although talent selection is an imprecise pro-
endurance (ES, 0.05�0.95 ; ES, 0.31�0.73 ). The pres- cedure owing to the many factors involved in the devel-
ent findings underline the importance of certain physical opment of a prospective player, knowledge of the fitness
attributes, especially serve velocity and strength- and profiles of successful players has been indicated as a valu-
power-related variables (upper body), and suggest the need able resource to guide talent selection and subsequent
to include these parameters in the area of training, physical training (34,37).
testing, and talent identification of young tennis players.
In an attempt to assess the strengths and weaknesses of
Address correspondence to Alexander Ulbricht, alexander.ulbricht@rub.de. a given player, standardized physical testing is commonly
used to provide a useful supplement to subjective coaching
30(4)/989�998 appraisals (15,34). In tennis, only a few studies have ad-
Journal of Strength and Conditioning Research dressed physical testing for high-level young players
� 2015 National Strength and Conditioning Association (4,15,33,34) with the aim of identifying the most influential
factors on tennis performance (i.e., ranking), and research
has been conducted with athletes of various backgrounds
(e.g., age, gender, performance level) using different testing
protocols (4,15,22,33). Results are contradictory, with some
989 VOLUME 30 | NUMBER 4 | APRIL 2016 |
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Impact on Fitness Characteristics on Tennis Perfomance
studies suggesting that physical qualities are weak predictors before participation. The Ruhr-University Bochum Ethics
of overall tennis performance (4) and others suggesting that Committee approved the study, and all procedures con-
specific qualities, such as agility (33) or speed and vertical form to the recommendations of the Declaration of
power (15), correlate with tennis performance. Moreover, Helsinki.
earlier studies did not systematically investigate (i.e., using
a standardized test battery) the impact of fitness character- Procedures
istics on tennis performance across a large sample of young
male and female tennis players (4,15,22,33). Thus, the aim Testing protocols were conducted over a 3-week period
of the present study was to detect whether fitness charac- beginning at the end of September. Test sessions were
teristics are related to players' performance (i.e., ranking) undertaken between 14:00 and 20:30 hours, and the players
and if there are age- and gender-associated differences. A were tested at their respective federation base. To ensure
secondary aim was to compare adolescent tennis players by standardization of test administration across the entire study
performance level (i.e., regional selected players and the period, all tests were performed in the same order, using the
national team). same testing devices and operators. All fitness tests were
performed in an indoor tennis court (Rebound Ace surface;
METHODS temperature, 24.4�26.48 C; relative humidity, 54.4�61.0%;
Kestrel 4000 Pocket Weather Tracker, Nielsen Kellerman,
Experimental Approach to the Problem Boothwyn, PA, USA). Testing began after a 15-minute indi-
vidual warm-up, which consisted of low-intensity forward,
From 2009 to 2012, a sample of the 902 best male and sideways, and backwards running, multidirectional accelera-
female tennis players in Germany (from the national and tion runs, skipping and hopping exercises, and jumps of
regional selection groups) was evaluated using a battery of increasing intensity. The physical performance tests that fol-
standard anthropometric and physical performance tests lowed were conducted in the same order of their description
implemented by the Deutscher Tennis Bund (DTB) at (anthropometrical measurement; grip strength; counter-
national level (The German Physical Condition Tennis movement jump [CMJ]; 20-m sprint; tennis-specific sprint
Test) (37). Players were recruited from their respective [TSS]; overhead, forehand, and backhand medicine ball
regional federations, and all the federations in the country throws [MBT]; serve velocity; and tennis-specific endurance
were tested. test [hit and turn tennis test]). The recovery time between
the different performance tests was set to be at least
Subjects 3 minutes.
A sample of male (n = 546; mean 6 SD: age, 13.14 6 1.39 Anthropometry. Sessions began with the anthropometrical
years) and female (n = 366; mean 6 SD: age, 13.06 6 1.29 measurement, which included body height, body mass, and
years) junior players was evaluated. For the purpose of the sitting height. Body height was measured with a fixed
present study, the players were grouped on the basis of stadiometer (60.1 cm; Holtain, Ltd., Crosswell, United
chronological age into 2-year age categories. The cohort Kingdom), sitting height with a purpose-built table (60.1
spanned 6 years and included male (under [U] 12: cm; Holtain, Ltd.), and body mass with a digital balance
n = 126; U14: n = 255; U16: n = 165) and female (U12: (60.1 kg; ADE Electronic Column Scales, Hamburg,
n = 76; U14: n = 177; U16: n = 97) tennis players. Addition- Germany). For further analysis, leg length was estimated
ally, 2 selection groups were used for further analysis. The by subtracting sitting height from body height according
first subgroup, defined as the "regional squad," comprised to Mirwald et al. (26).
the most talented players in each region and was selected
by the regional federations coaching staff based on technical Maturity Status. Pubertal timing was estimated according to
or tactical abilities and competitive performance (overall n = the biologic age of maturity of each individual, as
755; males: n = 468; females: n = 287). described by Mirwald et al. (26). The age of peak linear
growth (age at peak height velocity) is an indicator of
Through the national coaching staff, the German Tennis somatic maturity representing the time of maximum
Federation selects several junior players for a national squad growth in stature during adolescence (26). Biologic age
team. The selection of these players is based on repeated of maturity (in years) was calculated by subtracting the
observations of the players' technical or tactical abilities and chronological age at the time of measurement from the
their competitive performance. This subgroup comprised chronological peak velocity age (2,26). Thus, a maturity
players with an official entry on the national squad list, age of 21.0 indicates that the player was measured 1 year
and it was defined as the "national squad" (overall: n = before this peak velocity, a maturity of 0 indicates that the
147; males: n = 78; females: n = 69). player was measured at the time of this peak velocity, and
a maturity age of +1.0 indicates that the participant was
Participants were listed on the official youth (under 18 measured 1 year after this peak velocity (25).
years) ranking list, an age-independent ranking for junior
players established by the national tennis federation.
The players and parents were informed of all experimental
procedures, and written informed consent was completed
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Grip Strength. Handgrip strength was measured using Twenty-Meter Sprint Run. Time during a 20-m dash in
a hydraulic hand dynamometer (Baseline; Irvington, NY, a straight line (with 5- and 10-m split times) was measured
USA). The subject was asked to perform a maximal volun- by means of double beam photocell gates placed 1.0 m
tary contraction standing with the dynamometer at one side above the ground level (Sportronic TS01-R04; Sportronic,
(i.e., dominant hand) and gripping the dynamometer as hard Leutenbach-Nellmersbach, Germany). Each sprint was ini-
as they could for 3 seconds. This was repeated for each hand tiated from an individually chosen standing position, 50 cm
(i.e., dominant and nondominant hand). The average of the 2 behind the photocell gate, which started a digital timer. Each
trials for each hand was considered to be the maximum player performed 2 maximal 20-m sprints interspersed with
voluntary handgrip strength (17). 3 minutes of passive recovery. The fastest time achieved was
retained.
Vertical Jumping. Countermovement jumps without arm
swing (arms were positioned at the hip) were performed on Tennis-Specific Sprint Test. Players performed a TSS test to the
a contact platform (Haynl Elektronik, Germany) according to forehand and backhand side (37). For the TSS, a special
Bosco et al. (6). Each player performed 2 maximal CMJ inter- testing device was used, which consisted of a twofold signal
spersed with 45 seconds of passive recovery. The best jump (i.e., panel with 2 light-emitting diodes (LEDs) (right-left). By
highest height attained) was retained for further analysis (6). activating one LED of the signal panel (i.e., which remaining
TABLE 1. Correlation coefficients of anthropometric and fitness characteristics with player performance (ranking
position).*
Male players Female players
U12 U14 U16 U12 U14 U16
n = 122 n = 254 n = 165 n = 82 n = 177 n = 97
Chronological age (y) r 20.17 20.40 20.42 20.29 20.34 20.28
0.06 0.00 0.00 0.00 0.00 0.01
p
20.05 20.30 20.33 20.19 20.29 20.31
APHV r 0.59 0.00 0.00 0.10 0.00 0.00
p 20.06 20.29 20.27 20.17 20.18 20.15
0.53 0.00 0.00 0.13 0.01 0.15
Height (cm) r
20.07 20.23 20.34 20.17 20.17 20.30
p 0.44 0.00 0.00 0.13 0.03 0.00
Weight (kg) r 20.23 20.29 20.38 20.21 20.19 20.30
0.02 0.00 0.00 0.06 0.01 0.00
p 0.02 0.00 0.01 0.16
0.86 20.17 20.01 0.98 0.87 0.13
Grip strength dominant side (kg) r 0.14 0.01 0.87 0.15
0.13 0.23 0.13 20.06 0.05 20.06
p 0.16 0.00 0.12 0.58 0.19 0.56
0.08 0.31 0.23 0.01 0.00
CMJ (cm) r 0.00 0.00 0.00 20.05 0.16 0.97
1.00 0.17 0.16 0.67 0.03
p 0.18 0.01 0.04 0.01 0.28 20.10
0.04 0.26 0.21 0.91 0.00 0.37
10-m sprint (s) r 0.00 0.01 0.14 0.12
20.17 0.21 20.35 0.24
p 0.07 20.33 20.37 0.00
0.00 0.00 20.26 20.36
20-m sprint (s) r 20.20 0.02 20.47 0.00
0.03 20.42 20.43 0.00
p 0.00 0.00 20.15 20.38
20.24 0.20 20.49 0.00
TSS forehand (s) r 0.01 20.40 20.45 0.00
0.00 0.00 20.17 20.45
p 20.33 0.13 20.61 0.00
0.00 20.48 20.49 0.00
TSS backhand (s) r 0.00 0.00 20.43 20.64
20.19 0.00 20.20 0.00
p 0.04 20.39 20.30 0.04 0.01
0.00 0.00 0.71 20.46
MBT overhead (cm) r 0.00
p
MBT forehand (cm) r
p
MBT backhand (cm) r
p
Serve velocity (km$h21) r
p
Hit and turn test (level) r
p
*APHV = estimated age at peak height velocity; BMI = body mass index; CMJ = countermovement jump; TSS = tennis-specific
sprint; MBT = medicine ball throws.
991 VOLUME 30 | NUMBER 4 | APRIL 2016 |
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Impact on Fitness Characteristics on Tennis Perfomance
TABLE 2. Age, biological maturity, anthropometric, and fitness characteristics of national and regional selected male
tennis players.*
U12
Male Players National (n = 24) Regional (n = 102) Difference ES (90% CI)
Chronological age (y) 11.48 6 0.34 11.3 6 0.44 0.18 0.42 (0.05 to 0.8)
Under-18 ranking 1,059.08 6 637.4 2,233.4 6 1,001.7 21,174.3z 1.24 (21.63 to 20.84)
PHV 0.43 (0.05 to 0.81)
APHV 22.07 6 0.45 22.29 6 0.52 0.22 0.09 (20.46 to 0.28)
Height (cm) 13.55 6 0.43 13.59 6 0.45 20.04
Weight (kg) 151.22 6 7.03 149.65 6 7.79 0.2 (20.17 to 0.58)
BMI 40.49 6 5.63 1.57 0.34 (20.03 to 0.72)
Grip strength (kg) 17.63 6 1.36 38.5 6 5.81 1.99 0.38 (0.01 to 0.76)
CMJ (cm) 24.17 6 3.42 17.11 6 1.35 0.52
10-m sprint (s) 29.89 6 5.04 21.59 6 3.83 2.58� 0.68 (0.30 to 1.06)
20-m sprint (s) 28.85 6 3.81 1.04 0.25 (20.12 to 0.63)
TSS forehand (s) 2.00 6 0.08 20.04� 0.55 (20.93 to 20.17)
TSS backhand (s) 3.52 6 0.19 2.04 6 0.07 20.12� 0.63 (21.01 to 20.25)
MBT overhead (cm) 3.04 6 0.16 3.64 6 0.19 20.02 0.15 (20.53 to 0.22)
MBT forehand (cm) 3.08 6 0.13 3.06 6 0.12 20.08� 0.51 (20.89 to 20.14)
MBT backhand (cm) 573.18 6 97.82 3.16 6 0.16 48.97� 0.57 (0.20 to 0.95)
Serve velocity (km$h21) 734.09 6 95.03 524.21 6 81.68 63.94�
Hit and turn test (level) 707.05 6 88.94 670.15 6 89.93 74.71� 0.70 (0.32 to 1.08)
128.61 6 7.59 632.34 6 92.25 7.12�
13.93 6 2.3 121.49 6 9.33 1.52� 0.81 (0.43 to 1.19)
12.41 6 2.01 0.78 (0.40 to 1.17)
0.73 (0.35 to 1.11)
U14
Male Players National (n = 26) Regional (n = 229) Difference ES (90% CI)
Chronological age (y) 13.05 6 0.46 12.88 6 0.53 0,17 0.32 (20.02 to 0.66)
Under-18 ranking 360.46 6 193.55 1,057.13 6 688.35 2696.67z 1.06 (21.41 to 20.71)
PHV 20.72 6 0.71 0.36 (0.02 to 0.7)
APHV 20.99 6 0.75 0.27 0.17 (20.51 to 0.17)
Height (cm) 13.79 6 0.46 13.88 6 0.54 20.09 0.56 (0.22 to 0.91)
Weight (kg) 165.15 6 8.62 160.45 6 8.29 0.24 (20.1 to 0.58)
BMI 47.19 6 7.94 4.70�
Grip strength (kg) 49.09 6 8.09 18.21 6 1.72 1.90 0.2 (20.54 to 0.14)
CMJ (cm) 17.87 6 1.5 28.25 6 6.19 20.34 0.06 (20.28 to 0.4)
10-m sprint (s) 28.62 6 5.56 30.99 6 4.15 0.37 0.43 (0.09 to 0.78)
20-m sprint (s) 32.77 6 3.43 1.78� 0.09 (20.43 to 0.25)
TSS forehand (s) 1.96 6 0.11 20.01 0.13 (20.47 to 0.21)
TSS backhand (s) 1.95 6 0.08 3.47 6 0.16 20.02 0.32 (20.66 to 0.03)
MBT overhead (cm) 3.45 6 0.13 2.96 6 0.16 20.05 0.06 (20.28 to 0.4)
MBT forehand (cm) 2.91 6 0.14 3.08 6 0.17 0.01 0.66 (0.31 to 1.00)
MBT backhand (cm) 3.09 6 0.18 635.25 6 119.72 79.55�
Serve velocity (km$h21) 714.8 6 131.98 834.75 6 142.95 105.06z 0.74 (0.4 to 1.09)
Hit and turn test (level) 939.81 6 119.21 798.42 6 135.08 92.18�
890.6 6 154.2 137.74 6 11.85 8.15� 0.67 (0.33 to 1.01)
145.89 6 11.08 14.12 6 2.03 1.04�
15.16 6 2.06 0.69 (0.35 to 1.03)
0.51 (0.17 to 0.85)
U16
Male Players National (n = 28) Regional (n = 137) Difference ES (90% CI)
Chronological age (y) 14.97 6 0.46 14.87 6 0.52 0.10 0.19 (20.15 to 0.54)
Under-18 ranking 136.96 6 75.78 374.52 6 355.72 2237.56z 0.72 (21.07 to 20.38)
PHV 0.48 (0.14 to 0.82)
APHV 1.37 6 0.68 0.98 6 0.83 0.39�
Height (cm) 13.6 6 0.5 13.89 6 0.59 20.29� 0.5 (20.85 to 0.16)
Weight (kg) 179.14 6 6.3 174.07 6 7.36 0.7 (0.35 to 1.05)
BMI 65.33 6 7.42 60.56 6 8.74 5.07� 0.56 (0.21 to 0.9)
Grip strength (kg) 20.31 6 1.48 4.77� 0.23 (20.11 to 0.57)
CMJ (cm) 42.96 6 7.31 19.9 6 1.85 0.41 0.37 (0.03 to 0.72)
36.92 6 2.82 39.72 6 8.9 3.24 0.11 (20.23 to 0.45)
36.46 6 4.42 0.46
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10-m sprint (s) 1.85 6 0.07 1.85 6 0.11 0.00 0 (20.34 to 0.34)
20-m sprint (s) 3.22 6 0.12 3.25 6 0.17 20.02 0.18 (20.52 to 0.16)
TSS forehand (s) 2.75 6 0.11 2.77 6 0.14 20.02 0.15 (20.49 to 0.19)
TSS backhand (s) 2.90 6 0.13 2.90 6 0.22 0.00 (20.34 to 0.34)
MBT overhead (cm) 976.85 6 132.8 875.23 6 152.81 0.00 0.68 (0.33 to 1.02)
MBT forehand (cm) 1,252.41 6 161.53 1,127.91 6 169.9 101.62� 0.74 (0.39 to 1.08)
MBT backhand (cm) 1,210.74 6 162.22 1,073.1 6 155.29 124.5� 0.88 (0.53 to 1.23)
Serve velocity (km$h21) 172.65 6 11.38 160.06 6 12.23 137.64� 1.04 (0.68 to 1.39)
Hit and turn test (level) 16.90 6 1.7 16.34 6 1.81 0.31 (20.03 to 0.65)
12.59z
0.56
*ES = effect size; 90% CI = 90% confidence intervals; PHV = estimated age from or to peak height velocity; APHV = estimated
age at peak height velocity; BMI = body mass index; CMJ = counter movement jump; TSS = tennis-specific sprint; MBT = medicine
ball throws.
Estimated mean and SD of anthropometric and fitness characteristics of the national and regional teams.
zSignificant difference between the national and regional selected players (p , 0.001).
�Significant difference between the national and regional selected players (p # 0.05).
on during the whole repetition), the time was initiated. The and then thrown vigorously forward as far as possible
player stood with his or her racket in a frontal position (i.e., without the player crossing the line. Additionally, players
looking toward the net) in the middle of the baseline. Upon performed a forehand and backhand MBT according to
seeing a signal, players turned sideways and ran to the pre- previous methods (34). Players stood sideways to the start-
scribed backhand or forehand corner. The players were in- ing line and simulated a forehand-backhand stroke tossing
structed to run forward in a straight line, perform a stroke the ball as far as possible without crossing the line. For all
simulation against a ball pendulum (PracticeHit, WA, USA), MBT, the distance from the line to the point where the ball
and turn 1808 when their feet were in line with the hitting- landed was measured, and the best performance between 2
turning point marked with the ball pendulum. After perform- efforts was recorded to the nearest 5 cm.
ing the stroke, they returned to the initial position. Each
sprint time was measured using a photocell system (Spor- Hit and Turn Tennis Test. The hit and turn test was developed
tronic TS01-R04). Each player performed 2 maximal repe- as an acoustically controlled progressive on-court fitness test
titions to each side, interspersed with 90-second rest of for tennis players, which can be performed simultaneously
passive recovery. The fastest time achieved was recorded. by one or more players (12). The test involves specific move-
ments along the baseline (i.e., side steps and running) com-
Serve Velocity. A radar gun (Stalker Professional Sports Radar; bined with forehand and backhand stroke simulations at the
Radar Sales, Plymouth, MN, USA) was used to measure first doubles court corner (distance 11.0 m). This was performed
serve velocity. The radar was positioned at the center of the following the methods previously published (12). Maximal
baseline, 4 m behind the server, aligned with the approxi- completed level was used for the determination of tennis-
mate height of ball contact and pointing down the center of specific aerobic fitness.
the court. The serves for subjects who were right handed
served to the left serve box (from the right) and the ones Statistical Analyses
who were left handed served to the right serve box (from the
left). Athletes were instructed to perform 8 maximal serves To conclude the physical abilities that relate to competitive
down the "T" (center line). A target area (150 3 60 cm) was ranking position, based on the national youth ranking
placed in the serve box. Shots landing within the target area established by the German Tennis Federation (calculated
were awarded 2 points, serving into the serve box was from the results achieved in official tournaments), the players
counted as 1 point, and balls landing outside the serve box were ranked according to gender and age groups. Indepen-
were associated with 0 points. A total score was recorded for dent sample t-tests were used to determine differences
each trail. The average speed of the serve was used for fur- between national and regional players in anthropometric
ther analysis. and physical performance characteristics. In addition, the
standardized difference or effect size (ES) of changes in each
Medicine Ball Throws: Overhead, Forehand, and Backhand. For parameter between the national and regional groups was
the overhead MBT, the players stood on a line with their calculated using the pooled standard deviation. Threshold
feet side-by-side and slightly apart, facing the direction to values for Cohen's ES statistic were .0.2 (small), 0.5 (mod-
which the ball was to be thrown, and holding a 2-kg erate), and .0.8 (large) (7). Spearman's rank correlations
medicine ball. The ball was brought back behind the head were used to determine the relationship between perfor-
mance variables. Correlations were classified as trivial
993 VOLUME 30 | NUMBER 4 | APRIL 2016 |
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Impact on Fitness Characteristics on Tennis Perfomance
TABLE 3. Age, biological maturity, anthropometric, and fitness characteristics of national and regional selected female
tennis players.*
U12
Female Players National n = 17 Regional n = 65 Difference ES (90% CI)
Chronological age (y) 11.46 6 0.30 11.41 6 0.34 0.14 0.15 (20.3 to 0.6)
Under-18 ranking 698.71 6 520.57 1,176.14 6 562 2477.43z 0.85 (21.32 to 0.39)
PHV 20.39 6 0.52 0.45 (20.01 to 0.9)
APHV 20.61 6 0.48 0.22 0.38 (20.83 to 0.08)
Height (cm) 11.85 6 0.38 12.00 6 0.40 20.15 0.28 (20.17 to 0.73)
Weight (kg) 151.36 6 6.86 149.5 6 6.38 0.52 (0.07 to 0.98)
BMI 38.12 6 6.44 1.86
Grip strength (kg) 41.42 6 5.44 16.96 6 1.94 3.30 0.57 (0.12 to 1.03)
CMJ (cm) 18.04 6 1.53 20.56 6 4.14 1.08
10-m sprint (s) 23.24 6 4.10 28.56 6 4.00 2.68z 0.64 (0.19 to 1.10)
20-m sprint (s) 27.99 6 2.93 20.57 0.15 (20.60 to 0.30)
TSS forehand (s) 2.03 6 0.09 20.01 0.12 (20.57 to 0.33)
TSS backhand (s) 2.02 6 0.06 3.61 6 0.14 20.01 0.07 (20.52 to 0.37)
MBT overhead (cm) 3.60 6 0.11 3.11 6 0.13 20.02 0.15 (20.60 to 0.30)
MBT forehand (cm) 3.09 6 0.13 3.21 6 0.16 0.04 0.26 (20.19 to 0.71)
MBT backhand (cm) 3.25 6 0.12 505.48 6 92.12 19.81 0.23 (20.22 to 0.68)
Serve velocity (km$h21) 525.29 6 59.41 637.71 6 104.43 50.82 0.49 (0.04 to 0.94)
to Hit and turn test (level) 688.53 6 98.33 616.43 6 103.31 35.63 0.35 (20.1 to 0.8)
652.06 6 88.69 112.24 6 9.19 8.36z 0.92 (0.46 to 1.39)
120.60 6 8.07 11.78 6 1.96 20.09 0.05 (20.5 to 0.4)
11.69 6 1.57
U14
Female Players National n = 28 Regional n = 149 Difference ES (90% CI)
Chronological age (y) 12.87 6 0.51 12.86 6 0.51 0.01 0.02 (20.32 to 0.36)
Under-18 ranking 227.68 6 94.78 578.66 6 325.59 2350.98� 1.16 (21.51 to 0.80)
PHV 0.28 (20.06 to 0.62)
APHV 1.06 6 0.71 0.88 6 0.63 0.18 0.42 (20.76 to 0.07)
Height (cm) 11.81 6 0.49 11.98 6 0.39 20.17z 0.39 (0.05 to 0.73)
Weight (kg) 163.26 6 8.39 160.45 6 6.89 0.31 (20.03 to 0.65)
BMI 50.91 6 7.63 48.65 6 7.18 2.81 0.12 (20.22 to 0.46)
Grip strength (kg) 19.02 6 1.77 18.80 6 1.81 2.26
CMJ (cm) 29.00 6 5.53 27.42 6 5.19 0.22 0.3 (20.04 to 0.64)
10-m sprint (s) 30.11 6 3.78 29.78 6 3.76 1.58 0.09 (20.25 to 0.43)
20-m sprint (s) 0.33 0.12 (20.21 to 0.46)
TSS forehand (s) 1.99 6 0.08 1.98 6 0.08 0.01 0.00 (20.34 to 0.34)
TSS backhand (s) 3.50 6 0.14 3.50 6 0.14 0.00 0.30 (20.64 to 0.04)
MBT overhead (cm) 2.95 6 0.14 2.99 6 0.13 20.04 0.13 (20.47 to 0.21)
MBT forehand (cm) 3.10 6 0.15 3.12 6 0.15 20.02 0.58 (0.24 to 0.92)
MBT backhand (cm) 668.21 6 108.54 611.2 6 96.24 57.01z
Serve velocity (km$h21) 868.04 6 100.84 771.98 6 102.43 96.06� 0.94 (0.59 to 1.28)
to Hit and turn test (level) 836.79 6 106.91 743.85 6 105.31 92.94�
138.54 6 9.99 127.80 6 10.61 10.74� 0.88 (0.53 to 1.22)
13.76 6 1.74 12.66 6 1.92 1.10z
1.02 (0.67 to 1.37)
0.58 (0.24 to 0.92)
U16
Female Players National n = 24 Regional n = 73 Difference ES (90% CI)
Chronological age (y) 14.89 6 0.47 14.76 6 0.49 0.13 0.27 (20.12 to 0.65)
Under-18 ranking 41.54 6 16.54 287.38 6 300.54 2245.84� 0.93 (21.33 to 0.53)
PHV 0.32 (20.07 to 0.71)
APHV 2.58 6 0.44 2.41 6 0.55 0.17 0.09 (20.48 to 0.3)
Height (cm) 12.31 6 0.47 12.35 6 0.43 20.04 0.27 (20.12 to 0.66)
Weight (kg) 168.96 6 7.04 167.30 6 5.78 0.44 (0.05 to 0.83)
BMI 60.24 6 4.81 57.49 6 6.65 1.66 0.34 (20.05 to 0.73)
Grip strength (kg) 21.11 6 1.33 20.51 6 1.87 2.75 0.76 (0.36 to 1.16)
CMJ (cm) 35.25 6 4.37 32.13 6 3.96 0.60 0.16 (20.22 to 0.55)
31.76 6 4.34 31.14 6 3.56 3.12z
0.62
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10-m sprint (s) 1.93 6 0.09 1.96 6 0.15 20.03 0.22 (20.60 to 0.17)
20-m sprint (s) 3.38 6 0.15 3.41 6 0.14 20.03 0.21 (20.60 to 0.18)
TSS forehand (s) 2.86 6 0.13 2.88 6 0.11 20.02 0.17 (20.56 to 0.22)
TSS backhand (s) 2.98 6 0.13 3.03 6 0.17 20.05 0.31 (20.7 to 0.08)
MBT overhead (cm) 759.38 6 105.67 709.79 6 105.68 49.59z 0.47 (0.07 to 0.86)
MBT forehand (cm) 987.5 6 124.97 909.06 6 111.62 78.44z 0.68 (0.28 to 1.07)
MBT backhand (cm) 942.08 6 111.82 872.93 6 105.93 69.15� 0.64 (0.24 to 1.03)
Serve velocity (km$h21) 152.73 6 9.67 142.29 6 10.28 1.02 (0.62 to 1.43)
to Hit and turn test (level) 15.55 6 1.55 13.83 6 1.86 10.44� 0.95 (0.55 to 1.36)
1.72�
*ES = effect size; 90% CI = 90% confidence Intervals; PHV = estimated age from or to peak height velocity; APHV = estimated
age at peak height velocity; BMI = body mass index; CMJ = counter movement jump; TSS = tennis specific; MBT = medicine ball
throws.
Estimated mean and SD of anthropometric and fitness characteristics of the national and regional teams.
zSignificant difference between the national and regional selected players (p # 0.05).
�Significant difference between the national and regional selected players (p , 0.001).
(0�0.1), small (0.1�0.3), moderate (0.3�0.5), large (0.5�0.7), weight, MBT [overhead, forehand, and backhand], and
very large (0.7�0.9), almost perfect (0.9), and perfect (1). serve velocity; p # 0.05).
A 5% level of significance (p # 0.05) was used to deter- In female players (Table 3), results also showed significant
mine statistically significant correlations. All the measure- differences between national and regional selected players in
ments were moderate to highly reliable, with the interclass the ranking position in all age groups, with the national
correlation coefficient ranging from 0.69 to 0.97 in the per- selected players showing a better ranking (U12 to U16;
formance tests. p # 0.05). Significant differences between national and
regional selected players were also found for U12 (grip
RESULTS strength and serve velocity; p # 0.05), U14 (MBT [overhead,
forehand, and backhand], serve velocity and hit and turn
The correlations between physical performance and player's test; p # 0.05), and U16 (grip strength, MBT [overhead,
ranking are presented in Table 1. In male players, values forehand, and backhand], serve velocity, and hit and turn
showed small-to-moderate correlations (r values ranging test; p # 0.05).
from 20.17 to 20.49; p # 0.05). The highest correlations
in male players were observed in serve velocity (r values DISCUSSION
ranging from 20.31 to 20.49), MBT forehand (r = 20.20
to 20.42), MBT backhand (r = 20.24 to 20.49), MBT over- The aim of the present study was to detect whether fitness
head (r = 20.33 to 20.37), and hit and turn test (r = 20.19 characteristics are related to players' performance (i.e., rank-
to 20.39). A similar trend was observed in female players, ing) and if there are age- and gender-associated differences.
with values showing small-to-large correlations (r values A secondary aim was to compare adolescent tennis players
ranging from 0.15 to 20.64). The highest correlations in according to performance level (i.e., regional selected players
female players were observed in serve velocity (r = 20.43 and the national team). Results showed that among all the
to 20.64), MBT forehand (r = 20.32 to 20.47), MBT back- physical characteristics analyzed, serve velocity and upper-
hand (r = 20.45 to 20.49), MBT overhead (r = 20.26 to body power (e.g., MBT) were found to be moderate predic-
20.36), and hit and turn test (r = 20.20 to 20.46). tors of tennis performance in both female and male young
tennis players, with stronger correlations as athletes mature.
Tables 2 and 3 show the physical and performance (i.e., Moreover, in respect of statistical differences between group
ranking) characteristics of the national and regional selected levels (e.g., national and regional), female and male national
players according to the different age groups. In male players selected players showed better performance levels mainly in
(Table 2), results showed significant differences between the most predictive physical characteristics (i.e., serve velocity,
national and regional players in the ranking position in all MBT and tennis-specific endurance [e.g., hit and turn test]).
age groups, with the national players showing a better rank-
ing (U12 to U16; p # 0.05). Analyzing the age groups, sig- The results regarding correlations between physical quali-
nificant differences between national and regional players ties and performance (Table 1) showed that power-related
were also found in U12 (grip strength, 10- and 20-m sprint, qualities (i.e., serve velocity and MBT) presented the largest
TSS backhand, MBT [overhead, forehand, and backhand], correlations with the players' ranking in all age and gender
serve velocity, and hit and turn test; p # 0.05), U14 (height, groups, followed by tennis-specific endurance with small-to-
CMJ, MBT [overhead, forehand, and backhand], serve moderate correlation values. Comparisons are difficult
velocity, and hit and turn test; p # 0.05), and U16 (height, because previous studies analyzing the physical characteristics
995 VOLUME 30 | NUMBER 4 | APRIL 2016 |
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Impact on Fitness Characteristics on Tennis Perfomance
of tennis players typically involved small sample sizes, which players to outperform regional selected players in terms of
were tested on 1 or 2 occasions and used different testing the tested fitness characteristics. In this regard, the results are
protocols (4,14,21,32,33). In this regard, the results are con- in line with previous research concerning youth athletes that
trary to previous studies of advanced prepubescent tennis reports significant differences in fitness measures between
players, which suggested that specific qualities such as agility age-matched players with different standards of play in other
(32,33) or speed and vertical jumping (15) correlated most sports (i.e., nonelite and elite) (16,23,31).
strongly with tennis performance, and findings indicating that
physical performance tests do not predict the ability to play Tennis-specific endurance and tennis performance re-
tennis at a competitive level (4,22). Present results revealed no vealed small correlations, with the largest correlation
significant correlations or only small correlations, between observed in female players (U16; r = 20.46), and it was also
linear and TSS performance, as well as jumping abilities and found to be significantly different between national and
ranking position for all age groups. Given the fact that most regional selected players in most age groups (i.e., from U12
tennis movements are within a 3- to 4-m radius, there is rarely to U14 in male players; ES, 0.5�0.7 and from U14 to U16 in
a chance for tennis players to reach maximum speed and female players; ES, 0.6�0.9). Although earlier investigations
when extended movements (.4 m) do occur, immediate did not show a connection between general endurance pa-
deceleration follows (27). In terms of jumping performance, rameters and tournament play (4), it has been shown that
a possible explanation is that jump contribution in tennis is aerobic fitness levels (e.g., maximal oxygen uptake, V_ O2max)
likely to be mainly coordinative and reaching the maximal are important in tennis because the oxidative metabolism
jump height to make a good serve may not be essential (5). helps to replenish energy sources during the course of
Moreover, the low sample sizes in previous research and the a match (36), enabling players not only to repeatedly gener-
evolution of the game to a more powerful and explosive sport ate explosive actions (e.g., strokes and on-court movements)
with higher stroke and ball velocities (i.e., the fastest serve but also ensuring fast recovery between rallies, especially
among male players is 263 km$h21 [Samuel Groth in 2012] during long matches (1,12). In this regard, values above 60
and for female players 210.8 km$h21 [Sabine Lisicki in 2014]) ml$kg21$min21 reported in elite male tennis players seem to
could be related to these contradictory findings. Accordingly, confirm the importance of possessing a medium-to-high aer-
some more recent investigations have also observed a link obic capacity (11). We assume that the diverse findings could
between muscular strength in the dominant lower and upper be related to the test specificity because it mimics tennis-
extremities and ranking among mature competitive tennis specific movement patterns by including stroke activities
players (21,29). The present results show that for both male and specific footwork. In this regard, the involvement of
and female players, the serve velocity test presented the larg- the upper-body muscles required for the ball stroke and
est correlations with their ranking. In this regard, the results the additional muscles (e.g., biarticulate leg muscles and
underline the importance of serve velocity, partly strengthen- hip adductors) that are active during specific actions (i.e.,
ing the existing research, which claims that the serve is the running and sidestep movements) could increase the validity
most powerful, potentially dominant shot (9,14,20), with sig- of this test as a performance predictor (12,18).
nificant relationships between serve velocity and the proba-
bility of winning the point (28). In the case of female players, the results show the
increasing importance of aerobic fitness as athletes mature.
The medicine ball test was found to achieve small-to- Because of the lower strength and power levels of female
moderate correlations with the ranking in both male and players compared with male players (24), we can suggest
female players in most age groups (no significant correla- that performance in female players relies more on a combi-
tions were found in U12 male players for MBT overhead and nation of upper-body power (e.g., serve velocity) and aerobic
U12 female players for MBT forehand and MBT backhand), fitness (i.e., hit and turn test).
while specific tests (i.e., TSS and tennis-specific endurance
test) were less correlated. From these findings, we can For both genders, the youngest group of players (U12)
postulate that upper-body power and the ability to transfer reported the smallest correlations between tested variables
power from the lower to the upper body (i.e., coordination) and tennis performance compared with the other age
seem to be especially important for tennis performance in groups. In this group, moderate correlations were only found
adolescent players. Accordingly, significant differences for serve velocity (i.e., r = 0.33 for male players and r = 0.43
between national and regional selected players primarily for female players). These findings support previous
occur in upper-body strength and power-related character- research, indicating that success in prepubescent tennis play-
istics (i.e., MBT and serve velocity) and the specific ers can be mainly attributed to the ability to generate con-
endurance test. More specifically, serve velocity was found sistent, accurate, and powerful shots (33), whereas physical
to be the only variable that was consistently better in the performance characteristics are not a useful tool to predict
national selected players in all groups (ES ranging from 0.48 tennis performance at this stage of development (4). At this
to 1.02 [trivial to large]). Overall, the results for female and age (U12), tactical, technical factors and the frequency of
male athletes reveal a tendency for the national selection of tournament play seem to be predominant factors, and this
can be explained as a consequence of the insufficient devel-
996 Jothue rnal of Strength and Conditioning ResearchTM opment of physical attributes (13,33). Accordingly, physical
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