Water polo is a very stressful body-contact team sport that combines high-intensity short duration efforts such as swimming at maximum speed, elevation of the body from the water, and throwing, with rest or low-intensity actions (29). In addition, players need considerable strength to hit, block, and push other players during game play (27,32). For these reasons, the basic characteristics of the elite water polo player includes high levels of strength, swimming speed and lean body mass, and specific technical and tactical capabilities (1,17,23).
Although water polo requires high levels of physical fitness (22,30), throwing velocity is considered to be one of the most important aspects of performance (27,32). The extent of throwing speed will depend on the muscle-skeletal strength added to coordinating factors between body segments (lower limbs, body and upper limbs) and player technique (16). Consequently, there are many studies that have analyzed the biomechanical factors of water polo shot (5–7,9,21,28,32,33). Furthermore, accuracy and throwing velocity are 2 crucial factors for the efficacy of the throw (24). Nevertheless, studies that have included tactical situations when examining throwing velocities are scarce (6,32).
Anthropometry is another key aspect in elite water polo players, and this characteristic is developing continuously in sport (25). In fact, in water polo, Lozovina and Pavicicet (17) have noted anthropometrical changes across generations. In the last decade, there are some studies that have analyzed the anthropometric characteristics of elite male water polo players (1,4,11,23,31). However, studies that analyze the anthropometric characteristics of male water polo players in the last 5 years are again scarce (1,31).
In summary, physical (strength, power, throwing velocity) and anthropometrical factors are important for determining the outcomes in water polo. However, each of these variables has been defined in different studies in isolation. So, this is insufficient when it comes to describing the whole profile of elite water polo players. In addition, Hughes and Bartlett (12,13) explain that greater emphasis should be placed on the notation analysis for increasing performance from a biomechanical and physical point of view. Actually, it has been demonstrated that tactical awareness could be more decisive than physical aspects when the aim is detection of talent and early development of elite water polo players (8). Even, significant differences have been found in some efficacy indices between men's winning and loosing water polo teams (3) and for different competition levels (18,19). Some of these parameters are the offensive tactical phases: even, counterattack, and power play.
Thus, this study had 2 aims: The first was to define the anthropometrical characteristics, maximum isometric grip strength, competition throwing velocities (both by zones, and by the different offensive tactical phases), and the efficacy indices in high-level competition. The second was to determine the relationships or differences between the variables mentioned above in elite male water polo players.
Experimental Approach to the Problem
The study was developed in 2 phases. The training month before (precompetitive phase) and during the 2008 European Championship (competitive phase). In the precompetitive phase, standard anthropometry (height, body mass, arm span, skinfolds, body girths, and skeletal breadths) and grip strength were assessed. In the competitive phase, efficacy indices, and average and maximum throwing velocities from all the participants in the complete championship were recorded.
Eleven elite trained male water polo players (age = 26.9 ± 4.5 years; height = 187.7 ± 7.4 cm; weight = 94.9 ± 12.5 kg; body mass index [BMI] = 26.9 ± 2.5 points; and grip strength = 48.7 ± 7.8 kilogram force [kgf]) were recruited from the Spanish water polo team (field players only). The participants read and signed statements of informed consent before participation in the study, and approval for the study was given by the Human Subjects Ethics Committee of the Catholic University San Antonio. For the 2008 Men's European water Polo Championship records, formal authorization from the Spanish Royal Swimming Federation and the Ligue Européenne de Natation (LEN) were obtained.
The protocols of the International Society for the Advancement of Kinanthropometry (14) were used to determine the anthropometric profile of the water polo players. The subjects were measured in the early morning during a single session. Unilateral measurements were taken on the right side of the body. The participants wore ‘light clothing’ but no shoes. Physical characteristics were measured in the following order: height, body mass, arm span, skinfolds, body girths, and skeletal breadths. The anthropometric program included 25 measurements. Height and weight measurements were made on a leveled platform scale (Seca, Hamburg, Germany) with an accuracy of 0.01 kg and 0.001 m, respectively. Eight skinfolds (triceps, subscapular, biceps, axillary, abdominal, iliac crest, suprailiac, front thigh, and medial shank) were measured by means of a Holtain Skinfold Calliper (Holtain, Crymych, United Kingdom) with 10 g·mm−2 constant pressure. Ten limb/body girths (arm relaxed, arm flexed and twitched, forearm, wrist, chest, waist, gluteus, thigh, shank, and ankle) were measured using a diameter steel tape (Lufkin Executive Thinline, Lufkin, TX, USA), and 5 skeletal breadths (biacromial, biepicondylar-humerus, biepicondylar-femur, biiliocristal, and bistyloid) were measured using an anthropometer (GPM, Zurich, Switzerland).
Double measures for each of 25 anthropometric dimensions (triple measures for skinfolds) were obtained by 1 accredited levels 2 and 3 accredited level 1 ISAK anthropometrists. The technical error of measurement was <2% for all skinfolds and <1% for all bone breadths and body girths.
Other derived variables included the following: (a) the BMI was calculated as weight (kilograms) divided by height2 (meters); (b) percentage of body fat was estimated from the measurements of skinfold thickness using the method described by Jackson et al. (15); and (c) fat-free mass (kilograms) using the method described by Martin et al. (21).
Maximum Isometric Grip Strength
Maximum isometric hand-grip strength was recorded using a handheld hand-grip dynamometer (TKK 5401, Tokyo, Japan) to the nearest 0.1 kgf. The participants were familiarized with the dynamometer and performed 3 warm-up repetitions on the same day of the testing, with 3 minutes of rest. After that, the players performed 2 repetitions at maximum intensity with the dominant hand, with 3 minutes of rest. They carried out the test from a standing position and the dynamometer set parallel to the body. In this position, the player was invited to exert maximal grip force without arm or wrist flexion. The best trial was used for further analysis.
Championship Throwing Velocities
To assess ball velocity, a radar gun (StalkerPro Inc., Plano, TX, USA) with a record data frequency of 33 Hz was used. The radar was placed 10 m behind the goal post and aligned with the penalty line (Figure 1). Usually, it is recommended that the throwing velocities registered by radar should be done from a frontal plane. However, a recent study has validated the radar vs. a photogrammetric method with a high-speed video camera from different zones of the pool (player θ = 20° from the radar gun) with coefficients correlations of r = 0.97 and p = 0.001 (10). We analyzed all the shots carried out in the 2008 Men's European Water Polo Championships by the male Spanish team (163 throws in 7 matches). Individual average and maximum throwing velocities were classified by different zones (Figure 1): zone 0 was defined by the area between the goal and the 1/2 pool line; zone 1 was defined by the area between the goal and the first 2 m; zone 2 was defined by the area between 2 and 5 m from the goal; and zone 3 was defined by the area between the 5 m and the 1/2 pool line from the goal. The zone from 0 to 2 m (off-side area) from the goal was not selected for the analysis because there were very few throws from this zone for all the players. In zone 0, a minimum of 5 throws and a maximum of 30 by each player were assessed (average = 14.8 ± 8.9 shots); zone 2 had min = 2, max = 13, average = 7.4 ± 4.0 shots, and zone 3 had min = 1, max = 17, average = 8.2 ± 6.2 shots.
The analysis of the tactical variables was based on an observational methodology from previous research (26). The selected variables were determined by a group of expert coaches and researchers. The matches were analyzed through systematic observation by 2 experienced observers, trained using the methodology described by Anguera and Santoyo (2). Additionally, the interrater reliability of 2 separate observations was calculated to guarantee the quality of the observation system, with a subsequent reliability index of 0.95 being observed (intraclass correlation coefficient and kappa index).
Furthermore, throwing velocities were also analyzed in relation to the following offensive tactical phases (i.e., even, counterattacks, and power play). In particular, even situations are characterized by a number of offensive players relative to the ball position, which is never larger than that of the defense; counterattacks refer to playing situations in which the number of offensive players relative to the ball position is larger than that of the defense; power play actions are played further to an exclusion foul of a defensive player who has to go out of the court for 20 seconds of clock time (18,19).
The variables recorded have been divided into offensives (i.e., when the Spanish team had possession of the ball) and defensives (i.e., when the Spanish team was not in possession of the ball). In addition, we subdivided the offensives into 4 categories. These were (a) percentage of shot definition (PSD) = sum of goals × 100/sum of throws performed; (b) percentage of shot resolution (PSR) = (sum of goals × 100/sum of throws performed − [sum of throws went out + sum of throws blocked + sum of throws went post]); (c) percentage of shot precision (PSP) = (sum of throws performed − [sum of throws went out + sum of throws blocked + sum of throws went post]) × 100/sum of throws performed; and (d) percentage of blocked shots received (PBSR) = sum of blocked received × 100/sum of throws performed. The defensive values were subdivided into 2 categories. In this case, they were (a) PSR when defending (PSRD) = throws detain × 100/total throws; (b) percentage of shots stopped when defending (PSSD) = throws detain × 100/total throws − (sum of throws went out + sum of throws blocked + sum of throws went post). Furthermore, the efficacy indices were classified by zones (0, 2, and 3; Figure 1).
Mean and SD scores were calculated for all the variables measured in the study. Significant differences between efficacy indices by zones and throwing velocities between the offensive tactical phases were analyzed using 1-way analyses of variance. When significant differences were obtained, Tukey's post hoc test was applied over zones and offensive tactical phases. Pearson product-moment correlation coefficients (r) were used to determine the relationships of all anthropometric measures and tactical variables with throwing velocities and grip strength. Effect sizes were calculated using Cohen's d and were reported when appropriate (small effect size; d = 0.2–0.3). The p ≤ 0.05 criterion was used for establishing statistical significance.
Table 1 summarizes the mean values (±SDs) of the upper and lower girths and breadths of the players. The body composition was as follows: muscular = 48.6 ± 2.2%; bone = 15.7 ± 0.8%; fat = 11.6 ± 2.4%; sum of 4 skinfods (triceps, subscapular, suprailiac, and abdominal) = 67.7 ± 22.2 mm).
Table 2 describes the maximum and average throwing velocities (by zones and by offensive tactical phases) of the Spanish national team at the 2008 Men's European Water Polo Championships. Regarding the maximum competition velocities by zones, the only significant differences found were between zone 0 and zone 2 (p = 0.027). Also, significant differences were found between average velocities from zone 2 and zone 3 (p = 0.001). Concerning the average throwing velocities by offensive tactical phases, significant differences (p = 0.043) were found between even and power play situations.
The efficacy indices shown in Table 3 indicate that there are differences between zones; however, these differences were not statistically significant. As expected, in the offensive variables, the percentages are higher when the players are nearer the goal. However, in the defensive variables, they are lower when the players are farther from the goal.
Relationships between physical fitness and anthropometric characteristics and efficacy indices were also analyzed, and different significant correlations were found. With regard to grip strength, significant correlations were found with different body composition (muscular mass: r = 0.69, p = 0.017; bone mass: r = 0.72, p = 0.011), girth (mesosternal: r = 0.65, p = 0.031; gluteus: r = 0.72, p = 0.013; upper thigh: r = 0.70, p = 0.016; medial thigh: r = 0.61, p = 0.047), and breadth (biacromial: r = 0.67, p = 0.024; femur: r = 0.76, p = 0.007) variables. Regarding the championship throwing velocities, significant correlations were found between these velocities and different offensive efficacy indices (V0average vs. PBSR: r = 0.66, p = 0.05; V2average vs. PSP: r = −0.68, p = 0.03; V3max vs. PBSR: r = −0.88, p = 0.049).
To our knowledge, this study is the first to concurrently define and investigate the relationships between anthropometry, grip strength, competitive throwing velocities, and tactical characteristics of elite male water polo players. One of the major finding of the present research was that throwing velocities are different between some of the offensive tactical phases. A second major finding was that grip strength has a strong correlation with body composition and different body girths and skeletal breadths, whereas competition throwing velocities significantly correlate with different efficacy indices in highly skilled water polo players.
Although, some authors (3,18–20) considered tactical aspects of elite water polo, especially in relation to playing situations involving an even or uneven (i.e., power play and counterattack) numbers of players. To our knowledge, this is the first study that compares the throwing velocity between the different offensive tactical phases. In this study, the even actions were characterized by a high throwing velocity (17.9 ± 2.4 m·s−1) vs. the lower velocity (16.7 ± 2.6 m·s−1) in the power play situation, suggesting that the players have more time for preparing the shot, and this throw is faster and, consequently, more dangerous. For this reason, the higher occurrence of goals scored by the winning teams during even actions (20) could be explained by the higher velocity reached by the players in the situation mentioned.
Competition throwing velocities significantly correlated with some offensive efficacy indices. Blocks received significantly and inversely correlated with average throwing velocity from zone 0 and maximum throwing velocity from zone 3. Although we have not found research that correlated efficacy indices with high-level water polo throwing velocities, again, we can deduce that the faster the ball is, the lower is the goalkeeper and defender reaction time to block the throw. From zone 2, an inverse and significant correlation was found between shot precision and average throwing velocity. It should be noted that from zone 2 throwing velocities are typically lower, this occurs probably because the players have the aim of being more accurate.
Regarding the efficacy indices, the highest values were registered at zone 2, for both offensive and defensive situations, although these differences were not significant. It is clear that zone 2 is the higher efficacy zone (PSD, PSR, PSP). The key actions relating to losing a match (i.e., PBSR, PSRD, PSSD) took place mostly in zone 3. The data could not be compared, because other studies that relate the efficacy indices in water polo were not found. Concerning the significant correlations between physical characteristics and anthropometry and tactical indices, biacromial and biepicondylar-femur breadth showed a positive and significant correlation with hand-grip strength. We only found significant correlations between mesoesternal girths with throwing velocity from zone 3. Therefore, the anthropometric characteristics do not seem to be much representative of competition throwing velocities.
After studying the physical and anthropometric characteristics and efficacy indices and correlating them in highly skilled water polo players, we conclude that (a) throwing velocities in the even situation is higher than in the power play situation; (b) there is a strong and significant correlation between conditioning and performance factors with anthropometrical and tactical characteristics; (c) grip strength is significantly related to some anthropometrical variables of lower and upper limbs; (d) offensive tactical aspects (blocked received and shot precision) are related to throwing velocities; and (e) in the zone close to the goal, precision and accuracy seem to be more important than throwing velocity is. On summarizing, this study is applied to training because it shows a lot of different determinant variables related to each other in high-level water polo players. In this sense, coaches should pay attention to these indices for the development of performance throughout the season.
The authors wish to thank the Spanish Royal Swimming Federation and the LEN for the facilities offered for measuring in the 2008 Water Polo European Championships. In addition, they would like to thank the collaboration of Peter Hastie. This Research is supported by a grant from the Spanish Ministry of Science and Innovation (DEP2008-06114).
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