Wetenschap en waterpolo


Discriminatory power of water polo game-related statistics at the 2008 Olympic Games.
J Sports Sci. 2011 Feb;29(3):291-8.
Escalante Y, Saavedra JM, Mansilla M, Tella V.
Facultad de Ciencias del Deporte, AFIDES Research Group, Universidad de Extremadura, Cáceres, Spain

The aims of this study were (1) to compare water polo game-related statistics by context (winning and losing teams) and sex (men and women), and (2) to identify characteristics discriminating the performances for each sex. The game-related statistics of the 64 matches (44 men's and 20 women's) played in the final phase of the Olympic Games held in Beijing in 2008 were analysed. Unpaired t-tests compared winners and losers and men and women, and confidence intervals and effect sizes of the differences were calculated. The results were subjected to a discriminant analysis to identify the differentiating game-related statistics of the winning and losing teams. The results showed the differences between winning and losing men's teams to be in both defence and offence, whereas in women's teams they were only in offence. In men's games, passing (assists), aggressive play (exclusions), centre position effectiveness (centre shots), and goalkeeper defence (goalkeeper-blocked 5-m shots) predominated, whereas in women's games the play was more dynamic (possessions). The variable that most discriminated performance in men was goalkeeper-blocked shots, and in women shooting effectiveness (shots). These results should help coaches when planning training and competition.

Notational analysis of American women's collegiate water polo matches.
J Strength Cond Res. 2011 Mar;25(3):753-7.
Lupo C, Tessitore A, Minganti C, King B, Cortis C, Capranica L.
Department of Human Movement and Sport Science, University of Rome Foro Italico, Rome, Italy.

Women's water polo is a relatively recent addition to the program of the Olympic Games, making its debut in 2000. Although technical and tactical aspects of men's water polo performance have been studied, there is a paucity of information on the women's competition. Thus, the present study aimed to analyze the technical and tactical aspects of 12 National Collegiate Athletic Association (NCAA) women's water polo matches in relation to 3 playing situations (Even, Counterattack, Power Play) and match outcome (winning and losing teams). The notational analysis included the following indicators: frequency of occurrence of the offensive actions, duration, players, passes, turnovers, exclusion and penalty achievement, goal, and origin and type of shot. Differences between winning and losing teams emerged for duration of actions (p = 0.024), number of players (p = 0.033), passes (p < 0.0001), exclusions and penalties achieved (p = 0.026), shots originating inside (p = 0.002) and outside (p = 0.002) the 5-m area, and occurrence of goals (p < 0.0001) during the Even situation; exclusions and penalties achieved (p = 0.029), shots following up fake (p = 0.049), and goals (p = 0.021) during the Counterattacks; and passes (p = 0.02), and goals (p = 0.003) during the Power-Play actions. In conclusion, winners showed a better ability to perform faster actions, with more effective passes leading to goals. Thus, women's water polo NCAA coaches and conditioners are encouraged to evaluate the studied technical and tactical parameters when analyzing game performances of their teams.

Relationship among maximal grip, throwing velocity and anthropometric parameters in elite water polo players.
J Sports Med Phys Fitness. 2011 Mar;51(1):26-32.
Ferragut C, Vila H, Abraldes JA, Argudo F, Rodriguez N, Alcaraz PE.
Universidad Católica San Antonio, Murcia, Spain.

AIM: As independent aspects, body size, body composition, and physiological performance of elite athletes have aroused the interest of sports scientists but, unfortunately, studies that combine these aspects are scarcely avalaible in water polo. The aim of the present study was to: 1) to develop an anthropometric profile of highly skilled male Water Polo players, and 2) to identify significant relationships between these features and overhead throwing velocity in highly skilled male water polo players.
METHODS: Thirteen male water polo players, with a mean age of 26.10±4.82, were recruited from the Spanish Water Polo team and an anthropometric assessment on all of them was carried out. Throwing velocity was evaluated in three different situations from the 5 m-penalty line on the center of the water polo goal: A) throwing without a defender nor a goalkeeper; B) throwing with a goalkeeper only, and C) 3) armfuls running shot with goalkeeper. Maximal handgrip was also tested.
RESULTS: Biacromial breadth shows a significative correlation with hand grip in water polo players (r=0.792; P=0.001) and also correlates with Throwing velocity (r=0.716; P<0.001). Biepicondylar femur breadth correlates significatively with hand grip (r=0.727; P<0.05) and also with throwing velocity in "throwing with goalkeeper" situation (r=0.664; P<0.05). Hand grip shows a significant correlation with throwing velocity in "throwing with goalkeeper" situation (r=0.603; P<0.05).
CONCLUSION: In conclusion, body mass aspects are not related with throwing velocity in highly skilled Water Polo players. Maximal hand grip is related with throwing velocity in "throwing with goalkeeper" situation. More investigations about water polo are necessary.

Networks as a novel tool for studying team ball sports as complex social systems.
J Sci Med Sport. 2011 Mar;14(2):170-6.
Passos P, Davids K, Araújo D, Paz N, Minguéns J, Mendes J.
Faculty of Human Kinetics/Technical University of Lisbon, Portugal.

This paper describes and evaluates the novel utility of network methods for understanding human interpersonal interactions within social neurobiological systems such as sports teams. We show how collective system networks are supported by the sum of interpersonal interactions that emerge from the activity of system agents (such as players in a sports team). To test this idea we trialled the methodology in analyses of intra-team collective behaviours in the team sport of water polo. We observed that the number of interactions between team members resulted in varied intra-team coordination patterns of play, differentiating between successful and unsuccessful performance outcomes. Future research on small-world networks methodologies needs to formalize measures of node connections in analyses of collective behaviours in sports teams, to verify whether a high frequency of interactions is needed between players in order to achieve competitive performance outcomes.

Assessment of the left ventricular chamber stiffness in athletes.
Echocardiography. 2011 Mar;28(3):276-87. doi: 10.1111/j.1540-8175.2010.01311.x.
Popovic D, Ostojic MC, Petrovic M, Vujisic-Tesic B, Popovic B, Nedeljkovic I, Arandjelovic A, Jakovljevic B, Stojanov V, Damjanovic S.
Division of Cardiology Division of Endocrinology Department of Medical Ecology, School of Medicine, University of Belgrade, Serbia.

Since diastolic dysfunction is an early sign of the heart disease, detecting diastolic disturbances is predicted to be the way for early recognizing underlying heart disease in athletes. So-called chamber stiffness index (E/e')/LVDd was predicted to be useful in distinguishing physiological from pathological left ventricular hypertrophy, because it was shown to be reduced in athletes. It remains unknown whether it is reduced in all athletic population. Standard and tissue Doppler were used to assess cardiac parameters at rest in 16 elite male wrestlers, 21 water polo player, and 20 sedentary subjects of similar age. In addition to (E/e')/LVDd index, a novel (E/e')/LVV, (E/e')/RVe'lat indices were determined. Progressive continuous maximal test on treadmill was used to assess the functional capacity. VO(2) max was the highest in water polo players, and higher in wrestlers than in controls. LVDd, LVV, LVM/BH(2.7) were higher in athletes. Left ventricular early diastolic filling velocity, deceleration and isovolumetric relaxation time did not differ. End-systolic wall stress was significantly higher in water polo players. RV e' was lower in water polo athletes. Right atrial pressure (RVE/e') was the highest in water polo athletes. (E/e'lat)/LVDd was not reduced in athletes comparing to controls (water polo players 0.83 ± 0.39, wrestlers 0.73 ± 0.29, controls 0.70 ± 0.28; P = 0.52), but (E/e's)/RVe'lat better distinguished examined groups (water polo players 0.48 ± 0.37, wrestlers 0.28 ± 0.15, controls 0.25 ± 0.16, P = 0.015) and it was the only index which predicted VO(2) max. In conclusion, intensive training does not necessarily reduce (E/e'lat)/LVDd index. A novel index (E/e's)/RVe'lat should be investigated furthermore in detecting diastolic adaptive changes.

The effect of mouthguard design on respiratory function in athletes.
Clin J Sport Med. 2011 Mar;21(2):95-100.
Gebauer DP, Williamson RA, Wallman KE, Dawson BT.
School of Dentistry, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.

OBJECTIVE: To test the hypothesis that 2 types of custom-made mouthguards will have no effect on ventilation (.V(E), L•min?¹), oxygen uptake (.VO2, mL•kg?¹•min•?¹), and heart rate (beats per minutes) at varying exercise intensities (10 km•h?¹ and 12 km•h?¹) and at subjective maximal effort (.VO2peak) in male field hockey and water polo players.
DESIGN: A randomized, prospective, crossover study.
SETTING: The Physiology Testing Laboratory, School of Sports Science, Exercise and Health at the University of Western Australia, a tertiary educational institution.
PARTICIPANTS: Twenty-seven male team-sport athletes.
INTERVENTIONS: Each athlete participated in 3 experimental exercise sessions separated by 1-week intervals. Testing involved a graded exercise test (GXT) performed on a treadmill wearing either a custom laminated mouthguard with normal palatal surface, a custom laminated mouthguard with palatal coverage up to the gingival margin, or no mouthguard. The experimental trials were performed in a random counterbalanced order.
MAIN OUTCOME MEASURES: .V(E) (L•min?¹) and .VO2 (mL•kg?¹•min•?¹) were measured during the GXT at intensities that equated to 10 km•h?¹, 12 km•h?¹ and subjective maximal effort (.VO2peak).
RESULTS: There were no significant differences between trials for .V(E) (L•min?¹) and .VO2 (mL•kg?¹•min•?¹) at any of the intensities assessed (P < 0.05).
CONCLUSIONS: The wearing of 2 different custom-made mouthguards during a GXT did not impair .V(E) or .VO2 during varying levels of exercise intensity in team sport athletes.

Effect of first ball possession on partial and final scores in 2003, 2005, and 2007 Water Polo World Championships.
Percept Mot Skills. 2011 Apr;112(2):349-52.
Argudo FM, Arias JL, Ruiz E, Alonso JI.
Department of Physical Education, Sport, and Human Movement Autonomous University of Madrid, Spain.

The purpose was to analyze the influence of winning the first ball possession on the partial and final score in male and female water polo. The 288 matches disputed by the teams participating in the 2003, 2005, and 2007 Water Polo World Championship were recorded. The results reflect statistically significant differences for the influence of gaining the first ball possession on the partial and final scoreboard of each period and for the influence between the total number of first possessions obtained and the final result.

Increased p wave dispersion in elite athletes.
Indian Pacing Electrophysiol J. 2011 May 1;11(3):73-80.
Puerta RC, Aliz EL, Lopez-Calleja MA, Ramirez RR, Pena GP.
Department of Clinical Cardiac Electrophysioloy and Pacing, Cardiocenter "Ernesto Che Guevara", Santa Clara, CUBA.

BACKGROUND: Few studies have been performed on P wave indices in athletes. The aim of this study was to determine the behaviour of maximum P wave duration (Pmax), minimum P wave duration (Pmin) and P wave dispersion (PWD) in young high performance athletes, as well as the relationship of PWD with training history, heart rate (HR) and echocardiographic parameters.
METHODS: We performed a cross-sectional observational study in 38 athletes of high performance in sports: water polo, distance running and weight lifting compared with 34 sedentary controls.
RESULTS: The average age in both groups was 20.6 years. Note that PWD was increased in athletes (57 ± 14 ms vs. 40 ± 12 ms, p <0.001) while Pmin was significantly lower (57 ± 13 ms vs. 72 ± 13 ms, p <0.001), and there was no difference when comparing Pmax (114 ± 9 ms vs. 117 ± 14 ms, p> 0.05). The correlation between the duration of training (r = 0.511) and resting HR (r = 0.461) with PWD was significant (p <0.01).
CONCLUSIONS: PWD is increased in young athletes of high performance and was positively correlated with duration of training and baseline HR. The increase in PWD was secondary to a significant decrease in Pmin.

Relationships between anthropometric and physiological characteristics with throwing velocity and on water jump of female water polo players.
J Sports Med Phys Fitness. 2011 Jun;51(2):185-93.
Platanou T, Varamenti E.
Department of Aquatic Sports, School of Physical Education and Sports Science, University of Athens, Athens, Greece

AIM:  The aim of this study was to examine the relationship between the anthropometric, the physiological, as well as performance related characteristics of elite female water polo players and the two important technical game parameters such as throwing velocity and on water jump.
METHODS: Thirty-three female professional water polo players (age:21.7±5.4 years, height: 171.5±5.8 cm, body mass: 65.5±8.0 Kg) members of the top four teams of the Greek A1 women league were assessed for anthropometric and body composition characteristics, for physiological and performance related characteristics as well as technical characteristics. All tests were completed a month prior to an extremely important sport event.
RESULTS: The percentage of body fat was 23.6±7.0 % and lean body mass was 50.0±5.6 kg. VO2peak was 47.5±5.8 ml·kg-1 ·min-1, La peak 7.50±1.50 mmol·l-1 and the swimming speed at 25-m sprint test as an indicator of the anaerobic power was 1.76±0.1 m·s-1. The throwing velocity was 15.54±0.71 m s-1 and vertical jump on water 61.65±3.68 cm. External-internal rotator muscles torque showed about a 1:1 ratio. Body lengths, swimming speed, internal-external torque of shoulder muscles as well as VO2 were significantly correlated with ball throwing velocity (r=0.36 to r=0.70, P<0.05). Body composition and swimming speed were associated with the on-water jump (r=0.34 to r=0.72, P<0.05).
CONCLUSION. Knowledge of the physiological and anthropometric features that correlate with the two mainly used techniques in water-polo (throwing velocity and on water jump) can be used by coaches to implement effective training programs.

Incidence of exercise-induced asthma in adolescent athletes under different training and environmental conditions.
J Strength Cond Res. 2012 Jun;26(6):1644-50. doi: 10.1519/JSC.0b013e318234eb0c.
Sidiropoulou MP, Kokaridas DG, Giagazoglou PF, Karadonas MI, Fotiadou EG.
Laboratory of Developmental Medicine and Special Education, Department of Physical Education and Sports Science, Aristotle University of Thessaloniki, Greece.

The aim of this study was to establish if there were differences in the incidence of exercise-induced bronchospasm between athletes in different sports, which take place under different environmental conditions such as open places, closed courses, and swimming pools with similar exercise intensity (football, basketball, water polo) using the free running test. The study included 90 adolescents (3 groups of 30) aged 14-18 years recruited from academies in northern Greece. All the participants were initially subjected to (a) a clinical examination and cardiorespiratory assessment by a physician and (b) free running test of a 6-minute duration and measurement with a microspirometer of the forced expiratory volume in 1 second (FEV1). Only the participants who had measured a decrease in FEV1 = 10% were reevaluated with the microspirometer during a training session. The examination of all the participants during the free running test showed that 22 athletes, that is, 9, 8, and 5 of football, basketball, and water polo athletes, respectively, demonstrated an FEV1 = 10 drop. Reevaluation of the 22 participants during training showed that 5 out 9 (55%) football athletes, 4 out of 8 basketball athletes (50%), and none of the 5 athletes of the water polo team displayed a drop of FEV1 = 10%. Despite the absence of any significant statistical differences between the 3 groups, the analysis of variances did show a trend of a lower incidence of EIA in the water polo athletes. It was found that a football or basketball game can induce EIA in young athletes but to a lesser degree than the free running test can induce. The water polo can be a safer sport even for participants with a medical history of asthma or allergies.

Comparison of the home advantage in nine different professional team sports in Spain.
Percept Mot Skills. 2011 Aug;113(1):150-6.
Gómez MA, Pollard R, Luis-Pascual JC.
Faculty of Physical Activity and Sport Sciences, Polytechnic University of Madrid.

Home advantage is a well-established phenomenon in many sports. The present study is unique in that it includes different sports analysed in the same country, at the same level of competition, and over the same time period. Nine team sports from Spain were included: baseball, basketball, handball, indoor soccer, roller hockey, rugby, soccer, volleyball, and water polo. Data for five seasons (2005-2006 to 2009-2010) were obtained, totaling 9,472 games. The results confirmed the existence of home advantage in all nine sports. There was a statistically significant difference between the sports; home advantage was highest in rugby (67.0%), and lowest in volleyball (55.7%), water polo (56.2%), and roller hockey (58.3%). The design of the study controlled for some of the likely causes of home advantage, and the results suggested that the high home advantage for rugby was likely a reflection of the continuous, aggressive, and intense nature of the sport.

Functional abilities as a predictor of specific motor skills of young water polo players.
J Hum Kinet. 2011 Sep;29:123-32. doi: 10.2478/v10078-011-0046-5.
Aleksandrovic M, Radovanovic D, Okicic T, Madic D, Georgiev G.
Faculty of Sport and Physical Education, University of Niš, Niš, Serbia.

The purpose of this study was to assess the influence of functional abilities on specificmotor skills. A total number of 92 male water polo players (age 12±0.5 years, body height 156.96±22.3 cm, body weight 51.02±33.18 kg) with at least two years' experience, were enrolled in the study. The investigation protocol consisted of standardized anthropometric measurements, estimation of maximum oxygen uptake, determination of the lung function values, specific swim tests and swim tests with a ball. The factor analysis was used for the estimation of the structure of specific motor skills. The influence of functional abilities on specific motor skills was estimated by regression analysis. Out of 15 correlations in total between the variables of space of functional abilities of water polo players, 6 were significant at the level of 95% (between the variables of aerobic power and lung function) and all of the correlations (15) between the variables of specific motor skills in water polo players were significant at the 99% level. Only one principal component, the General factor of specific motor skills in water polo (GFSWP) was obtained by way of factorization of the tests of specific motor skills, so the GFSWP represents the latent space of specific motor skills as a criterion. The regression analysis showed that functional abilities (as group predictors) (p= 0.00) and forced expiratory volume in 1 second (as a separate variable) have a significant influence on GFSWP (the criterion). The results of the study pointed out the impact of functional abilities on specific motor skills of selected young water polo players. This may be important for the selection and effective coaching in the early period of training and can affect the development of more appropriate and specific training programmes for optimal physical fitness preparation in young water polo players.

The Components Of Jumps In Expert And Intermediate Water Polo Players.
J Strength Cond Res. 2011 Nov 19
Gobbi M, D'ercole C, D'ercole A, Gobbi F.
aAusl-Pescara Department of Health Prevention, Services and Protection in Sports Activities, Laboratory of Ergospirometry, Pescara, Italy; bInstitut Nacional d' Educaciò Fisica de Catalunya Barcelona, Spain; cNaval Academy, Medicine and Surgery Department of Pisa,Italy.

The aim of this study is to show the different multifactorial structure of jump capacity in expert and intermediate water polo players, using the Principal Component Analysis (PCA) and multiple regression. We adopted the Teknotrain3, an instrument which enabled us to measure maximal height out of the water and dynamic components like force, velocity and power. The structure of the experts consisted of high power levels (t=2.75 p<0.04) and velocity(t=4.4 p<0.007) with a considerable maximal height while (t=2.73, p<0.04) (mh), of the intermediate players showed only an average velocity and maximal height as well as an inverse relation between power, velocity and temporal variability in jumps, r = -0.89(p<.01) r = -0.94(p<.01). The intermediate players need a physical preparation of resistance training aimed at developing the rapid force rate (RFD) and the maximal dynamic force and power as well as reducing temporal variability.

Throwing velocities, anthropometric characteristics, and efficacy indices of women's European water polo subchampions.
J Strength Cond Res. 2011 Nov;25(11):3051-8. doi: 10.1519/JSC.0b013e318212e20f.
Alcaraz PE, Abraldes JA, Ferragut C, Rodríguez N, Argudo FM, Vila H.

Biomechanics Laboratory, Department of Physical Activity and Sport Sciences, San Antonio Catholic University of Murcia, Guadalupe, Murcia, Spain. Water polo is a team sport characterized by a high-intensity, intermittent activity, where technical and tactical aspect are of a great importance. For that reason, the main aim of this study was to define the anthropometrical characteristics, maximum isometric grip strength, training and competition throwing velocities, and the efficacy indices in female high-level water polo players. A second purpose was to examine the differences between the throwing velocities in training vs. European championships in the water polo female national team. Ten elite trained female water polo players participated in this study. Before the competitive phase of their season, the following measures were taken: standard anthropometry, static and dynamic training throwing velocities, and hand-grip dynamometry. In the competitive phase, efficacy indices, average and maximum throwing velocities from all the participants were also determined. Significant differences (p = 0.05) were found between different training situations and different competitive throwing velocities. We concluded that elite female water polo players modify their throwing velocity depending if the throw is performed during training or competitive situation.

Comparison of dynamic visual acuity between water polo players and sedentary students.
Res Q Exerc Sport. 2011 Dec;82(4):644-51.
Quevedo-Junyent L, Aznar-Casanova JA, Merindano-Encina D, Cardona G, Solé-Fortó J.
Department of Optics and Optometry, Polytechnic University of Catalonia, Spain.

In this study, we examined differences in dynamic visual acuity between elite and subelite water polo players and sedentary students. To measure dynamic visual acuity binocularly, we asked participants to indicate the orientation of a broken ring, similar to the Landolt C, which increased in size as it moved across a computer screen. Two different speeds, three possible trajectories, and two different levels of contrast were evaluated. There were statistically significant differences between elite players and sedentary students for each combination of speed, contrast, and trajectory. Elite players achieved better dynamic visual acuity scores, and results also improved for some combinations of speed, contrast, and trajectory. Comparison between elite and subelite groups failed to reveal any

Throwing velocity and kinematics in elite male water polo players.
J Sports Med Phys Fitness. 2011 Dec;51(4):541-6.
Melchiorri G, Padua E, Padulo J, D'Ottavio S, Campagna S, Bonifazi M.
School of Sport and Exercise Sciences, University of Roma Tor Vergata, Rome, Italy.

AIM: Fifty-three members of the Italian Men Water Polo Team were filmed using two synchronized cameras, while they were shooting a goal. Considering the differences in body mass, height, training strategies and the technical-tactical features of the players, the aims of this study were to employ video-analysis techniques in order to investigate selected kinematic parameters in water polo throwing, and to provide comprehensive quantitative information on the throwing movement in relation to the different team player positions.
METHODS: Video analysis was used to estimate the elbow angle at release, the shoulder angle at follow through, the back and head height at ball release, trunk rotation angle and ball velocity at release.
RESULTS: Ball release velocities ranged from 21.0 to 29.8 m/s (average value 25.3±1.4 m/s), for field players. Goal keepers show the lowest team values (average 21.7±0.3 m/s). Similar to previous study results, ball release was typically reached just prior to the elbow approaching full extension (151.6±3.6°), and the follow through shoulder angle was 143±5.9°.
CONCLUSION: No significant statistical difference was recorded between injured and non-injured athletes. No positive association was demonstrated between physical characteristics (body mass and height) and ball velocity.

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