Wetenschap en waterpolo


Notational analysis of elite and sub-elite water polo matches.
J Strength Cond Res. 2010 Jan;24(1):223-9.
Lupo C, Tessitore A, Minganti C, Capranica L.
Department of Human Movement and Sport Science, Università degli Studi di Roma Foro Italico, Rome, Italy.

This study aimed at comparing elite (i.e., Euro League and Italian "Serie A1") and sub-elite (Italian "Serie B") matches. A notational analysis was performed on 17 men's water polo matches during the 2005-2006 season to evaluate the following technical and tactical parameters of the offensive play: frequency of occurrence of the actions; mean clock-time duration; mean number of players involved and passes; frequency of occurrence of the turnovers; and frequency of occurrence of the number, outcome, position, and type of the shots. All the indicators were analyzed in relation to even (i.e., equal number of offensive and defensive players), counterattack (i.e., higher number of offensive players than that of the defense), and power play (i.e., a team defending for 20 seconds without a player because of an exclusion foul) situations. A multivariate approach (multivariate analysis of variance) was applied to the playing situations (even, counterattack, and power play) as dependent variables and competition levels (Final Four of Euro League Championship, Serie A1 Championship, and Serie B Championship) as between factor (p < 0.05). Significant differences among competition levels emerged in (a) the frequency of occurrence of counterattack and power play actions, (b) the duration of even situations, (c) the mean number of players directly involved during power play actions, (d) the mean number of the passes during even and power play actions, (e) the frequency of occurrence of the shots during counterattack and power play actions, (f) the frequency of occurrence of goals during even actions, (g) the frequency of occurrence of shots originating from different zones of the court, and (h) the type of shots performed. The present results showed that the competition level has a relevant impact on the occurrence of technical and tactical indicators especially in relation to even, counterattack, and power play situations. Thus, notational analysis proved to be a valuable tool for better coaching through the interpretation of technical and tactical aspects of water polo in relation to its competition level.

Physiological profile of water polo players in different competitive levels.
J Sports Med Phys Fitness. 2010 Mar;50(1):19-24.
Melchiorri G, Padua E, Sardella F, Manzi V, Tancredi V, Bonifazi M.
University of Rome Tor Vergata, Rome, Italy.

AIM: The purpose of this study was to determine if there are different physiological characteristics in water polo players of three different competitive levels (national team, NT, junior national team, NJ, and amateur club, AC).
METHODS: To better define the training levels of water polo players competing at different levels, we administered a shuttle swim test (SST, a specific test used by Italian coaches) and a classic speed-lactate test. The shuttle swim test is based on actions at maximum intensity followed by incomplete recoveries. To compare the athletes, we used their morphological characteristics, the speed during an incremental test associated with fixed blood lactate concentrations of 2 mmol*1-1 (Aerobic Threshold, AT) and 4 mmol*1-1 (Anaerobic Threshold, AnT), and the SST data (speed, heart rate and lactate concentration).
RESULTS: The heart rate at the end of the SST was 164+/-12 beats*min-1 for NT, 166+/-10 beats*min-1 for NJ (no significant difference, P>0.05) and 179+/-9 beats*min-1 for AC (significantly different from NT and NJ, P<0.05). The AT and AnT speeds were significantly higher in NT than in AC and NJ (P<0.05). No significant differences were found in AT and AnT speeds between AC and NJ (P>0.05). The mean speed during the shuttle swim test was significantly higher in NT and NJ than in AC (P<0.05). Lactate values were similar in the NT, AC and NJ groups (P>0.05). The SST mean speed was significantly correlated with the AT (P<0.01) and AnT speeds (P<0.05) in three groups . In all groups no significant correlation was found between SST blood lactate and AT or AnT speeds (P>0.05).
CONCLUSION: Some differences were found among the senior and junior professional and amateur water polo players in both SST performance and Aerobic and Anaerobic Thre-shold speeds. The shuttle swim test for water polo provides conditioning coaches and sport scientists with data on the sport-specific movement speed and the competition-specific fatigue resistance in each athlete.

Throwing velocity and jump height in female water polo players: performance predictors.
J Sci Med Sport. 2010 Mar;13(2):236-40.
McCluskey L, Lynskey S, Leung CK, Woodhouse D, Briffa K, Hopper D.
School of Physiotherapy, Curtin University of Technology, Perth, Western Australia 6845, Australia

Throwing velocity and vertical jumping ability are essential components for shooting and passing in water polo. The purpose of this study was to determine whether there is a relationship between throwing velocity and water jump height in highly skilled female water polo players. Throwing velocity and head height at ball release were measured in twenty-two female players (age 20.41 years (6.16); weight 68.28 kg (8.87)) with two 50 frames per second cameras while shooting at goal. Water jump height was also measured with a modified Yardstick device. Multiple regression analyses showed that peak lower limb power was the most significant predictor of maximal velocity. Power alone accounted for 62% of the variance in maximum velocity (p<0.001). Once power was entered into the model none of the other physical characteristics (lean mass, fat mass, land jump height and anthropometry) made a significant contribution to throwing velocity. After controlling for the effect of power, head height at ball release accounted for an additional significant proportion of the variance in maximal velocity (R(2) change 7%; p=0.049). Lower body power was a significant predictor of higher throwing velocity in highly skilled female water polo players. Players with relatively higher underlying levels of lower limb power who are able to generate greater elevation out of the water are able to throw the ball faster.

Reliability of an in-water repeated-sprint test for water polo.
Int J Sports Physiol Perform. 2010 Mar;5(1):117-20.
Tan FH, Polglaze T, Dawson B.
School of Sport Science, Exercise, and Health, University of Western Australia, Crawley, WA, Australia.

Time-motion studies indicate the importance of repeated high-intensity activities during water polo match play. The purpose of this study was to assess the reliability of an in-water repeated-sprint test, which comprised 6x10-m all-out sprints, departing every 17 s. This protocol was chosen to replicate the regular intense periods of match play.

Nutritional supplementation habits and perceptions of elite athletes within a state-based sporting institute.
J Sci Med Sport. 2010 Mar;13(2):274-80. doi: 10.1016/j.jsams.2009.03.005
Dascombe BJ, Karunaratna M, Cartoon J, Fergie B, Goodman C.
Western Australian Institute of Sport, Australia.

The purpose of this investigation was to examine the nutritional supplement intake of athletes from a state-based sports institute. Athletes (n=72) from seven sports (kayaking, field hockey, rowing, waterpolo, swimming, athletics and netball) completed a questionnaire detailing their daily usage and rationale therefore. The large majority (63/72; 87.5+/-12.5%) of surveyed athletes reported using nutritional supplements, with no difference between female (31/36; 86.1+/-13.9%) and male (32/36; 88.9+/-11.1%) athletes. Kayakers (6.0+/-2.9) consumed a higher number of nutritional supplements than swimmers (4+/-2.2), field hockey (1.5+/-1.0), rowing (2.4+/-1.4), waterpolo (2.3+/-2.4), athletics (2.5+/-1.9) and netball (1.7+/-1.0) athletes. The athletes believed that nutritional supplements are related to performance enhancements (47/72; 65.3%), positive doping results (45/72; 62.5%), and that heavy training increases supplement requirements (47/72; 65.3%). The cohort was equivocal as to their health risks (40/72; 55.6%) or their need with a balanced diet (38/72; 52.8%). The most popular supplements were minerals (33/72; 45.8%), vitamins (31/72; 43.1%), other (23/72; 31.9%), iron (22/72; 30.6%), caffeine (16/72; 22.2%), protein (12/72; 16.7%), protein-carbohydrate mix (10/72; 13.9%), creatine (9/72; 12.5%) and glucosamine (3/72; 4.2%). The majority of supplementing athletes (n=63) did not know their supplements active ingredient (39/63; 61.9%), side effects (36/63; 57.1%) or mechanism of action (34/63; 54.0%) and admitted to wanting additional information (36/63; 57.0%). Only half of the athletes knew the recommended supplement dosages (33/63; 52.4%). The performance enhancing perception may explain the large proportion of athletes that reported using nutritional supplements, despite over half of the athletes believing that supplements are not required with a balanced diet and can cause positive doping violations.

Effect of swim sprints on throwing accuracy and velocity in female collegiate water polo players.
J Strength Cond Res. 2010 May;24(5):1195-8.
Stevens HB, Brown LE, Coburn JW, Spiering BA.
Human Performance Laboratory, Department of Kinesiology, California State University, Fullerton, California, USA.

Swim sprints are a central component of water polo competitions; however, a paucity of data describes the effect of repeated swim sprints on game-like performances. Therefore, the purpose of this study was to investigate the effect of repeated swim sprints on water polo throwing velocity and accuracy. Eleven female community college water polo players (age: 18.91 +/- 1.04 years, height: 165.91 +/- 4.69 cm, and mass: 70.22 +/- 15.36 kg) performed 2 conditions: control and sprint. The control condition consisted of 10 shots at the 5-m line, each with a 35-second rest period and aimed at a specific target on the goal. The sprint condition also had the same 10 shots but included a sprint between each throwing attempt. The sprints consisted of "head-down" swimming from the 2-m line to half court, then "head-up" swimming from half court to the 5-m line where the ball was shot and aimed at a specific target on the goal. Analysis was performed on ball velocity and accuracy between conditions. Ball velocity in the control condition (26.01 +/- 3.13 mph) was significantly (p < 0.05) greater than the sprint condition (25.08 +/- 2.76 mph); however, there was no significant difference in accuracy (shots made; Control: 3.00 +/- 1.67; Sprint: 2.45 +/- 1.03). These results indicate that ball velocity decreases in female collegiate water polo players after repeated swim sprints when compared with a control condition, yet accuracy is unaffected. Therefore, coaches should incorporate "game-like" conditions during practice that include repeated sprints--while focusing on maintaining high velocity to promote goal scoring.

Effects of induced alkalosis on simulated match performance in elite female water polo players.
Int J Sport Nutr Exerc Metab. 2010 Jun;20(3):198-205.
Tan F, Polglaze T, Cox G, Dawson B, Mujika I, Clark S.
Sports Science Dept., Singapore Sports Council, Singapore.

This study investigated the effects of sodium bicarbonate (NaHCO3) ingestion on simulated water polo match performance. Twelve elite players from the Australian National Women's Water Polo Squad (age 23.7 +/- 3.0 yr, height 1.73 +/- 0.05 m, body mass 75.7 +/- 8.0 kg) participated in the study. In a randomized cross-over double-blind design, players ingested 0.3 g/kg of NaHCO3 or placebo 90 min before performing a 59-min match-simulation test (MST) that included 56 x 10-m maximal-sprint swims as the performance measure. Capillary blood samples were obtained preingestion, pre- and post-warm-up, and after each quarter of the MST. Preexercise ingestion of NaHCO3 was effective in enhancing extracellular pH from baseline levels of 7.41; +/- 0.01 (M; +/- 90% confidence limits) to 7.49; +/- 0.01 and bicarbonate levels from 24.4; +/- 0.3 to 28.5; +/- 0.5 mmol/L. The percentage difference in mean sprint times between trials showed no substantial effects of NaHCO3 (0.4; +/- 1.0, effect size = 0.09; +/- 0.23; p = .51). These findings are contrary to those of previous NaHCO3 studies on simulated team-sport performance, but this investigation is unique in that it examined highly trained athletes performing sport-specific tasks. In conclusion, water polo players should not expect substantial enhancement in intermittent-sprint performance from NaHCO3 supplementation.

Empirical verification of the weighted system of criteria for the elite water polo players quality evaluation.
Coll Antropol. 2010 Jun;34(2):473-9.
Hraste M, Dizdar D, Trninic V.
Faculty of Natural Sciences and Mathematics, Split University, Split, Croatia.

The aim of this research was to check the validity of the weighed system of criteria for evaluating the actual quality of water polo players proposed by Hraste, Dizdar and Trninic. The authors have determined the attributes of the measurement instrument for assessment of the overall performance efficiency of elite water polo players. Based on the determined descriptive indicators, on the coefficients of the relative importance of criteria, and on the degree of the objectivity level (interobservers' agreement) of the expert evaluations, it can be concluded that the measuring attributes (objectivity and sensitivity) for most of the criteria are in accordance with their relative importance coefficients for a particular position in the game. Consequently, a structure of relevant criteria is proposed for each play action position in the water polo game. The established instrument for evaluation the actual quality of the elite water polo players is a precondition to establish the professional system orientation, but it would also mean and a hypotheses for adequate design tactic model of play and a process of sports preparation. In succeeding steps of developing the system of criteria and its applicability, the latent structure of the criteria variables should be determined as well as overall importance of criteria with respect to the game of water polo.

Sports injuries and illnesses in the 2009 FINA World Championships (Aquatics).
Br J Sports Med. 2010 Jun;44(7):522-7.
Mountjoy M, Junge A, Alonso JM, Engebretsen L, Dragan I, Gerrard D, Kouidri M, Luebs E, Shahpar FM, Dvorak J.
McMaster University Hamilton, Hamilton, Canada.

BACKGROUND: Analysis of injury and illness prevalence in elite sport provides the basis for the development of prevention programmes.
OBJECTIVES: To analyse the frequency and characteristics of injuries and illnesses occurring during the 13th Federation Internationale de Natation (FINA) World Championships 2009.
DESIGN: Prospective recording of newly incurred injuries and illnesses.
METHODS: The 13th FINA World Championships hosted 2592 athletes from 172 countries in the disciplines of swimming, diving, synchronised swimming water polo and open water swimming. All team physicians or physiotherapists were asked to complete daily a standardised reporting form for all newly incurred injuries and illnesses for their teams. To cover teams without medical staff, the physicians of the Local Organizing Committee also submitted daily report forms.
RESULTS: 171 injuries were reported resulting in an incidence of 66.0 per 1000 registered athletes. The most affected body parts were the shoulder (n=25; 14.6%), and head (n=21; 12.3%). Half of the injuries occurred during training. The most common cause of injury was overuse (n=61; 37.5%). 184 illnesses were reported resulting in an incidence of 71.0 per 1000 registered athletes. The respiratory tract was most commonly affected (n=91; 50.3%) and the most frequently classified cause was infection (n=81; 49.2%). The incidence of injuries and illnesses varied substantially among the five disciplines, with the highest incidence of injury in diving and the lowest in swimming.
CONCLUSIONS: As the risk of injury varied with the discipline, preventive measures should be discipline specific and focused on minimising the potential for overuse. As most of the illnesses were caused by infection of the respiratory and gastrointestinal tract, preventive interventions should focus on eliminating common modes of transmission.

Ultrasonographic evaluation of the shoulder in asymptomatic overhead athletes.
Acta Orthop Belg. 2010 Aug;76(4):456-61.
Ocguder DA, Tosun O, Bektaser B, Cicek N, Ipek A, Bozkurt M.
Ataturk Research and Training Hospital, Orthopaedic and Traumatology Clinic, Ankara, Turkey.

This study aimed to evaluate the efficiency of ultrasonography (US) in the examination of soft tissue anatomical structures of the shoulder in overhead athletes. The study evaluated the shoulders of overhead elite premier league athletes involved in basketball, handball, volleyball, body building, and water polo. US examination of both shoulders was performed prospectively in 45 asymptomatic overhead athletes and 43 asymptomatic volunteers matched for age. On US examination, subacromial-subdeltoid bursa effusion was observed in 16 of the dominant shoulders and in 2 of the non-dominant shoulders of 45 overhead athletes and in none of the asymptomatic volunteers. The mean thickness of the subacromial-subdeltoid bursa was significantly larger in the dominant and non-dominant shoulders of the overhead athletes than in the asymptomatic volunteers (p < 0.001, p < 0.05 respectively). Ultrasonography appeared as an effective, convenient and non-invasive tool for the early diagnosis of shoulder pathologies occurring in overhead athletes, even in the asymptomatic stage.

Aquatic sports dermatoses: part 1. In the water: freshwater dermatoses.
Int J Dermatol. 2010 Aug;49(8):874-85. doi: 10.1111/j.1365-4632.2010.04536.x.
Tlougan BE, Podjasek JO, Adams BB.
Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY 10016, USA.

The first of this three-part series on water-related dermatoses involving the athlete will include sports occurring with the majority of time spent in the water. These sports include swimming, diving, scuba, snorkeling and water polo. Numerous authors have described dermatologic conditions commonly seen in swimmers. This series provides an updated and comprehensive review of these water dermatoses. In order to organize the vast number of skin conditions related to water exposure, we divided the skin conditions into groupings of infectious and organism-related dermatoses, irritant and allergic dermatoses and miscellaneous dermatoses. The vast majority of skin conditions involving the water athlete result from chemicals and microbes inhabiting each environment. When considering the effects of swimming on one's skin, it is also useful to differentiate between exposure to freshwater (lakes, ponds and swimming pools) and exposure to saltwater. This review will serve as a guide for dermatologists, sports medicine physicians and other medical practitioners in recognition and treatment of these conditions.

Game activity and blood lactate in men's elite water-polo players.
J Strength Cond Res. 2010 Oct;24(10):2647-51.
Melchiorri G, Castagna C, Sorge R, Bonifazi M.
School of Sport and Exercise Sciences, Faculty of Medicine and Surgery, University of Roma Tor Vergata, Rome, Italy.

The purpose of this study was to examine game demands during highly competitive men's water-polo games after the introduction of the new Federation International Natation Association (FINA) rules. Participants of this study were 77 outfield international level men's water-polo players (age 25.9 ± 4.5 years, height 188 ± 4.5 cm, body mass 93 ± 10.9 kg). Game earlobe blood lactate, speed, and distance covered (semiautomatic image recognition system) were measured during 6 highly competitive matches (FINA International Tournament). In the game, players covered 1,613 ± 150 m (n = 68). This corresponds to a mean coverage rate of 54 ± 5.8 m•min (n = 68). At speeds faster than 1.4 m•s?¹ (high-intensity swimming), players covered 44% of the total distance. A significant decrease in coverage rate was detected during the final stage of the game. Mean blood-lactate concentration was 7.7 ± 1.0 mmol•L?¹ (range 2.2-14.3). Center Defenders (1,816 ± 496 m) covered significantly (p < 0.05) more distance swimming compared to Field (1,676 ± 348 m) and Center-Forward (1,317 ± 281 m) players. Mean match blood-lactate concentrations for Center Forwards, Center Defenders, and Field Players were 11.2 ± 1.0 (3-14.3), 6.7 ± 0.9 (1.4-8), and 5.3 ± 0.9 mmol•L?¹ (2.2-11.9), respectively. This study confirmed the high-intensity nature of male elite level water polo showing remarkable role-dependent game demands. As a result, strength and conditioning interventions should be individualized and mainly address intermittent high-intensity endurance and anaerobic fitness.

Lower white blood cell counts in elite athletes training for highly aerobic sports.
Eur J Appl Physiol. 2010 Nov;110(5):925-32.
Horn PL, Pyne DB, Hopkins WG, Barnes CJ.
Australian Sports Commission, Australian Institute of Sport, Sport Science and Sport Medicine, Bruce, ACT, Australia.

White cell counts at rest might be lower in athletes participating in selected endurance-type sports. Here, we analysed blood tests of elite athletes collected over a 10-year period. Reference ranges were established for 14 female and 14 male sports involving 3,679 samples from 937 females and 4,654 samples from 1,310 males. Total white blood cell counts and counts of neutrophils, lymphocytes and monocytes were quantified. Each sport was scaled (1-5) for its perceived metabolic stress (aerobic-anaerobic) and mechanical stress (concentric-eccentric) by 13 sports physiologists. Substantially lower total white cell and neutrophil counts were observed in aerobic sports of cycling and triathlon (~16% of test results below the normal reference range) compared with team or skill-based sports such as water polo, cricket and volleyball. Mechanical stress of sports had less effect on the distribution of cell counts. The lower white cell counts in athletes in aerobic sports probably represent an adaptive response, not underlying pathology.