Journal of Human Kinetics volume 45/2015, 149-156 DOI: 10.1515/hukin-2015-0015 149 Section III – Sports Training Strength, Endurance, Throwing Velocity and in-Water Jump Performance of Elite German Water Polo Players by Christoph Zinner1,2, Billy Sperlich2, Malte Krueger1, Tim Focke1, Jennifer Reed3, Joachim Mester1 The purpose of this study was threefold: 1) to assess the eggbeater kick and throwing performance using a number of water polo specific tests, 2) to explore the relation between the eggbeater kick and throwing performance, and 3) to investigate the relation between the eggbeater kick in the water and strength tests performed in a controlled laboratory setting in elite water polo players. Fifteen male water polo players of the German National Team completed dynamic and isometric strength tests for muscle groups (adductor, abductor, abdominal, pectoralis) frequently used during water polo. After these laboratory strength tests, six water polo specific in-water tests were conducted. The eggbeater kick assessed leg endurance and agility, maximal throwing velocity and jump height. A 400 m test and a sprint test examined aerobic and anaerobic performance. The strongest correlation was found between jump height and arm length (p < 0.001, r = 0.89). The laboratory diagnostics of important muscles showed positive correlations with the results of the in-water tests (p < 0.05, r = 0.52-0.70). Muscular strength of the adductor, abdominal and pectoralis muscles was positively related to in-water endurance agility as assessed by the eggbeater kick (p < 0.05; r = 0.53-0.66). Findings from the current study emphasize the need to assess indices of water polo performance both in and out of the water as well as the relation among these parameters to best assess the complex profile of water polo players. Key words: team sports, strength diagnostics, jump height, anaerobic and aerobic testing. Introduction Water polo is a team sport characterized opponents. Total swimming distance during a by high-intensity, intermittent exercise with standard water polo match (4 x 8 min) ranges varying energetic demands (Melchiorri et al., from 1500 to 1650 m (Melchiorri et al., 2010; 2010). During match play, 50-60% of athletes’ Snyder 2009). The heart rate exceeds 150 beats per energy is derived by aerobic, 30-35% by anaerobic min for the majority (92%) of net playing time and 10-15% by anaerobic-lactic pathways (Snyder (Snyder 2009). As a result of these varying 2009). Strong and well-developed alternating cardiovascular and metabolic demands, water circular movements of the legs known as the polo players require optimal physical fitness to eggbeater kick are important in resisting fatigue achieve success (Melchiorri et al., 2010; Smith and optimizing aerobic endurance performance. 1998; Tan et al., 2009). The energy derived from anaerobic pathways is The eggbeater kick is a form of treading necessary for jumps, short sprints and wrestle water that allows water polo players to keep 1 - Institute of Training Science and Sport Informatics, The German Research Centre of Elite Sport, German Sport University Cologne, Am Sportpark Müngersdorf, Cologne, Germany. 2 - Department of Sport Science, University of Würzburg, Judenbühlweg, Würzburg, Germany. 3 - Faculty of Health Sciences, University of Ottawa, ON, Canada, USA. Authors submitted their contribution to the article to the editorial board. Accepted for printing in the Journal of Human Kinetics vol. 45/2015 in March 2015. 150 Strength, endurance, throwing velocity and in-water jump performance of elite water polo players afloat in an upright position while the arms are consent. The study was approved by the German free to shoot, pass, dribble and control the ball. Sport University in Cologne, Germany and The player´s torso is upright while the thighs are conducted in accordance with the Declaration of parallel, knees bent and lower legs perpendicular Helsinki. All participants were instructed to be to the water surface. As the left leg makes a adequately hydrated and refrain from consuming clockwise rotation, the right leg makes a counter alcohol or caffeine for 24 hours and food for 3 clockwise rotation. Water polo players are able to hours prior to each test. produce “boosts” by using the eggbeater kick to Procedures propel their hips out of the water. Game analyses In brief, isometric and dynamic strength have shown that more than 330 changes in of the water polo players was measured in a direction occur during an elite water polo match controlled laboratory setting. Four hours in which the eggbeater kick is used (Tan et al., following these measures, the participants 2009). Activity is intermittent, with durations performed six water polo specific tests in a lasting less than 15 s (Lilley 1982; Smith 1998). swimming pool in a randomized order. Elite players must, therefore, possess a high degree of skill to perform these high-intensity Strength Diagnosis eggbeater movements. The 5 kN force sensors (Mechatronik, Although goal scoring is essential for Hamm, Germany) in different strength machines winning a water polo match, a high level of (Edition-Line, Gym80 International MbH, throwing velocity and precision is also of crucial Gelsenkirchen, Germany) assessed maximal importance. Elite male water polo players achieve voluntary isometric and dynamic strength for the maximal throwing velocities of 58 to 88 km·h-1 lower limb adductors and abductors as well as (Darras 1998). Several investigators have noted abdominal muscles (left and right in “twister” that the eggbeater kick is the most important skill machine). A “pull-over” machine measured the in achieving high vertical reach above the water forces produced by the pectoralis muscles (major surface to clear the opponents defence and reach and minor) separately for the left and right side. high throwing velocities (Feltner and Taylor 1997; The athletes performed three trials per muscle Marrin and Bampouras 2008). To our knowledge, with one minute of rest between each of them. studies evaluating the eggbeater kick and strength The investigators verbally encouraged the athletes performance measured in laboratory conditions in throughout all trials to ensure maximal effort. elite water polo players are scarce. For the dynamic maximal voluntary The purpose of this study was threefold: contraction the athletes moved a counter weight 1) to assess the eggbeater kick and throwing with a fixed percentage of the isometric maximal performance using a number of water polo voluntary contraction determined by pretests. The specific tests, 2) to explore the relation between highest maximal voluntary isometric and the eggbeater kick and throwing performance, dynamic strength achieved was used for statistical and 3) to investigate the relation between the analysis. Trials with an initial counter movement, eggbeater kick in the water and strength tests identified by a visible drop in the signal preceding performed in a controlled laboratory setting in the force curve, were discarded. Maximal German elite national squad water polo players. voluntary contraction was calculated by The knowledge gained from this study may aid averaging the values of force registered during designing effective conditioning programs for 600 ms, which included the instant of maximal elite water polo players. peak force. For all trials, the rotating axis of the machine was adjusted to align in a perpendicular Material and Methods manner with the participants’ individual joint Participants axis. Members of the German elite national Water polo specific testing squad participated in this study (n=15). During an To measure the endurance performance of initial visit, all water polo players received the eggbeater kick, participants carried an added detailed study information and participation weight (+12.5% of their body weight) above the requirements and all provided written informed water surface for as long as possible, while Journal of Human Kinetics - volume 45/2015 http://www.johk.pl by Christoph Zinner et al. 151 performing the eggbeater kick. The test stopped swam 16 laps (400 m) between the buoys as fast as when either the participant’s chin or elbow possible to simulate a swim during a water polo dropped below the water surface. match. To measure the agility endurance of the Metabolic blood sample eggbeater kick, the participants positioned Blood samples (20 µl) were collected from themselves in the middle of the two goal posts the participants’ right ear lobe once they finished and then had to alternately touch two balls the last lap of the aerobic performance test (400 m (installed in the upper corners of the two water front crawl swim) as well as 1, 3 and 7 minutes polo goalposts) as often as possible within 60 s. after the anaerobic performance test using a All participants conducted three trials and capillary tube (Eppendorf, Germany). Samples received 70 s of rest at the pool edge in the water were measured in duplicate for blood lactate between each trial. concentration using an amperometric-enzymatic A modified jump-and-reach test sensor (Ebio Plus, Eppendorf AG, Hamburg, performed in the pool assessed the maximal Germany). The mean of the two measures was vertical jump (MVJ). Participants started in a used for statistical analysis. prone position on the water surface and then tried to reach the highest possible point on a 3-m Statistical Analysis jumping platform. The highest of three jumps was In a pre-study the technical error of measured with a high-definition video camera measurement (%TEM) for maximal voluntary (Sony, Minato, Tokio) positioned on the opposite isometric and dynamic strength of the pectoralis edge of the pool, and used for statistical analysis. (4.2%), adductor (4.0%), abductor (4.1%) and Maximal throwing velocity (MTV) was abdominal (4.2%) muscles was obtained from 10 measured using a power shot in the water. water-polo players on two separate days. The Participants positioned themselves in the water 5 TEM for all in-water tests showed acceptable m in front of the goal line and in the middle of the coefficient of variation for the multiple-trial tests.