The penalty throw in water polo: A cinematographic analysis

Three‐dimensional (3‐D) high‐speed cinematography was used to record the penalty throw in water polo by six elite male (M) and six elite female (F) players. The direct linear transformation technique (DLT) was used in the 3‐D space reconstruction from 2‐D images recorded via laterally placed phase‐locked cameras operating at 200 Hz. Five of the twelve subjects lifted the ball from underneath at the start of the throw whilst the remaining subjects opted for a rotation lift. As the ball was brought behind the head the females used very little hip and shoulder rotation compared to the male players so that four of the six female subjects were square on to the target at the rear point. At the completion of the backswing the wrist was flexed to a similar angle (M‐162°; F‐158°); the elbow angle showed significantly greater flexion for females (85°) than males (107°).

During the forward swing, from rear point to release, the wrist joint of the female players flexed from a rear point angle of 158° to 148° at release. The wrist movement for male subjects was different from the females in that it flexed from 162° to 147°, 0.10 s prior to release and then extended to 159° at palmar release before again flexing to 156° at release. The amount of elbow extension during the forward swing was 48° for both groups; however, the females actually released the ball with the forearm vertical (89°) compared to the male forearm angle of 78°. Maximum angular velocity of the wrist and elbow occurred at release for 9 of the 12 subjects. Both the wrist and elbow joints (F‐148°; M‐156° at wrist and F‐126°; M‐148° at elbow) demonstrated greater flexion at release in female subjects, compared with males. Maximum linear endpoint velocities for the forearm and hand segments occurred at ball release resulting in mean ball velocities of 19.1 m s ^‐1 and 14.7 m s^{‐ 1} for male and female subjects respectively.     

Kinematic analysis of three water polo front crawl styles

During water polo matches, players use different front crawl styles. The purpose of this study was to conduct a kinematic analysis of three water polo front crawl styles: front crawl with head under water, front crawl with head above water, and front crawl when leading the ball. Ten proficient water polo players performed 3 × 15 m sprints in each front crawl style, which were recorded three-dimensionally by two surface and four underwater cameras. The results showed no differences in performance and several kinematic characteristics among the water polo front crawl styles. However, front crawl when leading the ball showed shorter stroke length and greater stroke frequency. Front crawl with head underwater presented greater maximal finger depth and elbow angle at mid-stroke position. Front crawl with head above water and when leading the ball showed greater trunk obliquity and maximal depth of right and left foot, and shorter kick stroke frequency. The findings suggest that proficient players learn to master front crawl with head above water to achieve top velocity. Despite the common use of the front crawl with head underwater as the basis for water polo fast displacement, coaches should emphasize the use of the specific water polo styles to attain high performance.     

Throwing performance in water polo is related to in-water shoulder proprioception

ABSTRACT

Water polo players require a high level of upper-extremity strength, flexibility and coordination to achieve a peak level of throwing performance. Increased levels of shoulder proprioceptive acuity, strength and range of motion (ROM) have been previously associated with higher sporting performance. A coach-rating scale, used to quantify an athlete’s kicking proficiency in soccer; was adapted in the current study to measure each coach’s subjective expert opinion regarding athletes’ throwing mechanics, velocity, and accuracy. To examine this hypothesis shoulder proprioception acuity of 18 water polo players was measured both in-water and on-land using an AMEDA apparatus and correlated with coach-rated throwing performance and clinical measures of shoulder strength and ROM. There was a moderate positive correlation between the in-water and the on-land proprioception acuity (r = 0.47, p < 0.05). The in-water score showing a strong positive correlation with coach rated throwing mechanics (r = 0.68, p < 0.05) and velocity (r = 0.75, p = 0.02), suggesting that superior proprioception acuity contributed to fast, mechanically-efficient throwing. These findings support the notion that in-water proprioceptive acuity is an important determinant of the throwing performance achieved by water polo athletes and its measurement may be a valuable adjunct to current athlete screening.     

对水球中锋训练的探讨

中锋在水球比赛中的重要作用及加强中锋训练的几点措施和方法．     

The effects of fatigue on decision making and shooting skill performance in water polo players

The aim of this study was to assess the effects of fatigue on decision making and goal shooting skill in water polo. Fourteen junior elite male players (age 17.2 +/- 0.5 years; mass 84.2 +/- 7.6 kg; height 1.85 +/- 0.05 m) completed four sets of eight repetitions of an approximately 18 s maximal water polo specific drill. Progressively declining rest ratios for each successive set of the drill were employed to induce increasing fatigue and reflect the demands of match-play. A video-based temporally occluded decision-making task (verbalized response to various tactical situations) or goal shooting skill test (qualitative and quantitative analysis of goal shooting) was performed after each set. Heart rate, rating of perceived exertion (RPE) and blood lactate concentration were recorded. Heart rate (159 +/- 12, 168 +/- 13, 176 +/- 12, 181 +/- 12 Deats min-1; P < 0.001) and RPE (13.1 +/- 2.2, 15.5 +/- 1.7, 17.3 +/- 1.6, 19.1 +/- 1.1; P < 0.001) increased with declining rest ratios. At very high fatigue, decision-making accuracy was 18.0 +/- 21.8% better than at low fatigue (P = 0.008). Shooting accuracy and velocity were unaffected by incremental fatigue; however, skill proficiency (technique) decreased by 43 +/- 24% between the pre-test and high-fatigue conditions (P < 0.001). In conclusion, incremental increases in fatigue differentially influenced decision making (improved) relative to the technical performance (declined), accuracy and speed of the ball (unchanged) of a water polo goal shot.     

The effects of fatigue on decision making and shooting skill performance in water polo players

Abstract

The aim of this study was to assess the effects of fatigue on decision making and goal shooting skill in water polo. Fourteen junior elite male players (age 17.2 ± 0.5 years; mass 84.2 ± 7.6 kg; height 1.85 ± 0.05 m) completed four sets of eight repetitions of an approximately 18 s maximal water polo specific drill. Progressively declining rest ratios for each successive set of the drill were employed to induce increasing fatigue and reflect the demands of match-play. A video-based temporally occluded decision-making task (verbalized response to various tactical situations) or goal shooting skill test (qualitative and quantitative analysis of goal shooting) was performed after each set. Heart rate, rating of perceived exertion (RPE) and blood lactate concentration were recorded. Heart rate (159 ± 12, 168 ± 13, 176 ± 12, 181 ± 12 Deats min^?1; P < 0.001) and RPE (13.1 ± 2.2, 15.5 ± 1.7, 17.3 ± 1.6, 19.1 ± 1.1; P < 0.001) increased with declining rest ratios. At very high fatigue, decision-making accuracy was 18.0 ± 21.8% better than at low fatigue (P = 0.008). Shooting accuracy and velocity were unaffected by incremental fatigue; however, skill proficiency (technique) decreased by 43 ± 24% between the pre-test and high-fatigue conditions (P < 0.001). In conclusion, incremental increases in fatigue differentially influenced decision making (improved) relative to the technical performance (declined), accuracy and speed of the ball (unchanged) of a water polo goal shot.     

优秀水球运动员膝关节肌群等速向心收缩力量特征研究

利用等速测试及康复系统对优秀水球运动员膝关节肌群进行等速向心收缩测试与分析,结果发现,峰力矩可作为评价水球运动员膝关节肌力大小的一个敏感指标,峰力矩值越大,肌肉做功能力越强,做功效率越高。水球运动员膝关节慢速肌力与快速肌力呈非常显著相关,其左右膝关节肌力相当平衡,快速屈伸肌比率大于慢速屈伸肌,屈肌的慢速力量较弱。     

Attention towards the goalkeeper and distraction during penalty shootouts in association football: a retrospective analysis of penalty shootouts from 1984 to 2012

In the present study, we tested the consequences of attention towards goalkeepers in association football penalty shootouts that have exclusively been derived from laboratory experiments. We conducted a retrospective analysis of all penalty shootouts during FIFA World Cups (1986–2010) and UEFA European Football Championships (1984–2012). We linked key variables of previous laboratory research to observable behaviour in the field that was coded by two independent coders. The following hypotheses were tested: first, attention towards goalkeepers results in more saves/better goalkeeper performance; second, goalkeepers can deliberately distract penalty takers by drawing attention towards themselves which results in less accurate penalty kicks/better goalkeeper performance. Results were in line with previous laboratory analyses as they showed that attention towards goalkeepers resulted in more saves/better goalkeeping performance. Further, if goalkeepers distracted penalty takers this also resulted in better goalkeeping performance. The applied implications of these findings are discussed for both goalkeepers and penalty takers in association football.     

The underarm throw for accuracy in children

Forty boys and girls of two age groups (mean ages 52 and 70 months, respectively) performed 35 trials on a throwing task demanding accuracy. As might be expected, the older children were significantly more accurate than the younger ones but there were no sex differences. Film analysis of the throws showed that, although both age groups attempted to employ the adult strategy of varying velocity while keeping ball-release angle constant, the younger group was less successful in the latter aspect. The manner in which consistent release angles were arrived at by the older group was through the use of a movement pattern in which the elbow angle did not change during the forward swing. Such a movement pattern appeared less frequently in the younger age group. The results of this study provide support for a mode of research identifying functionally relevant kinematic variables that can subsequently be shown to follow from distinctive execution categories. In such a way, changes in outcome measures with increasing age and/or skill level can be functionally understood and identified.     

The influence of game duration and playing position on intensity of exercise during match-play in elite water polo players

In this study, we assessed exercise intensity in 20 water polo games of different duration. The hypothesis that right wing players perform at a higher intensity than back and forward central players was also tested. Thirty water polo players, equally split between three field positions, participated in the study. Initially, their performance-related physiological capabilities were evaluated. Subsequently, during water polo games of short (4 x 7-min periods) or long duration (4 x 9-min periods), heart rate was monitored continuously and blood lactate concentration was measured at the end of each period. Activity patterns were also recorded using a video camera. Mean heart rate over the entire game was 156 +/- 18 beats x min(-1). Overall exercise intensity fluctuated around a value corresponding to the lactate threshold (4.03 +/- 0.96 mmol x l(-1), 86 +/- 5% of peak heart rate) and decreased (P < 0.003) with game time (4.22 +/- 1.8 and 3.47 +/- 1.9 mmol x l(-1) in the second and fourth quarter, respectively). During the last 6 min, heart rate was higher (P < 0.001) in games of short duration (156 +/- 3 beats x min(-1)) than in games of long duration (152 +/- 8 beats x min(-1)). Video analysis showed that the percentage of time spent in low-intensity activities (i.e. "out of game") was lower (23 vs. 26%), whereas that in high-intensity activities (i.e. "sprinting crawl") was higher (21 vs. 19%), in games of short compared with long duration. No difference was observed among players of various field positions in any of the variables examined. Thus during match-play, games of long duration produced significantly lower heart rate responses than games of short duration, and the physiological response exhibited by the players was not affected by field position. The water polo authorities should consider these results before changing game duration and coaches should prepare their athletes accordingly.     

The influence of game duration and playing position on intensity of exercise during match-play in elite water polo players

Abstract

In this study, we assessed exercise intensity in 20 water polo games of different duration. The hypothesis that right wing players perform at a higher intensity than back and forward central players was also tested. Thirty water polo players, equally split between three field positions, participated in the study. Initially, their performance-related physiological capabilities were evaluated. Subsequently, during water polo games of short (4×7-min periods) or long duration (4×9-min periods), heart rate was monitored continuously and blood lactate concentration was measured at the end of each period. Activity patterns were also recorded using a video camera. Mean heart rate over the entire game was 156 ± 18 beats · min^?1. Overall exercise intensity fluctuated around a value corresponding to the lactate threshold (4.03 ± 0.96 mmol · l^?1, 86 ± 5% of peak heart rate) and decreased (P < 0.003) with game time (4.22 ± 1.8 and 3.47 ± 1.9 mmol · l^?1 in the second and fourth quarter, respectively). During the last 6 min, heart rate was higher (P < 0.001) in games of short duration (156 ± 3 beats · min^?1) than in games of long duration (152 ± 8 beats · min^?1). Video analysis showed that the percentage of time spent in low-intensity activities (i.e. “out of game”) was lower (23 vs. 26%), whereas that in high-intensity activities (i.e. “sprinting crawl”) was higher (21 vs. 19%), in games of short compared with long duration. No difference was observed among players of various field positions in any of the variables examined. Thus during match-play, games of long duration produced significantly lower heart rate responses than games of short duration, and the physiological response exhibited by the players was not affected by field position. The water polo authorities should consider these results before changing game duration and coaches should prepare their athletes accordingly.     

The development of a method for identifying penalty kick strategies in association football

Penalty takers in association football adopt either a keeper-independent or a keeper-dependent strategy, with the benefits of the keeper-independent strategy presumed to be greater. Yet, despite its relevance for research and practitioners, thus far no method for identifying penalty kick strategies has been available. To develop a validated and reliable method, Experiment 1 assessed characteristics that observers should use to distinguish the two strategies. We asked participants to rate 12 characteristics of pre-recorded clips of kicks of penalty takers that used either a keeper-independent or keeper-dependent strategy. A logistic regression model identified three variables (attention to the goalkeeper, run-up fluency and kicking technique) that in combination predicted kick strategy in 92% of the penalties. We used the model in Experiment 2 to analyse prevalence and efficacy of both the strategies for penalty kicks in penalty shoot-outs during FIFA World Cups (1986–2010) and UEFA Football Championships (1984–2012). The keeper-independent strategy was used much more frequently (i.e., 78–86%) than the keeper-dependent strategy, but successes did not differ. Penalty takers should use both the strategies to be less predictable. Goalkeepers can use the developed model to improve their chances to succeed by adjusting their behaviour to penalty takers’ preferred penalty kick strategy.     

The effects of differential and variable training on the quality parameters of a handball throw

The aim of this study was to undertake a comprehensive temporal, effective, and practical training study (variable and differential learning) that would offer athletes the opportunity to increase their performance, and to analyse the effects by measuring kinematics and quality parameters. Two participants of differing standards--a player of the first Austrian League and an Olympic and World Champion--but of similar anthropometric characteristics were recruited. One of the participants (Austrian League) was tested on five different occasions (pre-test and four retests) to measure the effects of four different training phases using kinematic analysis. The results of the study indicate an increase in ball velocity within the differential training phases (first, second, and fourth phases), different proximal-to-distal sequences of the participants, and a change of movement pattern during training measured by the segment velocities and the angle-time courses.     

The effects of differential and variable training on the quality parameters of a handball throw

The aim of this study was to undertake a comprehensive temporal, effective, and practical training study (variable and differential learning) that would offer athletes the opportunity to increase their performance, and to analyse the effects by measuring kinematics and quality parameters. Two participants of differing standards – a player of the first Austrian League and an Olympic and World Champion – but of similar anthropometric characteristics were recruited. One of the participants (Austrian League) was tested on five different occasions (pre-test and four retests) to measure the effects of four different training phases using kinematic analysis. The results of the study indicate an increase in ball velocity within the differential training phases (first, second, and fourth phases), different proximal-to-distal sequences of the participants, and a change of movement pattern during training measured by the segment velocities and the angle–time courses.     

Dueling in the penalty box: evidence-based recommendations on how shooters and goalkeepers can win penalty shootouts in soccer

In soccer, penalty kicks can decide the outcome of a match and in recent years, much effort has been invested in trying to identify the factors that influence successful performance. This overview presents some of the most important findings in order to compile a reliable set of facts that can improve the probability of success for either penalty takers or goalkeepers. Particular attention is paid to various strategic aspects in the shooter–goalkeeper interaction as previous research suggests that the chances of success on both sides may be greatly enhanced by applying findings from research in sport psychology. The article ends with a checklist that goalkeepers and penalty takers may use to improve their chances of success alongside recommendations to continue and intensify the efforts to carry out ecologically valid experiments in future research.     

Dynamics of visual feedback in a laboratory simulation of a penalty kick

Sport scientists have devoted relatively little attention to soccer penalty kicks, despite their decisive role in important competitions such as the World Cup. Two possible kicker strategies have been described: ignoring the goalkeeper action (open loop) or trying to react to the goalkeeper action (closed loop). We used a paradigm simulating a penalty kick in the laboratory to investigate the dynamics of the closed-loop strategy in these controlled conditions. The probability of correctly responding to the simulated goalkeeper motion as a function of time available followed a logistic curve. Kickers on average reached perfect performance only if the goalkeeper committed him or herself to one side about 400 ms before ball contact and showed chance performance if the goalkeeper motion occurred less than 150 ms before ball contact. Interestingly, coincidence judgement--another aspect of the laboratory responses--appeared to be affected for a much longer time (> 500 ms) than was needed to correctly determine laterality. The present study is meant as groundwork for experiments in more ecological conditions applicable to kickers and goalkeepers.     

Dynamics of visual feedback in a laboratory simulation of a penalty kick

Sport scientists have devoted relatively little attention to soccer penalty kicks, despite their decisive role in important competitions such as the World Cup. Two possible kicker strategies have been described: ignoring the goalkeeper action (open loop) or trying to react to the goalkeeper action (closed loop). We used a paradigm simulating a penalty kick in the laboratory to investigate the dynamics of the closed-loop strategy in these controlled conditions. The probability of correctly responding to the simulated goalkeeper motion as a function of time available followed a logistic curve. Kickers on average reached perfect performance only if the goalkeeper committed him or herself to one side about 400 ms before ball contact and showed chance performance if the goalkeeper motion occurred less than 150 ms before ball contact. Interestingly, coincidence judgement?-?another aspect of the laboratory responses?-?appeared to be affected for a much longer time (>500 ms) than was needed to correctly determine laterality. The present study is meant as groundwork for experiments in more ecological conditions applicable to kickers and goalkeepers.     

A mathematics-based new penalty area in football: tackling diving

ABSTRACT

A novel penalty area (PA) for football (soccer) is proposed; it is based on considering mathematically the actual scoring possibility on the 2 dimensions near the goal. It is shown that the 150-year-old rectangular area is mathematically disproportionate; this can be causing too much diving or simulation by players around the goal and also too many matches that are decided unfairly. The goal or objective is to reduce these problems – and others – with a new PA based on the proposed scoring potential measure which is in turn based on the angle towards the goal line (between posts) and the distance to the centre of this line.     

On the temporal and behavioural consistency of pre-performance routines: An intra-individual analysis of elite basketball players' free throw shooting accuracy

Abstract

The effectiveness of pre-performance routines on skilled performance in a self-paced skill has yet to be verified. In this study, we examine the importance of temporal and behavioural consistency in these routines. The duration and specific pattern of behaviours exhibited before each free throw (n = 284) were observed during 14 National Basketball Association play-off games. An intra-individual standardized score was calculated for each shot's duration. Each player's dominant behavioural routine was identified and each shot was classified as “sequence followed” or “sequence not followed”. No difference was observed in the success rates of shots associated with brief, long, and regular duration routines (P > 0.05). However, players were more successful when they followed their dominant behavioural sequence (83.77% success) than when they deviated from their specific behavioural pattern (71.43% success) (P < 0.05). The findings are interpreted in light of relevant theory and implications for practice are discussed.