Amiliarization and a testing session. The subjects performed a series of single-leg jumps, dry land and aquatic with and without devices, which were randomized to avoid fatigue effects. Peak concentric force, rate of force development, impact force, and time of the jumps were determined using a force plate. Results: Peak concentric force and rate of force development were significantly (P < 0.05) higher in the aquatic jumps, whereas impact force was significantly (P < 0.05) lower. There was a shorter total jump time (P < 0.05) for the aquatic jump without devices, whereas the time required to reach peak force was not significantly different between the two environments, despite the greater resistance to movement in the aquatic medium. Discussion: Aquatic jump exercises result in greater force production and rate of force development in the same amount of time with less impact and can thus offer a viable alternative to traditional dry-land jump exercises, which may also be beneficial for rehabilitating or aging populations. The benefits of this type of exercise include an exercise mode that can be performed without compromising speed while reducing the potential for joint injury....

The aim of this study was to investigate the effects of rule changes on game-related statistics in men’s water polo matches. A total of 856 men’s matches played in all Olympic Games and World Championship since 1936 was analysed. The game-related statistics considered were: total goals, winners’ goals, losers’ goals, goals per minute, goals difference, relationship difference goals and total goals, and relationship difference goals and winners’ goals. The rule changes were grouped by structural (game and period) and functional changes (possession time, exclusion time, timing, minimum distance to take a direct shot). Differences between rule changes were determined using a one-way ANOVA. In general, the changes in water polo rules were shown to have an effect on the final result of the matches. There were differences in each rule change of duration (increased total goals and winners’ goals), period (increased total goals and winners’ goals), possession time (increased losers’ goals), timing (increased total, winners’, losers’, and decreased % goals and total goals) and fouls (increased total goals and losers’ goals). The analysis in game-related statistics through the rule changes could be used to evaluate their effects and/or justify future modifications.

The objectives of this study were (i) to compare water polo game-related statistics by match outcome (winning and losing teams) after the application of the new rules, and (ii) to develop a classification tree model explaining the performance in elite men’s water polo. Forty-eight matches that were played in the 18th FINA World Championships were analysed. The dependent variable was match outcome and the independent variables were the game-related statistics. To determine the differences between the winning and losing teams, a parametric (paired-sample t-test) or non-parametric (Wilcoxon signed-rank test) test was applied, depending on whether or not the variable satisfied normality. The effect sizes (ES) of the differences were calculated. In order to determine which variables best predict the final outcome, a decision tree was constructed. This was a tree based on the supervised learning method called QUEST (Quick, Unbiased, Efficient, Statistical Tree). Ten variables differentiated between winning and losing teams (ES ≥ 0.80): four were related to the effectiveness of throwing, three to the effectiveness of the goalkeeper, and three to other actions. The decision tree correctly classified 83.9% of the teams with the variables GB shots, actions goals, time-outs, and steals.

The aims of this study were: (i) to compare water polo game-related statistics by context (winning and losing teams) and final score differences (using three categories – “close” games, “unbalanced” games, and “very unbalanced” games); and (ii) to identify characteristics that mark the differences in performances for each of these three categories of final score differences. The game-related statistics of the 213 women’s matches played in seven international championships were analysed. Differences between contexts (winning or losing teams) and final score differences (close, unbalanced, and very unbalanced games) were determined using the chi-squared statistic, also calculating the effect sizes of the differences. A discriminant analysis was then performed applying the sample-splitting method according to context in each final score. It was found that the game-related statistics differentiate the winning from the losing teams in each final score group, with one variable (penalty goals) differentiating winners from losers in close games, 12 in unbalanced games, and 13 (both offensive and defensive variables) in very unbalanced games. In all three types of game, the game-related statistics were shown to discriminate performance (82% or more), with three variables being discriminatory by context (winning or losing teams): goals, offensive fouls, and goalkeeper-blocked shots.

It is currently difficult to have a global state of the art vision of certain scientific topics. In the field of physical activity (PA) and exercise, this is due to information overload. The present study aims to provide a solution by analysing a large mass of scientific articles using text mining (TM). The purpose was to analyse what is being investigated in the PA health field on young people from primary, secondary and higher education. Titles and abstracts published in the Web of Science (WOS) database were analysed using TM on 24 November 2020, and after removing duplicates, 85,368 remained. The results show 9960 (unique) words and the most frequently used bi-grams and tri-grams. A co-occurrence network was also generated. ‘Health’ was the first term of importance and the most repeated bi-grams and tri-grams were ‘body_mass’ and ‘body_mass_index’. The analyses of the 20 topics identified focused on health-related terms, the social sphere, sports performance and research processes. It also found that the terms health and exercise have become more important in recent years.

The aim of this study was to examine the effects of a notational analysis-based intervention on coaches’ verbal behaviour considering their physiological activation during competition and game actions. Verbal behaviour, physiological activation (heart rate), and game actions of 4 handball coaches were recorded for a total of 28 matches. Each coach was recorded in 7 matches, three pre-interventions, two post-intervention, and two retention. Verbal behaviour was assessed using the Coach Analysis and Intervention System (CAIS: Cushion et al., 2012), and game actions were coded as positive or negative depending on their outcome. In total, 15223 verbal behaviours and 3780 game actions were recorded. The intervention programme sought to help coaches to provide constructive information (corrective feedback and instructions) after negative events or actions, encourage players (especially when the team is losing or playing badly), reduce the protests to the referee, and reduce or eliminate punishment to players. Chi-square analysis suggested that the intervention stimulated the intended changes in coaches’ behaviour, and that these changes were retained for subsequent games. Verbal behaviour changed depending on the physiological activation. This study suggests that a brief (two-session) notation-based intervention can elicit changes in coaches’ verbal behaviour during competition.