How players exploit variability and regularity of game actions in female volleyball teams

Variability analysis has been used to understand how competitive constraints shape different behaviours in team sports. In this study, we analysed and compared variability of tactical performance indices in players within complex I at two different competitive levels in volleyball. We also examined whether variability was influenced by set type and period. Eight matches from the 2012 Olympics competition and from the Portuguese national league in the 2014–2015 season were analysed (1496 rallies). Variability of setting conditions, attack zone, attack tempo and block opposition was assessed using Shannon entropy measures. Magnitude-based inferences were used to analyse the practical significance of compared values of selected variables. Results showed differences between elite and national teams for all variables, which were co-adapted to the competitive constraints of set type and set periods. Elite teams exploited system stability in setting conditions and block opposition, but greater unpredictability in zone and tempo of attack. These findings suggest that uncertainty in attacking actions was a key factor that could only be achieved with greater performance stability in other game actions. Data suggested how coaches could help setters develop the capacity to play at faster tempos, diversifying attack zones, especially at critical moments in competition.     

The core musculature in male prepubescent tennis players and untrained counterparts: a volumetric MRI study

The effects of exercise on the core musculature have not been investigated in prepubescents. The main purpose of the present study was to determine the volume and degree of asymmetry of rectus abdominis, obliques and transversus abdominis, quadratus lumborum, iliopsoas, gluteus and paravertebralis muscles in prepubescent tennis players and in untrained boys. The muscle volume was determined using magnetic resonance imaging (MRI) in 7 male prepubescent tennis players and 10 untrained controls (mean age 11.0 ± 0.8 years, Tanner 1–2). After accounting for height and body weight as covariates, the tennis players had 14–34% greater volume than the controls in all the muscles analysed (P < 0.05) except in paravertebralis, dominant quadratus lumborum and non-dominant gluteus, which had similar volumes in both groups (P = NS). Compared to controls, the tennis players displayed a greater degree of asymmetry in quadratus lumborum and rectus abdominis (3% vs. 15%, P < 0.01 and 8% vs. 17%, P = 0.06, respectively). The level of asymmetry of obliques and transversus abdominis, iliopsoas, gluteus and paravertebralis muscles was similar in both groups (P = NS). In conclusion, tennis playing at prepubertal ages induces a selective hypertrophy of the core musculature and exaggerates the degree of asymmetry of quadratus lumborum and rectus abdominis compared to untrained boys.     

Validity and reliability of the Very Short form of the Physical Self-Inventory among Turkish adolescents

The study aimed to test the validity and reliability of the Very Short form of the Physical Self-Inventory (PSI-VS) among a sample of 635 Turkish adolescents. These adolescents have completed the 12 original items of the PSI-VS, plus a positively worded reformulation of the single reverse-keyed item of the physical attractiveness subscale. A series of confirmatory factor analyses was used to examine the psychometric properties of the original and modified versions of the PSI-VS. Findings revealed superior psychometric properties with the modified version than with the original set of items. The modified version was thus subsequently used to examine its factor structure invariance across sexes, age groups and sport practice involvement. Results not only report that this version was fully invariant across, but also that latent means were significantly different across sexes and sport practice involvement. In sum, the Turkish modified version of the PSI-VS presents acceptable psychometric properties and may be used to repeatedly and/or intensively assess participants’ physical self-perceptions in the context of sport and exercise interventions.     

Mechanical Player Load™ using trunk-mounted accelerometry in football: Is it a reliable,task- and player-specific observation?

The aim of the present study was to examine reliability and construct convergent validity of Player Load? (PL) from trunk-mounted accelerometry, expressed as a cumulative measure and an intensity measure (PL · min^–1). Fifteen male participants twice performed an overground football match simulation that included four different multidirectional football actions (jog, side cut, stride and sprint) whilst wearing a trunk-mounted accelerometer inbuilt in a global positioning system unit. Results showed a moderate-to-high reliability as indicated by the intra-class correlation coefficient (0.806–0.949) and limits of agreement. Convergent validity analysis showed considerable between-participant variation (coefficient of variation range 14.5–24.5%), which was not explained from participant demographics despite a negative association with body height for the stride task. Between-task variations generally showed a moderate correlation between ranking of participants for PL (0.593–0.764) and PL · min^–1 (0.282–0.736). It was concluded that monitoring PL^® in football multidirectional actions presents moderate-to-high reliability, that between-participant variability most likely relies on the individual’s locomotive skills and not their anthropometrics, and that the intensity of a task expressed by PL · min^–1 is largely related to the running velocity of the task.     

The Last and Most Developed Naṣrid Palace in the Alhambra: The Alijares and Its Country Estate (Fourteenth Century)

The country estate (al-munya, almunia in Spanish) of the Alijares occupied grounds near the Alhambra and the Generalife, although it was higher up. It was constructed at the peak of the Na?rid dynasty's splendour, during the last stage of the reign of Mu?ammad V (r.1354–1359 / 1362–1391), after he had finished the Palace of the Lions.

The Alijares formed the last link in the chain in the stylistic development of the palaces of al-Andalus. When its founder decided on the features of the Alijares, he was in search of something that was completely innovative, as he had already undertaken work in the medinas of Granada and in the Alhambra that turned out to be a transformation of the architectural forms so far developed.

Life in the palace and the al-munya was cut short by sizeable earthquake in 1431, which coincided with a hard Castilian military campaign against the Kingdom of Granada. The consequences of the allegiance formed after the Na?rid defeat hindered the reconstruction of the Alijares, and so the royal buildings above the Royal Water Channel (Acequia Real) of the Alhambra were abandoned. Although time has erased many of the traces of the palace and its al-munya, we have extensive knowledge of its main architectural features, thanks to an analysis of all the available sources.     

The belief revision model: asymmetrical effects of noncontingency on human covariation learning

A noncontingent experience affects the subsequent detection of positive and negative contingencies between the same events. Experiments 1 and 2 showed that such preexposure can produce both an impairment in the detection of subsequent positive contingency and a facilitation of a negative one, independent of the level of contingency during the contingent phase. Experiment 3 raised difficulties for a model that assumes that associations to the context can explain this asymmetrical effect. Experiment 4 suggested that the different weights usually assigned to the different types of trials when computing the contingency between events can change as a result of a noncontingent experience with the same events. This change supports an account of the asymmetrical effect by a belief revision model based on a mechanism that updates the weights of the different trial types as a function of previous experience. More generally, the belief revision model is a statistical (i.e., nonassociative) model of learning that is capable of accounting for trial-order effects, which have long posed problems for statistical models.