Montenegrin Journal of Sports Science and Medicine

5-10

Authors: Mohammad Fayiz AbuMoh'd, Walid Alsababha, Yazan Haddad, Ghaid Obeidat, Yaser Telfah

The present study was designed to determine the acute effect of sodium bicarbonate (NaHCO3) on the number of sprint repetitions during sprint high-intensity intermittent testing. In addition, blood biochemical (pH, HCO3-, and lactate) responses measured in three occasions were investigated. Thirteen male well-trained sprinters (24.65±3.44 yrs) performed two consecutive trials (7 days apart). Athletes were assigned randomly either to ingest a single dose of NaHCO3 (0.3 g/kg) 1 h prior to exercise or placebo using a double-blind crossover design. The intermittent sprint test consisted of 60 s treadmill sprints (90% of maximal work done) and 30-s recovery repeated intermittently until volitional exhaustion. Blood samples were collected from all athletes before exercise, after 1 h of dose intake, and after exercise in each trial. Paired sample t-testing showed that athletes complete significantly more sprint repetitions (p=0.036) during the intermittent sprint test with NaHCO3 (6.846±3.114) than with the placebo (5.538±3.872). Data also revealed no differences between trials in all blood responses at pre-exercise. After 1 h of dose consumption, however, blood pH and HCO3- were higher with NaHCO3 than with placebo (p<0.05), but no differences were noted in lactate between trials (p>0.05). After completion of the test, all blood responses were significantly higher with NaHCO3 than with placebo (p<0.05). In conclusion, intake of 0.3 g/kg of NaHCO3 1 h prior to treadmill sprint-intermittent performance increased sprint repetitions in well-trained sprinters, probably due to activated glycolysis caused by intracellular protons efflux into the blood.

19-24

Authors: Lorenzo Laporta, Beatriz Valongo, José Afonso, Isabel Mesquita

In sports, it is often assumed that distinct game patterns may influence the outcome of the play differently. However, a few articles about men’s volleyball have suggested that play efficacy may rely more on the quality of individual attack actions, and not on game patterns. Therefore, the goal of this paper was to scrutinize if and how game patterns influence play efficacy in high-level women’s volleyball. Eigenvector Centrality was assessed to integrate direct and indirect relationships between games actions. Thirteen matches from the women’s World Grand Prix’2015 were analysed (46 sets; 2,016 plays). Actions were categorized according to game complex (K0 to KV) and three levels of the efficacy of each play: error, continuity, and point. The results showed that play efficacy was independent of game patterns (the central pattern was non-ideal setting conditions in all complexes and preference for using slow attacks in the extremities of the net). There were, however, some regularities for each game complex. For example, while in KI to KIII, Zone 4 was the most used attack zone, in KIV and KV there was a complete inversion to Zone 2. Moreover, results revealed that women’s volleyball games are more predictable in relation to the play space (attack zones) while increasing the risk through enhanced game speed (attack tempo), in comparison with what studies in men’s volleyball have shown. Future studies should consider situational variables (e.g., match status, home vs away matches), and individual players’ actions should be considered in order to understand their relationships with team patterns better.

31-35

Authors: Neda Boroushak, Hasan Khoshnoodi, Mostafa Rostami

Head injuries are dangerous injuries that are common in combat sports. Nevertheless, the mechanisms of concussion in sport have are not precisely known. Thus, this study aimed to investigate the dynamic response of the head based on linear and rotational accelerations in boxing using computer simulation. The ADAMS software model was used to determine the linear and rotational acceleration of boxing’s straight punch. The peak linear acceleration, average linear acceleration, peak rotational acceleration, and average rotational acceleration resulted from the straight punch to head were obtained: 75 g, 20 g, 4036 rad/s², 1140 rad/s², respectively; the impact times were 30 ms and 3 ms, respectively. The comparison of acceleration tolerance thresholds of head injury and obtained results of this study showed the rotational acceleration only leads to head injury. Furthermore, it is biomechanically improbable that the head would be moved only translationally or rotationally as a result of a straight punch. Therefore, both rotational and linear accelerations should be observed together for future studies.

45-54

Authors: Joao Bernardo Martins, José Afonso, Patrícia Coutinho, Ricardo Fernandes, Isabel Mesquita

This study aimed to develop an instrument for analysing the attack in high-level volleyball considering the refined variables adjacent to the attack action, the interconnection between direct and indirect actions, the impact of the previous action, and the formation of composite variables. The game complexes were approached as interacting subsystems. The primary goal was to understand the influence of game actions adjacent to the attack. Three matches of a National Women’s 1st Division 2018/2019 (nine sets, 415 plays) were analysed, considering all game complexes (except attack coverage due to reduced occurrence). An Eigenvector Centrality network with 420 nodes and 7367 edges was created. The networks showed that ideal setting conditions, and strong attacks by the outside and opposite hitters without having received a perfect ball, were central in side-out. In transition, we highlight ideal setting conditions, preferences of the outside hitter, quick attacks in Z4, and high balls in Z2. This study is distinct because it considers different aspects related to the systemic review of the game by using composite variables and the actions prior to the attack. Of these results, we highlight that players attacked with slower tempos for the double action of receive-attack, and these were either preferably directed to the parallel or explored the block. Moreover, for the double defence-attack actions, attackers sought the soft spike in Z2, Z4, and Z8; and when two consecutive individual errors occurred, the players did not err but instead continued to attack to force the opponent’s error.

61-66

Authors: Filipe Rodrigues, Pedro Forte, Diogo Santos Teixeira, Luís Cid, Diogo Monteiro

The current study aims to examine the Physical Activity Enjoyment Scale (PACES) as a two-dimensional scale assessing two correlated but distinct dimensions of enjoyment. In total, 277 individuals (female = 108) aged between 18 and 53 years (M = 35.66; SD = 7.42) participated in the study. The unidimensional model solution displayed good fit. However, the exploratory structural equation modelling specification considering two correlated but distinct dimensions of enjoyment showed a better fit. This study was the first attempt to examine the possible existence of two dimensions within the eight-item PACES measure. The distinct aspect of the current research is to emphasize the complex and constant process of instrument validation. Scales should be viewed as a continuous process, and future methodological procedures will increase our understanding of instrument examination with more innovative statistical approaches.