Mohsen Shafizadeh

Performance consistency of international soccer teams in euro 2012: a time series analysis.

Abstract The purpose of this study was to examine the consistency of performance in successive matches for international soccer teams from Europe which qualified for the quarter final stage of EURO 2012 in Poland and Ukraine. The eight teams that reached the quarter final stage and beyond were the sample teams for this time series analysis. The autocorrelation and cross-correlation functions were used to analyze the consistency of play and its association with the result of match in sixteen performance indicators of each team. The results of autocorrelation function showed that based on the number of consistent performance indicators, Spain and Italy demonstrated more consistency in successive matches in relation to other teams. This appears intuitive given that Spain played Italy in the final. However, it is arguable that other teams played at a higher performance levels at various parts of the competition, as opposed to performing consistently throughout the tournament. The results of the cross-correlation analysis showed that in relation to goal-related indicators, these had higher associations with the match results of Spain and France. In relation to the offensive-related indicators, France, England, Portugal, Greece, Czech Republic and Spain showed a positive correlation with the match result. In relation to the defensive-related indicators, France, England, Greece and Portugal showed a positive correlation with match results. In conclusion, in an international soccer tournament, the successful teams displayed a greater degree of performance consistency across all indicators in comparison to their competitors who occasionally would show higher levels of performance in individual games, yet not consistently across the overall tournament. The authors therefore conclude that performance consistency is more significant in international tournament soccer, versus occasionally excelling in some metrics and indicators in particular games.

Effect of different external attention of focus instruction on learning of golf putting skill

The effect of different sources of external attentional focus on learning a motor skill was assessed in the present study. 30 students (12 men, 18 women) participated voluntarily and were divided, according to type of external focus, into target, club swing, and target-club swing groups. The task was a golf putting skill. The target focus group attended to the target (hole), the club swing focus group attended to the execution of the clubs swing, and the target-club swing focus group attended to both. All participants performed 50 trials of the putting skill in the acquisition phase and 10 trials in the 24-hr. delayed retention phase. The dependent variable was the error in the putting skill measured as the distance from the hole to the ball after each strike. Results showed the target-club swing focus group had better scores in the acquisition and retention phases than the other groups. It was concluded that external focus instruction helped the learners to integrate target cue with action cue and is more effective in skill learning than other external-focus instructions. These results support the claims of ecological psychology theorists concerning the effects of external focus of attention.

Effects of Focus of Attention and Type of Practice on Learning and Self-Efficacy in Dart Throwing

The present investigation studied the effect of focus of attention and type of practice on self-efficacy and learning during a demonstration of the dart-throwing skill. 48 university students (M = 22.5 yr., SD = 3.6) without any experience of dart throwing were divided into four groups according to the type of practice (physical and observational) and focus of attention (internal and external) and practiced a dart-throwing task. Self-efficacy in dart throwing was measured at the pre-test, acquisition, and transfer phases. The internal-focus group concentrated on their limb function, whereas the external-focus group concentrated on the darts and the target during the demonstration. Observational groups only watched during the acquisition phase, then performed the task in the retention and transfer phases. There was a main effect of focus of attention in the retention and transfer phases after controlling self-efficacy, with external focus groups showing higher performance than internal focus groups. External focus of attention could facilitate the acquisition of a motor skill during observation and may build and/or be supported by self-efficacy.

Effects of different focus of attention rehabilitative training on gait performance in Multiple Sclerosis patients

The present investigation studied the effects of different focus of attention training on gait performance. Twelve volunteers with Multiple Sclerosis and with an average disability score (Expanded Disability Status Scale=6.5) were selected from a Medical School and took part in a three-phase intervention including baseline, internal focus, and external focus, for eight weeks. In the baseline condition, the participants walked on a treadmill without any information. In the first (internal-focus) intervention they focused on foot performance and in the second (external-focus) intervention they focused on external markers and auditory information. The results of within-group analysis of variance showed that the external intervention was significantly (p<.05) better than the other conditions for stride length, step length, step speed, and gait energy expenditure, but not for force and stride timing (p>.05). In conclusion, the second (external-focus) intervention was found to be an appropriate perceptual training method and to result in improvements in some of the gait performance parameters.

An exploratory analysis of losing possession in professional soccer

The aim of the present study was to develop a measure that determines the reasons for losing possession in professional soccer. Fifty five national soccer teams that took part in 2006 and 2010 World Cup games were selected for this study. The Losing Possession Observational Checklist for Soccer was developed and applied to games in these tournaments. The results of interrater and intra-rater reliabilities showed that the new checklist had good stability (K= .75) and objectivity (K= .75). In addition, the results of exploratory factor analyses showed that losing possession in soccer included skill execution and parameterization, skill under stress, and speed and timing problems that accounted for 77% of common variance. In conclusion, current findings demonstrated that losing possession in soccer is multidimensional in nature and consists of motor and cognitive factors on the basis of specialist and statistical confirmation.

Effects of the level of expertise on the physical and technical demands in futsal

The purpose of this study was to examine the differences between elite and semi-elite futsal players in terms of the technical and physical demands of the sport. 12 elite senior teams that competed in the World Cup 2012 and 5 futsal clubs that competed in the north of England were selected non-randomly. Time-motion analysis was used to quantify physical movements during matches and the movement classifications included standing, walking, jogging and sprinting. Technical skills assessed were offensive movements including the percentages of successful passes, dribbles and shots. The results of Hotelling T2 showed that there were significant differences in both the technical and physical demands between the two groups (p<0.05). The follow-up tests showed that elite players demonstrated more successful attempts in passing, dribbling and shooting. In addition elite players spent more time during a match on sprinting, whereas semi-elite players recorded higher percentages on standing and walking activities (p<0.05). In conclusion, the findings of this study showed that by improving the proficiency of skills through practice the ability to exploit space during a match is also improved through using more intensive activities and the most accurate performance predictors in attacking play are passes, dribbles and shots.

Informational constraints on interceptive actions of elite football goalkeepers in 1v1 dyads during competitive performance

ABSTRACT The aim of this study was to examine whether perceptual variables can provide informational constraints for the goalkeepers to intercept the ball successfully in 1v1 dyads. Video images of 42 actions (1v1 in direct shots) were selected randomly from different matches and divided into conceded goals (n = 20) and saved actions (n = 22) to investigate interceptive actions of 20 goalkeepers in the English Premier League in season 2013–2014. Time to Contact (TTC) of the closing distance gap between shooter and goalkeeper was obtained by digitising actions in the 18-yard penalty box. Statistical analyses revealed that, in sequences of play resulting in an intercepted shot at goal, goalkeepers closed down outfield players in the X axis, whereas when a goal was conceded, there was a significantly delayed movement by goalkeepers toward the shooters in this plane. The results of canonical correlations showed that a decreasing distance between a shooter and goalkeeper, and accompanied reduction in relative interpersonal velocity followed a temporal pattern. Findings of this study showed how perception of key informational constraints on dyadic system relations, such as TTC, interpersonal distance and relative velocity, constrain elite goalkeepers’ interceptive actions, playing an important role in successful performance.

The emergence of coordinative structures during offensive movement for goal-scoring in soccer

This study examined how offensive movements leading to goal-scoring opportunities emerge through coordinative actions between players in professional soccer. Twenty soccer clubs in the English Premier League were observed and analysed for 12 successive competitive Premier League matches each during the 2011-12 season. A coordinative structure was defined as the partnership between the player who delivered the assist pass and the goal scoring player. According to conditions of two players in the last action before a goal being scored four coordinative states were defined: Passer Standing-Receiver Standing; Passer Standing-Receiver Moving; Passer Moving-Receiver Standing; Passer Moving-Receiver Moving. The result of repeated-measures Analysis of Variance (F3, 57=1.94, p>0.05) showed that there was no significant difference between the occurrence of different coordinative states. The Markov chain model was used to examine the predictability of coordinative structure states in successive matches. We found a low transition probability and small transitional rate in each coordinative state. The results showed that the emergence of coordinative structure during offensive movements varies between EPL soccer clubs and it follows a stochastic process in successive matches. One implication of these findings for coaches is the need for varied tactics in attack through using different states of coordinative actions between players in order to increase goal-scoring opportunities.

Temporal Analysis of Losing Possession of the Ball Leading to Conceding a Goal: A Study of the Incidence of Perturbation in Soccer:

The aim of this study was to examine the temporal occurrence of losing possession of the ball in soccer and its association with conceding a goal. Thirty two senior national teams competing in the 2010 World-Cup in South Africa and twelve youth soccer clubs were selected for match analysis. The results of time distribution analysis showed a significant positive skewness (K-SZ =3, S=0.463, p=0.000) for losing possession of the ball, transition time in senior (K-SZ =1.82, S=1.57, p=0.003) and youth groups (K-SZ =2.85, S=1.29, p=0.002) and normal distribution for variability of time to losing the ball (K-SZ =1.07, S= −0.280, p=0.19). The results of an independent t test showed that there was a significant difference (t=2.71, p=0.008) in transition time between youth and senior groups. In conclusion, this study showed that the number of times that the ball was lost increased near to a goal being conceded and the duration of the most recent loss was very close to goal-conceding. Thus effective strategies that have been employed to destabilise opponents include increasing the number of perturbations through losing possession of the ball, speeding up the transition periods and the final strike after the opponents lose the ball.

Aerobic exercise interventions reduce blood pressure in patients after stroke or transient ischaemic attack: a systematic review and meta-analysis

Objective Secondary vascular risk reduction is critical to preventing recurrent stroke. We aimed to evaluate the effect of exercise interventions on vascular risk factors and recurrent ischaemic events after stroke or transient ischaemic attack (TIA). Design Intervention systematic review and meta-analysis. Data sources OVID MEDLINE, PubMed, The Cochrane Library, Web of Science, The National Institute for Health and Care Excellence, TRIP Database, CINAHL, PsycINFO, SCOPUS, UK Clinical Trials Gateway and the China National Knowledge Infrastructure were searched from 1966 to October 2017. Eligibility criteria Randomised controlled trials evaluating aerobic or resistance exercise interventions on vascular risk factors and recurrent ischaemic events among patients with stroke or TIA, compared with control. Results Twenty studies (n=1031) were included. Exercise interventions resulted in significant reductions in systolic blood pressure (SBP) −4.30 mm Hg (95% CI −6.77 to −1.83) and diastolic blood pressure −2.58 mm Hg (95% CI −4.7 to −0.46) compared with control. Reduction in SBP was most pronounced among studies initiating exercise within 6 months of stroke or TIA (−8.46 mm Hg, 95% CI −12.18 to −4.75 vs −2.33 mm Hg, 95% CI −3.94 to −0.72), and in those incorporating an educational component (−7.81 mm Hg, 95% CI −14.34 to −1.28 vs −2.78 mm Hg, 95% CI −4.33 to −1.23). Exercise was also associated with reductions in total cholesterol (−0.27 mmol/L, 95% CI −0.54 to 0.00), but not fasting glucose or body mass index. One trial reported reductions in secondary vascular events with exercise, but was insufficiently powered. Summary Exercise interventions can result in clinically meaningful blood pressure reductions, particularly if initiated early and alongside education.