ECSS Paris 2023: OP-AP05
INTRODUCTION: Sports teams are frequently interpreted as (dynamical) systems to examine their collective behaviors, (CB; i.e., states) under stable environmental conditions (1). However, it is unknown whether the states of such a system are time-dependent, i.e., sensitive to previous environmental conditions (2). One particularly suitable system to study this dependency is soccer teams, where variations in pitch dimensions across contexts, e.g., from training to competition, are pervasive. The present study examines time-dependency by investigating hysteresis effects in the spatial organization of soccer teams responding to systematic changes in pitch dimensions. METHODS: Twenty-two male soccer players (6th division or higher) participated in a 11-vs-11 crossover, controlled, trial-based approach (3). They were instructed to perform an organized attack in 4-4-2 formation. Following six warm-up trials on an official-sized pitch (105x68 m; 7,140 m²), twelve experimental trials were conducted across four pitch size conditions (50%, 100%, 150%, 200%). To observe time-dependent adaptations in CB, each team performed three experimental trials per condition, scaling UP from 50% pitch size to 100%, 150%, and 200%. After a short break, this procedure was reversed, scaling DOWN from 200% back to 50%, totaling 54 trials. Player positions were tracked using GPS (10Hz) and verified with video footage. For each trial, effective playing space (EPS), team spread, stretch index, and relative field usage were calculated as parameters of CB. Multiple linear regression was employed to assess the influence of pitch size (50%, 100%, 150%, 200%), scaling direction (UP, DOWN), and their interaction on the CB. RESULTS: Linear regression analysis resulted in significant main effects for pitch size across all calculated CB parameters (EPS, team spread, stretch index, relative field usage; p<.0001). Interaction effects between pitch size and scaling direction were significant for EPS (p=.04), team spread (p=.05), relative field usage (p=.03), and a trend towards significance in the stretch index (p=.06). Hysteresis was particularly present at 50% pitch size, with average differences between UP- and DOWN-scaling as follows: Stretch index delta of 1.07 m, relative field usage of 3.5%, EPS of 127 m², and team spread of 14.5 m. These findings indicate time-dependency of changes in CB. CONCLUSION: The discovered hysteresis effects provide empirical evidence for a time-dependency of soccer teams states on historical environmental conditions. This result demonstrates how a (dynamical) systems perspective on soccer teams may lead to important insights, showing that soccer teams CB is highly sensitive and adaptable to previous stimuli. Better understanding the dynamics of team system configuration in sports contexts is a fertile ground for future research. 1. Duarte et al. (2012). 10.2165/11632450-000000000-00000 2. Couzin et al. (2002). 10.1006/yjtbi.3065 3. Low et al. (2021). 10.1080/02640414.2021.1925424
Read CV Albert DeukerECSS Paris 2023: OP-AP05
INTRODUCTION: In fast-paced team sports like soccer, defenders anticipation skills are crucial in decisions-making, often determining success or failure [1]. Studies show that expert athletes use more effective visual search strategies and focus on more relevant areas than less experienced athletes, implying that gaze behaviour such as saccades and fixations may be relevant for anticipation and successful decisions in soccer [2]. The aim of this pilot study was thus to investigate differences in gaze behaviour with correct or incorrect decisions in young elite soccer players. METHODS: The study enrolled 10 young elite soccer players, including six defenders and four offensive players aged 16-18 years, (16.7 ± 0.68) with an average of 11.2 years of soccer experience. Participants viewed standardized videos of 48 defensive 1:1 game situations which were occluded at -150, -300, and -450ms before the critical last ball contact. Study participants were instructed to decide within 10 seconds after occlusion whether the opponent player depicted in the video was about to run to the left or right. Gaze behaviour was registered with an Eye Tracking System (Tobii Pro Glasses 3) measuring total saccades and fixations. Fixations were analysed with respect to regions of interest defined by Krzepota et al [3]. Differences between correct and incorrect decisions with regard to total saccades and fixations were calculated using the Mann-Whitney-U Test. The alpha-level was set at 0.05. RESULTS: Significant differences were observed for total saccades (p = 0.026), fixations at the “zone-in front of-of the-ball/ foot“ (p = 0.008), and the “zone beyond the player and ball" (p = 0.020) at -300ms while correct decisions showed more total saccades, shorter fixation duration at the “zone in front of the ball” and longer fixation duration at the “zone beyond the player and ball”. Video sequences at occlusion timestamps of -150ms and -450ms revealed no significant differences between correct or incorrect decisions. CONCLUSION: The differences in gaze behaviour (saccades and fixations) underline their importance in correct decision-making. Young soccer players may make better decisions with respect to anticipated opponents’ movement when they exhibit more saccades and shorter fixation duration at the “zone in front of the ball”. Future research should explore integrating gaze strategies into training and further investigate the relationship between saccades, player position, and decision accuracy. References: 1. Williams & Ford (2008) 2. Savelsbergh et al. (2002) 3. Nagano et al. (2004) 4. Krzepota et al. (2016)
Read CV Mona HerdenECSS Paris 2023: OP-AP05
INTRODUCTION: According to previous studies on the neuromuscular demands (Harper et al., 2019), professional football is more decelerative than accelerative. However, it is not known whether this is respected in terms of intensity ranges. The aim of the study is to compare whether this trend in favor of deceleration is maintained in the different intensity ranges. METHODS: External load from official competitions in three age categories (2nd team, 20.8 ± 4.4 yrs; U19, 17.0 ± 0.7 yrs; and U17, 15.8 ± 0.6 yrs) of elite football academy were measured by 10 Hz GPS technology during two consecutive seasons, 2021/22 and 2022/23. 2nd team played in third and second professional Czech leagues, both youth teams played the highest youth competitions. Various thresholds were used for examining the number of accelerations (ACC) and decelerations (DEC): ACC12 (from 1 to 2 ms-2), ACC23 (2-3 ms-2), ACC34 (3-4 ms-2), ACC45 (4-5 ms-2), ACC5 (>5 ms-2), with negative sign for decelerations (from DEC12 to DEC5), respectively. From official matches with 4-3-3 formation in which the players participated for the entire duration (>90 minutes), were calculated averages for every player/season. Repeated measures ANOVA with Bonferroni’s post-hoc test, Student t pair test and Wilcoxon signed-rank test were used (JASP, Version 0.18.3). Cohen´s d values were employed to assess effect sizes. Effect magnitude was interpreted according to power analysis (G*power, version 31.9.7). RESULTS: ANOVA revealed a significant influence of category on the results. Significant differences were found in all parameters only between the 2nd team and U17, although with small effect sizes according to power analysis (p<0.05, d= 0.47-0.60). There were found, in all categories, greater number of ACC than DEC in thresholds of 2-3 ms-2 (ACC23>DEC23) and 3-4 ms-2 (ACC34>DEC34). In all other thresholds more decelerations were found (ACC12 < DEC12, ACC45 < DEC45, and ACC5 < DEC5). In the lowest level ACC12 and DEC12, there were found statistically significant differences only in U17 (p< 0.01, d= 0.38) and U19 (p< 0.01, d= 0.53) categories with low and high effect size, respectively. For all other thresholds statistically very significant differences were found for all the categories (p<0.01). Magnitude of effect size exceed the counted thresholds by power analysis in all other thresholds except for U17 ACC34 versus DCC34 (d= 0.49) and ACC45 versus DCC45 (d=0.51). CONCLUSION: The results confirm that more DEC than ACC occur in football matches when higher thresholds are considered. On the contrary, the opposite is true in lower speed changes. Additionally, the team category significantly impacts the results, with U17 showing significantly lower number of ACC and DEC compared to the 2nd team in all thresholds. In addition, one of the main findings for practice is, that integrating accelerations and decelerations into one variable (i.e. mean value) is not recommended for greater thresholds (>4 ms-2), where the difference between ACC a DEC is greater.
Read CV Jindřich VampolaECSS Paris 2023: OP-AP05