Name: MAXWELL VIANA MORAES NETO
Publication date: 14/12/2023
Examining board:
Name |
Role |
|---|---|
| RODRIGO LEAL DE QUEIROZ THOMAZ DE AQUINO | Advisor |
Summary: The objective of this dissertation was to analyze the effects of contextual variables on the dynamics of space occupation and on the physique of professional Brazilian football players based on positioning data. Furthermore, the aim was to investigate the independent and interactive effects of contextual variables (match halves, quality of opposition, match location, match status) on team spatial organizations during official matches in professional soccer. Forty-eight male outfield players were observed during 22 matches over the entire season. Positional data were obtained using global positioning system devices (10 Hz). The following variables were calculated: team surface area; distances between centroids of defensive-midfield lines, midfield-offensive lines, and defensive-offensive lines; width; length; and length-per-width ratio. The main results were: i) variables related to team spatial organizations were not influenced by match halves (1st vs. 2nd half) (p>0.05); ii) matches played against weak opponents presented higher distances between centroids of defensive and offensive lines (p=0.03) and distances between centroids of defensive and midfield lines (p=0.03) than matches against strong opponents; iii) away matches presented greater values of the distance between centroids of the defensive and midfield lines (p=0.01), the distance between centroids of the defensive and offensive lines (p=0.01), team length (p=0.02), and length per width ratio (p<0.001) compared to home matches; iv) in general when the reference team was losing the matches, higher values of team spatial organizations were observed compared to when the team was winning the matches (p<0.05). With regard to physical performance, the objective was: i) to describe the weekly external load according to match-contextual difficulty (based on match location and quality of opposition) and playing position over the competition; ii) to compare the external load between low and high match-contextual difficulty in professional soccer players. Eighteen professional players were monitored using global position systems units and accelerometers for 13 weeks during the competition by individual observations. Players who played 60 min during non-congested weeks were considered for data analysis. The variables analyzed were total distance, total distance covered in high-speed running (19.8-25.1 km·h-1), total distance covered in sprint running ( 25.2 km·h-1), total distance covered in high-acceleration (> 2 m·s2), total distance covered in high-deceleration (< -2 m·s2), and Player Load. Match-contextual difficulties were classified based on scores attributed to match location and quality of opposition, including two contexts: “high” (i.e., total score > 10) or “low” (i.e., total score 10). The results revealed that the highest values of external load were verified in the middle week (e.g., MD-3) and the lowest values at the end week (e.g., MD-1). External defenders and external/central midfielders presented higher weekly physical demands during the competition. In contrast, central defenders and forwards showed the lowest running outputs. The linear mixed models revealed significantly higher values for the external load (p < 0.001 – 0.030) in low match-contextual difficulty than high match-contextual difficulty in the total weekly load, MD-4, MD-3, and MD-2. Higher distance-based volume measures and mechanical work were found during the high match-contextual difficulty in the MD-3 and MD-1 compared to low match-contextual difficulty (p < 0.001 – 0.020). It was then concluded that in organizational terms, playing against weak opponents, playing away from home, and losing the match were the contextual variables that increased the team's spatial organization values, and in physical terms that the weekly external load varied considerably according to the difficulty. context of the match. Therefore, these results provide insights for coaches and sports scientists about the effects of contextual variables on the dynamics of space occupancy and contextual variables and game position on the programming of weekly external loads.
Keywords: game demands; contextual variables; positional data; tactics; sports science; load monitoring.
