Contextualised Physical Metrics: The Physical Demands Vary with Phase of Play during Elite Soccer Match Play

Practical Applications

This research can be used to inform the design of training drills that mimic the physical demands of specific phases of play in football. This includes drills that focus on the physical preparation strategies such as the total distance covered at different speeds, the rate of acceleration and deceleration, and the number of accelerations and decelerations. This information can be used to develop more contextually specific training drills which mimic the unique physical demands of different match play phases in order to enhance the specificity of training drills as applied in practice.

Coaches could consider the location of the ball to inform specific training interventions. For example, teams in a more deeper, or more advanced position, than indicated by the location of the ball (e.g. team in the centre) could consider the tactical/strategic approach of each player to more accurately capture team data. This would allow the error inherent within a small number of data samples to be avoided.

It's important to note that this study used global positioning system data based on recommendations derived using match data, and was based on all matches this specific club played within a duration of a season. Future work should consider more specific playing positions (e.g., attacking vs. defensive fullback) or specialized player roles (e.g., tracking defensive midfielder). Future work could also use match definitions that included information pertaining to the phase of play.

Summary

This research paper examines the physical demands of elite soccer players during different phases of a match. Traditionally, these demands have been measured using aggregated match metrics, which provide an overall view of player performance but do not account for variations in intensity during specific phases of play. The study aimed to provide a more comprehensive understanding of how physical demands vary with the phase of play and playing position.

The research analysed data from 1083 matches of a major European professional soccer league using tracking data from five distinct phases of play:

1. In-possession: Build-up, progression, chance creation, fast attack
2. Out-of-possession: High block, mid block, low block, fast defence

The research aimed to address the lack of research on physical metrics during specific phases of play and to provide a more nuanced understanding of match play intensity. This involved examining how physical intensity varies within specific phases of play, like attacking and defensive transitions.

Introduction:

• Traditionally, physical demands in soccer have been measured using aggregated match metrics, which provide a general overview but do not account for variations in intensity during different phases of play.
• The influence of the phase of play on physical demands is largely unknown.
• This research aimed to investigate how physical demands, particularly intensity, vary during different phases of play in elite soccer.

Highlighting Existing Research Gaps:

• Previous studies have highlighted the varying physical demands in soccer.
• Researchers have observed differences in acceleration and deceleration rates during different phases of play, particularly in attacking and defensive transitions.
• The number of accelerations and decelerations varies significantly depending on the phase of play, with attacking and defensive transitions involving more short, sharp movements.
• Despite this knowledge, research has primarily focused on aggregated match data, neglecting the influence of specific phases of play on physical metrics.
• This research aims to address this gap by providing the first comprehensive examination of how physical demands, including distance covered, speed, acceleration, and deceleration, vary with the phase of play.

Research Aims and Objectives:

• The primary aim of the research was to provide a comprehensive examination of the physical demands during different phases of play in elite soccer.
• This involved analysing a large dataset of 1,083 matches and examining metrics such as distance covered, speed, acceleration and deceleration rates.
• Specific objectives included:
  • Examining the differences in physical metrics between in-possession and out-of-possession phases of play.
  • Evaluating positional differences in physical demands across different phases of play.
  • Determining how the proportion of time spent accelerating and decelerating varied between phases of play and playing positions.
  • Discussing the practical implications of the findings for physical training and match preparation strategies.

Methodology:

Data Collection and Sample Size:

• The research used a large dataset of 1,083 matches from a major European professional soccer league.
• Raw data collection involved tracking data from the league's official provider at a frame rate of 25 Hz.
• Event data was manually coded by performance analysts to identify different phases of play and player actions.
• The dataset included 9,846 midfielders, 10,251 forwards, and 7,702 defenders.
• Data from goalkeepers was excluded as their physical demands differ significantly from outfield players.

Defining Phases of Play:

• The research divided match play into five distinct phases based on ball possession and attacking/defending transitions:

In-possession:

1. Build-up: Ball possession in a team's own half.
2. Progression: Ball possession between the halfway line and the opposition team's 45 m line.
3. Chance creation: Ball possession within the opposition team's 45 m and half-of-pitch.
4. Fast attack: The in-possession team rapidly advancing the ball forward towards the opposition goal.

Out-of-possession:

1. High block: Out-of-possession team pressing high up the pitch, typically in the opposition team's half.
2. Mid block: Out-of-possession team defending in their own half.
3. Low block: Out-of-possession team defending close to their own goal.
4. Fast defence: Out-of-possession team transitioning quickly to defend a counter-attack.

Physical Metrics Analysis:

• Physical metrics for each phase of play were calculated, including:
  • Physical Intensity: the rate of distance covered per minute in total and within five speed categories: walking, jogging, running, high-speed running and sprinting.
  • Acceleration and Deceleration: the total number, accumulated time, and proportion of time spent accelerating and decelerating.

Statistical Analysis:

• The Shapiro-Wilk test was used to assess the normality of distribution.
• Two-way analyses of variance were used to examine the main and interaction effects of phase of play and playing position on physical metrics.
• Bonferroni post-hoc tests were used to identify specific differences between phases and positions.
• Statistical significance was set at p < .05.

Key Points from Methodology Section:

• The research used a large dataset of tracking data from 1,083 matches.
• Matches were divided into five distinct phases of play based on ball possession and attacking/defending transitions.
• Physical metrics included distance covered, speed, acceleration, and deceleration rates.
• Two-way analyses of variance and Bonferroni post-hoc tests were used to analyse the data.

Results:

Duration of Each Phase of Play:

• Teams spent the majority of match time in possession phases (build-up and high block) and the least time in fast attack and fast defence phases.

Distance Covered During Different Phases of Play:

• The rate of distance covered was significantly different between all phases of play for all players.
• In-possession: forwards covered the greatest distance, followed by midfielders and defenders.
• Out-of-possession: midfielders covered the most distance, followed by defenders and forwards.
• The highest rates of distance covered were observed during fast attack (in-possession) and fast defence (out-of-possession) phases.

Acceleration and Deceleration During In-Possession Phases:

• There were significant differences in the time spent accelerating and decelerating between all in-possession phases for all players.
• Forwards spent the most time accelerating, followed by midfielders and then defenders.

Acceleration and Deceleration During Out-of-Possession Phases:

• Similar to in-possession phases, significant differences were observed in the time spent accelerating and decelerating between out-of-possession phases for all players.
• Midfielders spent the most time accelerating and decelerating, followed by defenders and then forwards.

Key Findings:

• Influence of Phase of Play on Physical Intensity: The research found a significant influence of the phase of play on physical intensity, with in-possession and out-of-possession phases having distinctly different physical demands.
• Higher Intensity During Fast Attack and Fast Defence: Fast attack and fast defence phases, despite their short duration, exhibited substantially higher physical intensity compared to other phases.
• Positional Differences in Physical Demands: Significant positional differences in physical demands were observed, with forwards covering more distance at higher speeds during attacking phases and midfielders showing greater acceleration and deceleration demands in both in-possession and out-of-possession phases.
• Implications for Training and Match Preparation: The findings suggest that coaches and practitioners should consider the specific physical demands of different phases of play when designing training drills and match preparation strategies.