title: An investigation of internal and external load-monitoring in soccer goalkeepers
Creators: name: Wright, Morgan
Publisher: name: University of Glasgow
Year: 2024

description: Background: Previous investigations into the changes in training load, using internal and external loading metrics, in soccer for outfielders and in small sample sets of GKs have found benefits of using load monitoring strategies to guide periodization of training across the competition season but are limited by sample size, age or lack of GK-specific metrics. Aims: There were two key themes which prompted this study, with the overarching main aim being to add to the limited body of research currently available on soccer goalkeepers: 
 
1. To investigate changes in internal and external load-monitoring parameters for goalkeepers throughout a four-day match-day lead-in and match day. 

2. To determine the effects of changes in Total Distance, Metres per Minute, Dive and Jump metrics on RPE across each day of the four-day match-day lead-in and match day. 

The aims of the study were investigated within a Scottish Premiership soccer team and sought to determine additional information about the soccer goalkeeper which could improve the training and match preparation practices currently in place. 

Methods: Goalkeepers were monitored using GPS units during training and games and an RPE questionnaire carried out within 30minutes post-training/games, across a four-day matchday lead-in and match day throughout the season. Statistical analysis was carried out on internal and external loading metrics. Subjects were goalkeepers from 1st team, Development squad, U18s and U16s squads of an elite Scottish Premiership soccer team. Ten subjects were used in the study design, training full time across the academy and 1st team (mean age 22.8years ±8.19 years StDev, height 189.5cm ±5.5cm and weight 77kg ±11.4kg). 

Results: Results showed RPE was lowest on MD-1, TD was highest on MD-3. M.Min-1 was the same on MD-3 and MD. Effect sizes showed key differences between MD-1 and both MD-4 and MD-3 for RPE; between MD-3 and both MD-2 and MD-1 for TD. RPE showed a weak relationship with TD and Total Dives. Overall, differences between each day of the MDLI and MD were marginal when compared to each other. 

Conclusions: Results suggest that GK training physical outputs will vary depending on session content throughout the lead-in to a game. On the day before a game, all metrics were lower except Total Jumps, and Time-to-Feet which was slightly quicker. These results added to the existing literature surrounding game demands for the role of a GK, allow the periodization of training to optimize performance capacity. In response to the aims of the investigation, minimal changes to internal and key external loading metrics were found across the MDLI and MD, with MD-3 showing the most significant differences to the subsequent days leading into the MD. In consideration of the second aim, RPE was found to have a weak relationship with total dives and total distance, suggesting that certain external load monitoring metrics could be used to provide information about the GK perceptions of internal load of training and games during the MDLI. 

Further research could investigate differences between role requirements for GKs at different levels of involvement on match-days. Additionally, age differences between GKs in 1st teams and development squads could be investigated across more than one club system.