Are GPS systems truly effective for goalkeepers? An analysis of the relationship between internal and external load demands in professional goalkeepers

Abstract

The effectiveness of Global Positioning Systems (GPS) in accurately capturing the unique internal load of profesional goalkeepers, and its relationship with subjective perceived exertion (RPE), remains a question. This study aimed to examine the correlation between goalkeepers' RPE and objective external load parameters. Data were collected over 40 weeks during the 2022–2023 La Liga Santander season from professional goalkeepers across 216 training sessions and 46 competitive matches. Findings revealed microcycle-dependent associations. A moderate correlation was observed between RPE and session duration on MD-2 (r=0.66, p=0.05). In contrast, RPE consistently lacked correlation with maximal acceleration (ACC max). Intriguingly, strong positive correlations emerged between RPE and high-intensity accelerations (ACC+3) on MD+1 (r=0.78, p=0.01) and MD-2 (r=0.88, p=0.001), and high-intensity decelerations (DCC-3) on MD-2 (r=0.78, p=0.01). However, many other RPE-external load correlations remained weak or non-significant. These results suggest cumulative, repeated high-intensity efforts, not isolated maximal movements, primarily drive perceived exertion in goalkeepers. A limitation of standard GPS in soccer, especially for goalkeepers, is its inability to fully capture the true physiological demand of short, explosive, multi-directional movements, isometric holds, or specific technical actions within small areas. These unique, stationary-yet-explosive goalkeeping demands often don't translate directly into high-speed running or total distance, overlooking crucial aspects of their workload. This research underscores the need to integrate subjective RPE with objective GPS metrics for a more comprehensive understanding of goalkeeper training load, promoting position-specific GPS algorithms.