Relationships between heart rate-based training load and running metrics in field hockey players

Monitoring training load (TL) is essential for optimizing performance and reducing injury risk in team-sport athletes; however, how internal, and external load interact across different competition contexts remains unclear in elite field hockey. This study aimed to examine the structure of GPS-derived running metrics and their associations with heart rate (HR) -based internal TL during simulated and international competitions in elite female field hockey players.

Individual data recordings from 18 female field hockey players during 13 simulated competitions and 8 international competitions were analyzed, with HR-based internal TL calculated from heart rate data and GPS-derived running metrics used to examine load structure and associations.

Exploratory factor analysis identified two running load factors, with PA1 component comprising total distance covered, duration, total player load, sprint effort, decelerations, and accelerations and PA2 component comprising high-speed distance, maximal speed, sprint distance, and relative distance, together explaining 70.4% of the total variance. Linear mixed-effects models showed that PA1 (Δ=0.42) and HR-based internal TL(Δ=1.35) were significantly higher during international competitions than simulated competitions, whereas PA2 did not differ between conditions. HR-based internal TL was positively associated with both PA1 (β=0.031) and PA2 (β=0.019); however, this association was moderated by competition conditions only for PA1, with a stronger coupling observed during international competitions.

These findings demonstrate that the relationship between GPS-derived external load and HR-based internal load varies by competition context, emphasizing the need for context-specific TL monitoring.