A Comparative Analysis of the Physical Activity Profiles of K League 1 Referees in the 2023 and 2024 Seasons: In-Match Physiological Demands Measured via GPS and Heart Rate Monitoring

Purpose: This study investigated the physical and physiological demands of elite football referees in Korea’s K League 1 over two consecutive seasons (2023 and 2024), focusing on intra-match (first vs. second half) and inter-seasonal differences in internal load. Research design, data, and methodology: Twenty-five referees (15 in 2023, 10 in 2024), all holding the highest officiating certification from the Korea Football Association, participated. Match data were collected using wrist-worn wearable devices with integrated GPS and optical heart rate monitoring. Key performance metrics included match duration, distance covered, peak speed, and heart rate, segmented by match half. A two-way mixed ANOVA was used, with average heart rate (AvgHR) as the primary dependent variable. Results: Significant main effects were found for match half, F(1, 35) = 5.46, p = .025, and season, F(1, 35) = 6.85, p = .013, showing higher AvgHR in second halves and during the 2024 season. No interaction was observed (F(1, 35) = 0.37, p = .546). Conclusions: These results emphasize the value of combining GPS and HR monitoring to capture both internal and external loads, supporting the development of referee-specific training programs that address fatigue and evolving match demands.