FLUCTUATIONS IN HEART RATE RESPONSE AND EXTERNAL DEMANDS RELATIVE TO GAME PERIOD IN RECREATIONAL FOOTBALL

This study aimed to investigate fluctuations in external demands and heart rate (HR) response across two game periods (half-times) in recreational football players. Eighteen recreationally active, male college students (goalkeepers: n = 2; outfield players: n = 16; age: 20.9 ± 1.5 yr; height: 179.4 ± 5.0 cm; body mass: 76.9 ± 8.1 kg; fat mass: 15.3 ± 5.5%) participated in this study. Two sessions were used to administer 4-a-side small-side games (SSG). Differences in activity demands and HR response were analyzed using a paired sample t-test. The magnitude of the differences in each dependent variable was quantified with effect size (ES) analyses and interpreted as: trivial, <0.2; small, 0.2–0.59; moderate, 0.6–1.19; large, 1.2–1.99; very large, >2. An ES analysis showed, small to moderate, significant decreases in distance covered at 0-6.00 km·h-1 (ES = -0.54, small), 6.01-12.00 km·h-1 (ES = -0.99, moderate), 12.01-18.00 km·h-1(ES = -0.66, moderate), >24 km·h-1 (ES = -0.72, moderate), total distance (ES = -0.91, moderate) and high-intensity accelerations (ES = -0.60, moderate) during the second rather than the first half. In addition, unclear significant decreases in HRmean, and percentage of time spent working 81-90% HRmax were observed across two game periods. Our findings indicate game-related fatigue, whereby players demonstrated a consistent HR response across two game periods despite diminutions in activity demands during the second half. Similarities in HR response across two game periods might be due to the lower physical fitness of recreational players, eliciting slower HR recovery.