Comparison of match accelerations and decelerations using continuous absolute thresholds in Czech U17, U19, and B team academy soccer players

The present study revealed disparities between accelerations and decelerations across various continuous thresholds and different soccer academy age categories. External loads from official matches were analyzed in U17 (72 matches; 376 observations; 62 players), U19 (72; 379; 73), and B team (59; 315; 58) across three consecutive seasons (2021–2024) using 10 Hz GPS technology. Averages were computed for each player/season from all official matches (> 90 min). Thresholds ranging from 1 to 2 m s−2 to > 5 m s−2 were employed to analyze the frequency of accelerations and decelerations. Linear mixed models with random effects for players and fixed effects for age category were used to compare accelerations and decelerations values. Statistical analysis showed a significantly higher frequency of accelerations than decelerations (p < 0.01) within the 2–3 m·s⁻2 and 3–4 m·s⁻2 thresholds. At higher thresholds (4–5 m·s⁻2 and > 5 m·s⁻2), decelerations occurred significantly more often (p < 0.01). Moreover, the age category significantly affected most acceleration and deceleration metrics (p < 0.05, d > 0.5), with differences observed only between U17 and B team. The correlation between accelerations and decelerations decreased with increasing threshold intensity, ranging from strong (r = 0.78 at 1–2 m·s⁻2) to moderate (r = 0.45 at > 5 m·s⁻2). The present outcomes underscore the prevalence of accelerative over decelerative actions at lower intensities but the opposite prevalence at high intensities. Differences between team categories indicate increasing demands on players transitioning to adult-level football. Additionally, caution is advised when relying solely on the average values for parameters that exceed specific thresholds.