Trends in Semiprofessional Scottish Football Players' Acceleration and Deceleration Loads Across Playing Positions During Competitive Play and Training.

BACKGROUND: High-intensity accelerations (HIAccs) and high-intensity decelerations (HIDecs) are critical to football performance, yet little is known about their demands in semiprofessional contexts where training frequency and resources differ from the professional game. PURPOSE: This study quantified HIAcc and HIDec loads during competitive match play and training across playing positions in semiprofessional Scottish football. METHODS: Thirty-three players were monitored over two competitive seasons (2021-2023) using 10-Hz Global Positioning System (GPS) devices, generating 1333 individual observations. Linear mixed models assessed total distance, frequency and peak magnitude of HIAcc and HIDec at two intensity thresholds (3-4 m/s2 and > 4 m/s2) across playing positions and session types (MD-4, MD-2 and match day). RESULTS: Position (p < 0.001) and session type (p < 0.001) significantly influenced HIAcc and HIDec demands. Full-backs recorded the highest deceleration loads, particularly > 4 m/s2, whilst wide midfielders accumulated greater acceleration distances than central players. MD-4 sessions often exceeded match-day acceleration values (106%-120%), whereas match days consistently imposed higher deceleration demands. These patterns diverged from those reported in professional cohorts. CONCLUSION: Semiprofessional players display distinct positional and session-specific loading patterns compared with professional football. Tailored, position-specific training and modified periodisation strategies appear necessary to align training with the physical demands of competition in this population.