This observational repeated-measures study investigates differences between absolute and individualized normalized acceleration and deceleration thresholds across the football microcycle. Match-derived locomotor metrics are commonly used to guide training prescription, although match performance may not reflect each player's maximal physical capacity. Therefore, this study monitored under-23 male football players across a full competitive season using 10-Hz GPS technology during training sessions and matches. High-intensity normalized thresholds were defined as 75-100% of individual maximum acceleration and deceleration, and were compared with conventional absolute thresholds (>3 m/s² and <-3 m/s²). The study aims to determine whether normalized approaches provide a more accurate representation of high-intensity locomotor demands across microcycle sessions relative to match load.

This season-long observational cohort study examined the distribution of acceleration and deceleration external load across the football microcycle using both absolute and individualized normalized thresholds. Twenty-seven under-23 male football players competing at the national level were monitored throughout one competitive season using 10-Hz GPS devices during all training sessions and official matches.

Individual maximum acceleration and deceleration were determined using the average of the three highest values recorded across the season while excluding potential measurement artefacts. High-intensity normalized thresholds were defined as 75-100% of these individual maxima and compared with conventional absolute thresholds (>3 m/s² and <-3 m/s²). Outcome measures included counts and distances of acceleration and deceleration efforts across microcycle days relative to match load, adjusted for playing position.

Generalized linear mixed models were used to evaluate differences between threshold definitions and temporal patterns across the microcycle. The primary objective was to determine whether normalized thresholds provide a more sensitive and ecologically valid characterization of high-intensity locomotor demands compared with fixed absolute thresholds, with implications for training load monitoring and prescription in football.

Inclusion Criteria:

• Male under-23 outfield football players competing at national level and participating in regular training sessions and official matches with valid GPS data.

Exclusion Criteria:

• Goalkeepers, players with long-term injury preventing participation, or sessions with missing or invalid GPS data.

Male under-23 outfield football players from a Portuguese national-level team monitored across one competitive season using GPS technology during routine training sessions and official matches.

Individual participant data will not be publicly shared due to privacy considerations and institutional agreements with the participating football club. Aggregated data may be available from the corresponding author upon reasonable request.