Match-Induced Dehydration and Its Association with External Load in Elite Academy Football Players

Abstract

Purpose: The aim of this study was to investigate pre- to post-match changes in hydration status and examine associations
between dehydration markers and GPS-derived external load variables in elite academy football players during official
competition.
Methods: Thirty-eight elite male academy football players (15–19 years) participated in the study, resulting in 69 match
observations collected across 10 official matches. Hydration-related variables included pre- and post-match body mass
(BM), urine specific gravity (USG), handgrip strength (HS), percentage dehydration (%deh), fluid intake (W), and estimated
rehydration requirements (REHA). External load was monitored using 10-Hz GPS devices and included total distance
covered, relative running intensity, maximal velocity, high-intensity running distance, sprint distance, and accelerations/
decelerations. Pre- to post-match differences were assessed using paired-samples t-tests, while associations between
dehydration and GPS variables were analyzed using Spearman’s rank correlation coefficients.
Results: Significant reductions in body mass were observed following match play (P < 0.001), with players losing 0.9 ± 0.5 kg
on average, corresponding to a mean dehydration level of 1.2 ± 0.7%. Urine specific gravity increased significantly post-match
(P = 0.001), indicating deterioration in hydration status. Although mean dehydration remained below the commonly cited
2% threshold, 11.6% of observations exceeded this value. Fluid intake during matches (1.0 ± 0.5 L) appeared insufficient
relative to estimated rehydration requirements (2.9 ± 1.1 L). A significant positive correlation was observed between %deh
and total distance covered (rho = 0.283, P = 0.019), whereas no significant associations were found for other GPS variables.
Midfield players demonstrated significantly greater relative running intensity than defenders and forwards (P < 0.001),
although no positional differences in dehydration were identified.
Conclusions: Elite academy football players demonstrated significant match-induced deterioration in hydration status
during official competition. Individualized hydration monitoring and fluid replacement strategies may be important for
optimizing recovery and reducing exercise-induced fluid deficits in elite youth football.