Author(s): FRANCESCHI, A., ROBINSON, M., OWENS, D., BROWNLEE, T., CONNOLLY, D., PONZETTO, F., FERRARI BRAVO, D., ENRIGHT, K., Institution: JUVENTUS FOOTBALL CLUB, Country: ITALY, Abstract-ID: 904

INTRODUCTION:
In football, the optimisation of training, recovery and performance requires a comprehensive understanding of the acute responses to training load [1]. This study aimed to characterise the acute neuromuscular, metabolic and perceptual responses to an in-season training session in high-level youth football players.
METHODS:
Thirteen Italian Serie A youth academy players (age: 18.2 ± 0.6 years; height: 183.0 ± 6.3 cm; body mass: 75.1 ± 6.9 kg) were assessed before (pre) and after (post) a typical training session using neuromuscular performance tests (countermovement jump, CMJ, and isometric posterior chain test, IPC), metabolic markers (capillary blood samples) and perceptual measures (muscle soreness and fatigue using visual analogue scales). From the capillary blood samples, serum fractions were assessed via untargeted proton nuclear magnetic resonance metabolomics. Training loads (global navigation satellite system, heart rate, HR, and session rating of perceived exertion methods, sRPE) and energy intake (remote food photographic method) were quantified. Differences between pre- and post-training in neuromuscular and perceptual measures were analysed using paired t-tests and Hedge’s g (g) effect size. Metabolites were analysed using multivariate and univariate analyses to identify differences in the serum metabolome between pre- and post-training.
RESULTS:
The training session consisted of a 60-minute duration with moderate training loads (total distance: 5009 ± 440 m; high-speed running distance: 310 ± 49 m; accelerations: 53 ± 17 events; time > 85% HRmax: 8 ± 7 min; sRPE: 3.3 ± 0.7 au). The training demands induced significant reductions in CMJ eccentric peak force, concentric peak force and force at zero velocity at post-training (p < 0.05; g: small to moderate), whilst no significant changes were observed in other CMJ measures (p > 0.005, g: trivial to small). Similarly, no significant changes were observed in IPC peak force and torque (p > 0.005, g: trivial), perceptual fatigue (p = 0.947, g: trivial) and muscle soreness (p = 0.281, g: small). Of the 54 identified metabolites, 21 showed significant changes post-training (p < 0.05), with increased concentrations of lactate, alanine, isoleucine, tyrosine and 3-hydroxisobutyrate, and decreased abundances in 16 other metabolites related to amino acid and lipid metabolism.
CONCLUSION:
This study suggests that, although a moderate‑load training session elicited minimal perceptual fatigue and only small neuromuscular impairments, it provoked marked alterations in the serum metabolome, underscoring the need to monitor both neuromuscular and physiological load–response pathways to better inform training and recovery interventions in high-level youth academy football players.

References:
[1] Vanrenterghem et al. (2017), Sports Medicine