Can Standardized Small-Sided Games Be Used as a Tool to Monitor Post-Match Fatigue?

<jats:p>This study aimed to analyze residual post-match fatigue using time-motion analysis across small-sided games (SSGs), fitness performance, and heart rate variability (HRV) in youth soccer players. Fifteen academy players (18.3 ± 0.6 years) performed four SSGs formats: 3 vs. 3 and 3 vs. 3 + 2 goalkeepers, played on small (25 × 18 m; 75 m2 per player) and large (36 × 25 m; 150 m2 per player) areas in a four-week experimental design. Two non-match weeks served as control weeks, and two weeks followed an official match. Time-motion during SSGs was monitored via GPS. Before each training session (24, 72, and 120 h post-match), HRV, countermovement jump (CMJ) height, and maximum isometric force (MIF) of the hamstring were measured. Time-motion was generally lower in post-match sessions than in control weeks, particularly at 24 h post-match; however, reliability was low. These reductions were more evident in SSGs on large areas, with GK. CMJ height and MIF were reduced post-match, whereas HRV showed only transient changes. Post-match fatigue was evident in fitness performance but was inconsistently reflected in SSGs outputs. CMJ height and hamstring MIF are sensitive markers of post-match fatigue in elite youth soccer players and should be prioritized when monitoring recovery.</jats:p>