Assessment of weekly workload in relation to match workload in U-21 football: Analysis of ten competition microcycles

Football has experienced considerable technological and methodological advancenments, which have also influenced youth football. Currently, youth development faces the challenge of preparing players who can meet the rigorous demands of modern football. Objective: To assess and compare the internal and external training throughout the microcycle (MD-4 to MD-1) with the match-day load in under-21 players from a professional team. Method: Sixteen under-21 footballers from a Chilean professional club (age: 24.9 ± 4.2 years; height: 180.9 ± 6.3 cm; body mass: 78.5 ± 8.5 kg) were monitored over 10 official microcycles corresponding to the Fundación-Collahuasi youth football championship, organized by the Chilean Football Federation. Results: Large differences (p < 0.001 and η²p > 0.2) were found in all variables between the training days and match day. The highest external load occurred on match day, particularly in TD (10,087 ± 708 m), HSR (709 ± 316 m), and PL (130 ± 21.1 au). The highest weekly training loads were recorded on MD-3 and MD-2, while MD-1 showed significant reductions in all variables. Internal load was also highest on match day (RPE: 7.87 ± 1.54) compared to training sessions. Conclusion: There are significant differences in internal and external load throughout the competitive microcycle in under-21 footballers. MD-3 stands out as the highest-load training day, with values comparable to match day in most variables, positioning it as a key session in the weekly plan. In contrast, MD-1 consistently showed the lowest loads, confirming its role as a tapering day before competition.