Performance and durability profiles in junior cyclists: insights for talent identification

The junior category is a pivotal stage for talent identification in professional cycling, with durability emerging as a critical performance determinant. This observational field-based study compared critical power (CP), maximal aerobic power (MAP), mean maximal power (MMP), and power output decay (% Decay; the percentage drop in MMP between fresh and fatigued states) between international-level group (ILG, n = 20, top 30 worldwide) and national-level group (NLG, n = 26, high-level national) junior male cyclists over a competitive season. Metrics were derived from field data, with % Decay assessed at 1000–2500 kJ (≈15.4–38.5 kJ·kg⁻ 1 for a 65 kg cyclist). ILG exhibited significantly higher CP (in fresh state) (383 ± 48 vs. 341 ± 36 W, p = 0.003, d = 1.02), MAP (434 ± 54 vs. 391 ± 44 W, p = 0.004, d = 0.89), and 5 s MMP (1304 ± 101 vs. 1214 ± 94 W, p = 0.004, d = 0.95). At 38.5 kJ·kg⁻ 1 , ILG showed lower % Decay (e.g., 5 s: −7.97% vs. −30.04%, p < 0.001, d = 1.20), indicating superior durability. These findings highlight durability as a key factor in maintaining high power outputs under fatigue, providing benchmarks for talent identification and training optimization.