After a 140-min fatiguing protocol that included 5 × 8 min at 105-110% of critical power, 25 male cross-country (XCO) mountain bikers produced less power at every duration from 5 s to 10 min (Hedges' g 0.32-1.52); the slowest third on a later XCO time trial lost about 14-20% against about 4-8% in the fastest third (except at 15 s); the comparison of faster and slower riders is correlational

Inoue and colleagues asked how a fatiguing ride changes the power profile of Olympic cross-country mountain bikers and how power profile and durability combine to shape performance.

Twenty-five male XCO riders completed a power-profile test, covering efforts from 5 s to 10 min, once fresh and once immediately after a 140-min fatiguing protocol that included five 8-min efforts at 105-110% of critical power, in random order 48 h apart.

Seventy-two hours later they rode an individual time trial on an XCO track and were ranked on it; the fastest third (n = 9) and slowest third (n = 9) were compared, leaving out the middle seven. Power at every duration and total work (kJ and kJ/kg) were lower in the fatigued condition (p < 0.05 to < 0.0001; Hedges' g 0.32-1.52).

Both groups lost power, but the low performers lost about 14-20% against about 4-8% in the high performers, a difference with moderate-to-large effect sizes (g 0.93-1.88) at every duration except 15 s. The authors conclude that fatigue impairs the XCO power profile and that better riders show more durability.