Is all work the same? Performance after accumulated work of differing intensities in male professional cyclists.

Objectives: Although the ability to attenuate power output (PO) declines after accumulated work (i.e., 'durability') is increasingly recognized as a major determinant of cycling performance, the potential role of the intensity of the previous work is unclear. We assessed the effect of work-matched levels of accumulated work at different intensities on performance in male professional cyclists.

Design: Observational field-based study.

Methods: PO data was registered in 17 cyclists during a competition season, and the critical power (CP) was repeatedly determined every 4 weeks from training sessions and competitions. Participants' maximum mean power (MMP) for different durations (5 s, 5 min, 10 min, and 20 min) and the CP were determined under 'fresh' conditions (0 kJ·kg) and after varying levels of accumulated work (2.5, 5.0 and 7.5 kJ·kg) at intensities below and above the CP.

Results: A significant decline was found for all MMP values following all levels of accumulated work above the CP (-4.0 %, -1.7 %, -1.8 %, and -3.2 % for 30s, 5 min, 10 min and 20 min-MMP, respectively; all p < 0.001), versus no change after any level of accumulated work below the CP (all p > 0.05). Similar results were observed for the CP, which decreased after all levels of accumulated work above (-2.2 %, -6.1 %, and -16.2 %, after 2.5, 5.0 and 7.5 kJ·kg, p < 0.001) but not below this indicator (p > 0.05).

Conclusions: In male professional cyclists, accumulated work above the CP impairs performance compared with work-matched, albeit less intense efforts. This raises concerns on the use of mechanical work per se as a single fatigue/stress indicator in these athletes.