Durability and repeatability of professional cyclists during a Grand Tour.

Durability and repeatability (i.e. the ability to sustain high power output values under fatigue and to endure repeated high-intensity efforts, respectively) are emerging as cycling performance determinants. We aimed to analyze whether these markers differ between professional cyclists of two competition levels (WorldTour [WT] and Proteam [PT]) during a Grand Tour. We studied 8 WT and 7 PT cyclists who competed in "La Vuelta 2020". Durability was assessed with the mean maximal power (MMP) values attained between 5 sec-30 min after different levels of mechanical work done (0-35 kJ·kg-1). Repeatability was assessed as the ability to repeat efforts >95% MMP. Although no differences were found for durability during the whole race (p = 0.209), a significant interaction effect was found in separate analyses by week (p = 0.011). Thus, during the first week and in the "fresh" state (0 kJ·kg-1), WT cyclists solely attained significantly higher MMP values for 30-min efforts. However, these differences enlarged with accumulating levels of fatigue (e.g. significantly higher MMP values in WT cyclists for 30-sec, 1-min, 5-min, 20-min and 30-min efforts after 35 kJ·kg-1). On the other hand, no between-group differences were found in repeatability for the whole race (p = 0.777) or in separate analyses by week (p = 0.808). In summary, the present results support the role of durability (but not of repeatability) as a performance indicator during professional cycling races.