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 (<i>p</i> = 0.209), a significant interaction effect was found in separate analyses by week (<i>p</i> = 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 (<i>p</i> = 0.777) or in separate analyses by week (<i>p</i> = 0.808). In summary, the present results support the role of durability (but not of repeatability) as a performance indicator during professional cycling races.<b>Highlights</b> The present study suggests that cyclists from different professional team categories (WorldTour [WT] or ProTeam [PT]) show comparable mean maximal power (MMP) values during a Grand Tour when fatigue is not considered.However, WT cyclists seem to attain greater MMP values than PT ones as the race progresses (from the first to the third week) and with accumulating levels of work done (from 0 to 35 kJ·kg^-1) during a given stage.In turn, no differences were found between WT and PT cyclists in the number of high-intensity efforts (>95% of their individual MMP) performed during the race.These findings would highlight the role of durability (the ability to attenuate fatigue-induced decline in performance during prolonged exercise) as a determining factor of cycling performance.