The Calculation of the Uphill Energy Cost of Running from the Level Energy Cost of Running in a Heterogeneous Group of Mountain Ultra Endurance Runners

Ultra-endurance mountain running has become extremely popular in recent years, and the energy cost is one of the factors that influence the final performance. The aim of this study was to determine if the energy cost of uphill running (uphill Cr) can be calculated from level Cr (Energy cost of running in mLO₂.kg^-1.mn^-1) in a heterogeneous group of mountain ultra-endurance runners using the di Prampero equation, and if fatigue could change this relationship. Twenty-four male ultra-trail runners ran on a level and uphill (10%) treadmill at 60% of velocity at V O₂max (velocity at V O₂ max in m.s^-1) before and after a mountain ultra-marathon (MUM). The mean performance on the MUM was 728 ± 117 minutes. Positive and strong correlations were found between level and uphill Cr pre-MUM (r = 0.84, P < 0.001) and post-MUM (r = 0.86, P < 0.001), in mLO₂.kg^-1.mn^-1. This study demonstrated that level and uphill Crs are related in a heterogeneous group of mountain runners. However, the differences observed between theoretical and real uphill Crs (7.9 and 8.5% pre and post-MUM) demonstrated that an uphill Cr measurement is necessary to predict the performance of high level runners.