Uphill Walking Economy and Maximal Oxygen Consumption in Trail Runners: Relationship with Ultra-Trail Performance

The aim of this study was two-fold. Firstly, to assess whether uphill walking economy was related with step and ventilatory kinematics. Secondly, to examine whether uphill walking economy represented an independent performance factor in ultra-trail races. Thirty-six athletes (25 men and 11 women) completed an uphill peak exercise test and an uphill walking economy test 4-8 weeks before a 106-km ultra-trail race. Ventilatory and gait parameters were recorded during uphill walking. Body composition, jumping, and isometric and inspiratory strength were also measured. Step length and tidal volume were associated (<i>r</i>=0.72; <i>p </i>< 0.001) and they correlated with uphill walking economy (<i>r</i> between 0.47 and 0.58;<i>p </i>< 0.01). Peak speed and running power and speed and running power linked to ventilatory thresholds all correlated with race time (<i>r</i> between 0.51 and 0.80;<i>p </i>< 0.01). Uphill walking economy, when expressed as a percentage of peak oxygen uptake, explained 58% of performance variation; however, multiple regression analysis revealed that the best model comprised peak oxygen uptake alone, predicting 79% of performance. In conclusion, longer step length and greater tidal volume align with lower energy expenditure during uphill walking. Uphill walking economy is not an independent performance factor in ultra-trail races. Uphill-obtained peak oxygen uptake predicts a large percentage of performance variation in ultra-trail races.