Uphill walking economy & VO2max in trail runners: relationship with ultra-trail performance

Our aim was twofold. 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. 36 athletes (25 men; 11 women) completed an uphill peak exercise test and an uphill walking economy test 4 to 8 weeks before a 106-km ultra-trail race. Ventilatory and gait parameters were recorded during uphill walking. Body composition, jumping, isometric and inspiratory strength were also measured. Step length and tidal volume were associated (r = 0.72; p<0.001) and they correlated with uphill walking economy (r between 0.47 and 0.58; p<0.01). Peak speed and running power, and speed and running power linked to ventilatory thresholds all correlated with race time (r between 0.51 and 0.80; p<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.