Influence of the world's most challenging mountain ultra-marathon on energy cost and running mechanics.

Purpose - To examine the effects of the world’s most challenging mountain ultra-marathon (Tor des Géants® 2012) on the energy cost of three types of locomotion (cycling, level and uphill running) and running kinematics.Methods - Before (pre-) and immediately after (post-) the competition, a group of ten male experienced ultra-marathon runners performed in random order three submaximal 4-min exercise trials: cycling at a power of 1.5 W kg−1 body mass; level running at 9 km h−1 and uphill running at 6 km h−1 at an inclination of +15 % on a motorized treadmill. Two video cameras recorded running mechanics at different sampling rates.Results - Between pre- and post-, the uphill-running energy cost decreased by 13.8 % (P = 0.004); no change was noted in the energy cost of level running or cycling (NS). There was an increase in contact time (+10.3 %, P = 0.019) and duty factor (+8.1 %, P = 0.001) and a decrease in swing time (−6.4 %, P = 0.008) in the uphill-running condition.Conclusion - After this extreme mountain ultra-marathon, the subjects modified only their uphill-running patterns for a more economical step mechanics.