Thousands of runners gather in Chamonix for the 2025 UTMB after months or years of training and preparation. Each runner brings unique fitness, strengths, and capabilities that inform strategy choices such as aggressive starts, hiking uphills, bombing downhills, or steady pacing. The course spans about 108 miles with over 32,000 feet of elevation gain, featuring steep climbs and punishing descents that critically affect outcomes. Small tactical adjustments in pacing and terrain approach can shift results from a DNF to a course record. Data from live trackers and custom running models supports development of individualized optimal race strategies.
This week, thousands of runners are in Chamonix, France, for one of the most anticipated events of the year: the 2025 UTMB. For the participants, this is the culmination of months or years of hard work and preparation. Hundreds of miles run, hurdles overcome, and bricks stacked, one by one, until each runner is in a position to start this race.
Every runner arrives at the start line with a unique level of fitness, set of strengths, and capabilities to help them complete the race. These factors play into something they will all need to decide on: their race strategy. Do they go out fast and try to hold on until the end? Do they hike the uphills and bomb the downhills?
UTMB is a notoriously challenging course, with this year's statistics at about 108 miles and with over 32,000 feet of elevation gain. The steep climbs and punishing downhills have challenged runners over the years who are looking to optimize their performance. Jim Walmsley has taught us that the line between a DNF and a course record can be razor-thin, with small tweaks in how to approach the course resulting in significantly different outcomes.
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