Race preparation guide
How to prepare for TDS — Complete Guide
TDS receives less attention than UTMB, but many runners find it rougher. Over 145 km and 9,100 m of climbing, the challenge is not only endurance. You need to stay efficient on wilder alpine terrain that is more technical, more abrasive and often harder to manage mentally.
Race overview
The TDS profile offers fewer comfortable runnable stretches. You spend more time on steep climbs, unstable descents and sections where slowing down is the smart option if you want to keep clear judgement. It rewards patient runners who hike strongly, avoid fighting the downhills and protect their quadriceps long before fatigue becomes obvious.
The best preparation combines long endurance with terrain skill. Technical trail sessions, downhill-heavy blocks and outings where you manage effort with poles are especially useful. TDS also asks for genuine confidence in altitude and variable weather. You do not need flashy workouts. You need to become reliable, precise and steady when the terrain gets messy and the pace keeps breaking.
What you actually need to prepare
That reliability also comes from rehearsing the full race strategy. Nutrition has to stay simple and robust because technical terrain reduces the number of easy eating windows. Your kit should be tested with the exact pack you will use on race day, including shell, gloves, warm layer and headlamps. The more these actions are automated in training, the less energy you waste when focus needs to stay on the trail.
Logistics to solve early
TDS logistics deserve early planning. Starting on the Courmayeur side and finishing in Chamonix means you have to think carefully about accommodation, cross-border transport and how you will get back after the race. If you drive, you need to choose between start-line convenience and finish-line recovery. If you travel by train or plane, valley transfers usually require more margin than expected. And because alpine weather can shift quickly, mandatory gear is not just an admin detail.
A good TDS Prep should connect your training load to the real constraints of race week. Start from the TrailCompanion race page to confirm the race format, then build a plan that also covers aid stations, bags, travel, accommodation and recovery. That continuity between terrain and logistics is what prevents expensive mistakes.
Turn the guide into action
In practice, preparing well for TDS means respecting what it is: less glamorous, more abrasive and very unforgiving of improvisation. If you arrive with fit legs but fuzzy organisation, the race will expose it quickly. If you arrive with a tested, realistic plan, a daunting event becomes a manageable project.