The questions everyone asks before an ultra

Each guide answers one precise question, then works it out on a real race: the projected time, and the grams of carbohydrate, litres of fluid and milligrams of sodium that it represents.

• How many carbs per hour on an ultra?Between 60 and 90 g/h beyond three hours of effort, provided you have trained your gut. Below 60 g/h the deficit builds hour after hour; above 90 g/h you need a glucose-fructose blend to absorb it without gut trouble.
• What will I find at the aid station?It varies a great deal from one station to the next, and from race to race: some offer water only, others a partner brand's products, others a hot meal. The official rulebook states it station by station — it is the only reliable source, and it changes every edition.
• How long will it take me?Based on your UTMB® Index, each segment's duration comes from actual times logged by runners in your bracket on previous editions. When the race has no history, a model trained on 45 other races steps in. Riegel's law is a last resort only, if no data exists.
• What goes in the crew bag?Only what covers the leg to the next crew point, plus a safety margin — and nothing more. An overstuffed bag costs you time at the stop, exactly when you are least able to make decisions.
• How do I avoid nausea late in the race?Late-race nausea comes most often from too high a sugar concentration in a gut whose blood supply has dropped. Diluting more, switching to savoury and liquid, and splitting intake into smaller, more frequent feeds solves most cases.
• What if it is hot on race day?Above 25 °C, fluid needs rise to 800–1,000 mL/h and sodium becomes limiting before carbohydrate. It is the one parameter of the plan to revise upwards in the days before the race, once the forecast firms up.
• Will I make the cut-off times?Check your margin at every intermediate cut-off, not just the one at the finish: it's almost always one of them that knocks you out. That margin is counted in clock time — running plus stops — and the only one that matters is the tightest on the course, never the average.
• Where and when should my crew wait?Only at points the rules allow: elsewhere, taking help can cost you a disqualification. At each of these points your crew needs three things — GPS coordinates, a time window rather than a single time, and the list of what they're preparing.