Fuelling a Backyard Ultra by the hour
· 7 min read
The most common way to lose a Backyard Ultra is not the legs. It is the stomach, or rather what did or did not go into it hours earlier. Eat too late and the deficit catches up with you. Eat too much of the wrong thing and the stomach shuts down. Either way, you find out long after the mistake was made.
A word before the numbers: nutrition is highly individual. What follows is the common guidance from the Last Soul Ultra checklist and similar sources, not a prescription. Test it in training, not on race day.
The hourly targets
Because a Backyard runs on the hour, it makes sense to think about nutrition per hour too. The usual targets:
| Per hour | Target |
|---|---|
| Carbohydrates | 60–70 g |
| Energy | at least 450 kcal |
| Sodium | 300–600 mg |
And the rule that matters most: eat from loop 1. Do not wait until you are hungry. By the time you feel hungry in an ultra, you are already behind, and catching up later is much harder than staying on top from the start.
A rhythm, not a menu
What goes in follows a simple rhythm:
| When | What |
|---|---|
| Every loop | A loop bag (~350–400 kcal) plus a drink |
| Every 3 loops | A solid or hot meal |
| At night | Lower expenditure; liquid, easy-to-digest calories |
A loop bag is exactly what it sounds like: a small bag the runner takes out on the next loop, prepared by the crew during the previous one. A typical one, at around 380 kcal, might be one flask of sports drink or carb mix (~150 kcal), two gels (~200 kcal) and a pack of carb chews (~118 kcal) — a little under what the hour costs, the rest coming from drinks and the meal every few loops.
Over a long race, most of what a runner eats falls into a handful of groups:
- Fast carbs: gels, chews, sports drink, cola
- Real or hot food: pasta, rice, potatoes, ramen, soup, eggs, sandwiches
- Sweet snacks: fruit, dried fruit, bread with spread, fruit pouches, bars
- Salty snacks: pretzels, salted potatoes, crisps, pickles, olives, broth
- Drinks: water, sports drink, broth, tea, juice spritzer, non-alcoholic beer, coffee
- Electrolytes: tablets and capsules
Variety matters. Twenty hours of gels is something very few stomachs will accept. Salty and savoury food becomes more attractive the longer the race goes. For a concrete list with per-unit values to start from, see A starter catalog for the crew box.
At night, go liquid
At night the body burns less and digestion slows. Under sleep deprivation, liquid calories are often tolerated much better than solids: soup, broth, sports drink, a milky coffee. The targets do not disappear at night, but the form changes.
When the stomach rebels
At some point, most runners have a loop where the stomach says no. The usual steps:
- Stomach too full? Pause solids, switch to liquids for a while.
- Nausea? Look at what went in last. Too much fluid? Too many solids? Too much salt, or too little?
- White salt marks on the clothes (the "salty sweater")? The runner is losing a lot of sodium and probably needs more.
Notice what the second point needs: an honest answer to what went in over the last few loops. Not what was planned, not what someone remembers, but what was actually eaten. At hour 18, after two crew shifts, that is exactly the information nobody has.
Caffeine adds up
Caffeine is one of the most useful tools in the second night, and one of the easiest to overdo, because it comes from everywhere at once: caffeinated gels, cola, coffee, tablets. A crew that tracks only the tablets is missing most of it. The same goes for medication in general: the crew should always be able to say who took what, and when, including across shift changes. Which medication to take, and whether at all, is something to clear with a doctor before the race. Painkillers like ibuprofen in particular are controversial in ultras because of the strain on the kidneys.
Why the crew keeps the record
The runner cannot keep count. They are running, and every hour they have fewer good decisions left in them. So the crew records everything that goes in, loop by loop.
That record is not bookkeeping for its own sake. It is what lets the crew see that the runner has been under on sodium for four loops in a row, before the cramps start. It is what answers "what did they just eat?" when the stomach turns. And it is what shows, over twenty hours, whether the plan is actually being followed or just being hoped for.
The trouble is that on paper, or in someone's head, that record gets worse exactly when it becomes most important. We wrote more about that in Why paper fails at 3 a.m.