How to Crew an Ultramarathon: The Complete Crew Guide

How to crew an ultramarathon: build a crew sheet, run a two minute aid station, read the warning signs, and know when to push and when to stop the race.

Nobody teaches you how to crew an ultramarathon. You get asked by a friend, you say yes, and then at 2am you are standing in a field in the rain holding a bag you cannot see into while someone you love says something unkind about the soup. Crewing is a real job with a real skill set, and doing it well can be worth an hour or more to your runner over a hundred miles. Doing it badly costs them time, warmth, and morale. This guide covers what the job actually involves, how to prepare, and the specific things that separate a useful crew from a well-meaning one.

What crewing an ultramarathon actually involves

Your runner's decision-making degrades steadily across an ultra. By hour fifteen they cannot reliably choose between two socks. Your job is to remove decisions from them, not add to them.

Four functions:

  1. Logistics. Getting the right kit to the right place at the right time
  2. Nutrition. Having food and drink ready that they will actually eat
  3. Triage. Spotting problems, feet, chafing, hypothermia, before they become race-ending
  4. Morale. Being reliably calm, whatever they are like

The last one is the hard part. Runners in ultras get irritable, tearful, unreasonable, and occasionally cruel. None of it is personal and none of it should be answered in kind.

Before race day

Read the rules properly. Crew access points, vehicle restrictions, parking, and what you are permitted to hand over vary enormously. Some races ban crewing outside designated zones entirely, and penalties can include disqualification. Western States permits pacers only from mile 62 onward, for example (WSER, 2026).

Build a crew sheet. One page, printed, waterproofed. It should contain:

  • Aid station names, distances, and cutoff times
  • Estimated arrival times at each, in a fast, expected, and slow column
  • What the runner wants at each stop
  • Drop bag contents and locations
  • Emergency contacts and the runner's medical information

The three-column time estimate is the single most useful thing on the sheet. Runners slow down more than they expect, and a crew planning for the optimistic column ends up waiting four hours in the cold or, worse, missing them.

Trailia's Race Predictor is a good source for those splits, since it accounts for the course elevation profile rather than assuming steady pace.

Agree the rules in advance. Ask your runner, while they are rational, what they want you to do when they say they want to quit. Write down their answer. It is much easier to hold someone to a decision they made themselves.

Pack the vehicle logically. Clear boxes, labelled, with the most-needed items accessible. A head torch for you. A camping chair. Warm clothes for yourself, because standing still at 3am at altitude is colder than running.

The aid station routine

Have a system and use it every time.

Before they arrive:

  • Set up 15 minutes early, minimum
  • Lay out chair, food, drink, and the kit they might want in a visible line
  • Have hot drink ready if it is cold
  • Check the cutoff and work out their buffer

When they arrive:

  1. Take their bottles and vest immediately, without asking
  2. Sit them down if the stop is longer than a minute
  3. Ask three questions: how is your stomach, how are your feet, are you warm enough
  4. Refill and restock while they answer
  5. Tell them the plan for the next section, distance, climb, and cutoff buffer
  6. Get them moving

Aim for two to four minutes at most stops. Longer stops become much longer stops. The chair is a tool, not a destination. Conservative early pacing and consistent fueling are what separate finishers from withdrawals over 161 km, and your job is to protect both (Hoffman & Fogard, 2011).

What to say. Specific and factual beats enthusiastic. "You are 40 minutes up on your slow estimate, next section is 11 km with a 600 m climb, then I see you at Foresthill" is worth more than "you look amazing."

What not to say. Never mention how far is left in aggregate. Never mention how other runners are doing unless asked. Never say "you're nearly there" when there are 30 km left.

Reading your runner

You are the objective observer they no longer have.

Watch for:

  • Stopping eating. The most reliable predictor of a bad stretch. Push liquid calories if solids have stopped going down
  • Slurred speech, stumbling, confusion. Could be fatigue, could be hyponatremia or hypothermia. Take it seriously
  • Shivering that does not stop when they put on a layer. Get them warm, get them moving, escalate if it continues
  • A limp that has changed. Look at the feet. Blisters treated at 60 km are a two minute job, at 90 km they are a race
  • Silence from a normally chatty runner. Often the first sign of a low patch

When to intervene versus when to push. Physical warning signs, altered mental state, chest pain, or a fall with a head impact mean stop and get medical help. Feeling terrible, wanting to quit, and crying are all normal parts of an ultra and are usually best answered with food, a warm layer, and twenty minutes of walking.

Our electrolyte guide covers the signs of sodium problems, and the post-race recovery nutrition guide covers what to have ready at the finish.

The crew kit list

For the runner: spare shoes half a size up, multiple sock pairs, full change of clothes, warm layers, waterproof, headlamps and spare batteries, chafing balm, blister kit, tape, painkillers if they use them, sunscreen, wet wipes, and their preferred foods in reachable containers.

Food that works: broth, instant noodles, boiled potatoes with salt, rice, quesadillas, fruit, crisps, cola, ginger, and something savoury for when sweet stops working.

For yourself: warm clothes, a chair, a head torch, your own food and drink, a power bank, paper maps in case signal fails, and something to do during the waiting.

Crewing overnight

The night section is where crews earn their reputation.

  • Sleep in shifts if you have more than one person. A crew that has been awake for 30 hours makes mistakes
  • Set multiple alarms and add 45 minutes of margin to every arrival estimate
  • Have hot food and drink genuinely ready, not theoretically ready
  • Layer them up before they get cold, not after
  • Expect the 2am to 5am window to be the worst of the race emotionally, and check the assistance rules for night sections in advance (UTMB Mont-Blanc, 2026)

Key takeaways

  • Your job is to remove decisions, not offer choices
  • Build a one-page crew sheet with fast, expected, and slow arrival times for every stop
  • Two to four minutes per aid station, with the chair used deliberately
  • Watch for stopped eating, changed limp, and unrelenting shivering as early warnings
  • Agree in advance what to do when they say they want to quit

Where to go from here

If you are crewing for the first time, read the race rules end to end, build the sheet, and pack the car the night before. If you are the runner, hand your crew this article and then have the conversation about quitting while you are still sensible.

The better your runner's pacing plan, the easier your job. Trailia builds race-specific pacing and fueling plans from the course profile, which gives your crew realistic split estimates to work from rather than optimistic guesses.

Citations

  • WSER (2026). 2026 Participant Guide, crew and pacer regulations. Western States Endurance Run.
  • UTMB Mont-Blanc (2026). Race regulations, assistance zones and mandatory equipment.
  • Hoffman, M. D., & Fogard, K. (2011). Factors related to successful completion of a 161-km ultramarathon. International Journal of Sports Physiology and Performance, 6(1), 25-37.
  • Hardrock 100 (2026). Crew, pacer and aid station information.

Frequently Asked Questions

What does crewing an ultramarathon involve?

Four things: logistics, getting kit to the right place at the right time; nutrition, having food ready your runner will actually eat; triage, spotting feet and warmth problems before they end the race; and morale. The overarching principle is removing decisions from a runner whose judgement is degrading, rather than offering them choices.

How long should an aid station stop take?

Two to four minutes at most stops. Longer stops reliably become much longer stops, particularly once a runner sits down and gets comfortable. Use the chair deliberately as a tool for foot work or a kit change, not as a default.

What should I say to my runner at an aid station?

Specific and factual beats enthusiastic. Telling them they are 40 minutes up on their slow estimate, that the next section is 11 km with a 600 metre climb, and where you will see them next is far more useful than saying they look great. Never mention the total distance remaining or how other runners are doing unless asked.

What warning signs should a crew watch for?

Stopping eating is the most reliable predictor of a bad stretch ahead. Slurred speech, stumbling, and confusion could be fatigue but could also be hyponatremia or hypothermia and need taking seriously. A changed limp means look at the feet immediately, since a blister treated at 60 km is a two minute job.

What should I do if my runner wants to quit?

Ask them in advance, while they are rational, what they want you to do, and write the answer down. Wanting to quit at 3am is a normal part of an ultra and usually responds to food, a warm layer, and twenty minutes of walking. Physical warning signs and altered mental state are different and mean stopping.

How do I estimate when my runner will arrive?

Build a crew sheet with three columns of arrival times: fast, expected, and slow. Runners almost always slow more than they predict, so planning only for the optimistic column leaves you waiting for hours or missing them entirely. Use a course-aware prediction tool rather than assuming a steady pace.

What food should a crew bring to an ultramarathon?

Broth, instant noodles, boiled salted potatoes, rice, quesadillas, fruit, crisps, and cola cover most needs. Include something savoury for the point where sweet food stops working, usually around hour six. Keep it in reachable containers so you are not rummaging in the dark.

Can I crew anywhere on an ultramarathon course?

No, and getting this wrong can disqualify your runner. Crew access points, vehicle restrictions, and what you may hand over vary enormously between races, and some ban assistance outside designated zones entirely. Read the race rules end to end before race day.

How do I crew through the night?

Sleep in shifts if you have more than one crew member, since a crew awake for 30 hours makes mistakes. Set multiple alarms and add 45 minutes of margin to every arrival estimate. Have hot food and drink genuinely ready rather than theoretically ready, and layer your runner up before they get cold.

What should a crew member pack for themselves?

Warm clothes, a camping chair, a head torch, your own food and drink, a power bank, and paper maps in case mobile signal fails. Standing still at 3am is considerably colder than running. Bring something to occupy the waiting, which will be most of your day.

Tools for this race