⏵ Course guide · Arizona Strip, near Mesquite, Nevada
Grandmaster Ultras is built entirely around one idea: an exclusive field for runners 50 and older, racing desert ATV trails across the Arizona Strip near Mesquite, Nevada. I will walk you through the distance format and cutoffs first, then give you a pacing and fueling plan built for a desert ultra at this life stage. There are free calculators along the way to dial in your own numbers.
These facts come from the official Grandmaster Ultras race site. Check the current year details before you commit.
Every distance builds off the same 50K loop, and every entrant, regardless of distance, must be at least 50 years old.
The 50K is the foundation. The 50 Mile adds the "Thelma & Louise Loop" onto that route and runs the combination twice. The 100K repeats the 50K course twice, and the 100 Mile repeats the 50 Mile course twice. Knowing the shorter distance gives you a genuine preview of what the longer one demands.
The defining feature here is not the terrain, it is the field: entry is limited to runners 50 and older. That changes the character of the event, a supportive community built around a shared life stage rather than a race dominated by runners decades younger.
The course runs on ATV trails across the Arizona Strip, described by the race itself as offering "wide-open desert vistas." Expect exposed, rolling desert terrain rather than technical singletrack, with real elevation on both the 50K loop (about 1,580 feet) and the 50 Mile loop (about 2,450 feet).
The 100 Mile and 100K start a full day earlier than the 50 Mile and 50K, and get twice the cutoff window, 48 hours against 24, which changes how you should think about sleep and pacing.
If you are on the 100K or 100 Mile, your Friday 7:00 AM start means you will be out through at least one full night before you finish, so build a deliberate rest strategy into your plan rather than pushing straight through. The 50 Mile and 50K runners starting Saturday at 8:00 AM have a tighter 24-hour window and should pace more like a single long push with planned aid station stops.
⏵ Free tools to plan your effort
Aid stations every 4 to 7 miles give you frequent support, but a desert day at this time of year can swing from a warm afternoon to a cold night fast, especially on the longer distances.
Aim for roughly 60 to 90 grams of carbohydrate per hour while moving and sodium in the 300 to 700 mg per liter range. If you are on the 100K or 100 Mile and will be out overnight, plan for both a warm-day and a cold-night version of your fueling and layering strategy, since the Arizona Strip in late February can be genuinely hot by midday and cold after dark.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a late-February desert day with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a training plan built around YOUR fitness and the kind of durable, multi-loop desert endurance this race demands. Summit Line reads your real training, builds the durability your distance asks for, and rehearses your fueling so race day is something you execute, not guess at.
This is an exclusive 50-and-older field: every entrant, in every distance, must be at least 50 years old. That is the entire premise of the event, a supportive community of masters-age runners racing each other rather than competing against a field skewed younger, and it shapes everything from the pace of the aid stations to the atmosphere on course.
The 50K is the base loop. The 50 Mile adds the "Thelma & Louise Loop" onto the 50K route and runs the combination twice. The 100K simply repeats the 50K course twice, and the 100 Mile repeats the 50 Mile course twice. If you have run the shorter distance before, you already know a real share of what the longer one asks of you.
The terrain is desert ATV trail across the Arizona Strip, wide-open and exposed rather than technical singletrack, but the per-loop elevation adds up: about 1,580 feet for the 50K loop and about 2,450 feet for the 50 Mile loop, both repeated for the 100K and 100 Mile respectively. Combine that with a late-February desert environment, where days can warm quickly and nights can turn cold, and this is a real endurance test even before you factor in the generous but real 24 or 48 hour cutoffs.
The 50 Mile and 50K have a 24-hour cutoff, and the 100K and 100 Mile have a 48-hour cutoff. Both the 100 Mile and 100K start a full day earlier, Friday at 7:00 AM, than the 50 Mile and 50K, which start Saturday at 8:00 AM, so plan your sleep and pacing strategy around your own start time and cutoff window.
If you are 50 or older and new to the distance, the 50K is a reasonable entry point: a real desert ultra with aid stations every 4 to 7 miles and a 24-hour cutoff that gives you real room to finish. The exclusive 50+ field means you will be racing and running alongside people at a similar life stage, which many runners find changes the whole feel of a first ultra for the better.
With aid stations every 4 to 7 miles, you have frequent support to lean on, but a late-February Arizona Strip desert day can still swing widely between a warm afternoon and a cold night, especially if you are out on the 100K or 100 Mile overnight. Aim for roughly 60 to 90 grams of carbohydrate per hour while moving and sodium in the 300 to 700 mg per liter range, adjusting both for how long you expect to be out there and for age-related differences in heat tolerance and recovery. Use the free ultra fueling calculator to build your own numbers.
Link this guide
Race directors and clubs: link or embed this guide anywhere. It stays current.
<a href="https://runsummitline.com/guides/grandmaster-ultras">The Grandmaster Ultras course guide</a><iframe src="https://runsummitline.com/embed/race/grandmaster-ultras" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Grandmaster Ultras course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, and entry rules come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.
The timeline
Get the week-by-week countdown for this race: when to build, when to peak, when to taper.
One email with the timeline, plus training notes for this race. Unsubscribe any time.