The Science-Backed Strategy for Pacing Western States 100

Greg Marshall
13 hours ago
4 min read

A starting line banner at Western States 100

“The Super Bowl of Ultra Running,” also known as the Western States 100 Mile Endurance Run, is the penultimate one hundred mile trail running race in the United States. In some ways, Western States weekend feels like it is where the entire sport of ultra running moves forward. Sometimes by seconds, and other times, by minutes, like this past June as Vincent Bouillard and Jennifer Lichter both made history with record-setting wins. For non-elites, the WSER lottery is infamous. It can consume athletes’ hopes for close to a decade before their name is drawn. Each year, they must re-qualify to keep their chances of running this hallowed race alive.

But once the hurdle of entry is cleared, suddenly runners are registered for a hundred-mile footrace through the mountains of northern California, and they’re left with the burning question:

“How am I going to finish this thing?”

A new analysis, by Srdjan Markovic and colleagues at Singidunum University in Serbia, examines more than 15 years of finisher data to help us understand how it’s done.

Traditional Pacing Methods Fail at 'States

The physiology of energy production (called ‘bioenergetics’ in academic circles) governs running races on the roads over the marathon distance and below. The strategy for non-elites in those events is pretty simple: aim for a small negative split. If you can run the second half just a hint faster than the first half, whether it be a mile on the track or a marathon on the road, you are likely to be happy with the result you post. The physiological foundation for pacing that way has to do with how the body chooses to burn fats and carbohydrates for fuels. We covered exactly how that all plays out a bit ago here on the blog.

A flow chart of ATP production — *A flow chart of how ATP, also known as the molecule of energy in the body, is produced from carbohydrates stores in the body. Figure taken from a previous blog post,* *The Metabolic Basis of Endurance*.

For somewhat obvious reasons, the level-set pacing strategy of the roads goes out the window when we’re suddenly climbing a mountainside at altitude. In order to keep the energy cost steady, we slow our pace down as the hill becomes steeper. Unlike in road running, trail runners don’t necessarily get that time back on the descents. Whereas on the roads, descents are somewhat mild and can be run fast, the descents on the trails are steep and technical, often costing runners more in time and energy than a flat-and-smooth trail would.

The problem with traditional pacing runs even deeper in ultra running though. Fatigue levels are massive after we’ve run for six, seven hours… and previous research has shown that even the best run a slower second half than their first half.

The paper examined seventeen years of Western States finisher results, available publicly on the Western States website. The team examines the pace runners held between each checkpoint along the one hundred mile route, as well as the average pace runners finished the race with. Then, they assessed how much a runner’s pace for each section of the race related to their final average pace. The end product is a clear picture of which sections lend themselves to running relatively fast or slow, when we account for all of the unique challenges of States (heat, technical sections, late-race fatigue, etc.)

Pacing 'States, section by section

It’s not a new finding in general, but the results indicate that women start more conservatively than men do, and they’ll pace a bit more steadily throughout the whole race (less variation in their pace from one section to the next). Previous research has shown this relationship of male and female pacing strategies before, and the potential explanations as to why those differences exist are a good topic for another day. Markovic also found that older finishers seem to vary less in their section-by-section pacing than younger finishers.

Race pace for males versus females

The average pace for male and female finishers was almost exactly the same– 17:05 and 17:09 per mile, respectively. That translates to finishing times of 28 hours and 29 minutes for men, and 28 hours and 34 minutes for women. Pretty similar, but States also has a 30-hour cutoff that’s likely to be influencing those averages.

Projecting your finish time?

The last detail that sticks out is something special about the Foresthill aid station at Mile 62. Markovic’s analysis indicates that the pace runners hold for the section out of Foresthill en route to Dardanelles at Mile 70 is potentially predictive of the average pace they’ll finish the race in. In other words, if a runner paces the race well for their fitness, and they run the Foresthill-to-Dardanelles section at 15-minute pace, then they’re on track to average 15 for the entirety of States and finish in a final time of about 25 hours.

A chart showing how to pace Western States 100, section by section — The Westerns States course elevation profile is shown in blue, while the black and red points indicate how the pace for each section of the race course relates to the average pace of finishers (shown on the right-side axis). For example, runners average a pace in Section 1 that's about 10% faster than their overall race pace will be at the finish, whereas runners average a pace almost 40% slower than their overall pace in Section 14. (Figure from Markovic et al. 2025)

Bottom Line

Markovic and the team analyzed almost four thousand runners and shared what those runners collectively ended up doing at Western States. The changes in pace shown in Markovic’s analysis are almost an inevitability. The runners that finish ‘States will largely pace the race like the chart above indicates, whether they mean to or not.

The curve draws a common thread through what it takes to finish the race, assuming we can get the average goal pace right for ourselves. A conservative pacing aim is a safe one, as long as we keep a bit of a gap on cutoff times. We have to finish the race in order to post a strong time, so it’s best to set ourselves up to at least finish, and then worry about the extras, like time and place, as the later stages of the race unfold.