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Pulse Endurance Runs (Pickled Feet) Course Guide

The Pulse Endurance Runs, better known as Pickled Feet, is Idaho’s premier timed ultra: a flat 2.5-mile dirt loop in Eagle Island State Park just west of Boise that you run against the clock for 6, 12, 24, or 48 hours, or chase as a straight 100 mile. There are no mountains here and almost no vert, so this race is won and lost in your head, your stomach, and your feet. I will walk you through the format and the loop first, then give you a lap-by-lap pacing and fueling plan. Free calculators along the way let you dial in your own numbers.

⏵ At a glance

Pulse Endurance Runs (Pickled Feet) quick facts

Date
March 19 to 21, 2026 (a Thursday-to-Saturday timed event, mid-to-late March)
Location
Eagle Island State Park, Eagle, Idaho, about 8 miles west of Boise
Distances
48 hr · 24 hr · 12 hr (day and night) · 6 hr (day and night) · 100 mile · 100-mile relay
Elevation gain
Flat. A 2.5-mile dirt-trail loop along the Boise River and Eagle Island pond, negligible climbing
Start times
48 hr 6 PM Thu · 100 mile 10 AM Fri · 24 hr / 12 hr-night / 6 hr-night 6 PM Fri · 12 hr-day 6 AM Sat · 6 hr-day noon Sat
100-mile cutoff
32 hours (40 laps of the 2.5-mile loop), finishing by 6 PM Saturday
Qualifier
No Western States, UTMB, or Hardrock qualifier status listed by the race

These facts come from the official race site and UltraSignup. Check the current date, start times, and cutoffs in the race-day details before you commit. Race logistics change year to year.

The loop: where Pickled Feet is won and lost

The whole race happens on one flat 2.5-mile loop along the Boise River and the Eagle Island pond, a mix of soft dirt trail and hard-packed dirt road. You pass the aid station and the start/finish pavilion every single lap. There is no climb to hide on and no descent to recover on, which sounds easy and is, physically. The challenge is entirely the format.

Pick your format: timed or the straight 100

First decision is what you are even racing. The fixed-time options (48, 24, 12, and 6 hour) are a distance-against-the-clock game: you start, and whatever mileage you bank before your clock expires is your result, no DNF possible. The 100 mile is the opposite, a fixed distance with a generous 32-hour cutoff, which works out to 40 laps. If your goal is a first hundred, the 100 mile is the line you want. If your goal is a distance PR or a 24-hour number, pick the timed race and run the clock, not a finish line.

There are day and night versions of the 6 and 12 hour, and a relay on the 100 mile, so read the start-time table carefully. A 6 PM Friday start means you are running into the dark from the gun, and a 6 AM or noon Saturday start means daylight and probably warmer temps. That choice changes your whole plan.

The short loop is a mental game, not a terrain one

A 2.5-mile loop comes around fast, and that cuts both ways. The gift is that aid, your crew, your drop bag, and a bathroom are never more than 2.5 miles away, so you are never deep in the backcountry rationing water. The curse is that you see the same trail dozens of times, and somewhere after dark the loop starts to feel like a hamster wheel. This is the part nobody trains and everybody underestimates.

Beat the loop by breaking the day into chunks instead of laps. Think in blocks of hours or in segments between meals, give yourself small jobs (this lap I eat, next lap I add a layer, the one after I change socks), and let the lap counter be the scoreboard, not the focus. Music or a podcast for the dark hours, a pacer or a friend to run a few laps with you late, and a plan for the 3 AM low all matter more here than any hill-repeat session.

Flat and runnable will quietly wreck your feet and legs

Do not let the word flat fool you into thinking this is gentle on the body. Running the same flat motion for hours, with no climbing to break up the muscle pattern and no descents to change your gait, hammers the exact same tissues over and over. Feet, in particular, take a beating: this race is literally nicknamed Pickled Feet, and macerated, blistered, trashed feet are the classic reason a strong runner slows to a crawl here.

Get ahead of it. Lube early and often, change into dry socks before you think you need to (every few hours, and any time your feet get wet), and consider a shoe swap partway through to give your feet a different pressure pattern. Practice flat, sustained long runs in training so your legs are used to the monotony, and do not store all your blister kit at home, keep it in the lap-side drop bag where you actually pass it.

Pacing strategy for a flat timed loop

On a flat course your pace actually means something, unlike a mountain race, so the trap here is going out too fast because it feels effortless in the first few hours. The runners who put up the big numbers are almost always the ones who started slower than they wanted to and barely slowed down.

Start embarrassingly easy and run an even effort

The single biggest mistake on a flat timed race is banking early miles at a pace you cannot hold once the hours stack up. It feels great for the first 20 or 30 miles and then it quietly costs you double on the back half when you are walking the laps you should be jogging. Pick a pace that feels almost too easy at the start and treat the first quarter of your clock as a warm-up. On a flat course, even, conservative effort almost always beats a fast start.

Because the loop is short, you get a real-time read every 2.5 miles on whether you are on plan. Use your average lap time as your dashboard. If your laps are creeping faster than plan early, rein it in, and if the late laps are falling apart, that is the signal to switch to a deliberate run-walk rhythm rather than grinding yourself into a death march.

Set a real target with a flat-course prediction, then work back into the clock

Do not pull your goal distance or 100 mile time out of thin air. Use a recent race result to set an honest flat target, then translate it into a per-lap and per-hour budget so you know what each loop should cost you. For the 100 mile, work the math back from the 32-hour cutoff so you always know your buffer, and for a timed race, set a stretch number and a number you will be happy with, and pace for the happy one.

A grade-adjusted pace tool still earns its keep even on a flat course, because it lets you convert your real fitness into a sustainable effort target instead of guessing, and it keeps you honest when adrenaline says go faster. Plan the effort, then let the lap counter confirm it.

⏵ Free tools to pace this race

Fueling strategy for a long timed effort

A timed ultra or a 100 mile on this loop can mean 12, 24, or 30-plus hours of moving, and the aid station every 2.5 miles is both a help and a temptation. The runners who hold it together are the ones who fuel on a schedule and do not let the buffet derail the plan.

Carbs: steady, on a clock, and trained

Aim for a steady intake in the range of 60 to 90 grams of carbohydrate per hour, leaning higher only if your gut is trained for it. The danger on a long flat effort is not running out of food, it is your stomach quitting on you around hour 10 or 12 from neglect or from grazing junk every lap. Eat on a clock, take in real calories every loop or two, and rehearse your exact race-day carb rate on long runs so 80-plus grams an hour feels normal instead of nauseating.

Use the lap aid station as a tool, not a snack bar. It is fine to grab real food in the night when gels stop appealing, but have a default plan you fall back on so you are not improvising your nutrition at 2 AM when your decision-making is shot.

Sodium, fluid, and the overnight cold

Match your sodium and fluid to your sweat rate and the conditions, not a generic number. March near Boise can be cool, so you may sweat less than a summer race, but you can still get behind on salt over many hours, so keep electrolytes going (commonly somewhere around 300 to 600 milligrams of sodium per liter of fluid, more if you run salty). Weigh yourself before and after a long training run to learn your real sweat rate, then build the plan around your own number.

The cold overnight is the sneaky variable. As the temperature drops you stop drinking, your appetite fades, and your hands get clumsy, all of which quietly starve and dehydrate you. Stash warm options for the dark hours (broth, a hot drink, something easy to chew with cold fingers) and keep sipping and eating on schedule even when you do not feel like it.

⏵ Build your fueling plan

Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a long overnight effort 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 race-day plan built around YOUR fitness, this flat timed format, and your projected lap splits. Summit Line reads your real training, builds the durability you need to keep moving for hours, and rehearses your fueling so race day is something you execute, not guess at.

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Pulse Endurance Runs (Pickled Feet) FAQ

How hard is the Pulse Endurance Runs (Pickled Feet)?

The physical course is about as easy as ultras get: a flat, fully runnable 2.5-mile dirt loop with negligible climbing and an aid station every single lap. What is hard is the format. A timed race or a 100 mile on a short loop is a mental and pacing test, not a terrain test, and the loop will get into your head somewhere in the dark. With a generous 32-hour cutoff on the 100 mile and no cutoffs at all on the fixed-time options, almost anyone who keeps moving and keeps eating will get a number worth being proud of.

How much elevation gain is in the Pulse Endurance Runs?

Essentially none. The course is a flat 2.5-mile loop on soft dirt trail and hard-packed dirt road along the Boise River and the Eagle Island pond, so there is no real climbing to speak of. That is the whole point of a course like this: it is built for putting up a big distance number against the clock or chasing a fast, even 100 mile without mountains in the way. Train your flat-running durability and your feet, not your climbing legs.

What are the cutoff times for the Pulse Endurance Runs?

The 100 mile has a generous 32-hour cutoff, which is 40 laps of the 2.5-mile loop, finishing by 6 PM on Saturday. The fixed-time races (48, 24, 12, and 6 hour) do not have a finish-line cutoff in the usual sense: you simply run as far as you can before your clock runs out, and on a timed event there is no DNF unless you signed up for the 100 mile and came up short. Always confirm the current cutoff and start times in the official race details before you commit.

What is the course and the format like at Pickled Feet?

It is a flat 2.5-mile loop in Eagle Island State Park, run as a loop course you repeat. You pass the aid station and the start/finish pavilion every lap, which means a crew spot, a drop bag, and a bathroom come around every 2.5 miles instead of every several miles like a point-to-point mountain race. You can pick a fixed time (48, 24, 12, or 6 hour) and bank as much distance as you can, or run the fixed-distance 100 mile. The loop is short and social, which is both the gift and the curse of this kind of race.

What is the weather like in March for the Pulse Endurance Runs?

Mid-to-late March in the Treasure Valley near Boise is shoulder-season and genuinely variable, so plan for a wide swing rather than one forecast. Daytime can be mild and pleasant, but nights drop cold (often near or below freezing), and you can get wind, rain, or even a wet snow flurry. On a multi-hour or multi-day timed race the temperature change between a sunny afternoon and 3 AM is the thing to prepare for, so stage layers, a hat and gloves, and dry socks in your lap-side drop bag. Check the actual forecast the week of the race.

Is the Pulse Endurance Runs a good first 100 miler or first timed ultra?

It is one of the friendlier places to attempt a first 100 mile or a first big timed effort, and a lot of runners pick it for exactly that reason. The flat loop, the aid station every 2.5 miles, the easy crew and drop-bag access, and the forgiving 32-hour cutoff take terrain and navigation off the table, so you can focus on moving, eating, and staying mentally in the game. The trade is that a short repeating loop is a mental grind, and the flat, monotonous running can chew up your feet and the same muscles for hours. If you prepare your stomach, your feet, and your head, it is a very achievable first big one.

This guide is independent and for planning only. The course details, dates, start times, and cutoffs 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.