Backyard Ultra: the complete guide to the last one standing format

A backyard ultra is an endurance race with a unique format: all participants must complete a 6.706 km loop (4.167 miles) every hour, on the hour. When the bell rings, you go. If you're not at the start line when it rings, you're eliminated.

The race continues until only one runner remains capable of completing another loop. That runner is the winner — the last one standing. There's no maximum distance or time limit: the race can last 24, 48 or even over 72 hours.

Unlike a conventional ultra trail where the fastest runner wins, in a backyard ultra the one who endures the longest wins. You're not racing against the clock but against the other runners — and against your own ability to keep going loop after loop.

The backyard ultra format was created by Gary "Lazarus Lake" Cantrell, the same mind behind the legendary Barkley Marathons. The first edition of Big's Backyard Ultra was held in 2012 in Bell Buckle, Tennessee (USA), in Lazarus Lake's actual backyard — hence the name.

What started as an experiment among friends grew rapidly. In 2019, Big's Backyard Ultra went viral when Maggie Guterl won the mixed-gender edition by completing 60 loops (402 km) in over 60 hours. The format expanded with official satellite events worldwide.

Today there are over 400 satellite events in more than 50 countries, including Spain. The circuit has a pyramid structure: national backyards qualify runners for an annual World Championship, where the best from each country compete at Big's Backyard Ultra. The winner of the Spanish qualifier receives a Silver Ticket, a direct spot to represent Spain.

The format has simple but strict rules. The loop distance — exactly 4.16667 miles (6.706 km) — is not random: it's calculated so that 24 loops total exactly 100 miles (160.9 km).

• The bell rings every hour on the hour. If you're not at the start line when it rings, you're out. No second chances.
• There's only one winner — the last runner able to complete a loop that no one else completes. They're the Last One Standing.
• There's no second place. Everyone else receives a DNF (Did Not Finish), regardless of how many loops they completed.
• No assistance on the course. You can have your base camp at the start/finish area, but no one can accompany or help you during the loop.
• The course must be completed in the designated direction. Some events alternate direction each loop.
• No maximum distance or time limit. The race ends when only one runner remains — it can last 24, 48, 72 hours or more.
• Voluntary withdrawal: to drop out, simply don't show up for the next bell. No formal notification needed.

Preparing for a backyard ultra isn't like preparing for a conventional ultra trail. You don't need to climb mountain passes or accumulate elevation gain — you need to be able to repeat a moderate effort for many consecutive hours without wearing yourself out.

The key to training is aerobic base. Run frequently (5-6 days per week) at a comfortable pace, prioritising volume over intensity. A well-prepared backyard runner can maintain the 6.7 km in 45-50 minutes loop after loop without straining.

Specific training sessions

• Long runs at backyard pace: 3-4 hours at the pace you'd use in the race (not faster). The goal is to get your body used to moving for many hours without fatigue.
• Night training: Once a month, do a long session that includes dark hours. Test your headlamp, night clothing and ability to maintain pace while sleepy.
• Transition simulations: Run 45 minutes, stop 15, eat, and run again. Repeat 4-6 times. This trains the start-stop cycle that defines the format.
• Foot and ankle strengthening: The repetitive terrain hits the same points kilometre after kilometre. Work on ankle mobility, plantar fascia and calves.

Training duration: 12-16 weeks is enough if you already have a marathon or ultra base. If you come from running without long-distance experience, plan at least 20 weeks.

In a backyard ultra you have around 15 minutes of rest between loops (depending on how fast you complete the circuit). That window is your moment to eat, hydrate and prepare for the next hour.

The key is real, varied food. Gels work for the first few hours, but after 10-12 hours the stomach craves solid food. Sandwiches, rice, pasta, fruit, hot broth — variety prevents monotony and ensures a steady calorie intake.

Organise food into boxes by 4-6 hour blocks: morning, midday, afternoon, evening, overnight. Each box with everything you need for that stretch. That way you don't waste time rummaging through bags.

Sample nutrition plan by phase

• Loops 1-8 (first 8h): Gels, bars, fruit, nuts. Light, easy-to-digest food.
• Loops 8-16 (hours 8-16): Transition to solids. Sandwiches, omelette, cold pasta, rice. Hot broth if it's night.
• Loops 16-24 (hours 16-24): Comfort food. Soup, mash, warm sandwich. The stomach appreciates warm, soft food.
• Loops 24+ (beyond a day): Whatever your body asks for. Pizza, ramen, sweets. At this point, any calorie that goes in is a win.