Marathoners and ultrarunners are both endurance athletes, but in my experience, I’ve seen that their training strategies and mentalities differ wildly.
For instance, I’ve listened to podcasts in which ultrarunners—whether it be professionals like Courtney Dauwalter or amateurs like Andy Glaze—recap their weekend with stories of how they rallied through sleep deprivation–induced hallucinations, thousands of feet of rocky climbing at 2 a.m., and more than a little self-doubt to finally cross the line of a 100-miler. Most marathoners, myself included, would gladly pass on that experience in favor of 26.2 daylight miles on smooth, well-marked pavement.
But there’s definitely (at least) one thing we marathoners can learn from ultrarunners: how to keep running when you feel spent. And one of the best ways to replicate and run through the deep fatigue of late miles is adding a second long run to your schedule, as many ultrarunners do.
“Putting two long runs back to back helps build muscular endurance, teaches your body to run on tired legs, and gives you more confidence because you’re familiar with that fatigue,” Angie Spencer, an RRCA- and USATF-certified run coach, registered nurse, and founder of Marathon Training Academy, tells Runner’s World. Most runners won’t be able to recover 100 percent after the first long run, before starting the second, which is why it’s a useful tool to build the endurance needed for race day—whether you’re doing an ultra or a marathon.
That’s why Jason Fitzgerald, a USATF-certified run coach and creator of Strength Running, says marathoners can benefit from back-to-back long runs, too. “It’s an advanced training strategy that can be effective for an experienced, performance-oriented runner who has a specific goal race time in mind,” he explains.
But whether or not you should try back-to-back long runs depends largely on your training volume, injury history, and ability to fuel well and recover. Here’s what you need to know to determine if you might benefit from this form of doubles.
What Are Back-to-Back Long Runs, Exactly?
While there’s no blanket mileage requirement for a long run, Road Runners Club of America defines it as an effort lasting 90 minutes or more. By this logic, we’ll qualify a back-to-back as two runs, each of at least 90 minutes in duration, spaced over the course of two days.
The amount of time after finishing the first effort and before beginning the second should allow for one night’s sleep, as well as postrun recovery and nutrition.
Benefits of Back-to-Back Long Runs
Marathoners who use back-to-back long runs aren’t just simply trying to run farther each week. They are trying to improve their durability—the ability to maintain pace, form, and efficiency as fatigue accumulates later in the race, Fitzgerald explains.
Durability encompasses fitness adaptations like fatigue resistance, improved aerobic volume, tolerance for extended time on feet, and, according to Spencer, the mental fortitude that comes from honing these traits one step at a time. “There’s real mental benefit to these runs, too, because you’re getting familiar with that feeling of fatigue and realizing you’ve got more in you than you may have thought,” she adds.
“For someone trying to run a personal best, it can be so beneficial to simulate that feeling of running on tired legs in the last six to eight miles of a marathon,” she explains—and few things mimic that late-race fatigue like the second long run.
Sometimes Spencer will also use this second effort to target a specific training stimulus. “I coached an athlete who was trying to qualify for Boston at a downhill marathon. So during her second long run, we specifically focused on downhill efforts, since they’re particularly fatiguing on the legs,” she explains.
Who Should Try Back-to-Back Long Runs?
While many of Spencer’s and Fitzgerald’s athletes have had success with back-to-back long runs, they do not recommend them to everyone. Instead, both coaches carefully consider which runners are most likely to benefit from incorporating these sessions into their training plans.
Advanced Marathoners, Dedicated Amateurs, and Sub-Elites
According to Spencer, seasoned runners who have completed at least four marathons in the past two years without injury are likely good contenders. These runners have a proven aerobic foundation, manage the stress of training cycles well, and are looking to take the next step up in intensity.
Fitzgerald takes a similar view: He wants his athletes to nail the more basic elements of their training before incorporating any advanced strategies. These elements include a consistent mileage base between 50 and 60 miles per week and the ability to complete an 18- to 20-mile long run comfortably.
With this endurance base in place, it’s more likely a runner will respond well to increased training demands and face a much lower risk of injury.
Soon-to-Be Ultrarunners
Another group that may benefit from back-to-back long runs is individuals using their marathon training as a bridge to ultramarathons. For example, Spencer coaches runners who might have a marathon on their calendar, and then six weeks later, a 50K or 50-miler.
“We’ll incorporate back-to-back long runs—even in the midst of their marathon training cycle—to prepare for going right into the bulk of ultra training. We may even treat that marathon race like a long run in preparation for the ultra event after,” she says.
How Do I Start?
To get a runner started with back-to-back long runs, Spencer says she might schedule an easy jog of about four miles the day following a long run. As she watches their recovery, she’ll edge up the distance of that jog until it reaches about 12 miles. For example, after a Friday rest day, a runner might complete a 16-miler on Saturday, and then do an easy four-mile jog on Sunday.
Here’s how those Saturday and Sunday efforts might progress over nine weeks of a marathon training cycle:
16 miles / 4 miles
17 miles / 5 miles
18 miles / 6 miles
10 miles / 4 miles (deload or “step back” week)
19 miles / 7 miles
20 miles / 8 miles
12 miles / 9 miles (deload or “step back” week)
20 miles / 10 miles
16 miles / 12 miles
Fitzgerald says the best way to get into back-to-back long runs is to gradually build up the mileage of each effort. Following one of these efforts, runners can incorporate a deload week to help ensure recovery, as Spencer also describes above. But Fitzgerald typically only has a runner do one to three back-to-back long runs total in a training cycle.
“Even if you had the time, it’s not a good idea to do back-to-back long runs every week because you’re experiencing such high levels of stress on the body,” he explains. “A viable strategy is to alternate with traditional long runs and shorter efforts that include marathon-goal-pace running.”
Fitzgerald says runners should be careful when adding volume to their training schedules, but when done correctly, it’s much safer than some high-mileage-wary runners may think.
A recent study published in the British Journal of Sports Medicine found that increasing overall weekly mileage itself did not increase rates of injury in runners. Rather, it was the amount by which runners increased the distance of any single training run. Researchers found that running more than 10 percent farther than your longest run of the previous 30 days was associated with a significantly higher risk of an overuse injury. So, a good way to keep that risk down is simply by making sure you don’t bump up your long-run mileage by big numbers each week.
Why all the fuss about adding miles? Because according to Fitzgerald, mileage is arguably the most effective and easiest way to improve marathon running performance overall. “We shouldn’t just try to run our workouts harder,” he says. “We need to increase our aerobic capacity—and most of that comes from mileage.”
An often-used analogy among run coaches likens aerobic capacity to the engine of a car. Hard workouts teach you how to use that engine efficiently at race pace, but a larger engine provides the ability to do more work overall. While both are important, you’ll almost always benefit from increasing the size of your engine first, especially if you have a race like the marathon on your calendar.
How to Fuel and Recover
Fueling these runs matters—a lot. “The success or failure of the back-to-back long run could potentially hinge upon your ability to start that first long run well-fueled, fuel well during it, and then refuel afterward,” Fitzgerald says. “If you don’t, you might as well just not do them, because the risk far outweighs the reward.”
You’re not only trying to replace the energy you’ve expended during the first big effort, but you’re also trying to replenish and carb-load for another long run the next day. And if you’re not fueling for both of those efforts, the risk of injury—especially bone-stress injuries—increases significantly, according to Fitzgerald.
How do we do this? Spencer says it requires real effort and intention. “When you do back-to-back long runs, you sort of have to be mimicking the life of a professional runner—treating recovery like it’s your job for the weekend,” she explains. “There’s not as much margin for error because the next day, you’re going out doing a long run again.”
Fortunately, Spencer has tips to help you build a double-long run recovery plan. Here’s what a weekend might look like for a runner doing their back-to-back effort on Saturday and Sunday.
- Friday: Focus on hydration and begin adding electrolytes to your water. Prioritize carbohydrates through consistent meals and snacks.
- Saturday Morning: Eat a prerun meal of easy-to-digest carbs and hydrate well. Begin fueling early and often during the first long run.
- Saturday Afternoon and Evening: Refuel immediately postrun with a carb- and protein-focused meal. Incorporate your favorite recovery strategy—Spencer suggests a relaxing shower, compression, or “legs up the wall.” Avoid alcohol and prioritize sleep.
- Sunday Morning: Eat a prerun meal of easy-to-digest carbs and hydrate well. Begin fueling early and often during the second long run.
- Sunday Afternoon and Evening: Refuel immediately postrun with a carb- and protein-focused meal. Prioritize postrun recovery and sleep.
Depending on the distance and duration of your long runs, Fitzgerald adds that it can be challenging for some runners to get in enough calories to meet such high energy demands.
He tells athletes struggling with low appetite to find the nearest Cheesecake Factory—or a similar restaurant with an extensive menu—and order whichever plate of pasta or cheeseburger looks most delicious. This, of course, is a refueling strategy best used after your second long run, when you’re less concerned about stomach upset from unfamiliar foods.
How Do I Know If I’m Recovering Well?
Spencer keeps an eye on a few key factors to determine if her athletes are recovering well from back-to-back long runs in their training. These are a few red flags that may point toward under-recovery:
- Poor mood, irritability, negative training outlook, or significantly decreased motivation
- Insomnia, waking up frequently throughout the night, or nighttime restlessness
- Large spikes in resting heart rate or significant drops in heart rate variability (HRV)
- Difficulty hitting workout paces during the rest of the week
- New aches and pains that crop up regularly or don’t resolve
- Significant fatigue or legs feeling “dead”—unusually heavy and depleted
Spencer reminds runners that it’s totally fine if you find that the time commitment and recovery demands of back-to-back long runs don’t align with your schedule or goals. “Marathon training is an amazing thing, but it’s also another stressor,” she says. “You want to make sure that your running remains a life-giving activity—not something that takes too much from you.”
Morgan is a gear editor who has been with Runner’s World since 2017. She started as an intern ghostwriting The Warmup, a bygone version of the daily RW newsletter. Now, she tests and reviews anything you might find on runners’ feet-from crew socks and compression boots to carbon-plated super shoes.
A lifelong runner and shoe geek, Morgan has been chasing the perfect pair of kicks since she joined her grade school cross-country team. Since then, she ran as a Division I walk-on for the cross-country and track & field teams at the University of Delaware, where she studied English and Biology. She has one full marathon under her belt, and has raced more halfs and 5Ks than she can count.
