Long runs can take the life out of you and demand hours out of your weekends, especially if you’re in the middle of marathon training. If you’re used to dealing with an injury, or you’re simply too busy for four-hour long runs, bunched long runs can help you stick with your training without sacrificing key adaptations.
Instead of splitting up your long run by moving an arbitrary number of miles around without any real plan, bunched long runs help you alter long runs with purpose. For example, run an eight-miler one evening, followed by a 10-miler the next morning, about 12 to 15 hours apart. This way, you simulate the effects of one continuous long run while lowering your risk of injury and making your schedule more flexible.
We spoke with expert run coaches to unpack exactly what bunched long runs should look like in a marathon training plan, the major benefits, and tips on getting them right.
All the Benefits of Bunching
Reduces Injury Risk
The idea behind bunched long runs comes from ultrarunners, who may only work up to about a third of their race distance mileage for their longest training runs. “When you’re running for hours at a time during training, your running mechanics are likely going to break down,” like stride length and frequency, says Brian Rosetti, Philadelphia-based certified run coach and founder of the Run SMART Project and V.O2 (backed by legendary run coach Jack Daniels).
No matter how strong your core or other key muscle groups, broken mechanics lead to greater landing shock, which causes repetitive stress on your joints and muscles, he explains.
“That’s when the injuries come in,” says Rosetti. By stopping your run before that form breakdown, you can potentially sidestep overuse injuries—that is, as long as you build your mileage slowly, strength train, and fuel enough.
Mimics the Effects of a Regular Long Run
As long as you do each run within 12 to 15 hours of each other, you still gain similar physiological benefits of completing those miles in one go. “You don’t have time to replenish your glycogen stores before the second run, so physiologically, it’s similar to one long run,” says Rosetti.
It typically takes about 20 to 24 hours to fully restock glycogen stores, so keeping your second run within 15 hours means you have just enough of a window to sleep, hydrate, rest your legs, and refuel, without completely replenishing your energy stores, and that’s the effect that you’re looking for, he says.
Builds Fatigue Resistance
Another key benefit of bunched long runs is the ability to practice running on fatigued legs during the second run, which can help build physical and mental resilience, says Janet Hamilton, exercise physiologist, RRCA-certified run coach, and owner of Running Strong.
Plus, bunching an 18-miler into two parts first can help you feel better prepared to tackle a continuous 18-miler as your mileage builds. “Most runners find that 16 miles sort of represents a ‘threshold’ and pushing beyond that for the first time with a bunched approach might feel more doable to them,” says Hamilton.
Makes Scheduling Easier
You also might find that bunching your long runs is all your schedule will allow for on a particularly busy weekend. “Say you’re a young parent and don’t have childcare for a four-hour chunk of time on a weekend but you can round up a few two-hour chunks. That might allow you to get the miles in, but in a bunched format rather than all at once,” says Hamilton.
How to Add Bunched Long Runs to Your Training Plan
While bunching your long runs comes in handy during busy weekends, you should only include up to four bunched long runs into your program, says Rosetti, but it’s even worth starting with one or two. You could start by doing your 18-miler as an eight-miler Saturday evening and a 10-miler Sunday morning, or bunching your long run as two 10-milers for when you need to reach 20.
No matter how many bunched long runs you want to tackle, you should keep them three to four weeks apart to account for other non-bunched long runs on your plan.
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Bunched long runs can work for every kind of runner no matter your pace, but runners who are injury-prone or who need a little extra help transitioning to longer distances may gain the most advantages.
If it takes you four hours to complete a 20-mile long run, you’re going to spend lots of time on your feet, which creates a lot of impact, so you’ll want to take advantage of this method, Rosetti says.
3 Tips for Optimizing Your Bunched Long Runs
1. Use Them Sparingly
Bunched long runs do not replace all your longest long runs in marathon training. It’s still crucial to cross off a continuous 18-miler (or 20 or 22) in preparation for the full 26.2 because your body still needs to adapt to and prepare for the demands of the distance, says Hamilton. However, if you have two 18-milers on your plan or an 18, 20, and 22, you might swap one of those continuous long runs for a bunched one.
During the weeks in your training plan where you’re not bunching long runs, Rosetti suggests checking off a continuous long slow distance run (like that 20-miler during peak week, for example), or a long run with tempo efforts to vary your training efforts.
2. Schedule Them Around Your Rest
Thankfully, there’s no need to worry about soreness setting in by the second run because the 15-hour window isn’t quite enough time for delayed-onset muscle soreness (DOMS) to fully kick in, says Rosetti. After the bunched long run, though, you’ll likely still feel as sore as you would after a continuous long run, so take a rest day after that second run.
Runners often choose to bunch their weekend long run across Saturday evening and Sunday morning, preferably followed by a Monday rest day, Rosetti says. But you can bunch them within the same day if you prefer, he adds, like running early in the morning around 6 a.m. and the second run later that evening around 6 p.m., as long as you’re able to rest your legs throughout the day.
3. Watch Your Pace
The key is to maintain your typical easy long run pace on both the first and second runs (no tempo efforts mixed into the runs!). If you’re feeling nervous about maintaining pace, Rosetti suggests focusing on counting your steps to dial into your easy pace and maintain your typical cadence. This way, you can avoid going out too fast on the first run, and maintain your true easy pace for the second run as well.
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Kristine Kearns, a writer and avid runner, joined Runner’s World and Bicycling in July 2024. She previously coached high school girls cross country and currently competes in seasonal races, with more than six years of distance training and an affinity for weightlifting. You can find her wearing purple, baking cupcakes, and visiting her local farmers market.
