The Long Run

What the long run does

The long run has three jobs: aerobic capacity, resilience in the muscles and nerves that tire in the late miles, and practice eating while you run.

A 2021 review defines resilience, also called durability, as how long and how well you are able to maintain your running economy and speed as a run goes on¹. In 26 well-trained men matched on 10 km time, those who regularly ran 90 minutes or longer lost less running economy over a 90-minute run than those whose runs were all under 70 minutes (3.1% against 6.0% worse)². The runners who held up best also trained the most each week, so the study cannot separate the long runs from the volume around them.

How long it should be

How long a long run should be depends on your race goal, but there is a ceiling. Most long runs, though not always all of them, should be three hours or less. David Roche, who coaches trail, ultra and road athletes, says most of a run's aerobic benefit comes in roughly its first two hours, and that a run past about three hours is hard to recover from, costing you training in the days after it (Human Performance Outliers, episode 407).

For a marathon, three hours is about 16 miles at a slow pace and about 20 at a fast one. Luke Humphrey, whose Hansons plans have recreational runners training for the marathon, tops most runners out at 16 miles, about 25 to 30 percent of the week's miles, and says a 20-miler costs more recovery than it pays back; 16 miles takes between about 1:50 and 3:10 at common paces (Hansons Marathon Method: The 16 Miler). A marathon does not need a 20-mile run. It does need a long run that is not short.

A 5K needs less, because the race is over before durability decides it. A long run of 60 to 90 minutes every week or two is plenty, and a runner with a decent base can do without one.

How fast to run it

Long runs are easy runs. Run them at your conversational pace, zone 2 in a five-zone model. For a marathon runner that is about 1 to 2 minutes per mile slower than marathon pace, and for a half-marathon runner 90 seconds to 2.5 minutes per mile slower than half marathon pace. Finish strong, not destroyed. Too fast shows up as being beaten up afterward, a steep climb in heart rate late in the run, or running out of fuel.

Do not compare long-run pace week to week. Heat, hills and sleep move it, and effort is the measure.

Pace work inside a long run

In the last weeks before a marathon or half marathon, some long runs carry a stretch at race pace inside an otherwise easy run: 6 miles at marathon pace after 12 easy ones, or 3 x 2 miles or 2 x 3 miles at marathon pace with a half mile to a mile easy between. The whole run still stays within the three-hour limit. Add them gradually: one such long run in a training cycle, two in the next and three in the third, never going from none to three.

Pace work turns a long run into a hard session. It belongs only after you have built a base of easy long runs, and it needs at least 48 hours from any other hard session. The guide on race-specific preparation covers where it fits in the last weeks.

How to build it

Add time in small steps and match each run to the running you do now. Stachel, who coaches age-group marathoners, adds about 10 minutes a week to the long run early in a build, and Jason Fitzgerald warns that one run much longer than anything in the last three to four weeks raises injury risk more than weekly mileage does. If you miss a long run, do not double the next one.

Build for two weeks and then shorten the long run for a third, which gives you an easier week on a regular rhythm.

The long run takes a larger share of the week when you run few miles, and that is fine while it stays easy. As weekly miles rise it settles at about a quarter to a third of them.

What to eat and drink

Practice your race fueling on the long run, because your stomach adjusts with practice. Under 90 minutes you need no fuel. Past that, take the first gel before you feel empty, at 60 to 75 minutes, and one about every 30 minutes after that. If your stomach is touchy, start with a gel every 35 to 40 minutes and shorten the gap over time. Take as much carbohydrate as you can tolerate, found by practicing on every long run.

Eat 200 to 300 calories of easy carbohydrate with a little fat before the run, and a full meal after it. See the guides on carbohydrate during exercise, training your gut and hydration and electrolytes.

Related guides

For two long days in a row, see back-to-back long runs. For ultra training as a whole, see ultra training.