Measure it in time, not kilometres
Your body counts hours on its feet, not kilometres. A three-hour run covers about 35 km for a 3-hour marathoner and about 21 km for a 5-hour marathoner, and the strain is similar. That’s why Run 42 sets long runs in minutes and caps them at three hours: beyond that, the extra fitness is small and the recovery cost is large.
How it builds
- Base: from about 60 to 90 minutes.
- Build: from 90 minutes up to two hours.
- Peak: from two hours up to three, with the longest run about three weeks before race day.
- Cutback weeks: every fourth week the long run is about 25% shorter.
- Taper: a medium run of about 60% of the longest, then about 35%.
The pace
Easy pace: 15 to 27% slower than marathon pace. Slower than you think, and that’s fine. The long run builds endurance through duration, and running it fast costs you the rest of the week.
Adding marathon pace
From a third of the way into the peak phase, the long run finishes with 2×5 km at marathon pace in its second half. It teaches you to hold goal pace on tired legs. The test is simple: the second block should feel the same as the first. If it drifts, the easy part was too fast.
Fuel and drink
- On runs over 90 minutes, take carbohydrate: most runners do well with 30 to 60 g per hour, as gels, chews or a sports drink.
- Use the long runs to test exactly what you will use on race day, including the brand the race hands out if you plan to rely on it.
- Drink to thirst. In heat, add electrolytes.
After the run
Eat and drink within an hour, with carbohydrate and some protein. Expect the next day to feel heavy; keep it easy or rest. If you are still tired two days later, the long run was too long or too fast for where you are.
