Running a marathon under 4 hours: the symbolic barrier and the plan to break it
Under 4 hours for the marathon means 5:41 per kilometre for 42 km. It is the goal of most regular marathoners, and it depends less on speed than on the ability not to slow down after the 30th. Here is the VMA required, the role of the long run, and how your AI coach builds the 12 to 16 weeks.
Last updated: 2026-09-19
The VMA required, and what really counts
A marathon is run at about 80% of VMA. To hold 10.55 km/h for 4 hours, you need a VMA of at least 13.2 km/h. Most runners who miss 4 hours have the VMA: what they lack is the endurance not to lose 30 seconds per kilometre after the 32nd.
The coach reads your VMA and above all your volume of the last 30 days and your longest run on Garmin. Without 40 km a week and a 90-minute run already done, it adds base weeks.
The long run with marathon-pace blocks
It is the session that gets you under 4 hours: the long run climbs to 2 h 45, and from week 6 its last 45 minutes are run at 5:41 per kilometre. Learning to hold that pace on heavy legs is exactly what the 35th kilometre asks.
Threshold stays present every other week, at about 5:05, to keep a margin under marathon pace.
Race day: do not go out at 5:20
The classic sub-4 mistake: going out at 5:20 because it feels easy, and finishing at 6:30. The plan's instruction: first three kilometres at 5:51, then exactly 5:41 to the 35th, then grit your teeth without speeding up. Halfway split at 1 h 59.
- VMA of at least 13.2 km/h, but above all 40 km a week.
- Long run up to 2 h 45 with 45 min at marathon pace.
- Race day: exactly 5:41, halfway split at 1 h 59.
The watch carries the 5:38-to-5:44 range and alerts you at the first too-fast kilometre. Fuel every 20 minutes, tested on long runs.
Frequently asked questions
I run 4 h 15, how long to get under 4 h?
A 16-week plan is often enough if volume was the limit. If VMA is under 13 km/h, an intermediate 10K or half plan to raise it first.
Can three sessions a week be enough?
To finish, yes. To get under 4 hours, the four-session variant, with one more easy run, makes a real difference to endurance.
What half-marathon time validates the goal?
A half in 1 h 50 or less, six to eight weeks out, validates sub-4. The coach schedules it in place of a long run.
Ready to prepare for your marathon?
Pick your race date and weekly session count: your AI coach builds the plan and pushes it to your Garmin.
Start the marathon plan