What it takes
A sub 1:50 half marathon means holding 5:12 per km (8:23 per mile) from start to finish. In Jack Daniels' VDOT model, that is a fitness score of about 40.4.
The half marathon pace chart has the splits for it. It also covers every other time from 1:05 to 3:00.
One consistent block of training usually moves a runner a couple of points. So this plan suits someone who runs the half marathon in about 1:54:51 today.
Easy, threshold and interval paces come from that starting point, not from the goal, so you train at the fitness you have.
Sub 1:50: the long run is the new part
Sub 1:50 is 5:12 per km (8:23 per mile). It is the same fitness as 49:36 for 10K and 23:54 for 5K, so a runner who has just broken 50 minutes for 10K often has the speed already. What a half adds is the second hour.
That is the long run's job. Here it starts at 12 km and builds to 19 km, about 2 hours 5 minutes at 6:37 per km, longer than the race itself. Keep it at that pace. A long run that drifts towards 5:12 leaves you flat for Tuesday's session.
Tuesday is the only hard weekday: hills first, then threshold at 5:16 per km taking turns with 400 m and 800 m reps at 4:50. Half marathon pace only arrives in the peak weeks. The other runs stay easy, 6:19 to 6:37 per km, and the plan peaks at 42 km a week.
For pacing, think in 5 km blocks of 26:00. That gives 10 km at 52:00 and 15 km at 1:18:00, with the last 6 km to hold steady rather than claw time back.
Your training paces
Set from a 1:54:51 half marathon, the fitness this plan starts from.
| Pace | What it is for | Per km |
|---|---|---|
| Easy and long | Most of your running. | 6:19-6:37 |
| Threshold | Tempo runs. Comfortably hard. | 5:16 |
| Intervals | Hard repeats with recovery. | 4:50 |
The VDOT chart has the full set, repetition pace included.
The plan, week by week
4 running days a week, peaking at about 42 km. Every fourth week is easier, and a taper leads into race day.
Long runs are on Sunday. Hard sessions are on Tuesday.