How it works
What the numbers mean
Norwegian singles is three sub-threshold interval sessions a week with easy running in between, adapted by James Copeland from the elite Norwegian double-threshold model. The calculator turns your race into equivalent race paces with Riegel's formula, then sets the three sessions from Copeland's starting guide.
- Tuesday, long reps: about 10 minutes at 25–30K race pace, 90–120 s rest.
- Thursday, medium reps: about 6 minutes at around half marathon pace, 60–90 s rest.
- Saturday, short reps: about 3 minutes at 12–15K race pace, 60 s rest.
Quality work starts at 20% of your weekly running time, and below 4 hours a week you start with two sessions. Easy runs stay under about 70% of max heart rate, and the Sunday long run is roughly 1.7 times a normal easy run.
The paces are starting points. Start at the slower end, adjust for conditions, and keep every rep controlled. The full Norwegian singles guide explains how to check you are below threshold, how to start and progress, and lists every source.