02 / Where it comes from
From Ingebrigtsen
to your week
The Norwegian model
The method traces back to Marius Bakken, the Norwegian 5000 m runner who started measuring his blood lactate in the late 1990s and ended up running more than 5,500 tests. He moved his threshold work down from the textbook 4.0 mmol/L to between about 2.3 and 3.0 mmol/L, began doubling his threshold sessions in 1999, and kept easy runs under 70% of max heart rate. He later advised the Ingebrigtsen family.[3]
In that elite model, threshold work is done twice a day, morning and evening, usually on two days a week, inside weeks of 150 to 220 km.[3] A 2023 review by Casado, Foster, Bakken and Tjelta described the pattern among world-class distance runners: three to four lactate-guided threshold sessions a week, one faster session, and the rest low intensity, for a total of roughly 150 to 180 km.[4]
The amateur version
Almost nobody with a job can run 180 km a week or train twice a day. James Copeland, known online as sirpoc, took the core idea and turned it into one session a day: three standalone sub-threshold workouts a week, easy runs in between, one easy long run. He shared it on the LetsRun forum, then on Strava and Reddit, and the approach became known as Norwegian singles.[1][5]
His own reported progression, starting from roughly 19-minute 5K fitness, reached 15:01 for 5K, 30:41 for 10K, 1:08:51 for the half and 2:24 in the marathon at age 41. Those are his results, not a forecast for anyone else.[1][2]
03 / The week
Three sessions,
easy in between
The standard week alternates quality and easy days, so no hard session ever follows another.[2]
| Day | Session |
|---|
| Monday | Easy (or rest) |
| Tuesday | Long sub-threshold reps |
| Wednesday | Easy |
| Thursday | Medium sub-threshold reps |
| Friday | Easy |
| Saturday | Short sub-threshold reps |
| Sunday | Long easy run |
These are slots, not a demand to run seven days. Keep the rest days you already have. If structured intensity is new to you, start with two quality sessions and make Saturday easy. That is what the calculator does under 4 hours a week.[2]
The three sessions
Reps are set by time, not distance. A 3-minute rep might be 600 m for one runner and close to 1 km for another. Copeland's starting ranges:[1][2]
| Rep length | Starting pace | Rest |
|---|
| About 10 min | 25–30K race pace | 90 | 90–120 s | ndash;120 s
| About 6 min | About half marathon pace | 60 | 60–90 s | ndash;90 s
| About 3 min | 12–15K race pace | 60 s |
Rest by standing, walking or jogging very slowly. Shorter rests are not the progression. The breaks are what keep the lactate under control and let you correct a pacing mistake.[2]
A complete session is about 10 minutes of easy warm-up, the reps, then 7 to 10 minutes easy. Eight 3-minute reps with 1-minute rests take roughly 50 minutes in total.[2]
How much quality
Once established, about 20 to 25% of your weekly running time is sub-threshold reps. Count only the reps, not the warm-up or rests. Three sessions of 24 minutes of work make 72 quality minutes, not three hours of hard training. As volume grows, that share often settles nearer 20%.[2] The calculator starts you at 20%.
04 / Intensity control
How to know you are
below threshold
The whole method stands or falls on staying under the second lactate threshold. No single number guarantees it, so use several checks together.[2]
- Pace from current fitness. Set targets from a recent race, not a goal time or an old best. Start at the slower end of the range and slow down for heat, humidity, wind and hills.
- Heart rate as a guardrail. Estimate your lactate threshold heart rate (LTHR) as the average heart rate over the last 20 minutes of a hard, solo 30-minute effort. Copeland describes early reps finishing 10 to 15 beats below LTHR, with later reps approaching it from below. If you keep going over, the pace is too fast.
- Breathing and feel. Controlled breathing, enough left for another rep. If it feels unusually hard, slow down even when the watch looks fine.
- Lactate, optional. A meter can help, but a fixed reading of 2, 3 or 4 mmol/L does not mean the same thing for every runner. Bakken himself worked mostly between 2.3 and 3.0, and notes that thresholds vary between athletes.[3]
Watch-based critical speed or critical power is not the same thing as your lactate threshold. In well-trained runners, critical speed came out at 16.4 km/h against a maximal lactate steady state of 15.2 km/h, a clear gap.[6] Treat device numbers as one more estimate, not the answer.
05 / The easy days
Easy has to be
actually easy
The easy runs are what make three quality sessions a week possible. Copeland caps the average heart rate of an easy run at about 70% of measured max heart rate, and often runs below it. It is a ceiling, not a target. Walk hills if you need to.[2]
The Sunday long run stays easy too. A starting point is about 1.7 times your normal easy run: if a regular easy day is 45 minutes, Sunday is around 75 to 80 minutes. Higher-volume runners reach about 95 to 105 minutes.[2]
Same idea as 80/20, different hard minutes
Both Norwegian singles and polarized training keep most of the week easy.[7] The difference is where the hard minutes go. Polarized plans put them above threshold. Norwegian singles keeps them just below it, which costs less recovery and lets you do it three times a week.
