Norwegian double threshold
A description of how a few world-class runners train, not a tested method: no trial compares double-threshold days with anything, so below elite volume and without a lactate meter the answer is one or two sub-threshold sessions inside the week's quality budget, and it fits "80/20" only because the sessions stay below threshold
The question it answers
"Should I do double threshold days?", "is the Norwegian method compatible with 80/20?" and, for the few it fits, how to run a double-threshold day. Threshold formats, the intensity anchor and the default threshold session are SYNTH-27; how many quality sessions a week can hold is SYNTH-26; this entry does not restate them.
Default (what to prescribe first)
Not double threshold. For a Tier 1-3 athlete the default threshold prescription is the one in SYNTH-27 (B): one sub-threshold session a week as one of the week's quality days, a second only above ~8 h/week (that framework's own base practice). A double-threshold day is considered only when all four hold — not from a study; the base's own practice, set so that it cannot exceed the session budget of SYNTH-26 and SYNTH-27:
about 12 h/week or more of real training, the band where SYNTH-26 (B, its hour bands are base practice) says elite templates start to apply as written;
Tier 3 or above with a consistent base (SYNTH-27: not for Tier 1-2);
blood lactate is measured during the session — the method is defined by a lactate target checked every one to three repetitions (REF-301, B+);
the athlete already trains twice a day on some days and recovers from it.
If any one is missing, say so plainly and offer the adaptation: "two quality days a week, sub-maximal, stopped before it becomes hard" — which SYNTH-27 presents as an adaptation of the idea, not as the method.
Decision (who → what)
The left and middle columns are the base's own practice throughout (no entry tests who should run double days); the right column is what the cited entries say.
| Athlete | What to prescribe | Source and how sure |
|---|---|---|
| Under ~8 h/week, or Tier 1-2, any equipment | No double days. Two quality sessions a week in total, threshold is one of them | SYNTH-26 B+ (two quality sessions at 5-8 h, "do not add a third"; base practice); SYNTH-27 B+ |
| ~8-12 h/week, Tier 3 (Tier 2: the row above) | Still not the method. At most two sub-threshold sessions a week, on separate days. One long session may be split into morning and evening when it does not fit the day or costs too much — that is splitting a session, not adding one | SYNTH-27 (two threshold sessions only above ~8 h; base practice). The same 60 min split into two sessions 6.5 h apart gave a lower session load (sRPE 743 vs 929) and less next-morning fatigue in 14 well-trained male endurance athletes, running — acute responses, no adaptation measured (REF-159, B) |
| 12 h+/week, Tier 3+, lactate meter, used to two-a-days | One double-threshold day a week (two sub-threshold sessions) plus one harder session, held for a block and judged on a marker chosen in advance (SYNTH-42). A second double day only if the first is absorbed | No trial. The nearest evidence is a different design: six sub-threshold sessions in seven days, then six easy days, raised power at 4 mmol/L +4.0% vs −1.3% in 30 well-trained male cyclists (REF-137, B+) |
| Tier 4-5, elite volume, coach and lactate control | The model as described: three to four lactate-guided threshold interval sessions a week plus one VO2max session, easy running to 150-180 km/week | REF-301, B+, narrative review of a small number of world-class runners; no original data |
| No lactate meter, any volume | Not the method. Sub-threshold reps by feel: "hard but manageable", RPE 14-15 | REF-137 prescribed by RPE 14-15 (lactate ~2.8 mmol/L); using that as a stand-in for lactate control in a double day is inference |
How to run a double-threshold day (only for the row that qualifies)
| Rule | What to do | Source and label |
|---|---|---|
| Intensity | Stay inside the model's band of 2-4.5 mmol/L, measured every one to three reps; pace follows the lactate, not the plan | REF-301, B+ |
| Morning vs evening | Not from a study; the base's own practice: longer reps at about 2.0-2.5 mmol/L in the morning, shorter reps at about 3.0-3.5 mmol/L in the evening | No entry gives this split; the unsourced protocol REF-015 (C) describes 4 × 16 min between LT1 and LT2 twice a day and labels its own numbers base practice |
| Execution | Controlled, not exhaustive; intensity may rise through the session; stop when lactate leaves the band | Twelve coaches of world-class athletes describe voluminous, progressive, controlled interval sessions (REF-302, B, interviews); "stop when it leaves the band" is base practice |
| Gap between the two sessions | Not from a study; the base's own practice: at least 5-6 h | The only gap tested is 6.5 h (REF-159) |
| Eating between them | Treat the gap as a recovery window; amounts are SYNTH-02, two-a-day rules are SYNTH-70 | With 4 h between bouts, fructose plus maltodextrin gave a longer second run to exhaustion than glucose plus maltodextrin at the same total (REF-734, B+, n=8) |
| Days around it | Easy the day after; spacing to the next hard session is SYNTH-70 (its gaps are base practice) | After a threshold session HRV was back to baseline in ~30 min in 9 highly trained runners, while 8 less-trained men needed ≥90 min after an interval session above VT2 (REF-161, B, acute) — the less trained pay more |
| Sessions per week | Not from a study; the base's own practice: never more than two double days (four threshold sessions), the top of the range REF-301 describes | REF-301: three to four threshold sessions a week. Elite coaches describe 2-3 key-workout days a week holding 3-5 intensive sessions (REF-138, B) |
How to progress / periodise
When NOT to use it / red flags
What the evidence does and does not show
Shows.
Does not show.
Is it 80/20? The "80/20" figure is a count of sessions in athletes training 10-13 times a week: about 80% low intensity, about 20% dominated by high-intensity work near 90% VO2max (REF-087, B+, narrative review).
Inference: a week with three to four threshold sessions and one VO2max session has only one session of the kind that 20% counts; the threshold sessions are a third category, which makes the week pyramidal with a large middle rather than polarized.
That matches how elite runners are described — typically pyramidal, with a threshold session and a faster session at least weekly (REF-811) — and world-class 1500 m runners at 90/10% of sessions below versus at or above the anaerobic threshold (REF-768, B+, narrative review).
Calling it "compatible with 80/20" is the base's own reading, valid only while the threshold sessions stay below threshold.
What goes with performance in these cohorts is the easy volume (correlational, not causal): in 85 world-class male runners easy-run volume and tempo runs explained performance variance (REF-090, B, correlational), and in eight sub-elite runners time below the first threshold tracked race time (REF-817, B, observational).
Evidence gaps
How this entry was checked and changed
(the method is described, not tested: REF-301 B+ narrative review and REF-302, REF-138 B coach accounts; the only double-day experiment is acute, REF-159 B; the nearest training trials are one-week sub-threshold blocks, REF-137 and REF-421 B+; every eligibility threshold and session rule is base practice)