Few training ideas have spread through distance running quite as quickly as the Norwegian double-threshold method. Popularised by the Ingebrigtsen family and the coach Marius Bakken, the approach builds a training week around large volumes of controlled threshold work — often two threshold sessions in a single day, morning and evening — performed at blood-lactate levels of roughly 2 to 4 mmol/L. A systematic literature review completed in January 2026 set out to establish how much of the method’s reputation is backed by evidence, and how much rests on the results of a handful of exceptional athletes.
The mechanics are deceptively simple. Rather than hammering a small number of very hard interval sessions, the double-threshold runner accumulates time at a controlled, sustainable intensity, typically splitting the day into two efforts of 20 to 40 minutes of threshold running with six to ten hours of recovery in between. The theory is that keeping each session just below the point of serious fatigue allows an athlete to absorb a far greater weekly volume of quality work without tipping into the deep recovery cost that maximal intervals demand.
The reviewers’ central caution is an important one: no randomised controlled trial has yet directly compared polarised training with the Norwegian double-threshold model. Much of the supporting evidence is observational, drawn from what the world’s best middle- and long-distance runners are actually doing rather than from controlled experiments on ordinary athletes. That does not make the method wrong — the physiological rationale is sound and the elite results are hard to argue with — but it does mean the strongest claims should be treated with appropriate humility.
For recreational runners, the practical takeaway is one of proportion. The literature suggests that the greatest gains for most amateurs come not from replicating a full elite double-threshold programme but from simply doing more consistent, well-judged threshold work than they currently manage. Coaches typically advise starting with one or two threshold sessions a week and building towards two or three at most, with careful attention to pacing by feel or, ideally, by lactate or heart-rate feedback rather than chasing arbitrary splits.
The method also carries real demands that rarely feature in the highlight reels. Double-threshold days require the time and recovery capacity to train twice, the discipline to hold back when the legs feel good, and enough training history to tolerate the load without breaking down. For time-pressed runners juggling work and family, a single well-executed threshold session may deliver most of the benefit at a fraction of the logistical cost. The Norwegian model, in short, is a powerful tool — but one best applied with patience, and matched honestly to the life around it.