Threshold Running: Why Tempo Pace Is Where Most Races Are Actually Won
Every runner talks about VO2max. The data says lactate threshold is what separates good performances from great ones. Here's why — and how to train it.
VO2max gets the attention in recreational running science. Lactate threshold does the work. Among trained distance runners with similar aerobic capacities, the athlete with the higher lactate threshold — the pace they can sustain before lactate accumulation begins to compound — consistently outperforms. This is because threshold pace is the pace of racing: not 5K pace, which most runners cannot maintain for distances over 30 minutes, but the sustained effort of half marathon, marathon, and beyond. Training the threshold is training the race.
The lactate threshold (specifically LT2, sometimes called the anaerobic threshold) is the exercise intensity at which blood lactate concentration begins to rise exponentially — the physiological tipping point between sustainable and unsustainable effort. Below LT2, the aerobic system clears lactate as fast as muscles produce it. Above LT2, accumulation outpaces clearance, and the progressive acidosis that follows forces pace to drop. Raising LT2 — training the body to clear lactate at faster speeds — allows faster sustained paces at the same physiological cost.
Tempo runs target this adaptation directly. The correct tempo intensity is "comfortably uncomfortable" — an effort where conversation is reduced to short phrases, breathing is rhythmic but clearly elevated, and the pace feels like it could be held for 20-40 minutes but not much longer. Daniels' VDOT system quantifies this as 83-88% of VO2max intensity. In practice, this corresponds to approximately your half-marathon race pace for recreational runners, or 15-20 seconds per kilometre faster than marathon pace.
The most common tempo training error is running too fast. A runner who logs a 35-minute "tempo" run at near-10K effort has not done a threshold session. They've done an interval session with no recovery — high lactate stimulus, high recovery cost, low threshold-specific adaptation. The tempo zone is narrow and requires restraint. Running 5-8 seconds per kilometre slower than your true threshold, consistently over weeks, produces better adaptation than occasional heroic efforts above it.
Norwegian double threshold methodology has popularised two threshold sessions per week as the central quality training structure. Both sessions target just below LT2 — fast enough to stimulate threshold adaptation, controlled enough to allow full recovery within 48 hours for the second session. This higher threshold training frequency, with all other running at genuine easy pace, produces the remarkable performance density of Norwegian elite programmes. The principle scales to recreational runners: two controlled threshold sessions per week, separated by easy days, with everything else truly easy.