Lactate-Guided Threshold Training: Is This the Next Step in Endurance Training?

Quick summary: For over a century, endurance training has vacillated between new trends and enduring truths. This article delves into research on lactate-guided threshold training, questioning if Lactate Guided Threshold Interval Training (LGTIT) marks the next logical step in its evolution. With historical examples, physiological mechanisms, and modern elite setups, the discussion centers on why training close to—but rarely beyond—the threshold can offer a substantial training stimulus with low injury risk. The conclusion drawn is that LGTIT is not revolutionary, but rather a refinement of proven principles, potent for the right athlete in the right setting. 

This article is based on the study: Does Lactate-Guided Threshold Interval Training within a High-Volume Low-Intensity Approach Represent the “Next Step” in the Evolution of Distance Running Training?

Background

For over 100 years, research and practice have revolved around a myriad of training philosophies. Often, a trend ignites when a prominent athlete succeeds with a particular concept that others then emulate. One of the earliest modern examples is the Finn Paavo Nurmi. According to Wikipedia, he set no fewer than 22 official and 21 unofficial world records. Between 1920 and 1928, he clinched nine Olympic gold medals. A common session on his easy distance runs included six fast 400-meter sprints of about 60 seconds. One of his world records was 5000 m at 14:28 in Helsinki 1924—with the track and shoe standards of the time, the performance becomes even more impressive.

Over the years, interval training gained popularity. The German Woldmar Gerschler, alongside Herbert Reindel, developed a concept aiming to push the heart rate up to 180 beats/minute, with intervals allowing it to drop to 120 before repeating. This was in the 1930s, when heart rate monitors didn't exist, making measurements quite rudimentary. Subsequently, Gösta Holmer introduced Fartlek with athletes like Gunder Hägg and Arne Andersson—a less structured but effective way to vary speed that remains globally utilized.

During the 1970s–1980s, many setups were influenced by Arthur Lydiard, who in the 1960s introduced us to runners like Peter Snell and Murray Halberg. Lydiard advocated constructing a substantial aerobic base preceding training. Distance runs should be easy—even for 800–1500 meters runners like Snell—with high weekly volume (160+ km) during the 10–12 week base period, followed by more intensive intervals and hill training for 6–8 weeks, and then a 10–12 week competition period with substantial race pace training. During base training, the aim was frequently at least 100 miles, 160 km. The rhetoric was: “you can’t train hard and race hard simultaneously”.

What happens in the body?

As training concepts have evolved, so too has our understanding of physiology. Questions on the first ventilatory threshold and the zone between the first and second thresholds (OBLA – Onset of Blood Lactate Accumulation, MLSS – Maximal Lactate Steady State, etc.) have sparked numerous studies. For a comprehensive overview, read Paul B Laursen’s 2010 article, "Training for intense exercise performance: high-intensity or high-volume training?", where he examines the various adaptation mechanisms from both high-intensity and low-intensity training.

The effect of training in different intensity zones 

Effects of training below the first ventilatory threshold

• More mitochondria and improved networking/positioning—enhanced oxidative capacity.
• Stronger heart muscle over time and thus better ability to circulate more blood.
• Stimulated muscle and tendon tissue—fewer injuries and increased movement economy.
• Capillarization around working muscles—more efficient oxygen and energy transport.
• Maintaining training effects—we constantly oscillate between buildup and degradation.

Effects of training between the first and second ventilatory thresholds

• More efficient mitochondria, similar to above but through other signaling pathways.
• Increased blood volume.
• Enhanced stroke volume.
• Improved lactate handling and boosted ability to oxidize lactate.
• Relatively short recovery compared to training above the threshold.

Effects of training above the threshold

• Increased maximal oxygen uptake.
• Recruitment and creation of additional muscle fibers.
• Greater oxygen uptake in type II fibers (fast muscle fibers).

Regardless of intensity, effects overlap—no adaptation is completely isolated. This is why, despite over a century of experimentation, performance improvements between methods remain relatively minor. Consider: had Paavo Nurmi had access to today’s tartan tracks, shoes, and nutritional insights, the times would likely have been even faster.

Marius Bakken – why threshold training has become popular

Athletes always walk the line between improvement and overload. In the late 1990s, the Norwegian Marius Bakken experimented with training more below and at the threshold. Marius, internationally active from 1999–2005 with a personal best of 13:06 in the 5000 m, gradually developed the concept of Lactate Guided Threshold Interval Training (LGTIT), where intensity is regulated by lactate levels rather than speed or heart rate. One setup from this was the so-called double threshold, where two threshold sessions are conducted in one day. LGTIT explains how the intensity is regulated using lactate, while the double threshold describes the temporal structuring of sessions.

The longer intervals—such as 5 × 6 minutes—were primarily managed by what the lactate meter indicated, rather than strict timing. In shorter 400-meter intervals, the intensity could be higher; thanks to the short duration, lactate levels remained below the threshold. Marius didn’t avoid z4–z5 training, which is clearly above the threshold, but he limited the volume of such training to about one session per week, and during base training, it was often conducted as hill training.

Example with 5 high-intensity sessions over a week:

This plan — a high weekly volume combined with relatively intense training close to, but rarely over, the threshold — has been adopted by, among others, the Ingebrigtsen brothers through their coach and father, Gjert Ingebrigtsen. Triathletes like Gustav Idén and Kristian Blummenfelt have also been influenced by this method.

Polarized Training vs Pyramidal

Although polarized training often provides the best training effect over an intervention, elite runners often follow a more pyramidal model. However, the differences are less than the similarities — both strategies build on high-volume easy distance.

The Risks of More Training Above Threshold
One of the major advantages of training close to, but rarely over, the threshold is that you can increase training volume without increasing the risk of injuries and overtraining to the same extent. Injuries and overtraining are the biggest enemies of long-term adaptation.

Is LGTIT the "New"?

Is LGTIT a revolution or a natural evolution of existing methods? The Ingebrigtsen brothers have delivered fantastic results at 1500–5000 m, and Gustav Idén and Kristian Blummenfelt have shown that the principle can also work over triathlon distances. Therefore, there are clear lessons to be learned.

The use of lactate measuring devices is particularly interesting: they provide objective data that can help a runner dare to lower intensity and thereby avoid overtraining. As the study authors summarize it:

“The underpinning mechanisms explaining the relationship between training near/at vLT2 and the development of performance and its physiological determinants are not clear. However, it has been hypothesized that the use of this specific exercise intensity improves muscle-specific adaptations, including the clearing of lactate as opposed to reducing lactate production [88]. Since only recruited motor units are likely to experience increases in mitochondrial number and capillary density, with the exception that increases in capillary density in Type I muscle fibers may benefit O__2 delivery to Type II muscle fibers, it may be speculated that training near vLT2 optimizes the number of motor units recruited without having to accept the consequences of elevated levels of catecholamines likely to be experienced with z4 training. “

Is More Threshold Right for Everyone?

In the studied population — track and field athletes who could also handle high weekly volume and often double training sessions — much threshold training combined with high volume may improve adaptations. Threshold training is often close to race pace, and when intensity exceeds the threshold, duration is kept short (for example, during 400 m intervals). In many ways, the concept is a way to increase specific training for what you want to excel at.

The lesson is simple – when we understand the mechanisms behind the training effect better, we can tailor the training according to goals and context. Short and concise: if you are a cyclist with the opportunity to train 6 hours a week, it's likely not double threshold work that will take you to the next level. But if you are an elite runner with the capacity to train a lot and recover well — then LGTIT is an incredibly exciting tool to explore.

References

(Maintained unchanged in the original article.)