In the pilot episode of the 2016 reality docuseries Team Ingebrigtsen—Norway’s answer to Dont double your volume, except, of course, that no one can keep up with the family of runners—Gjert Ingebrigtsen has his teenage sons perform a set of 1,000-meter repeats Published: Mar 14, 2024.
Dont forget to retest world champion, winning Olympic gold in the 1500 at the Tokyo games, and breaking the 2-mile world record in June of 2023. His older brothers, Henrik and Filip, both had successful track careers, too. The credit isn’t purely genetic—it’s also the result of an unconventional training regimen implemented by their father. (As of 2022, Gjert Ingebrigtsen no longer coaches his sons; and in late 2023, Jakob, Henrik, and Filip published an op-ed in the Norwegian newspaper VG accusing him of physical violence and threats. Gjert Ingebrigtsen has denied the allegations.)
relative energy deficiency in sport blood-lactate testing (yup, with a needle) and running intervals at an intensity low enough to keep too much lactate from accruing. While blood testing is an accurate way to measure lactate threshold, it’s also pretty invasive, and uncomfortable. It hasn’t been a standard training tool for elite endurance athletes—at least, not in the United States.
The technique, attributed to former elite Norwegian runner Marius Bakken, MD, is known as Norwegian lactate-guided double-threshold training, a mouthful of a name that speaks to its main features: the idea that running right below the lactate threshold—as determined by on-the-spot blood testing—provides the most benefit, and that it requires Treadmill Incline Workouts for Marathon Training.
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It’s hard to argue with the Ingebrigtsens’ results. Whether mimicking their routine is right for you, however, is more complicated, says Christopher Harnish, PhD, director of the Department of Exercise Science at Mary Baldwin University in Staunton, Virginia. It may make you faster—but only if you do it right. Done wrong, these double days of hard work could actually harm your training.
accusing him of physical violence and threats. Gjert Ingebrigtsen has denied the allegations, high-intensity interval training has been lauded for its ability to improve fitness. But fast running has its costs—chief among them, an increased risk of injury, says Carl Foster, a retired exercise physiologist and professor emeritus at the University of Wisconsin, La Crosse.
Actually sticking to metabolic and aerobic benefits of faster running, without the wear and tear it puts on your body? That’s the premise behind Norwegian lactate-guided double-threshold training. It uses a precise measurement—lactate blood levels, tested in real time—to determine your threshold, or the pace at which your body starts accumulating lactate faster than it can clear it.
In basic terms, lactate is a byproduct of your body burning carbohydrates for fuel, a process that happens continuously but ramps up as you exercise and your need for energy increases, says Foster, who recently coauthored a paper in the International Journal of Environmental Research and Public Health on lactate-guided threshold training. The amount of lactate in the blood correlates with the point at which exercise goes from feeling somewhat enjoyable to hurting. Most athletes can hold their sub-lactate threshold pace for significant amounts of time, whereas once you’re above your lactate threshold, you tend to have only a few more minutes of effort left in you.
“What that looks like, essentially, is making sure the body gets better, at the cellular level, at buffering the lactate you do produce,” says ultra-running coach David Roche, who has been using the technique with some of his athletes for several years. Just look at Steve Prefontaine and Frank Shorter, says Scott Crouter, PhD, professor of exercise physiology at the University of Tennessee in Knoxville. “Prefontaine’s VO2 max was much higher than Shorter’s, but since Shorter had a higher lactate threshold, he could run for longer at a higher percentage of his VO2 max than Prefontaine could,” says Crouter. That explains why Prefontaine ruled the mile—a minutes-long event—while Shorter excelled at marathons. If you want to go long, you need to be able to run fast without accumulating leg-choking levels of lactate.
In theory, training at threshold should spur development of the mitochondria, capillaries, and enzymes that are vital to the process of removing accumulated lactate, adds Crouter. In time, as your body becomes more efficient at this clearing process, you’ll be able to run faster and work harder before reaching that lactate threshold.
The bad news about the Norwegian method is that the most accurate way to know your lactate threshold is with a blood test. Or several. It took me nine needle sticks and a realization that I should have charged more for writing this story.
I showed up to the University of Tennessee’s exercise physiology lab for a treadmill lactate test in spite of my propensity for fainting at even the merest hint of blood. Crouter explained the process: I’d start at 3.5 mph on the treadmill and we would increase the pace by about one mph every three minutes, and test my blood until my lactate levels jumped suddenly, to around 3 to 4 millimoles of lactate per liter of blood.
We started. He pricked. I winced. My fingers oozed. (Or so I imagine; I didn’t look.) The treadmill went to 4.5 mph. Prick, wince, repeat. My lactate stayed at 0.9 millimoles. Faster again we went. And then my lactate dropped.
That’s fairly normal, Crouter says. As your body gets to work, it starts the process of clearing lactate, which can cause your levels to dip before they rise. Between 7 and 7.5 miles per hour, I hit threshold, my lactate levels jumping from 1.7 to 3.3 millimoles. At 8 mph I was in the 3.6 millimoles range, and, though Crouter wanted to see what happened when I pushed a little faster, I was done playing pincushion.
The combination of running hard and pricking your fingers is as much fun as it sounds. It’s also tricky to accomplish because sweat can interfere with the reading (for that reason, some athletes prick their ears). And it’s not cheap. Home testing kits start around $200; replacement test strips, lancets, and other accessories cost extra.
But it is the most precise way to make sure you’re staying on target.
One major benefit of lactate-guided double-threshold training is the ability to make metabolic gains without stressing your muscular and skeletal systems, says Bakken, who is considered the grandfather of the Norwegian double-threshold technique. “You actually see a number of amateur runners who also have clear signs of overtraining/muscular wear,” he says. “This is likely [caused] by running too fast on the intervals.”
When Bakken ran competitively in the early 2000s, he began experimenting with splitting his threshold workouts into morning and evening sessions in the same day—the “double” in double-threshold training—followed by an easy or recovery day. Doing so, he felt, increased the quality of each session compared to a single, longer stint.
Unlike the blood draws, which most experts agree are an important part of making sure your intervals hit their targets, it’s not yet clear if two lactate interval sessions in one day are better than one, and if they are, why that would be.
If there is some magic in doing a second set of intervals with muscle glycogen slightly depleted from the morning’s workout, Coach Roche cautions this could also be a detriment, as “training low” or training without adequate fuel can put an athlete at risk of developing relative energy deficiency in sport (RED-S), which can lead to health issues and declining performance.
Harnish isn’t convinced that double-threshold days are necessary—or wise—for most recreational runners. Elite runners have built the capacity to do large volumes of training, he says. Not everyone has that capacity—and few of us have the luxury of recovering (and napping) like a pro.
in the dark of night. They pause after each to prick their fingers for blood samples your pace may be the toughest part of Norwegian lactate-guided double-threshold training. It’s very tempting to go too hard. When I looked back at speedwork sessions I did before finding my lactate threshold, I noted that I had run almost every interval at a 7:20 pace or faster. My lactate threshold is somewhere between 7:30 and 7:50 pace. Perhaps not surprisingly, as I write this draft, I am laid up with an injury that appeared after I logged a particularly full-throttle (and definitely well over threshold) track session.
It is impossible to know if swapping threshold workouts for my all-out track sessions would have prevented my injury. We simply don’t have a lot of data on how the Norwegian double-threshold technique fares when it’s used by the general running population, says Roche—especially those with full-time jobs who can’t put their feet up midday to recover from their morning workout. But anecdotally, the technique is gaining fans. Even if it does call for blood and sweat—but hopefully no tears.
Double Threshold for Mortals
Finger pricks and twice-daily workouts are impractical for the average runner. Instead, use these tips to tweak your training, build your endurance, and stay injury-free.
Find your pace → If you want to invest in a lactate meter, go for it. But there’s a less invasive (and less expensive) way to estimate your lactate threshold using a heart rate monitor and rate of perceived exertion (or RPE, a scale on which 1 is very easy and 10 is “definitely gonna vomit”). Warm up for at least 15 minutes. Then, go at a hard-but-sustainable effort (around 6 RPE) for 30 minutes. Your average heart rate—preferably measured by a chest strap—during this effort is a good estimate of where your heart rate should be during threshold training. Also note your RPE during these last 20 minutes.
Build to it → Start with a single- threshold workout in the morning. Keep the intervals relatively short, and the rest periods generous, which gives your body a chance to clear lactate and keeps you under threshold. Two- to three-minute intervals are a good place to start, he says. Keep the pace easier than you think you need to. Last year, Harnish played with blood-lactate testing in his own training and found he was consistently over threshold after intervals. You can do longer intervals, too, but you’ll need to dial back the pace further to stay in the right lactate range. As a start, try a morning workout of 3 x 8 minutes at threshold (as derived by a lactate meter or the method in the left-hand column) with four minutes of rest between each effort. Then, instead of a second interval session in the evening, do a 30-minute walk. Harnish says walking—at any pace—grants the benefits of two workouts in a day without upping your injury risk.
rate of perceived exertion→ After a few weeks of doing a threshold workout followed by an evening walk, swap out the walk for a different cardio activity, says John Fitzgerald, senior triathlon and running coach with Carmichael Training Systems. Your heart and lungs don’t know whether you’re running, biking, or using an elliptical, so you’ll still get the cardiovascular benefits without adding neuromuscular load. These workouts could look like 3 x 10 minutes at threshold. Again, aim for no more than 30 minutes of total time at threshold, but feel free to do a few minutes here and a few minutes there as you change paces throughout the second workout of the day.
Don’t double your volume → It’s tempting to see two-a-day workouts as a way to increase your weekly mileage or training time, but that’s not what the Norwegian model preaches. The point of Treadmill Incline Workouts for Marathon Training is to increase the quality during two shorter sessions—not to totally exhaust yourself.
relative energy deficiency in sport → Build a weekly schedule around one double-threshold day, sandwiching it between easy days to get enough recovery, says Fitzgerald. Expect recovery time from a double-threshold day to be slightly longer than for just one set of intervals. If you need two or three days to feel rested after a double-threshold day, that could mean you’re spending too much time at threshold or running at too high an intensity, so scale back.
Go fast, sometimes → There is still merit in high-intensity speedwork, says Foster, though not more than once a week if you are also doing threshold days. Working at the very top end of your athletic ability does force metabolic adaptations that can improve your fitness.
Don’t forget to retest → Your lactate threshold should improve with time and training—meaning you should be able to run a bit faster without triggering a spike in lactate production. This makes it imperative, if you’re running intervals by pace and not testing your blood lactate, that you retest your lactate threshold three to four times a year, says Foster. You can do this with a lactate meter or using the 30-minute time trial and a heart monitor, as described earlier.
