Guides · Norwegian 4x4 treadmill speed
Norwegian 4x4 treadmill speed: how to find yours, and when to judge it
You are one minute into the first rep of your first Norwegian 4x4 at 7.8, a 7:42 mile, and your watch shows only 80 percent of your max. Your thumb hovers over the up arrow. Is the speed too easy, or is your heart still catching up?
There is no set treadmill speed for the Norwegian 4x4. The right setting lifts your heart rate to 85 to 95 percent of your max within one to two minutes of each rep after the first, then holds it there. Judge the speed at minute two, not minute one.
Your heart rate arrives late
The 4x4 is four hard reps of four minutes, with three easy minutes between them. Your heart rate decides how hard a rep is, and the speed you type in only serves it. A Norwegian university heart lab that recommends the protocol puts the reps at 85 to 95 percent of your max heart rate and the breaks near 70 percent. One 2007 trial of the protocol followed 40 moderately trained men for eight weeks and used 90 to 95 percent.
Your heart does not jump to a new level the moment the belt speeds up. It climbs first. The lab expects the climb to take a minute or two in each rep after the first. For the first rep, it is satisfied if you touch 90 percent at some point in the four minutes. A reading at minute one tells you very little about the speed you chose. Mostly it tells you that your heart is still on its way.
Think of a car heater on a cold morning. You set the dial, and the cabin takes a few minutes to warm up. If you crank the dial to the top because the air still feels cold after thirty seconds, you are roasting by the next light. The dial also keeps showing the number you picked, whether or not the heater can deliver it. The speed button in a 4x4 rep behaves like that dial. A press at minute one is a press you pay for at minute three.
How to find your setting
- Start at a speed you are sure you can hold for four full minutes.
- Check your heart rate at the end of minute two, then again at the end of the rep.
- From rep two on, if your heart rate has not reached 85 percent by the end of minute two, raise the speed a little for the next rep. Leave it alone while your heart is still climbing.
- If your heart rate passes 95 percent, ease the next rep down the same way.
The setting that keeps reps two to four inside the band is your 4x4 speed on that machine, on that day. A layout the lab describes, from a study of teenagers, also includes a 10-minute warm-up before the first rep.
Incline is the other dial
Some runners only reach the band at a speed they cannot hold for four minutes. The lab's answer is grade. A high pulse is easier to reach uphill, because more of your muscles are working, unless you are already a very good runner. Uphill running is also gentler on your muscles and joints. On a treadmill, that means you can add grade until your heart rate lands in the band, then keep the speed you can hold. The display shows the grade you asked for, and whether the deck really sits at that angle is a separate question, covered in the guide on whether your treadmill incline is accurate.
The speed you programmed is a request
The same lab notes that a treadmill makes it harder to cheat, because you programmed the speed and the incline. For effort, that holds up. The belt will not let you drift off the pace when the third minute starts to hurt. That says nothing about what the pace really is, though. Like the heater dial, the display shows what you asked for.
In a lab check of four treadmills, average belt speed varied between about 98 and 103 percent of what the belt was set to. Picture two made-up belts at the edges of that range, one 2 percent slow and one 3 percent fast. Your 7.8 rep, a 7:42 mile on the display, would really be a 7:51 mile on the slow belt and a 7:28 mile on the fast one. The rep pace you write down as your 4x4 speed, and later chase as progress, is one belt's claim, so a new machine can make you look fitter or slower overnight. Your heart rate travels from machine to machine while the setting stays behind, which the guide on treadmill speed for zone 2 explains.
Check the setting you hold longest
Here is a 40-minute layout built on the one the lab describes for that study, with made-up settings.
Where a 40-minute 4x4 spends its time
Example settings only, not a speed we prescribe. Your own come from your heart rate.
| Block | Minutes | Example speed (mph) | Pace per mile |
|---|---|---|---|
| Warm-up | 10 | 5.2 | 11:32 |
| Four hard reps | 4 x 4 | 7.8 | 7:42 |
| Three easy breaks | 3 x 3 | 5.2 | 11:32 |
| Cool-down | 5 | 5.2 | 11:32 |
That adds up to 24 minutes at the easy setting and 16 at the hard one. The easy setting, 5.2 in the example, is the one you hold longest, so it is the one worth checking. Treadwell uses an iPhone Pro's camera and its LiDAR to read how fast a belt really moves. Take your reading at the warm-up and break setting, with nobody on the deck, once the belt has come up to speed. It tells you how this belt runs at that setting. It does not vouch for your rep setting, so keep judging the reps by heart rate.
Know what your break setting really runs
Before your next 4x4, read the belt at the setting you use to warm up and recover. Treadwell runs on an iPhone Pro, because the reading needs its LiDAR sensor.
Scan with your iPhone Pro to get the appQuick answers
What treadmill speed should I use for the Norwegian 4x4? There is no set treadmill speed for the Norwegian 4x4. The right setting lifts your heart rate to 85 to 95 percent of your max within one to two minutes of each rep after the first, then holds it there. Judge the speed at minute two, not minute one.
What incline should I use for the Norwegian 4x4 on a treadmill? The lab's advice sets no grade for it. Incline is a second way to raise the effort, since a Norwegian university heart lab that recommends the protocol says a high pulse comes more easily uphill. If your heart rate will not reach 85 percent at a speed you can hold for four minutes, add grade until it does. Choose the grade before the rep starts and judge it at minute two, the same as speed.
Why is my heart rate still low in the first minute of a 4x4 rep? Heart rate needs time to climb after the effort goes up. A Norwegian university heart lab that recommends the protocol expects one to two minutes to reach the target in each rep after the first, and in the first rep the lab only asks that you touch 90 percent at some point. Raising the speed at minute one chases a number that was already on its way. Wait for minute two, and make any change on the next rep.
Sources.
- The lab: NTNU's Cardiac Exercise Research Group (CERG), a Norwegian research group that uses and recommends the method, "Exercise advice", ntnu.edu/cerg/advice, read 2026-10-09. It gives the 85 to 95 percent band, is "happy as long as you reach 90 %" in the first interval, expects later intervals to take 1 to 2 minutes to reach the right intensity, says a high pulse is easier to reach uphill and that uphill running spares muscles and joints, and says it is easier not to "cheat" on a treadmill because you programmed the speed and inclination. The 10-minute warm-up, 3-minute breaks at 60 to 70 percent and 5-minute cool-down come from a study of teenagers it summarises, which is why this page treats the 40-minute session as a worked example rather than the lab's rule.
- A 2007 trial of the protocol: Helgerud J, Høydal K, Wang E, et al. "Aerobic high-intensity intervals improve VO2max more than moderate training." Medicine and Science in Sports and Exercise, 2007;39(4):665-71. Forty moderately trained men, four minutes at 90 to 95 percent of max heart rate with three minutes of active rest at 70 percent, three days a week for eight weeks. The abstract does not say the running was done on a treadmill.
- Belts against the speed they were set to: a lab study of four treadmills by Willwacher and colleagues, published in Scientific Reports in 2021 (volume 11, article 2244). Across the four treadmills, average belt speed came out somewhere from about 98 to 103 percent, measured against the speed each one was asked for.
- My own notes: the 7.8 and 5.2 settings, the belts 2 percent slow and 3 percent fast, the 40-minute session math and the car heater are an illustration, not a session or a machine I measured. Paces are my arithmetic.