The Norwegian 4x4
Repeat four hard four-minute intervals with controlled recovery
- Difficulty
- Advanced
- Time to result
- ~weeks to results
- Steps
- 6
- Confidence
- 99%
Estima presents the Norwegian 4x4 as an indoor alternative when track sprinting is impractical. On a bike, treadmill, or another cardio machine, the trainee works for four minutes at 85 to 95 percent of their known maximum heart rate, recovers for three minutes, and repeats the work interval four times. The name encodes the central structure: four minutes, four rounds. The mechanism is repeated exposure to a high but bounded cardiovascular intensity, separated by enough recovery to attempt the next interval. Estima connects the method to improving VO2 max and cites a study in older women, but the episode does not provide enough study detail to independently verify the reported percentages. Because the session is demanding, individual readiness and medical context matter more than copying the numbers blindly.
Origin
Estima describes using the established Norwegian 4x4 protocol on an indoor bike during winter; extracted from The Diary of a CEO.
Core principles
- 01Cardiorespiratory capacity must be trained to be retained
- 02Hard intervals alternate with deliberate recovery
- 03Intensity should be anchored to an individual maximum
- 04The protocol can transfer across cardio machines
How to run it
- 1
Check readiness
Select a modality you can perform safely and confirm that vigorous interval work is appropriate for you. Use professional guidance when health status or symptoms make that uncertain.
Pro tip A stationary bike can reduce the coordination demands of track sprinting.
Watch out Do not treat a podcast protocol as medical clearance.
- 2
Set the intensity reference
Use a credible personal maximum heart-rate value, which Estima describes as the highest heart rate actually achieved. Calculate the 85 to 95 percent working range.
Watch out An inaccurate maximum makes the target range unreliable.
- 3
Warm up
Raise effort gradually before beginning the first hard interval. Make sure the chosen movement and equipment feel stable.
Watch out The transcript specifies the interval structure but not a warm-up duration.
- 4
Complete four hard minutes
Work for four minutes within the stated 85 to 95 percent range. Keep the effort controlled enough to complete the interval safely.
Pro tip Use heart-rate feedback rather than guessing from speed alone.
Watch out Stop for concerning symptoms rather than forcing the clock.
- 5
Recover for three minutes
Reduce intensity for three minutes so you can attempt another quality interval. Continue moving at an easy level if appropriate for the modality.
- 6
Repeat and record
Complete four total work intervals, then cool down. Record heart rate, completion, and recovery to guide future sessions.
Pro tip Consistency matters more than making one session maximally punishing.
In the wild
When East Coast weather prevents track sprinting, Estima uses a bike. She performs four minutes at 85 to 95 percent of maximum heart rate, takes a three-minute break, and repeats the interval four times.
→ The indoor machine preserves a structured high-intensity session when outdoor sprinting is unavailable.
Common mistakes
Using an ungrounded heart-rate target
The protocol's working range depends on a credible individual maximum rather than a copied absolute number.
Skipping readiness checks
A vigorous interval prescription should not be copied without considering conditioning, symptoms, and relevant medical context.
Turning every session into a 4x4
Estima presents this as one sprinting option, not a complete weekly exercise programme.
Is it for you?
Best for
It is best for appropriately screened, experienced exercisers who want a demanding VO2-max-oriented session.
Not ideal for
It is not ideal for an unconditioned person, anyone with relevant symptoms or contraindications, or someone without a safe way to gauge intensity.
From the transcript
“85% to 95% of your heart rate max.”
“Then you take a three-minute break. And then you do that again four times.”
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