4x4 interval training: Your new go-to workout

Born in Norway, the 4x4 interval protocol is four rounds of four-minute pushes, broken up by recovery. It’s a shortcut to a stronger heart, higher VO₂ max and improved endurance in less than 40 minutes.

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What if your most effective workout could fit into your lunch break? That’s the idea behind 4x4s: four minutes on, three minutes off, repeated four times. Simple. Demanding. And surprisingly effective.

Designed in Norway to maximize VO₂ and heart efficiency in minimal time, the 4x4 method came out of research at the Norwegian University of Science and Technology (NTNU). Clinical studies there showed VO₂ max improvements up to 13% in just a few weeks of training.

Runners, cyclists and hybrid athletes use it to build endurance without the endless grind of long sessions. Fitness coach and run club leader, Trey Étseyatsé, discovered 4x4s while preparing for Hyrox training. “Four minutes hard, four minutes easy was the perfect balance of intensity and recovery,” he says. “It boosted my aerobic capacity and running efficiency in a way that carried over to both my running and Hyrox [training] performance.”

This guide breaks it down so you can try it out for yourself and see why four rounds might just change the way you train.

Why 4x4s are greater than the sum of their parts

Boosts your VO₂ max

Think of VO₂ as your body’s engine size: a measure of how efficiently you use oxygen when the effort peaks. The bigger the engine, the longer and faster you can go.

You can test it in a lab or estimate it through most smartwatches that track heart rate and pace. Everyday runners tend to sit around 30, elite athletes can top 70. The higher your number, the harder you can push, and the quicker you can bounce back.

Research from NTNU shows that 4x4 intervals hit the sweet spot (85-95% of max) where true adaptations occur. Training this way two to three times a week can significantly raise your VO₂ max, improving endurance, recovery and overall performance over time. So you can:

Hold pace longer.
Bounce back quicker.
Build stamina that feels effortless.

Though your VO₂ is just a number, improving it is about the difference you feel in each workout. As Étseyatsé puts it, “It’s seeing my endurance improve, being able to push harder for longer, and finishing each interval feeling strong instead of drained.”

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Supports your heart health

4x4 training started in Norway as cardiac rehabilitation, and for good reason. Working at near-max effort strengthens the heart muscle and improves blood flow.

Research shows it can lower resting heart rate and reduce blood pressure, two key markers of cardiovascular health. That’s why the Norwegian 4x4 remains a staple in rehab programs around the world.

For athletes, it’s the same story. A proven way to keep your heart strong and resilient for what’s next.

Revs metabolism beyond the workout

One of the biggest benefits of interval training is that the work doesn’t end when you stop. Thanks to a process called post-exercise oxygen consumption (EPOC), your metabolism stays elevated for hours after a session.

Those four-minute pushes drive your system into high gear. As your body restores balance, it keeps consuming oxygen and energy well after the workout window.

Where steady-state cardio mainly works during the activity, 4x4 intervals keep the benefits rolling into recovery, turning downtime into part of the training effect. It’s hardly surprising this has become one of the most popular workouts for runners looking to maximize every moment.

Fits serious training into less time

The beauty of Norwegian 4x4 interval training lies in its time efficiency. In just 35 to 40 minutes, you can unlock gains in VO₂ max, endurance and heart health, without stacking hours on your schedule. Two to three sessions a week are enough to see progress.

As fitness coach Étseyatsé says, “It’s intense but never completely draining. Holding that intensity for four minutes at a time is tough, but finishing strong and knowing each interval is building my endurance and efficiency keeps me coming back.”

Flexible by design, 4x4 intervals let you dial effort up or down depending on how you’re feeling. That makes it a perfect fit for busy weeks. Targeted, effective, and hard to skip once you’ve tried it.

How to crush a 4x4 workout

A 4x4 session is simple but it isn’t easy. You’ll need focus, consistency and about 40 minutes, including a warm-up and cool-down. It’s not an everyday workout. It’s intended to push your limits, and recovery is part of the plan.

Here’s how to do it right so you get the most out of every interval.

1. Start with a proper warm-up

A good warm-up is non-negotiable. It gets the blood flowing, loosens muscles and primes your system for the work ahead.

Spend about ten minutes on building effort. You can try easy jogging, dynamic stretches — anything that gradually lifts your heart rate to around 50%-60% of max. The goal is to feel ready for the 4x4 interval training, not tired.

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2. Hit your first 4-minute push

Now the interval training work begins. Go for four minutes at 85%–95% of your max heart rate (or about a 7-8 on the effort scale). This should feel tough, but sustainable.

Run, cycle, jump rope, do burpees, mountain climbers, squat jumps – anything that keeps your heart racing. You can stick with one move for the full four minutes or rotate two to three exercises to keep intensity high. Keep the effort steady, and pay attention to how your body feels as the minutes tick by.

Coach Étseyatsé breaks it down: “I focus on staying relaxed, keeping my form solid, and controlling my breathing, even when my lungs and legs are burning. I break it down minute by minute.”

Start steady, then build. You want to make sure you can endure the entire interval: this is four minutes of controlled intensity.

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3. Recover, but keep moving

Recovery is not a full stop. It’s still part of the workout and meant to flush the legs and get you ready for the next interval. After each push, keep moving at a low intensity for three minutes. Aim for about 60%-70% of your max heart rate, or a 3-4 out of 10 on the effort scale.

Étseyatsé uses this time to reset. “I use it to slow my breathing, shake out my legs, and prepare mentally for the next push so I can go in strong again,” he says.

Think of this as active recovery. Walk, jog, cycle, just don’t stop. You want to maintain momentum while lowering effort, so you’re ready for the next round.

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4. Repeat it four times

Complete this cycle of four-minute high-effort pushes. Four recoveries. That’s the 4x4. Stick to the cycle: four minutes on, three minutes off. Four rounds total.

Étseyatsé’s advice for beginners: “Don’t worry about hitting [the] perfect pace. Just get through four minutes of effort while keeping your form and breathing under control. Gradually, your body and mind will adapt, making each session feel more manageable and rewarding.”

As you progress, you can play with shorter recoveries or higher effort, but quality comes first. Each interval is a chance to test your limits (within reason) and build aerobic capacity.

5. Cool down and call it a win

Wrap it up with five minutes of light movement. Walk, jog, spin, whatever helps bring your heart rate down. Then follow it with some static stretches to release tension and keep soreness at bay.

And don’t skip the kudos. Recovery is where the gains stick, so give your body the chance to absorb the work. Each 4x4 you finish builds strength, resilience and momentum for what’s next.

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Make every interval count

Whether you want to increase running endurance or simply find an efficient workout, 4x4s prove that progress doesn’t have to take hours. Backed by decades of research and proven across sports, these high-intensity rounds turn into measurable gains.

And the right running gear makes it easier to give it your all. From cushioned shoes to breathable apparel, choose from plenty of pieces that support you through the highs and lows of training.

“Shoes that provide a balance of cushioning and responsiveness, like the Cloudmonster Hyper, help protect my joints during the hard efforts while giving me the energy return I need to push,” says Étseyatsé. “Knowing my gear is reliable lets me focus fully on the work and makes both the intense and recovery moments more effective.”

Lace up, set your timer, and see what you can do within four focused minutes.