Jessica Biel’s Intense Norwegian 4x4 Cardio Plan
The Norwegian 4x4 Workout: Why Jessica Biel Swears By This Cardio Protocol (And Why You Might Too)
When it comes to celebrity fitness routines, it's easy to dismiss them as unattainable or overly complicated. But every once in a while, a workout emerges that's both science-backed and surprisingly accessible—even if it's brutally effective. Enter the Norwegian 4x4 cardio workout, a high-intensity interval training protocol that has captured the attention of fitness enthusiasts and A-listers alike, including actress Jessica Biel.
So what exactly makes this workout worthy of the buzz? Let's dive in.
What Is the Norwegian 4x4 Workout?
Originally developed by Norwegian researchers studying cardiovascular health, the 4x4 protocol has been used in clinical settings to improve heart health in patients with various conditions. But its benefits extend far beyond rehabilitation—it's now recognized as one of the most efficient ways to boost cardiovascular fitness and VO2 max (the gold standard measurement of aerobic capacity).
Here's how it works:
The Structure:
- 4 sets of 4-minute intervals at 85-95% of your maximum heart rate
- 3 minutes of active recovery between each interval at 60-70% of max heart rate
- 10-minute warm-up before starting
- Cool-down period after completion
The entire workout takes roughly 40 minutes, making it a time-efficient option for those looking to maximize results without spending hours at the gym.
Why Jessica Biel Is a Fan
According to her longtime trainer Ben Bruno, Biel incorporates this challenging protocol into her routine five to six times per month. Bruno has described the workout as "extremely challenging" and a true testament to Biel's incredible work ethic.
What's notable here isn't just that a celebrity does hard workouts—it's which hard workout she's chosen. The Norwegian 4x4 isn't flashy or trendy. It doesn't require expensive equipment or a private studio. It's simply effective, grounded in research, and accessible to almost anyone willing to put in the effort.
The Science Behind the Sweat
You might be wondering: why is this protocol more effective than standard HIIT workouts?
The answer lies in the duration of the intervals.
Most traditional HIIT workouts feature short bursts of 20-30 seconds of maximum effort. While these are certainly beneficial, the four-minute intervals in the Norwegian protocol allow your cardiovascular system to spend more time in that critical high-intensity zone. This extended exposure creates powerful adaptations in your heart and lungs, leading to:
- Greater improvements in VO2 max compared to shorter interval protocols
- Enhanced cardiac output and stroke volume
- Improved metabolic efficiency
- Better endurance performance across various activities
Research published in journals like Circulation and the British Journal of Sports Medicine has consistently shown that the 4x4 method produces superior cardiovascular adaptations compared to moderate continuous training and even some other HIIT formats.
How to Try It Yourself
Ready to give it a shot? Here's your step-by-step guide:
Step 1: Choose Your Modality
The beauty of this workout is its versatility. You can perform it using:
- A stationary bike
- A treadmill (running or incline walking)
- A rowing machine
- An elliptical
- Outdoor running or cycling
Choose whatever feels most comfortable and sustainable for you.
Step 2: Warm Up Properly
Spend 10 minutes gradually increasing your heart rate. Start easy and progressively build intensity. This isn't optional—a proper warm-up prepares your cardiovascular system for the demands ahead and reduces injury risk.
Step 3: Execute the Intervals
- Interval 1: 4 minutes at 85-95% max heart rate
- Recovery 1: 3 minutes at 60-70% max heart rate
- Interval 2: 4 minutes at 85-95% max heart rate
- Recovery 2: 3 minutes at 60-70% max heart rate
- Interval 3: 4 minutes at 85-95% max heart rate
- Recovery 3: 3 minutes at 60-70% max heart rate
- Interval 4: 4 minutes at 85-95% max heart rate
Step 4: Cool Down
Spend 5-10 minutes bringing your heart rate back down gradually. Light movement and stretching are ideal.
Quick Tips for Success:
- Use a heart rate monitor to ensure you're hitting the right zones
- To calculate your max heart rate, subtract your age from 220 (this is an estimate, but it works for most people)
- Start conservatively—the first interval should feel challenging but manageable; you need to complete all four
- Don't skip recovery—active rest is essential to the protocol's effectiveness
Is This Workout Right for You?
Let's be honest: this isn't a beginner workout. The Norwegian 4x4 demands a solid baseline of cardiovascular fitness and the mental fortitude to push through extended periods of discomfort.
Consider trying this if you:
- Have been exercising consistently for at least several months
- Are looking to break through a fitness plateau
- Want to improve your endurance for sports or activities
- Enjoy challenging yourself with measurable goals
You might want to hold off if you:
- Are new to exercise (build your base first)
- Have cardiovascular conditions (consult your doctor)
- Are recovering from illness or injury
As always, listen to your body and consult with a healthcare provider if you have any concerns.
The Bigger Picture
What I find most compelling about Jessica Biel's fitness approach—and specifically her embrace of the Norwegian 4x4—is that it reflects a broader shift in how we think about exercise. Rather than chasing quick fixes or aesthetic-focused trends, more people are gravitating toward evidence-based protocols that deliver real, measurable health benefits.
The 4x4 workout isn't glamorous. There's no choreography, no motivational music playlist requirement, no special outfit needed. It's just you, your chosen cardio equipment, and 40 minutes of focused effort.
And sometimes, that simplicity is exactly what we need.
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Have you tried the Norwegian 4x4 workout, or are you curious to give it a shot? I'd love to hear about your experience with high-intensity interval training and what protocols have worked best for you. Drop a comment below and let's start a conversation!
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