Why the Standard 4 × 4 VO₂max Intervals Won't Work for You

If you Google "VO₂max workout," you'll find endless versions of the same prescription: 4 × 4 minutes hard, 2–3 minutes easy.

It's simple. It's famous. And for some athletes, it works.

But here's the truth: for most runners, the 4 × 4 is a blunt tool — sometimes too easy, sometimes too hard, and rarely the most efficient way to train.

Where the 4 × 4 Came From

The "4 × 4" model became popular through research in the early 2000s, particularly from Norwegian sports scientists (Wisløff, Helgerud, Hoff). They tested runners and found that 4 × 4-minute intervals at 90–95% HRmax improved VO₂max and endurance in recreational athletes.

The formula caught on. It was simple to prescribe, looked neat in a training plan, and didn't require complex testing.

But there's a problem: training isn't one-size-fits-all.

The Problem With 4 × 4

1. HRmax Is an Inaccurate Target

The 4 × 4 relies on percentages of max heart rate.

As we've seen, HRmax formulas are often ±10–20 bpm off (Tanaka et al., 2001)
This means your "90–95%" might actually be way above or below the intended intensity
One runner's 95% HRmax could be another's threshold pace

2. VO₂ Kinetics Differ Between Athletes

Some athletes reach VO₂max quickly (fast kinetics)
Others take longer to achieve peak oxygen uptake
For the latter, 4 minutes might not even be long enough to hit the target
Fast-kinetics athletes might plateau after 2 minutes, wasting the remaining time

3. Critical Speed and D′ Matter More

The 4 × 4 ignores Critical Speed (CS) and D′ (anaerobic reserve).

For some, 4 minutes at 90–95% HRmax is below CS — too easy for VO₂max stimulus
For others, it's well above CS — burning through D′ too quickly and causing premature fatigue
This leads to inconsistent training stress and adaptation

Research Evidence: Dupont et al. (2002) showed that shorter intermittent bouts (e.g., 30/30s) often produce more time at VO₂max than continuous 4-minute reps (PubMed 12179954).

4. It Ignores the Goal of the Session

Do you want to improve VO₂max? Threshold? Running economy?
The 4 × 4 doesn't distinguish. It just throws everyone into the same bucket
Different physiological systems require different training stimuli

What the Science Really Says

VO₂max Training

Requires repeated time at or above 90% VO₂max. How you get there depends on your VO₂ kinetics and individual response.

Threshold Training

Best targeted with cruise intervals or continuous tempos, not 4-minute max efforts that overshoot the target.

Efficiency Training

Comes from Zone 2/3 steady work, not from high-intensity 4 × 4s that stress different energy systems.

In other words: the 4 × 4 is a hammer. But not every training problem is a nail.

Better Alternatives

Billat 30/30s

Protocol: 30 sec at ~vVO₂max, 30 sec jog recovery

Benefits: - Allows much more time near VO₂max without full burnout - Proven to improve VO₂max and running economy (Billat et al., 1996) - Matches individual VO₂ kinetics better than long intervals

Cruise Intervals

Protocol: 5–6 × 6 min at LT2, 1 min recovery

Benefits: - Build threshold power and lactate clearance - Target specific physiological adaptations - Sustainable intensity for consistent quality

Over/Unders

Protocol: 2–3 min just above LT2, 2–3 min just below LT2

Benefits: - Trains lactate tolerance and clearance together - Develops metabolic flexibility - Race-specific stress patterns

Long VO₂max Reps

Protocol: 3 × 5–6 min at ~vVO₂max for experienced athletes

Benefits: - Demanding but tailored approach - Maximizes time at VO₂max for advanced runners - Progressive overload through duration rather than intensity

The Individual Response Problem

Athlete A: High VO₂ Kinetics

Reaches 90% VO₂max in 90 seconds
4 × 4 result: Spends only 2.5 minutes per rep at target intensity
Better option: 6 × 2.5 min at vVO₂max for consistent stimulus

Athlete B: Slow VO₂ Kinetics

Takes 3 minutes to reach 90% VO₂max
4 × 4 result: Only 1 minute per rep at target intensity
Better option: 3 × 6-8 min at vVO₂max for adequate stimulus

Athlete C: Large D′ Reserve

Can sustain efforts above CS for extended periods
4 × 4 result: Too easy, insufficient training stress
Better option: 3 × 5 min at 105% CS for appropriate challenge

Personalisation in Practice

Step 1: Determine Your Profile

VO₂max and vVO₂max from field testing
Critical Speed and D′ from power-duration modeling
Heart rate response patterns during intervals

Step 2: Match Intervals to Goals

For VO₂max Development: - Fast kinetics: 6-8 × 2-3 min at vVO₂max - Slow kinetics: 3-4 × 5-6 min at vVO₂max - Mixed: Billat 30/30s for 12-16 minutes total

For Threshold Development: - Cruise intervals at Critical Speed ± 2-5% - Over/under sessions around lactate threshold - Tempo runs at sustainable threshold pace

Step 3: Progressive Overload

Volume progression: Increase total time at intensity
Intensity progression: Gradual increases in target pace
Complexity progression: Add environmental stressors

How Technology Helps

Power Meters

Real-time feedback on intensity distribution
Precise pacing for interval targets
Post-session analysis of time in zones

Heart Rate Monitoring

Verification of intended training stress
Recovery monitoring between intervals
Long-term adaptation tracking

GPS Watches

Pace guidance during intervals
Structured workout delivery
Training load quantification

Common 4 × 4 Mistakes

Running Too Hard

Problem: Treating every rep like a time trial
Solution: Target specific physiological zones, not maximum effort

Insufficient Recovery

Problem: Not allowing D′ to recover between reps
Solution: Monitor HR recovery and adjust rest periods

Ignoring Environmental Factors

Problem: Same intensity regardless of heat, wind, hills
Solution: Adjust target paces for conditions

Lack of Progression

Problem: Same workout every week
Solution: Progressive overload through volume, intensity, or complexity

How Run Pace Pal Personalises Intervals

Instead of one-size-fits-all prescriptions, our approach:

Uses your Critical Speed, D′, VO₂max, and drift to prescribe intervals
Builds VO₂max, threshold, and tempo sessions tailored to your physiology
Adapts your plan as you retest, so intervals always match your current fitness
Provides multiple session types based on your training goals

Real Example: VO₂max Session Builder

Your Input: Critical Speed 4:00/km, D′ 350m, Goal: VO₂max development

Our Output: - Option 1: 5 × 3 min at 3:45/km (102% CS), 90s recovery - Option 2: Billat 30/30s for 15 minutes at 3:40/km (105% CS)
- Option 3: 3 × 5 min at 3:50/km (100% CS), 2 min recovery

All based on YOUR physiology, not population averages.

Where Lab Testing Adds Value

For athletes chasing ultimate precision, professional testing provides:

Direct VO₂max Measurement

Exact determination of aerobic capacity
Precise vVO₂max calculation for interval prescription
VO₂ kinetics assessment for optimal interval duration

Lactate Profiling

LT1 and LT2 identification for threshold training
Lactate kinetics during interval protocols
Recovery rates between efforts

Metabolic Flexibility Testing

Fat oxidation rates at different intensities
Substrate utilization patterns during intervals
Fueling strategy optimization

👉 Book professional testing: boxnutrition.co.uk/book-online

The Bottom Line

The 4 × 4 interval prescription treats all runners the same, but your physiology is unique.

What Doesn't Work:

Generic HRmax percentages that ignore individual variation
Fixed interval durations that don't match VO₂ kinetics
One-size-fits-all intensities that ignore Critical Speed and D′

What Works:

Personalised zones based on your testing data
Interval prescriptions matched to your physiological profile
Progressive protocols that adapt as you improve

Ready to Train Smarter?

Stop copying cookie-cutter intervals. Your training should be as individual as you are.

Our VO₂max Calculator and interval builders create sessions based on YOUR Critical Speed, D′, and physiological profile — not population averages or generic formulas.

Free testing takes 20 minutes. The insights transform your training.

Key Takeaways

The 4 × 4 works for some, but it's not a magic formula
HRmax-based training is too blunt for personalised results
VO₂ kinetics, Critical Speed, and D′ mean intervals affect athletes very differently
Better alternatives: Billat 30/30s, cruise intervals, over/unders, personalised prescriptions
Technology and testing enable precise, individual training prescription

Your next breakthrough is waiting in properly prescribed intervals.

Transform generic workouts into personalised training with our free calculators, or validate your zones with professional lab testing for ultimate precision.

Ready to Apply What You Learn?