What if improving your cardiovascular fitness didn’t require endless hours of training?
In a recent YouTube video, exercise physiologist Dr. Gomar Natta from ETH Zurich tackled one of fitness’s most pressing questions: exactly how much endurance training do you actually need to meaningfully boost VO2 max and overall aerobic capacity?
Using intervention studies and comprehensive research reviews, he breaks down practical recommendations for everyone from complete beginners to elite athletes.
The answers might surprise anyone who thinks more is always better.
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The Groundbreaking Frequency Study
A landmark 2014 study by Montero and Karsten Lundby from University Hospital Zurich provided elegant insights into training frequency. Researchers divided 78 previously sedentary but healthy adults into five groups, each training for 60 minutes per session but at different weekly frequencies.
One group trained just once weekly, while others trained two, three, four, or five times per week. All participants started with medium VO2 max levels between 35-40 ml per kilogram body weight—typical for most active, healthy individuals.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Four Training Styles That Deliver Results
Participants cycled through four distinct training protocols, all designed to average 65% of maximal wattage across 60 minutes:
- Continuous endurance: 60 minutes at steady 65% of max wattage
- Sprint intervals: 10 rounds of 30 seconds at 130% max wattage with extended rest periods
- Pyramid training: 3-minute blocks alternating between 60-75% max wattage
- Threshold sessions: 4 minutes at 75% max wattage followed by 6 minutes recovery at 65%
Despite different intensities throughout sessions, average power output remained consistent across all protocols.
The Dose-Response Revelation
Results revealed a clear dose-response relationship between training frequency and improvement. Training just once weekly proved largely ineffective—only three out of 16 participants showed meaningful VO2 max improvements above 3%.
The majority became non-responders. However, one genetically fortunate individual achieved a 10% improvement despite minimal frequency.
At two or three sessions weekly, approximately 50% of participants experienced meaningful gains. But at four or five weekly sessions, everyone improved without exception.
Critical insight: This transformation occurred in just six weeks of consistent training.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Expected Improvements From Interval Training
A comprehensive overview study by Bacon examined 37 studies including 334 participants (66% male, 33% female). Researchers analyzed protocols featuring two to three high-intensity interval sessions weekly with minimum 10 minutes accumulated high-intensity work.
Average improvements reached half a liter per minute in absolute VO2 max after 8-12 weeks. For someone starting at 3 liters per minute, that represents significant progress.
Studies incorporating longer intervals—3 to 5 minute blocks like Norwegian 4×4 protocols—produced even greater results: 0.8 to nearly 1 liter per minute improvement.
The longer the intervals are and the longer you can sustain your VO2 max level at those intervals, the higher the likelihood is that you will meaningfully improve your VO2 max.
What To Do When Progress Stalls
Hitting a plateau doesn’t mean genetic limitations have been reached. Two strategies consistently break through stagnation.
Strategy One: Maintain Consistency
Research by Mølmen and Almquist on mitochondrial adaptations revealed that VO2 max improvements don’t plateau quickly with proper training. During initial six-week periods, relatively untrained individuals remain in steeply rising adaptation phases.
Mitochondrial development and capillarization require time—sometimes more in certain individuals. Adaptations will manifest with patience and consistency.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Strategy Two: Increase Training Frequency
The Montero and Lundby study debunked the non-responder myth through a brilliant second phase. Participants who initially trained once weekly but didn’t improve were reassigned to three weekly sessions. Those at two sessions moved to four, and three-session participants increased to five.
Results? Everyone improved their wattage max and endurance capacity without exception.
The whole idea of this study was to refute the myth of non-responders. If you would up the training frequency from one to three or from two to four or from three to five times per week, would there be an improvement in VO2 max or watt max? And indeed, yes, everyone got better.
Practical Guidelines By Experience Level
Beginners: Foundation Building
Start with three weekly sessions focusing on high-intensity interval training for maximum efficiency. Each session should include 12-20 minutes of accumulated high-intensity work using 3-5 minute intervals.
This protocol delivers optimal return on time investment while establishing cardiovascular foundation.
Intermediate Athletes: Volume Expansion
Once plateau occurs (typically VO2 max between 45-60), maintain two weekly high-intensity sessions but increase volume to 18-30 minutes per session. That translates to four or five 5-minute intervals—substantially more challenging.
Add zone two continuous training to boost overall volume without excessive intensity that risks overtraining.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
Advanced and Elite Athletes: Strategic Polarization
Near-elite endurance athletes, including competitive Hyrox participants, require significant volume increases. Norwegian Olympic endurance athletes consistently train 15-25 hours weekly—approximately 1,000 annual training hours.
Sustaining this volume demands polarized training distribution:
- 80-90% low intensity: Zone one or two work that feels genuinely easy
- Only 1-2 quality sessions weekly: High-intensity intervals plus occasional threshold work
- Strategic timing: Intensity varies based on competition calendar
For Hyrox specifically, slightly more middle-zone intensity fits the demands, but substantial zone one/two volume remains essential.
The Bottom Line on Endurance Training Volume
Meaningful VO2 max improvement doesn’t require guesswork. Research clearly demonstrates that three weekly sessions provide sufficient stimulus for beginners, with 50% response rates at two sessions and universal response at four or more.
Longer intervals (3-5 minutes) consistently outperform shorter protocols for cardiovascular gains. When progress stalls, consistency beats program-hopping, but strategic frequency increases reliably overcome plateaus.
As Natta emphasizes, cycling’s concentric nature taxes cardiovascular systems without excessive muscular damage, making it ideal for high-frequency training that improves both cardiorespiratory fitness and overall health markers.
If you want something simple that actually works, this is one of the most effective tools I’ve used to build strength, conditioning, and endurance without needing a full gym setup.
- Full-body training with one weight using swings, squats, and presses
- Solid cast iron build that feels stable and lasts for years
- Comfortable grip that makes high-rep workouts easier to handle
The body adapts remarkably well when training volume increases systematically rather than dramatically—patience and progressive overload remain timeless principles regardless of starting fitness level.
