by Laurent Glatz – for Athletic Carnivore
You can lift heavy, run long, look lean, strong, and sharp. Yet still run out of breath when it really counts. That’s where VO2max draws a hard line. No flattery. No storytelling.
VO2max isn’t just a smartwatch gimmick. It’s the maximum amount of oxygen your body can capture, transport, and use during intense effort.
Simply put, it’s the speed at which your human machine can fuel its tissues when demand explodes.
Physiologically, it depends on the Fick equation: cardiac output on one side, and the muscles’ ability to extract oxygen on the other.
The heart must pump, the blood must deliver, the muscle must consume. If one link hits a ceiling, performance hits it too.
What VO2max Really Tells You
VO2max reveals much more than pure endurance. It speaks of cardiovascular reserve, aerobic power, effort tolerance, the ability to repeat accelerations, and to survive the metabolic chaos of a tough session.
For athletes, it doesn’t explain everything. Running economy, lactate threshold, technique, tactics, and mental resilience all matter greatly.
But without a solid aerobic base, the ceiling stays low. And a low ceiling always comes at a cost.
The Misunderstanding of Easy Miles
Many still believe VO2max mainly improves by piling up easy, clean, reassuring miles.
Biology tells a different story.
Yes, continuous training works. Yes, it builds a base. But when the goal is to quickly and efficiently raise maximal aerobic power, high-intensity interval training takes the lead in much recent research.
Hard intervals increase the time spent near VO2max. They force strong cardiac output demands, thus stroke volume, while pushing muscle fibers to enhance their oxidative machinery.
Over time, this leads to better central and peripheral adaptations: a more efficient heart, higher muscle oxygen extraction, improved capillary density, and mitochondrial content.
The Intensity Many Avoid
The message is simple but uncomfortable.
To raise VO2max, you must approach an intensity many shy away from. Not because it’s harmful, but because it forces you to face the true cost of improvement.
Among highly trained athletes, where progress margins shrink, HIIT still produces measurable gains.
A crucial nuance: the best results often come when recovery is long enough and very easy. This is counterintuitive for many.
They think too much recovery reduces the stimulus. In reality, adequate recovery often allows truly intense intervals to be repeated, preserving the quality that raises the ceiling.
HIIT, SIT, RST: What Really Matters
Recent comparative reviews often place repeated sprint training, HIIT, and sprint interval training ahead of continuous training for improving VO2max.
But selling an absolute hierarchy would be misleading. Honestly, interval formats dominate, and their implementation likely matters more than the protocol label.
Three sessions per week often emerge as a robust balance point between stimulus and recovery.
Intervals of two to four minutes near the maximal sustainable intensity for that duration, interspersed with sufficiently long recoveries to preserve quality, probably form the core of the most cost-effective method for many intermediate and advanced athletes.
Not because it’s magic. Because this format increases useful time spent at high oxygen consumption without completely destroying mechanics or the ability to repeat efforts.
SIT holds a formidable place. Very short, very intense sprints can yield significant gains. But these gains come with a high neuromuscular cost, perceived pain, and sometimes adherence challenges.
For some profiles, it’s too taxing to repeat properly. For others, it’s the spark that unlocks progress.
The Modality Matters Less Than the Right Dose
Running often produces slightly better VO2max gains than cycling, especially for those who tolerate impact well and know how to run.
But this superiority isn’t universal.
A cyclist often progresses better on the bike than running if running causes injury, technical limitations, or prevents reaching the right intensity.
The best modality is therefore the one that allows you to reach the right intensity dose with reproducible mechanics.
The Ceiling Doesn’t Rise Forever
VO2max doesn’t increase indefinitely. Training response varies greatly between individuals.
Some improve quickly. Others very little, despite serious effort.
This variability depends on initial level, genetics, age, accumulated volume, recovery, sleep, stress, nutrition, and likely many biological details we still imperfectly understand.
For beginners, the best entry point isn’t necessarily brutal intensity. It’s progression.
A moderate continuous base remains relevant to learn the movement, build tendon tolerance, stabilize session frequency, and avoid intensity becoming a poorly executed punishment.
Only then does interval training reveal its full value.
At its core, VO2max isn’t just a number. It’s a dynamic verdict on your capacity to deliver energy when demand becomes non-negotiable.
Improving this number isn’t about doing a bit more cardio. It’s about remodeling the heart, vascular network, cellular respiration, and physiological stress tolerance.
The real question isn’t whether HIIT, SIT, or RST are uncomfortable. They are.
The real question is more naked: how much longer will you train while avoiding precisely the intensity that could change your biological ceiling?
Discussion around this article
Ask a question or add your feedback directly below the article. The comment appears on the page and can be removed from the admin area if needed.
No comment published yet. Start the discussion.