Fastest vs. Best: What's the Most Effective Way to Increase Your VO₂ Max?

If you've spent any time around runners, cyclists, triathletes, or endurance athletes, you've probably heard someone talk about VO₂ max.

Some athletes obsess over it. Others track it on their watch. Many spend countless hours trying to improve it.

And for good reason.

VO₂ max is one of the strongest predictors of endurance performance ever identified. In simple terms, it reflects your body's ability to take in, transport, and utilize oxygen during exercise.

But here's where things get interesting:

The fastest way to improve VO₂ max isn't necessarily the best way.

In fact, some training methods can produce rapid gains in just a few weeks, while others may take longer but produce larger and more sustainable improvements over time.

Let's dive into what the science actually says.

What Is VO₂ Max?

VO₂ max refers to the maximum amount of oxygen your body can utilize during exercise.

It represents the combined ability of your:

• Lungs to bring oxygen into the body
• Heart to pump oxygen-rich blood
• Blood vessels to deliver oxygen
• Muscles to use oxygen for energy production

A higher VO₂ max generally means a greater aerobic engine.

Research consistently shows that VO₂ max is strongly associated with endurance performance across running, cycling, rowing, cross-country skiing, and many other endurance sports (Bassett & Howley, 2000).

Why Does VO₂ Max Matter?

VO₂ max isn't the only factor that determines endurance performance, but it does set the ceiling for your aerobic potential.

Think of it this way:

• VO₂ max = engine size
• Lactate threshold = how much of that engine you can use
• Running or cycling economy = how efficiently you use it

Elite endurance athletes often possess exceptionally high VO₂ max values, although many recreational athletes can dramatically improve theirs through training.

The Fastest Way to Increase VO₂ Max: High-Intensity Interval Training (HIIT)

If your goal is to increase VO₂ max as quickly as possible, the research overwhelmingly points toward high-intensity interval training (HIIT).

Numerous studies and meta-analyses have found that HIIT can improve VO₂ max in as little as 2–6 weeks (Milanović et al., 2015; Wen et al., 2019).

These workouts typically involve repeated intervals performed at or near VO₂ max intensity.

Examples include:

• 4 x 4 minutes hard with 3 minutes recovery
• 5 x 3 minutes hard with 2 minutes recovery
• 6 x 2 minutes hard with 2 minutes recovery
• 30-second all-out efforts with longer recovery periods

The reason HIIT works so well is that it places enormous demand on both the cardiovascular and muscular systems.

During these sessions, athletes spend significant time near their maximal oxygen uptake, which appears to be a powerful stimulus for adaptation.

The Famous 4x4 Protocol

One of the most studied VO₂ max workouts is the Norwegian 4x4 protocol.

Athletes perform:

• 4 minutes at 90–95% of maximum heart rate
• 3 minutes easy recovery
• Repeat four times

Research from Norwegian exercise physiologists has shown that this type of training can significantly improve VO₂ max over relatively short periods (Helgerud et al., 2007).

For athletes looking for rapid gains, it's difficult to beat.

The Problem With Chasing VO₂ Max Too Aggressively

Here's where many athletes make a mistake.

They discover that HIIT increases VO₂ max quickly and decide more must be better.

Unfortunately, that's usually not the case.

Excessive high-intensity training can lead to:

• Increased injury risk
• Excessive fatigue
• Poor recovery
• Reduced training consistency
• Performance plateaus

Research on elite endurance athletes consistently shows that the highest-performing athletes do not spend most of their training time doing VO₂ max intervals (Seiler, 2010).

Instead, they do something quite different.

The Best Long-Term Way to Increase VO₂ Max: Build a Massive Aerobic Base

While HIIT may be the fastest way to improve VO₂ max, a large body of evidence suggests that the best long-term strategy is accumulating a substantial volume of low-intensity aerobic training.

This type of training is often called:

• Zone 2 training
• Aerobic base training
• Low-intensity endurance training

At first glance, this may seem counterintuitive.

How can easy training improve VO₂ max?

The answer lies in the adaptations it produces.

Consistent aerobic training stimulates:

• Increased stroke volume
• Greater capillary density
• Increased mitochondrial content
• Improved fat oxidation
• Enhanced oxygen extraction

These adaptations form the foundation upon which higher-intensity training becomes more effective (Joyner & Coyle, 2008).

What Elite Athletes Actually Do

Research examining elite endurance athletes consistently finds that approximately 70–90% of training is performed at relatively low intensities (Seiler, 2010).

This approach is often referred to as polarized training.

A simplified breakdown looks like:

• 80% easy aerobic training
• 20% hard training

The easy training builds the aerobic machinery.

The hard training sharpens performance and pushes VO₂ max higher.

The combination appears to produce better long-term results than relying heavily on high-intensity work alone.

Can Easy Training Actually Increase VO₂ Max?

Yes.

While the improvements may occur more gradually, low-intensity endurance training has repeatedly been shown to increase VO₂ max, particularly in untrained and recreationally trained individuals (Montero & Lundby, 2017).

Even among highly trained athletes, increasing training volume often leads to improvements in aerobic capacity when recovery is properly managed.

This is one reason marathoners, cyclists, and ultrarunners often accumulate large amounts of relatively easy training.

The Ideal Strategy: Use Both

The fastest approach and the best approach aren't actually competitors.

They're teammates.

The most effective strategy for most athletes is:

Step 1: Build Your Aerobic Base

Spend the majority of your training time performing easy aerobic work.

This develops the cardiovascular and muscular adaptations that support endurance performance.

Step 2: Add Strategic VO₂ Max Work

Once a solid aerobic foundation exists, add one or two VO₂ max-focused sessions each week.

Examples include:

• 4 x 4 minutes
• 5 x 3 minutes
• 6 x 2 minutes
• Hill repeats

These sessions provide a powerful stimulus for improving maximal oxygen uptake without overwhelming recovery.

Step 3: Stay Consistent

The biggest determinant of long-term VO₂ max improvement isn't a specific workout.

It's consistency.

Years of uninterrupted training almost always outperform a few weeks of perfect interval workouts.

What About Genetics?

Genetics absolutely influence VO₂ max.

Research suggests that both baseline VO₂ max and trainability are partially inherited traits (Bouchard et al., 1999).

However, genetics are not destiny.

Many athletes can improve VO₂ max by 15–30% or more through structured training.

The goal shouldn't be maximizing someone else's VO₂ max.

The goal should be maximizing your own.

The Bottom Line

If you're looking for the fastest way to increase VO₂ max, high-intensity interval training is hard to beat. Studies consistently show that HIIT can improve aerobic capacity within a matter of weeks.

However, if you're looking for the best long-term strategy, the evidence points toward a large volume of easy aerobic training combined with a smaller amount of strategically placed high-intensity work.

The athletes who improve the most aren't the ones doing VO₂ max intervals every day.

They're the ones who consistently build a strong aerobic foundation and then layer high-intensity training on top of it.

In other words, the fastest way to improve VO₂ max is intervals.

The best way is consistency.

References

1. Bassett DR, Howley ET. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Medicine & Science in Sports & Exercise. 2000.
2. Bouchard C, et al. Familial aggregation of VO₂ max response to exercise training: results from the HERITAGE Family Study. Journal of Applied Physiology. 1999.
3. Helgerud J, Høydal K, Wang E, et al. Aerobic high-intensity intervals improve VO₂ max more than moderate training. Medicine & Science in Sports & Exercise. 2007.
4. Joyner MJ, Coyle EF. Endurance exercise performance: the physiology of champions. Journal of Physiology. 2008.
5. Milanović Z, Sporiš G, Weston M. Effectiveness of HIIT versus continuous endurance training for improving VO₂ max. Sports Medicine. 2015.
6. Montero D, Lundby C. Refuting the myth of non-response to exercise training. Journal of Physiology. 2017.
7. Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance. 2010.
8. Wen D, Utesch T, Wu J, et al. Effects of different protocols of high-intensity interval training for VO₂ max improvements. Journal of Science and Medicine in Sport. 2019.