How Can You Improve Your VO₂ Max?

VO₂ max responds to training, but not identically in everyone. Here is what controlled trials and meta-analyses actually support about HIIT, steady-state training, volume, frequency, age, baseline fitness, recovery, and sensible retesting, without the hype.

Can VO₂ max actually be improved?

Yes, on average. Controlled training studies across decades show that aerobic training raises VO₂ max in most people. But "on average" hides one of the most replicated findings in exercise science: people doing the identical program improve by very different amounts. In the HERITAGE Family Study, 20 weeks of standardized endurance training produced improvements ranging from almost nothing to very large gains, and the responses clustered within families, meaning genetics explains part of trainability. ^[4] That does not mean your result is predetermined. It means no honest program can promise every person the same percentage improvement.

What kind of aerobic training works?

Broadly, two styles have the most evidence behind them. Moderate-intensity continuous training (steady runs, rides, swims at a sustainable effort) builds aerobic capacity through accumulated volume. High-intensity interval training (HIIT) alternates short hard efforts with recovery, compressing a strong stimulus into less total time. Both appear across the research base, and both work. The ACSM's 2011 Position Stand recommends that most adults accumulate at least 150 minutes per week of moderate-intensity aerobic exercise, or at least 75 minutes of vigorous exercise, or an equivalent combination, as a baseline for developing and maintaining cardiorespiratory fitness. ^[5]

Is HIIT better than steady-state training?

Sometimes, slightly, on average. A 2015 systematic review and meta-analysis of controlled trials by Milanovic and colleagues found HIIT often produced larger average VO₂ max improvements than continuous endurance training, but results varied by population, protocol, and baseline fitness. ^[1] A 2016 meta-regression in young healthy adults found VO₂ max improved across all intensity ranges studied, with no statistically significant difference in average improvement between intensity groups; the higher-intensity programs achieved similar gains with less total training. ^[2] A 2023 women-specific meta-analysis found continuous and interval training improved VO₂ max similarly, with long-interval HIIT outperforming very short intervals and age modifying the response. ^[3]

The practical reading: intensity is a dial, not a switch. HIIT is time-efficient and effective. Continuous training is effective and often easier to recover from and sustain. The evidence does not support "HIIT is always best," and it does not support dismissing moderate training as useless. Efficiency and universal superiority are not the same thing.

How much training does it take?

Volume and frequency both matter. In the women-specific meta-analysis, greater improvement was seen in women completing more training sessions, across both continuous and interval formats. ^[3] ACSM's baseline recommendations above translate to most days of the week at moderate intensity. There is no magic weekly number that fits everyone; the consistent theme is that total accumulated work over weeks to months drives adaptation.

Does age or starting fitness change the answer?

Both matter. Lower baseline fitness generally leaves more room to improve, and untrained people often see the largest early gains. Age does not eliminate trainability, but the women's meta-analysis found the advantage of higher-intensity formats was smaller in older women, ^[3] and reference data show average VO₂ max declines with age, so realistic expectations should account for where you start. People with medical conditions, symptoms, or long periods of inactivity should talk with a qualified healthcare professional before beginning vigorous training; maximal-effort work is not the right starting line for everyone.

Where does recovery fit?

Training adaptation depends on balancing overload with recovery. The ACSM position stand recommends gradual progression and individualized exercise volume and intensity, ^[5] while the VO₂ max trials cited here do not isolate exact sleep targets, fueling rules, or rest-day ratios. Those specific prescriptions should therefore not be presented as findings from this evidence base. The supported editorial point is narrower: use a sustainable dose that allows consistent training and adjust it when fatigue, symptoms, or performance indicate that the current load is not being tolerated.

How often should you retest your VO₂ max?

There is no formal evidence-mandated retesting interval, and honesty requires saying so. Two evidence-based considerations do guide sensible timing. First, training adaptations measurable as VO₂ max change typically accrue over weeks to months, so retesting after only a couple of weeks is unlikely to show meaningful change. Second, measurement itself has variability from protocol, mode, effort, and normal biology, so retests should use the same modality and protocol to make comparisons fair. ^[6] In practice, many programs reassess after a dedicated training block of roughly 8 to 12 weeks or more; treat that cadence as practical convention, not a research finding.

A higher VO₂ max raises your aerobic ceiling, but performance also depends on thresholds, economy, durability, and skill, which is why athletes with similar VO₂ max values perform differently. ^[7] On the health side, higher cardiorespiratory fitness is consistently associated with lower mortality risk in observational research, though that evidence cannot guarantee that raising your number by a set amount produces a set benefit. Improving fitness is a reasonable goal on its own merits; the number is a marker of the work, not the point of it.

How do you know if your training is working?

Several signals may suggest that training is helping: a familiar pace may feel easier, heart-rate response at a comparable effort may change, or recovery between intervals may improve. Each signal can also be affected by heat, terrain, sleep, stress, medication, and measurement conditions. Wearable trends can add context but are estimates, with accuracy caveats covered in our wearables article. Direct retesting under consistent conditions is the clearest way to assess whether measured VO₂ max changed and by how much.

Frequently asked questions

Can everyone improve their VO₂ max?

Most people improve with consistent aerobic training, but response size varies widely between individuals, partly due to genetics. A small minority respond minimally to a given program, which is why retesting and program adjustment matter more than fixed promises.

Is HIIT the fastest way to raise VO₂ max?

HIIT often produces similar or slightly larger average gains than continuous training with less total time, according to meta-analyses. It is time-efficient, not magic: continuous training also reliably improves VO₂ max, and the best method is one you can sustain and recover from.

How long does it take to improve VO₂ max?

Controlled studies typically run 6 to 20 weeks and find measurable average improvements over that span. Meaningful change usually requires weeks to months of consistent training, so very short timelines and dramatic percentage claims should be treated skeptically.

How much can VO₂ max improve with training?

It depends on baseline fitness, program, age, and individual biology. The HERITAGE study found a wide spread of responses to identical training, from minimal to large. Average improvements in meta-analyses are meaningful but modest, which is why fixed-percentage marketing claims are not evidence-based.

Does walking improve VO₂ max?

For people with low baseline fitness, regular brisk walking can improve aerobic capacity, and public-health guidelines count moderate-intensity walking toward weekly targets. As fitness rises, greater intensity or volume is usually needed to keep improving.

When should I retest?

There is no formal evidence-based interval. Practical convention is to retest after a dedicated training block of roughly 8 to 12 weeks or longer, using the same test modality and protocol, since measurement variability can otherwise hide or fake change.