How to improve VO2 max: what the training studies and guidelines say

What does it take to raise VO2 max?

VO2 max is the most oxygen your body can use during hard exercise. The Cleveland Clinic gives it in milliliters of oxygen per kilogram of body weight per minute (mL/kg/min) and links higher values to stronger heart and lung function.⁷ Our published guide to VO2 max and what a good value is explains the number. This page asks how training changes it.

Two facts set the frame. The Cleveland Clinic says about 40% to 50% of VO2 max is determined by genes, and that studies show it tends to decline naturally after age 30.⁷ So your starting point and your ceiling are partly out of your hands. Training moves the number inside that frame, and the amount it moves differs by person.

The best evidence comes from meta-analyses of controlled trials, which pool many small studies. They measure VO2 max before and after a training block and compare groups. They cannot tell you what your own result will be, so every figure below is a group average.

Endurance training or intervals?

Milanović and colleagues pooled 28 controlled trials of healthy adults aged 18 to 45 (723 participants, average starting VO2 max 40.8 mL/kg/min). Endurance training produced a possibly large benefit of 4.9 mL/kg/min over no-exercise controls (confidence limits plus or minus 1.4).¹ Compared with endurance training, high-intensity interval training (HIT) gave a possibly small further benefit of 1.2 mL/kg/min (plus or minus 0.9).¹

The review also found that gains were larger in people with lower baseline fitness and in longer programs. For HIT against endurance, a lower starting fitness added 0.8 mL/kg/min and longer interventions added 1.7.¹ The authors conclude that both methods lead to large improvements, with gains greater after HIT.¹

Read this as a question of efficiency rather than a verdict. Wen and colleagues pooled 53 randomized trials and found that even short intervals (30 seconds or less), low volume (5 minutes or less) and short programs (4 weeks or less) clearly improved VO2 max against controls.² Against moderate continuous training, though, only long intervals (2 minutes or more), higher volume (15 minutes or more) and programs of about 4 to 12 weeks showed a benefit.²

Which interval sessions did the studies use?

Example sessions are only listed here when a study describes them. Helgerud and colleagues randomized 40 healthy, moderately trained men to four groups that were matched for total work. All trained 3 days a week for 8 weeks.³

A worked example of the arithmetic

Suppose your measured maximal heart rate is 180 beats per minute. For the 4 by 4 session, 90% to 95% is 162 to 171 beats per minute, and the 70% active rest is 126.³ If you do four hard intervals of 4 minutes with 3 minutes of active rest after each, that is 16 minutes of hard work and 12 minutes of recovery, 28 minutes in all. For the 15/15 session, 90% to 95% is the same 162 to 171 and the recovery is again 126.

Your own maximum is not 180 unless you measured it, and a formula gives only an estimate. See the guide to heart rate zones for how maximum heart rate is estimated and why that estimate can be off. Do not copy a trial protocol without checking with a health professional first, as the next section explains.

How much activity do the guidelines ask for?

Training for VO2 max sits on top of the general activity guidelines. The CDC says adults need 150 minutes of moderate-intensity activity a week, such as brisk walking, or 75 minutes of vigorous-intensity activity, such as jogging or running, or an equivalent mix. It also asks for muscle-strengthening activity on at least 2 days a week.⁵ The ACSM position stand sets the same weekly totals and adds a spread: at least 30 minutes a day on 5 or more days for moderate work, or at least 20 minutes a day on 3 or more days for vigorous work.⁴

How do you tell moderate from vigorous? The CDC offers a talk test. At moderate intensity you can talk but not sing. At vigorous intensity you cannot say more than a few words without pausing for breath.⁶ On a 0 to 10 effort scale, moderate is a 5 or 6 and vigorous starts at 7 or 8.⁶

As a sanity check, one session of the 4 by 4 protocol is 16 minutes of hard work. Two such sessions in a week add up to 32 minutes of vigorous activity, which is 43% of the 75 minutes in the guideline (32 divided by 75).⁵ The rest of the week would come from other activity. This is arithmetic, not a plan.

What do beginners and older adults need to know?

The Cleveland Clinic says beginners can realistically gain a 10% to 15% improvement in VO2 max within a few months, that consistency matters, and that you should increase the intensity and duration of workouts gradually. It also says mixing high- and moderate-intensity work tends to give the most gains with less injury risk.⁷ Treat that as a general expectation, not a promise.

Starting fitness changes the picture. In the Milanović analysis, a lower starting fitness added to the gain from training, and in the HIT-versus-endurance comparison, older subjects showed a small additional gain of 1.8 mL/kg/min, although for HIT against no exercise the modifying effect of age was unclear.¹ The review covered adults aged 18 to 45, so it does not speak for older adults.

The Cleveland Clinic advises checking with a healthcare provider first, especially if you are older or have health conditions.⁷ The ACSM adds that screening for signs and symptoms of coronary heart disease and a gradual increase in intensity and volume may reduce the risks of exercise.⁴ Interval work is hard by design, so this advice matters most for it.

What can a watch tell you about VO2 max progress?

The gold standard for measuring VO2 max is a graded exercise test in a lab with a breath-capturing mask, according to the Cleveland Clinic. Many trackers estimate the number from heart rate. The page says those numbers are not exact, though they are typically pretty close in various studies.⁷

The Cleveland Clinic adds a useful rule: changes under about 3% to 5% may be test variability. If you track progress, repeat the same test under the same conditions.⁷ Put another way, a watch showing a one-point change after two weeks is within the noise for most people.

Frequently asked questions