What Is Aerobic Capacity and How Can You Improve It?

Ever wonder how fit you really are? There are multiple ways to get an idea of your current fitness level — like tracking your reps, monitoring your heart rate, or measuring your body fat percentage.

But one metric you may be less familiar with is aerobic capacity.

Whether you’re new to exercising or consider yourself a workout pro, finding out your aerobic capacity can be a great way to gauge how fit you are and track your progress over time.

Here’s what you need to know about aerobic capacity — and how to improve yours.

What Is Aerobic Capacity?

Aerobic capacity is the point at which your body is using as much oxygen as it can, as efficiently as it can.

“Aerobic capacity is the maximum amount of oxygen the body can utilize during intense exercise,” explains Trevor Thieme, C.S.C.S. “Knowing your aerobic capacity can give you an objective idea of your current cardiorespiratory fitness level.”

Let’s go back to the basics: When you exercise, you breathe in oxygen, which is transferred via your lungs to your blood vessels.

The now-oxygenated blood travels to the heart to be dispersed to your tissues and muscles, where the oxygen gets utilized.

The oxygen works with glucose to create adenosine triphosphate (ATP) in order to fuel your muscles.

The more you exercise, the more efficient your muscles get at using oxygen — and the higher your aerobic capacity is.

Is Aerobic Capacity the Same as VO2 Max?

Yes. The terms aerobic capacity and VO2 max are often used interchangeably — and they’re essentially the same, Thieme says.

VO2 max is the the maximum volume of oxygen your body can use in a given amount of time — in other words, it’s a measurement of your aerobic capacity.

VO2 max is typically measured in terms of milliliters of oxygen per kilogram of body weight per minute (ml/kg/min).

You may also see the terms aerobic power or maximal oxygen uptake when referring to aerobic capacity, but these all boil down to the same concept: the rate at which you consume and use oxygen.

How to Measure Aerobic Capacity

Measuring your own VO2 max can help you get a baseline for your current fitness level and track improvements over time.

Choose from the methods below to calculate yours.

1. Fitness wearable

One easy option may be right on your wrist. Many fitness wearables — like Garmin, Jabra, and Fitbit — provide an estimated VO2 max calculation based on your heart rate, age, sex, and weight.

But the key word with these is estimate, Thieme says: “Wearables can give you a rough estimate of your aerobic capacity, but for a truly accurate assessment, you need to visit a sports performance lab for an indirect calorimetry test.”

2. Indirect calorimetry testing

For the most precise measurement of aerobic capacity, you’ll want to get an indirect calorimetry test performed.

Even weekend warriors and average Joes can pay to get this test done at a sports lab. (Some hospitals, training centers, and universities offer it as well.)

During the test, you’ll be fitted with a mask that measures your breathing while you perform an increasingly hard workout on a treadmill or stationary bike.

It’s less convenient (and less comfortable) than checking your fitness tracker, but for individuals truly looking to improve their aerobic capacity, this test is the best way to get an accurate VO2 max measurement.

How Can You Improve Aerobic Capacity?

Once you have a baseline for your aerobic capacity, you can focus on improving it.

“Research shows that high-intensity interval training (HIIT) is one of the best ways to increase aerobic capacity,” Thieme says.

“The key is to exercise at an intensity that’s at or above your lactate threshold (the point where you start to feel your muscles burning), which you’ll reach at about 80 percent of your max heart rate.”

Here are a few more workouts that can help you boost your VO2 max.

Tabata

Short on time? Tabata allows you to improve your VO2 max while blasting through super-short, super-intense workout segments (like burpees, jump squats, or mountain climbers) followed by a brief rest period.

This four-minute form of HIIT follows a pattern of 20 seconds of work, followed by 10 seconds of rest, for a total of eight sweat-inducing cycles.

Sprint intervals

One study suggests sprint interval training can be an effective way to increase aerobic capacity.

In just six sessions of sprint intervals, the trained athletes in the study improved their overall running time, time to exhaustion, and peak power.

Even better, you can adapt almost any sport into an effective sprint interval workout.

Love to swim? Instead of a slow-and-steady swim, do a 50-meter freestyle as fast as you can, with a recovery break between laps.

If you’d rather be biking, pedal hard at your maximum effort for 30 seconds, then go at an easy pace for up to 4 minutes while you catch your breath.

(This recovery time is crucial for letting your body recuperate so you can continue to give your max effort for each interval.)

Cross-training

Cross-training is simply mixing up your workouts — for example, doing a HIIT workout on Monday followed by low-intensity steady-state (LISS) cardio on Tuesday.

According to the American Council on Exercise, a LISS workout is a lower-stress way to improve aerobic capacity.

Doing a grueling HIIT workout every single day may put you at risk for overtraining — especially if you’re a fitness beginner.

By adding lower-intensity workouts into your week, you can continue to improve your aerobic capacity while giving your body a chance to recover.