The term ‘aerobic threshold’ is often confused with ‘anaerobic threshold’ and is usually underestimated by runners. In my early running years, I undervalued it too, and I had to make long involuntary breaks in my running schedule due to overtraining. Over time, I discovered that an aerobic threshold (AT) defines the distance you can run for two hours or more. Put another way, it determines the maximal pace you can run at a half-marathon and longer races. These are some benefits of knowing your AT, and I’ll give you more later in this post.

In this article, we’ll cover:

What is the aerobic threshold?

The aerobic threshold is the point during an exercise where your body starts to burn fat to fuel physical activity, while the primary energy source remains carbohydrates. Your muscles produce more lactic acid than your body can remove—about 2 mmol/l. The intensity below it is a recovery run; the load above AT is aerobic running. You can easily work out at your aerobic threshold intensity for several hours.

Why should I work on my aerobic threshold?

Improve physical fitness

When working at or post the aerobic threshold, the body learns to use oxygen more efficiently to synthesize energy. The heart and lungs work more effectively, and the body becomes better at utilizing oxygen to generate power. Ultimately, your cardiovascular fitness improves.

Achieve a better running economy

The more effectively you run, the less energy you burn to keep pace. Increasing the running economy leads to significant progress with running speed.

Track your running progress

Runners with a higher AT can maintain a fast pace longer before reaching the point of fatigue. The better your running shape is—the higher your aerobic threshold level.

Healthy weight loss

Runners with excessive weight experience an increased load on their heart, cardiovascular system, muscles, and joints. You need to exercise at and slightly above your AT for a safe and sustainable weight decrease.

Reduce the risk of injuries

Regular working at or above the aerobic threshold help your body adapt to the increased intensity. So, your muscles are less likely to become fatigued under extreme or durable workouts.

How to find my aerobic threshold?

There are three ways to find your AT.

Lactate threshold test

It is the most precise method of measuring your aerobic threshold. It involves taking a small blood sample from your earlobe or finger before and after exercise. The AT is the point at which there is an exponential increase in blood lactate levels.

RER test

Another option to accurately identify your aerobic threshold is measuring the respiratory exchange ratio (RER). You’ll have to run on a treadmill in a lab with different intensities and breathe through a valve. The balance of carbon dioxide produced and oxygen inhaled defines your AT.

Measuring your heart rate

A heart rate monitor is the most common way to find your aerobic threshold. The AT is typically associated with a heart rate of approximately 75-85% of your maximum heart rate. To roughly calculate your max heart rate, subtract your age from 220.

What is a good aerobic threshold?

A healthy AT is around the heart rate of 130-135 bpm. The pace and time you can run at your aerobic threshold depend on your age, physical fitness, and endurance. The more your running experience is—the faster your AT and the longer you can keep it without fatigue and injury.

How to improve aerobic threshold?

There are several ways to improve your AT.

#1 Increase your weekly mileage

Making more miles per week is the first step to lowering your heart rate while running at any intensity. Over time it will upgrade your heart, lungs, and legs to prepare your whole body for the next steps. Increase your mileage gradually—it will prevent injury and give your body time to adapt to the amplified activity.

#2 Incorporate running above the aerobic threshold intensity

Fartlek and interval workouts provide the necessary stress for your body to progress. These types of exercise alternate periods of high and low intensity. It is an effective way to improve your AT because your body becomes better at using fat as fuel.

#3 Do long runs once a week

You should perform long runs once a week at around aerobic threshold intensity for a prolonged time. It improves your AT and overall endurance by increasing your body's ability to perform at moderate intensity before fatigue appears. You’ll improve your aerobic threshold the most when extending the long runs up to 2-2.5 hours.

Four tips to improve your aerobic threshold

Improving your AT can take time and effort, but it’s worth it. These tips can help you make the most of your workouts and see the results you are striving for.

Adequate fueling before running

Eating a balanced diet that includes carbohydrates, protein, and fat will help ensure your body has the nutrients it needs to perform at its best. In addition, drinking plenty of fluids before, during, and after exercise will help keep your body hydrated and will help prevent fatigue. Lastly, avoid eating right before training and running when you are hungry.

Enough amount of sleep

Getting enough sleep is vital for overall health and well-being and impacts your aerobic threshold. Sleep helps your body recover from the stresses of exercise and top up the energy stores. Not enough sleep and intense training lead to burnout and injuries in weeks.

Decrease overall stress

Stress harms your current AT, and chronic stress leads to sustainable changes in your body that degrade your aerobic threshold. On the other hand, running is a way to escape from stress in your life. Although, if you're not feeling well mentally, consider running with lower intensity.

Quit smoking

Smoking pollutes your lungs and makes it harder for your body to get the oxygen it needs during exercise. That’s why progress with running is almost impossible while smoking. Quitting it improves your AT in just several weeks.

The difference between aerobic and anaerobic thresholds

The aerobic threshold is the point at which your body starts to need more oxygen to produce energy. In contrast, at the anaerobic threshold, your body can no longer keep up with the oxygen demands of muscles and starts to generate power without oxygen.

You work on 50-60% of your maximum heart rate at AT, which is a substantial effort. You reach the anaerobic threshold at 80-90% of your maximum heart rate, and it feels like backbreaking work.

The aerobic threshold is essential for people trying to lose weight and improve overall cardiovascular fitness. The anaerobic threshold is crucial for people trying to boost speed and endurance.

Final thoughts

While being a crucial runner’s benchmark, the aerobic threshold isn’t constant throughout your lifetime. It can change together with your running progress and depending on the environment you’re training in. A good rule of thumb is to check your heart rate zone and threshold points every 6 months. It will help you stay safe, get your body the necessary stress, and improve your running performance sustainably.

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Alex Roven
Alex Roven

I completed my first 10K on a dare. In a year, I ran a half-marathon. Another year later, I finished a marathon race. Today I run 4 marathons a year and a half-marathon every week. I learned everything about running the hard way. So, I help runners achieve better results easier.