As part of our new COROS Coaches service, we received quite a few questions on how to efficiently build a good aerobic base (or capacity) for the upcoming season. Below you will find our coaching insights on the matter as well as how to monitor this aspect through the Training Hub.

If you would like your own training questions answered, send us an email at and we’ll be happy to share insights!

What is Aerobic Base?

Often times, we will define aerobic base as your ability to use fat as fuel during exercise. The better your aerobic base is, the faster you can run while using aerobic (fat) sources. In more practical settings, a good aerobic base will allow you to delay fatigue during a long-distance race or even sustain a faster pace during a marathon.

Building this specific skill requires time and discipline, but we have broken it down to 3 foundational tips for you to focus on while building your aerobic base.

Pace Zone Distribution can be a great tool to monitor intensity during road runs.

1. Low-Intensity Training

Have you ever heard of “Slow runs make you faster”? By running at low intensity, your body will mainly use and improve those aerobic sources while limiting the stress to your body.

How Easy Should Those Runs Be?

Although there is a way to determine your “ideal” pace for aerobic base development in a lab, we often base it off the Talk Test: Aim to be able to maintain a full conversation throughout the session. Don’t be shy to reduce the intensity, explore your neighborhood, and have fun!
What to Look For on Training Hub

A great way to monitor your intensity is through the Threshold Heart Rate Zone Distribution graph. As aerobic base runs should be spent in zone 1, aim for 60-80% of your time in this zone during this phase.

Threshold HR Distribution graph.

2. Consistency

Unfortunately, your body can be quite slow when it comes to aerobic base adaptations. Multiple weeks/months are often necessary to see any change. This is why it’s important to build a routine of weekly distance while working on your aerobic base. In this situation, multiple shorter sessions are more beneficial than fewer, longer sessions.

What to Look For on Training Hub

In the calendar section, you have access to your weekly distance, activity time, and training load in an easy-to-understand graph. Aim to maintain a consistent schedule that fits with your own routine and that will illicit those long-term adaptations to your aerobic base.

Weekly distance as seen in the calendar section on Training Hub.

3. Progressive Overload

Unfortunately, if we keep the same volume and intensity over time, the body will adapt and eventually reach a plateau. In order to break this cycle, a slow increase in Training Load should be done to keep creating adaptations.

What to Look For on Training Hub

An easy way to monitor your intensity over time is through the Intensity Distribution graph. Although this rule should be individualized, aim for an increase of roughly 10% each week to prevent overreaching.

Progressive overload as seen in this 4-Week Intensity Distribution graph.

If you would like your own training questions answered, send us an email at and we’ll be happy to share insights!

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