The Difference: Aerobic vs. Anaerobic

Everything You Need to Know About Aerobic and Anaerobic Training:

This topic can confuse many runners, but understanding it can make a big difference in your training and fitness on race day. In this post, I’m going to explain both aerobic and anaerobic training in detail so you’ll be able to incorporate this knowledge into your training.

Let’s first briefly describe both of these concepts. When we run, our bodies need to break down sugar and convert it into glycogen to use as fuel. When the body has a sufficient supply of oxygen during this process, we call it aerobic. When there isn’t enough oxygen, such as when running at 10K pace, this is called anaerobic.

Now let’s dive into the details of both aerobic and anaerobic training.

Aerobic Training
Aerobic running is when the body has enough oxygen while running—pretty much like when we’re out for an easy run. With every breath we take, our bodies efficiently use all the oxygen it needs, and then we exhale what we don’t need. The waste products of this process are carbon dioxide and water. Aerobic training is super important for runners because it allows us to get stronger while also recovering from harder workouts. It’s the pace we most often run during training.

Anaerobic Training
Anaerobic running is when there isn’t enough oxygen to generate the energy we need while running at a faster pace. In this process, the muscles begin to break down sugar, but instead of producing carbon dioxide and water, they produce high amounts of lactate. Lactate is difficult to reconvert back into energy and has a downside compared to exhaling water and carbon dioxide. Without enough oxygen, our bodies can’t clear the extra ions created by this lactate. This is what causes the fatigue we feel in our muscles during workouts and races.

Why is it important to know the difference?
If we start running too fast in the middle of a workout or race, our bodies enter an anaerobic state and produce lactate. If we go anaerobic early in a race or workout, our legs will fatigue sooner, and we won’t be able to finish strong. Lactate will build up in the muscles, forcing us to slow down significantly to get back into an aerobic state. This could lead to a major decline in performance, especially at the end of a race. And if we’re talking about the marathon, knowing the difference between aerobic and anaerobic states is absolutely crucial! During a marathon, our bodies need to conserve as much fuel as possible. If we run too far above our aerobic threshold, we’ll burn through our fuel stores faster and may eventually “bonk.”

How can we learn to run aerobically when needed?
First, understand why it’s important to know the difference between anaerobic and aerobic running—so you can race faster! Then, you need to learn how to stay in an aerobic state. The best way to do this is by using the "talking test." When running, try talking to yourself or singing a song out loud. If you can say a few sentences without issues, you’re running aerobically. If you can only say a few words before needing to take a deep breath, you’re running anaerobically.

Now that you understand the difference between aerobic and anaerobic training, you’ll be able to train and race at a higher potential.