Your Aerobic Threshold - And Why You Should Know It

You may have heard of something called your anaerobic threshold or lactate threshold, but do you know much about your aerobic threshold?

Today I'm going to be talking about what it is, why it is so important to know and how to measure it.

Why is it important to know about your thresholds?

The reason why thresholds are important is because if we exercise at a specific intensity, it is will elicit or bring about a specific response. If we can target our training, we can bring about better improvement.

If you saw my last video about how to improve your VO2 max, you'll see that a lot of high volume, low intensity training can bring about improvements in endurance performance, and we see this in pretty much all successful athletes. This is where your aerobic threshold comes in.

Your Aerobic Threshold

As exercise intensity moves from a low or moderate intensity to a harder intensity, this is known as this the aerobic threshold or ventilation threshold 1 (VT1). If we're going to use the zone-three model, it will be the point from when we cross from zone 1 to zone 2.

Below this aerobic threshold, your body's going to use primarily fatty acids as its energy source. When you start going beyond this point (as exercise becomes harder), you're unable to reach the energy/fuel demands from these fatty acids, or, you can’t get the energy from fatty acids so you have to look elsewhere. This means you have to tap into other muscle fibres and start using carbohydrates as fuel too.

When lactate comes in

When you start using carbohydrates as a fuel, one of the bi-products is something called lactate. Lactate itself is not an actual problem as it’s recycled and used as fuel, however, if we produce too much of it, we’re unable to use it which results in an accumulation of hydrogen ions that will ultimately slow you down.

The benefits of targeting your type 1 muscle fibres

Lactate is recycled in your type 1 muscle fibres and by exercising below your aerobic threshold, you are able to target these muscle fibres to take on and re-use more lactate (increase MCT 1 and 4 transporters). If you can recycle more lactate, this means you can exercise at a higher intensity without fatiguing as quickly.

Training below this point will also optimise conditions to produce more mitochondria in these muscle fibres. As explained in my last video, these are important in being able to convert more fatty acids into energy. The more mitochondria you have, the more fatty acids you can convert without having to rely on carbohydrates and subsequently not producing any lactate.

This is the reason why knowing this aerobic threshold is so important, because if you can pinpoint your aerobic threshold, you know where to perform your low intensity or zone 2 training

Calculating your aerobic threshold

To calculate your aerobic threshold you can just use an RPE scale, which is a measure of how hard you’re trying (Google it!).

The other one is just using something called the MAF method, where you minus your age from 180, and if you're fairly fit and exercising regularly, this will give your top of your zone-two. However, there is a problem with this.

Below you can see 3 metabolic tests where I have measured the aerobic thresholds

MAF method = 146

Actual aerobic threshold/VT 1 = 135.

MAF method = 142

Actual aerobic threshold/VT 1 = 130

MAF method = 147

Actual aerobic threshold/VT 1 = 143

As you can see, that for two out the 3 there’s a fairly substantial difference. If these individuals began doing their low intensity work at these points, they would not be getting g the same desired benefits for low intensity training. The other danger of exercising too hard for your easy sessions is it’s impact on recovery, which could affect the quality of your harder more important sessions. "Keep your easy sessions easy and your hard sessions hard".

It’s important to note that these numbers are not binary, so we don’t need to be exact, however by having a clear idea where these thresholds lie can help unlock your training and make it a lot more targeted to what you're trying to achieve.

To Sum Up

Knowing your aerobic threshold is important to help guide your low intensity training
Below this point you’re targeting your type 1 muscle fibres
This brings about changes to help endurance performance such as recycling more lactate and using more fatty acids as fuel
The only real accurate way to measure it is through metabolic testing