What is VO2 max, running heart-rate zones and lactate threshold?

Running wearables can help you understand your VO2 max, running heart-rate zones and lactate threshold

What is VO2 max, running heart-rate zones and lactate threshold: Pictured here, a female runner looking at her running watch and phone
(Image credit: Getty Images)

Running terms such as VO2 max and lactate threshold can be confusing for beginner runners. What are these, and why do they matter? Do they matter at all? What are running heart rate zones, and why should you care about them? You can be a runner without understanding these terms, but you can't improve your running form without taking them into account.

A quick tip: wearing a running watch, heart rate monitor or triathlon watch can help you understand all of these and even make you a more efficient runner in the process. Adding a pair of the best running shoes to the mix might also help. Once you get the essential hardware, it's time to delve deeper into running theory.

Don't get too alarmed, though; it's not rocket science. It is worth mentioning that to get the most accurate VO2 max readings or to know your exact lactate threshold, you might want to visit a running lab. Assuming you haven't got access to one, we will use the data available in running watches and other wearable running devices to calculate these.

Without further ado, let's find out how to run faster.

What are running heart rate zones and how do they work?

The harder you work your muscles, the more oxygen they will require to work efficiently. To supply your muscles with oxygen, you need to breathe, which probably doesn't surprise you. Correct breathing is one of the fundamental skills a runner needs to master to be more energy efficient.

What is your maximum heart rate? The easiest way to calculate this is to subtract your age from 220. That will give you a rough estimate of your max heart rate. It's only a rough estimate because this method doesn't take some crucial details into account, like your fitness levels. 

Once you have your max heart rate, which a running watch would determine anyway once you set it up, you can forget about it because you never really want to do any workout anywhere near that number. Depending on your goal, whether weight loss or building endurance, you will have to perform exercises by keeping your heart rate in the correct zone.

These are:

  • Between 50-60%: Warm-up zone. Exercising in this zone will have a low impact on heart health. You should be able to run a long time in this zone and it is great for recovery runs, too.
  • Between 60-70%: Fat burning zone. Doing exercises in this zone will encourage your body to burn fat more by improving your metabolic system. This is still a low-impact zone.
  • Between 70-80%: Low-aerobic or endurance zone. This heart rate zone is ideal for medium to long-distance runs and can help your body improve its endurance levels as well as increase aerobic power.
  • Between 80-90%: Anaerobic or threshold zone. This heart rate zone is a high-impact zone and can only be sustained for short to medium distance runs only, especially if you are a less experienced runner. Running in this zone can further increase endurance levels.
  • Between 90-100%: VO2 max or maximum effort zone. If you are not a sprinter, you won't be running in this zone often, especially not during your training. You might end up bringing your heart rate up this much at the end of longer races, just before the finish line, as you try to squeeze out the last little bits of your energy left. Be very careful and don't try to sustain this level for too long.

Running heart rate zones VO2 max lactate threshold: people running on the street

Interval training can help you improve VO2 max levels

(Image credit: Nike)

What is VO2 max and how can you improve it?

In recent times, VO2 max has become one of the most commonly accepted ways to measure general cardio fitness levels, and many fitness wearables can give you an estimate as well, so there is no need to try to work it out yourself.

VO2 max stands for maximum oxygen uptake, and the higher it is, the better. A high VO2 max level indicates that your body can deliver a lot of oxygen to your muscles which means they will tire out later.

The best Garmin watches can estimate VO2 max while running, whereas Polar watches can perform a 'Fitness test' that assesses oxygen uptake while sitting still.

Your VO2 max level change as you get older (it gets lower), and it also depends on your biological parameters too. On the other hand, VO2 max can be improved by performing targeted exercises and interval runs.

Interval training is one of the best ways to improve VO2 max. After a 10-15-minute warm-up jog, run very hard for 30-60 seconds, then slow back down for another 30-60 seconds. Repeat this for 10-20 times, depending on your fitness levels. Doing this frequently, but not at every session, will gradually improve your VO2 max level.

Some gadgets, such as the Airofit Pro, can improve VO2 max by making you a more efficient breather. 

Running heart rate zones VO2 max lactate threshold: people running on mountain road

Improving lactate threshold levels can help you sustain a higher pace for longer

(Image credit: On Running)

What is lactate threshold and how can it help?

Lactate threshold is the intensity, or more like pace, after which your muscles start to build up lactic acid at a higher rate than your body can get rid of.

Lactic acid is the chemical released by muscles when they’re working without enough oxygen. Knowing your lactate threshold pace is essential for long-distance runners because that is the pace they can sustain for longer periods of time without muscle fatigue setting in.

The easiest – but not necessarily the cheapest – way to estimate your lactate threshold pace is to run a lactate threshold test using a high-end Garmin watch, like the Garmin Forerunner 945or the Garmin Forerunner 745 and a Garmin heart rate monitor, like the Garmin HRM-Pro.

To perform this test, you have to choose the Running from the sports profiles. Then, access the settings by long-pressing the action button, then select the 'Lactate Threshold (Guided test)' option.

The test lasts for 20-30 minutes, and after a 10-15 warm-up, you will have to run 3-4 minutes in each heart rate zone, starting from the lowest, all the way up to the maximum effort zone. If it sounds pretty exhausting, let me assure you, it is.

There are other ways to measure lactate threshold levels, but they involve more invasive methods, like taking blood samples and sending them off to a lab, which is not something many people would want to do, I assume.

Lactate threshold levels can be improved by doing interval training, much like VO2 max. The key here is to run longer, high-intensity intervals, like hill runs, for 3-4 minutes, with a shorter cool down periods. Depending on your fitness levels, repeat 8-12 times each time.

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Matt Kollat
Matt Kollat

Matt is T3's Fitness Editor and covers everything from smart fitness tech to running and workout shoes, home gym equipment, exercise how-tos, nutrition, cycling, and more. His byline appears in several publications, including Techradar and Fit&Well, and he collaborated with other fitness content creators such as Garage Gym reviews.