How to Calculate Your Lactate Threshold

Lactate Threshold Testing Female Runner on Track

The aim of my earlier article on lactate threshold training was to explain what lactate threshold actually is, and why threshold running workouts are an important part of any marathon training plan, for example.

In this second part of the series, you’re going to learn how to calculate your own lactate threshold, so you can be more specific in your training, and use the results to help train your body to run faster for longer.

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There are a number of ways to find your lactate threshold. These range from scientific testing in a lab, to making estimated guesses based on race results or time-trial efforts.

Let’s take a moment to discuss both approaches…

Lactate Threshold Testing at an Exercise Physiology Lab

The most objective, and in my opinion the best way to calculate your lactate threshold is to visit an exercise physiologist for metabolic testing.

There are many companies that offer this service, but if you’re looking for a good deal you might want to check out the sports science department at a local university, as they’re often on the look-out for willing research participants. Often the quid pro quo is that you’ll get a full work-up of physiological testing done in return for your time.

Here’s a video we shot when we took one of our runners to see an exercise physiologist at Pure Sports Medicine in London:

When you conduct a lactate threshold test you’ll either cycle a static bike or run on a treadmill for several minutes with the speed of the treadmill or resistance on the bike increasing incrementally. A pin-prick blood sample will be taken from a finger, at the end of each progressively difficult effort, and the lactate concentration measured.

How to Calculate Your Lactate Threshold

The diagram shown on the right shows a typical blood lactate concentration versus running speed plot. From these type of graphs, the exercise physiologist can determine your pace at lactate threshold. A heart rate monitor is typically worn, which provides heart rate data to cross-reference, from which heart rate training zones can be set.

How to Estimate Your Lactate Threshold?

Runners like you and I can also estimate our lactate threshold, based on race times, or time-trial results.

In my first article on lactate threshold training, I suggested how lactate threshold is one of the major factors in determining how quickly you can run a specific distance. That’s as true for 5km as it is the marathon distance.

I’ve found over the years that a good estimation of your lactate threshold pace is the average pace of your half marathon personal best time.

Research tells us that for most runners, their lactate threshold occurs around 85–92% of maximum heart rate. If you know your maximum heart rate, you can use this simple calculation to see what pace this equates to versus the average pace for half marathon PB.

So, you now have the tools and understanding to either have your lactate threshold estimated or objectively measured and an understanding of the pace and heart rate at which your threshold occurs.

In the third and final article of this series, I’ll be giving some examples of the basic types of threshold running workouts, and how runners like you and I can improve our lactate thresholds, and run faster for longer.

Read Part 3 >>
Three Running Workouts to Increase Your Lactate Threshold
Last updated on March 2nd, 2021.