Lactic Acid Threshold and How it Effects Endurance Training

Ever gone on a big run, and got that feeling stuck in your chest? It’s a really uncomfortable burning sensation that just won’t go away unless you slow down, and sometimes the faster you seem to go the harsher the feeling can get.

Lactic Acid Threshold and How it Effects Endurance Training

Don’t worry, you’re not alone here, the sensation you’re feeling is all to do with your body’s production of lactic acid, and when you run (especially for longer distances) you’ll really start to see issues arise with the production of your lactic acid.

In this article we’ll be talking all about lactic acid, what it is and how we can nullify that burning sensation, and how you can finish that last stretch of your run without feeling any more of that nauseating pain. Let’s get started.

What Is Lactic Acid?

Lactic acid is essentially a byproduct that our bodies produce as an additional source of energy.

When you’re working out, your muscles are essentially like the engines of your whole body, and will require a whole lot of energy, and your body uses oxygen as its main source of energy.

But when workouts are really intense, your body isn’t always able to produce enough energy just through oxygen alone.

This is where lactic acid comes in.The science here is relatively difficult to understand, so here’s the basics behind our body using lactic acid for energy: 

If you’ve been running for a while, you’ll eventually reach the end of your aerobic capabilities, no matter who you are.

In order for your body to catch up to the demands of intense physical exercise, your body will produce lactate which is also known as anaerobic energy, which is almost like your body’s emergency power source.

Using lactate as an energy source doesn’t require oxygen for the conversion process, which is exactly why it’s the system that’s used once you have no other way of producing energy.

Once this happens,  it’s easy for excess lactate to build up in your bloodstream because your body often produces it more quickly than it can use it. 

This excess lactate creates its own byproduct of hydrogen ions that make your blood more acidic, making it harder for your muscle fibers to contract properly.

As a result, you’re more prone to muscle fatigue and that all-too-familiar burning pain as you run, it’s all because you’re pushed to using that anaerobic system instead of aerobic.

Essentially, your body will try so hard to produce energy that it’ll actually create processes that make it harder for you to run and keep moving- talk about working too hard!

So, instead of letting your body’s natural system when it needs energy overpower you, you can prevent this lactic acid build up by training your lactate threshold. Let’s take a closer look at what that is.

Lactate Threshold

Whilst this all sounds super complex, it’s actually not that hard to wrap your head around once you understand exactly what’s happening.

Your lactate threshold is essentially the fastest speed that you can run that allows your body to produce and clear out lactate at an equal rate, keeping your blood lactate levels steady, which means you won’t be feeling that horrible burn.

It indicates the point where your body switches from using aerobic to anaerobic energy.

If you’re running at a lower intensity, you’re training under your lactate threshold because your body is still able to use oxygen as its primary source of energy.

But, once your body hits the point where it needs to rely more on lactate for its energy, you’ve started training over your lactate threshold, once this happens you’ll begin to feel that burning sensation coursing through your body. 

From starting off, there’s minimal lactic acid production, but as a runner begins to pick up pace, the lactic acid begins to build up.

Once the runner surpasses a certain intensity, which differs from person to person, the lactic acid spikes to unmanageable levels which is when you’ll feel that intense sensation.

Ultimately, the goal is to hit your lactate threshold and maintain that speed without tipping the scales in favor of excess lactate production.

That way, your body will be able to train at high intensities for a longer period of time without feeling the consequences of taking it too far.

It’s key to remember that your lactate threshold is more impacted by intensity, rather than by running pace.

People can run an 8-minute pace and feel fine, but if they were to try to keep that same 8-minute pace during an uphill portion, they would fatigue sooner because they’re training at a higher intensity, this just exemplifies how important it is to take each runner as a case by case basis, and understanding what your own personal body is capable of. 

Most major coaches and experts in the field have a great understanding of how important lactate threshold is for distance runners, it’s an incredibly important facet of training for any race distance greater than 800m, and it becomes even more essential over longer distances, so it’s incredibly important for long distance runners to nail this harmony between aerobic and anaerobic systems whilst running.

But in order to achieve this magic running speed and efficiency, your body’s going to need some practice to properly gain that kind of control.

It won’t be easy, and will take time, but let’s take a look at some methods people use to train their body this way. 

Training Your Lactate Threshold System

Training Your Lactate Threshold System

Training your body to be more efficient is at the core of what long distance running is all about.

Even if you’ve only ever been on one single run when you were feeling particularly healthy one day, everyone knows the feeling of being on a run when they’re not ready for it, it’s painful.

This is exactly why practice, and consistent training is a huge part of getting steadily better at running, especially when it comes to longer distances. 

Lactate threshold training is essentially a part of this, as we’re training to keep our lactate levels consistently low, so that we can push our body to the absolute peak of its limits, without any spikes in your blood lactate levels, which will slow you down. 

You might be thinking there’s a magical training solution to all this, but in actuality there’s really not.

Lactate threshold training simply involves running at a pace intense enough that you’re right on the cusp of your blood lactate levels spiking, so that way you’re getting the maximum efficiency out of your body.

It seems simple, but this actually works at slowly increasing the effectiveness of your aerobic systems, which means you’ll slowly start getting faster and faster without feeling that horrible pain. Let’s take a closer look at Tempo workouts.

Tempo Workouts

Instead of people referring to these workouts as lactate threshold training, they’re often called tempos or tempo runs, because they’re teaching your body to remain at a certain tempo.

Essentially, they’re shorter,  and more moderately paced runs which have a focus on being consistent with speed.

As mentioned above, they make you run just fast enough to utilize the excess lactate at the same rate that your body produces it, which ensures that the lactate doesn’t build up in your bloodstream. 

There’s two main different types of tempo workouts that you can choose from, either one long, continuous tempo, or break your tempo up into smaller intervals of runs that allow you to be much more controlled with your pacing.

Longer, and one continuous tempo on the other hand will allow you to get an understanding of exactly how fast and far you should be running during the whole thing in order to not go over that lactate threshold. So pick whichever works best for you!

In order to see clear results, and just to keep on top of everything, it’s advised by professionals that you should try a tempo workout at least once a week if you’re looking to make significant progress with developing your lactate threshold.

Below we’ve outlined some different tempo workouts (continuous and staggered) you can try out depending on how confident you are as a runner:


2-mile continuous tempo 


3 x 1-mile tempo with 30 second jog break between each mile


3-5-mile continuous tempo


4 X 1.5-mile tempo with 30 sec jog between each rep


5-10-mile continuous tempo 


4 x 3-mile tempo with 30 sec jog between each rep

It’s important to recognize that everyone’s different, so make sure to not stretch yourself too far here.

Tempo workouts are about slowly building up that lactate threshold, so if you’re confident in your running ability, then one long continuous run is going to work best for you, if you’re not so confident, or just want to take it easy, then breaking your tempo run up into multiple different sections will allow you to take a breather or two between workouts, and you’ll still see progress, just not as much as if you perform one continuous tempo run. 

You might still be thinking though, how do you determine your own personal pace in order to maximize your performance whilst staying below that lactate threshold? Let’s take a closer look at that question:

Finding The Right pace For You

Finding The Right pace For You

There’s loads of different ways to find the right pace for you when performing tempo runs (some more scientific than others!) so let’s take you through a few methods that we’d recommend:

The easiest way to find the right pace for yourself, is the 7 word talk test. Whilst you’re running during your tempo run, try to speak 7 words without having to gasp for air whilst doing so.

This can just be as simple as ‘i will continue to run this speed.’ If you find yourself unable to finish the sentence, or once you’re finished the sentence you’re gasping for air, then chances are that you’re running too fast in order to stick under that threshold.

There’s a direct correlation between your breathing and blood lactate levels, so increased or erratic breathing is a sign that your tempo is too intense, and you should slow down the pace, at least for a little while. 

It’s important that you recognize that you’re not pushing yourself too hard, pushing yourself harder than necessary will ultimately lead to you getting that burning sensation, and at that point there’s little point in performing a tempo run, so take your time, and be apprehensive of your speed.

If you’re looking to be ultra precise, then running on something that’s stationary like a treadmill, and getting a specialist to poke you with a needle and analyze your blood can be a very effective way to test the correct pace for you.

The specialist can detect exactly how high your blood lactate content is from the sample, and you can see how far away you are from hitting the threshold.

Whilst this is effective though, not everyone’s looking to get poked by a needle, and these tests can be expensive, especially if you’re looking to get multiple done. 

The last method is just by using our old friend, the internet. Looking up a simple tempo chart or tempo calculator will allow you to find multiple different charts that people have created online, and you can use these to find out precisely how fast you’re going to be running.

Obviously there’s a bit of guess work here, as not everyone’s going to be the exact same, even at the same height and weight ratio, but using trusted online graphs and spreadsheets to compare yourself too is an effective and completely free way to get a rough idea of where you should be hitting in order to train effectively.

Once you’ve determined your tempo, the key to training in this way is to make sure that you maintain the proper pace and intensity.

As long as you ensure consistency in your tempos, you’ll be well on your way to improving your body’s efficiency in clearing blood lactate, you might even be surprised at the effectiveness!

Including Tempo Runs In Your Workout

As you’ve probably already guessed, tempo runs aren’t going to be the best way for you to actively work out your body.

Sure they’re extremely effective at training you to run more effectively, but you’ll want to back them up with more mainstream, regular workouts too in order to stay healthy. 

In fact sometimes having tempo runs at all in your workout can not even be required.

Yes they’re effective at getting you to run further, but training in similar ways can be more effective at actually keeping your body fit, rather than maintaining lactate levels inside of your blood.

Before you even consider implementing tempo runs into your workout, you should consider a few things: 

  • What is the race distance you want to accomplish?
  • What is your level of experience with running?
  • What is your current mileage?
  • What are your race goals (i.e., do you want to run faster, or do you just want to finish a race)?
  • What is your most recent PR?
  • When is your next race? 
  • Are you more of a fast-twitch or slow-twitch runner?

And obviously there’s many more. It’s always a good idea to ask yourself various different questions before you start integrating different workouts into your routine, as some can even be detrimental to your fitness, rather than being helpful. 

To use an example: If you’re training for an 800m race, then you’re probably not going to need tempo runs, as by the time you’re going to be hitting the upper lactate limit, you’ll be nearly finished anyway, so different training will be more beneficial to you. 

As well as all this, planning in times for recovery, longer runs, different training altogether and your actual life can be difficult to do, so making use out of the time that you’ve got to work with can be challenging.

This is why it’s best to consult with a personal trainer, or any level of fitness coach that you might have, and work out what’s best for you.

Final Thoughts 

Lactic acid can be a real pain when running, and we all know the feeling of getting near to the finish line, and every breath is like molten lava, so sure getting rid of that feeling can be great, especially if you’re someone that frequently runs long distances (i’m talking distances past 800m) 

Sure, working out your lactic acid threshold can be great for allowing your body to keep going, and letting you get that extra distance without the hindrance of the dreaded burn.

But remember that your body (generally) knows what it’s doing. Whilst understanding the inner workings of your own body is a fascinating and super beneficial thing to do, allowing it to continue to function in its own way is completely fine. 

If you’re someone that doesn’t necessarily frequent long distance running, or doesn’t run at all, then maybe a different method of training would be more beneficial to you.

Or maybe not! Understanding exactly which parts of your body you want to exercise is your choice, so choose wisely! And happy running.

Richard Harris