Updated: February 4th, 2022
Lactate threshold: what it is, how to do it, and why beginners should use it too

If you have landed here, it’s probably because a ‘threshold’ workout has appeared on your training plan, and no doubt, you want to know exactly what that is and what you’re supposed to be doing.

So, what is Threshold training?
This is running at a pace where lactate does not rise significantly in the blood during the run, but rather, it stays at a constant level. Essentially, it is the point JUST BEFORE the moment where the amount of lactic acid build-up is greater than the body can efficiently get rid of.

When you hit that lactate threshold, fatigue will come at you, full steam ahead! Legs will feel heavy, you will slow down and feel sluggish – so the higher your threshold is (the fitter you are) will enable your body to run at faster speeds for longer. The less fit you are, and the lower your lactate threshold is, means you will hit that fatigue slap-in-the-face much sooner than desired.

women finishing run race lay on run track exhausted

Very unfit or beginners to exercise will have very low threshold levels; their heart is having to work very hard, even at a slower pace. This is why beginners will find running difficult and complain of leg pains, joint pains.

Stick with it because every level can benefit from working with their lactate threshold levels. Because, utilising your threshold sessions to the best of your ability will skyrocket your aerobic fitness levels. A run plan worth its money will feature threshold training in training plans from 5k up to ultra marathons because frankly, the benefits are endless:

How to find your lactate threshold

Identifying that sweet spot between even levels and the point of no return is a tricky one, And is most accurate via testing in a specialist physiology lab (which can get a bit pricey). You’re put onto a treadmill progressively getting quicker whilst blood is taken from a finger prick throughout, to establish the lactate curve. The curve is important because there will be an exact moment where lactate spikes.

The speed you are at just before that spike is your lactate threshold pace. Push past it and you’re entering anaerobic metabolism to fuel your running sessions – that’s fine if you’re racing for a 5k. Anything else can spell trouble, there is no need to put your body under that much pressure.

tired runner

Ultimately, if there is a threshold session on your run plan, take each session individually. Approach with the attitude of ‘this should be harder than my easier, usual run pace’ yet if you’re breathing gets too erratic, back off the pace a little.

Most smartwatches such as Garmin’s will have this feature built-in. Take the guided test, or complete a 20-30 minute run and the super-smart technology will give you a threshold result (training peaks is a fantastic app for this, and even adjusts workouts to your threshold intensity – one I personally recommend and use to train for my ultras).

Alternatively, as a ballpark figure, you can recognise when you are reaching your lactate threshold with Heart Rate (HR) training. HR training uses 5 zones and are based on your maximum heart rate (MHR). Lactate sessions are when your HR hits into zone 5, from zone 4. Zone 4 is based on 80-90% of MHR and so you’re hitting maximum heading into zone 5.

Polar heart rate monitor

How often should I do a threshold run?

I know, the benefits sound fantastic! And you genuinely do feel the difference in your own training after a couple of sessions HOWEVER, proceed with caution.

Running at a threshold pace (zone 5 = +90% of MHR remember) puts a lot of stress on the body, so do not get carried away here! If you are training for a PB 5k for example, then maximum 2 threshold sessions a week followed by plenty of rest. However should you be training for marathon and ultra-marathon endurance distances, then once a week, even one per two weeks is enough. See longer distances require 80% of sessions done at an easy pace, 20% of sessions intense (interval and tempo sessions).

Any more than this, you are literally running the risk of injury. There will not be enough adequate time for rest and recovery, so the benefits you’re chasing won’t actually happen. Understanding your resting HR and its implications can help you understand when to rest, if you need an extra day off and still benefit.


Comparing speeds, distances, and levels will never end well. If it takes you 12 minutes to run a mile at the threshold then it takes 12 minutes. DO NOT try to push to match your friends, or compete in any way. The only person you should be competing against is yourself, and not the watch, or the random runner on your route. – Ladies take note, running perceived exertion can alter week by week with your menstrual cycle. Some weeks are made for pushing and some are made for resting intently (and others for hitting the gym!) so be body aware, train with your heart rate, and compete with no one. After all, that’s half the fun of running, isn’t it? Challenging yourself.

Running finishers medal

So, fear not the threshold session in your run plan (and don’t think you’re not fit enough to train that way) it is there to get you to level up.

Threshold runs will improve our VO2 max and ability to cover longer distances at an easier rate (in the lower HR zones). A little hard work will no doubt make race days that little more enjoyable, with time, space and breathe to enjoy the wonderful picturesque views running races take you.

As an Amazon Associate we earn from qualifying purchases

Recommended reviews

Saucony Cohesion 15 Review

The Saucony Cohesion 15 has some serious "Dad Shoe" vibes. I was sent a boring ... (Read expert review)

New Balance FuelCell Rebel v3 Review

The New Balance FuelCell Rebel v3 is a lightweight daily trainer with a ... (Read expert review)

New Balance Fresh Foam X 880 v12 Review

VERDICT: The 880 is a great classic trainer with a modernized ride that ... (Read expert review)

Hoka Mach 5 Review

The Hoka Mach 5 is a lightweight, smooth-riding trainer which can fill a ... (Read expert review)

Adidas Adizero Adios Pro 3 Review

The Adidas Adizero Adios Pro 3 is a long-distance specialist. Its highly ... (Read expert review)

Reebok Nanoflex TR Review

The Reebok Nanoflex TR is one of the best budget training shoes on the market, ... (Read expert review)