If you have spent any time in running communities lately, you have probably heard the phrase "lactate threshold" come up more than once. It shows up in training plans, on podcasts, and now in the data from GPS watches and sports lab tests. For a term that sounds like it belongs in a biology textbook, it is getting a lot of attention from everyday runners.
Here is what it actually means, why it matters, and how to use it to run better.
What is lactate threshold?
When you run, your muscles produce lactate as a byproduct of burning fuel. At easy effort levels, your body clears lactate from the blood about as fast as it produces it. Push harder and lactate starts to accumulate faster than it can be cleared. The point at which this happens is your lactate threshold.
Once you cross that threshold, fatigue accelerates quickly. Your legs feel heavy, your breathing becomes laboured, and sustaining your pace becomes very difficult. Sound familiar? That is what hitting your threshold feels like mid-race.
Training around your lactate threshold teaches your body to clear lactate more efficiently, push the threshold higher, and sustain faster paces before that wall appears. It is one of the most evidence-backed ways to improve your running performance.
How is lactate threshold different from other zones?
If you have read about Zone 2 training for runners, you are already familiar with the idea of training at different intensity levels. Zone 2 sits well below lactate threshold, in the comfortable aerobic range where you can hold a full conversation. Most of your weekly mileage should be here.
Lactate threshold sits above Zone 2 but below your maximum effort. It corresponds roughly to your "comfortably hard" pace, the kind of effort you can sustain for 30 to 60 minutes in a race. Some coaches call this the "tempo pace" zone, and it is the focus of tempo runs, which are one of the most effective workouts for improving your threshold.
Above threshold is where high-intensity interval work lives, the type of training covered in more detail in the interval training guide. Both have a role, but threshold work is often the most underdone piece in a typical runner's program.
How to find your lactate threshold
There are a few ways to estimate where your threshold sits.
The most accurate method is a lab test. You run on a treadmill at increasing speeds while a technician takes small blood samples from your finger or earlobe at each stage. The lactate readings are plotted on a graph, and your threshold is identified at the point where lactate starts rising sharply. These tests cost between $100 and $200 at most sports science facilities in Australia and are increasingly available through running clubs and physio clinics.
If you are not ready to go to a lab, there are two practical field tests you can use.
The first is the talk test. Run at increasing effort and notice when you can no longer hold a full sentence of conversation without pausing for breath. The effort just below that point is close to your lactate threshold. Above that point is above threshold.
The second is a 30-minute time trial. Warm up, then run as hard as you can sustain for 30 minutes. Your average heart rate in the final 20 minutes is a reliable estimate of your lactate threshold heart rate. From there, you can use that heart rate to guide your threshold workouts.
How to train at lactate threshold
The most common lactate threshold workout is the tempo run: a continuous effort at threshold pace for 20 to 40 minutes, sandwiched between a warm-up and cool-down. For most runners, this pace feels like a seven or eight out of ten effort. You can still talk, but only in short phrases.
Cruise intervals are another option, particularly if you are newer to threshold work. These are shorter threshold efforts (usually 5 to 10 minutes each) with short recovery jogs in between. They give you more total time at threshold pace than a continuous tempo run, with less mental and physical stress.
The Norwegian Method, made famous by athletes like Jakob Ingebrigtsen, takes this a step further by stacking two threshold sessions in one day. It is a high-volume approach that elite runners use with great results, though most amateur runners will get more than enough stimulus from one well-executed threshold session per week.
The 80/20 training model puts roughly 80 percent of your weekly running at easy effort and 20 percent at moderate to hard intensity, including threshold work. This balance gives your body enough stimulus to adapt without accumulating excessive fatigue.
How much threshold work do you need?
For most recreational runners, one threshold session per week is plenty. More than that without a strong aerobic base can lead to accumulated fatigue that undermines your easy days and slows adaptation.
A well-structured week might look like this: two or three easy runs, one threshold session, one session of faster interval work, and a long run. The threshold session sits in the middle of the week, ideally after a rest day or easy recovery day.
The key is building the base first. If your easy running is not consistent, adding threshold work on top of it will not produce the results you are looking for. Building a proper running base is what makes threshold training effective.
Tracking progress
The clearest sign that your lactate threshold is improving is that your threshold pace gets faster at the same perceived effort, or the same heart rate. A pace that felt like eight out of ten a few months ago starts to feel like a seven. Your tempo runs feel more manageable at the same speed.
Most GPS watches now estimate your lactate threshold using heart rate and pace data, and while these estimates are not perfectly accurate, they are useful for tracking trends over time. VO2 max and running economy tend to improve alongside lactate threshold when training is structured well.
Gear for threshold sessions
Threshold sessions are typically done outdoors, which means you are putting in hard effort in whatever conditions the day brings. A few things make these sessions more consistent and comfortable.
A chest strap heart rate monitor gives more reliable readings than optical wrist-based sensors during high-effort running, which matters when you are using heart rate to guide your threshold efforts. The readings from wrist sensors can lag or drift, particularly at higher intensities.
A GPS watch with interval timer functions makes it straightforward to structure cruise intervals. Set the work and rest durations in advance so you are not watching the clock mid-effort.
Running shoes with a responsive midsole help at threshold pace, where you are moving faster than your easy pace and generating more ground force. Most runners find that a light, cushioned daily trainer works well for threshold sessions, though race-day shoes are generally kept for races.
Sunglasses matter more than most runners expect during outdoor sessions. Threshold work often happens in the morning or late afternoon, when the sun angle is low and glare is at its worst. A lens that handles variable light conditions, like the Adaptor lens from Re., adjusts automatically as you move through different light environments, so you are not squinting into glare on one section of your route and struggling with a dark lens in shadow on another. The full range is at reyourrun.com.au/collections/all-running-sunglasses.
Common mistakes with threshold training
The most common error is running threshold sessions too fast. It should feel hard but controlled. If you finish a tempo run feeling completely destroyed, you have probably gone above threshold into high-intensity territory. That is fine occasionally, but it defeats the purpose of threshold-specific work if it happens every session.
The second mistake is neglecting easy running. Threshold work delivers adaptation, but recovery and easy aerobic running is what allows that adaptation to consolidate. Too many runners do their easy days slightly too hard, which means they arrive at their threshold session already fatigued. If your recovery runs feel like a workout, slow them down.
Finally, expecting fast results. Lactate threshold improvements tend to show up over weeks and months, not days. Consistency across a training block matters far more than any single session.
The takeaway
Lactate threshold training is one of the most effective things a recreational runner can do to run faster over longer distances. It does not require a lab test or expensive equipment, though a field test helps you calibrate your effort accurately. One well-executed threshold session per week, built on a foundation of consistent easy running, is enough for most runners to see meaningful improvement over a training block.
If you want to understand more about what your lenses should do when you are training outdoors in variable conditions, the Re. lens guide covers each option and what it is best suited for.
Tim Golubev
Founder, Re. (Re Your Run)
Tim built Re. after years of running in sunglasses that bounced, fogged, and ended up on his forehead. After discovering the UV damage that builds up without eye protection (even on cloudy days) and hearing the same frustrations from hundreds of other runners, he decided it was a problem worth fixing properly. With a background in Product across multiple industries, he approached it like any product problem: figure out what's broken, then build something that actually fixes it. He runs daily, co-founded Rose Bay Run Club, and Re. is his attempt to make one less thing that gets in the way of a good run.
