When your legs start burning and your breathing gets heavier, you’ve likely crossed a physiological line that matters to every runner: the lactate threshold. This term has moved from the lab to sports watches and training apps, yet many runners still don’t know exactly what it is, how to measure it or how to train at it for maximum benefit. In this article we unpack the science behind lactate threshold, explain why it matters for performance and provide practical strategies to improve it. You’ll also see how the SnapRace app can help you design and record threshold-specific sessions.
What is the lactate threshold?
During aerobic exercise our muscles use oxygen to break down carbohydrates and produce energy efficiently. As intensity increases, the body relies more on faster anaerobic pathways, which generate lactate as a by-product. Far from being a “poison”, lactate can be reused as fuel, but when production exceeds clearance capacity it accumulates, acidity rises and fatigue appears. The point where this happens is known as the lactate threshold. According to exercise physiologists, it’s the highest intensity you can sustain without lactate skyrocketing.
Two key thresholds are commonly described:
- Aerobic threshold (LT1): occurs when blood lactate slightly rises above baseline (~2 mmol/L). It corresponds to a moderate pace you can hold for several hours, faster than easy running but below race pace. Tempo runs at marathon pace push this threshold upwards.
- Anaerobic threshold (LT2): happens when lactate production exceeds clearance (~4 mmol/L). This effort can be sustained for about an hour: roughly 10 km pace for beginners, 15 km pace for trained amateurs or half‑marathon pace for elites. When we talk about “lactate threshold” we usually mean this second threshold, as it determines your highest sustainable speed without rapid fatigue.
Why your lactate threshold matters
While maximal oxygen uptake (VO2 max) has long been viewed as the key predictor of performance in shorter races, recent research highlights that the speed or power at which lactate threshold occurs is a more specific indicator of middle‑ and long‑distance running ability. A study from Loughborough University found that the percentage of VO2 at which lactate accumulates doesn’t vary greatly between different ability levels, but the absolute speed at threshold correlates with performance. In other words, improving your threshold allows you to run faster without relying on anaerobic metabolism.
Training around lactate threshold also improves running economy and teaches the body to recycle lactate as fuel. Olympic champion Jakob Ingebrigtsen popularised the “double threshold” days, performing two threshold sessions in a day during base periods. This approach isn’t just for elites: recreational runners benefit too, because it allows lots of quality work without the strain of all‑out intervals.
How to measure your lactate threshold
The most accurate way to know your lactate threshold is via laboratory tests that analyse blood lactate and oxygen consumption while running on a treadmill. These require specialised equipment and staff. Fortunately, you can estimate your threshold with simpler methods:
- 30‑ to 60‑minute time trial: warm up well and run for 30 minutes at a steady, hard pace. Note your average heart rate during the final 20 minutes – this approximates your lactate threshold heart rate. If you can race for an hour, the average pace you sustain is also close to your threshold pace.
- Use pace and heart‑rate zones: many watches and platforms like COROS or RunningFront automatically estimate your threshold from training data. Generally it sits around 80‑90 % of your maximum heart rate and at a pace you could sustain for an hour.
- Perceived effort: running at threshold should feel “comfortably hard”: you can speak in short phrases but not hold a long conversation. If your legs flood with acid and breathing skyrockets, you’ve likely gone above threshold.
The SnapRace app lets you log heart rate, pace and perceived effort in each session to build a more accurate threshold over time. You can schedule regular tests and receive alerts when your training zones shift.
Workouts to raise your threshold
To elevate your lactate threshold you need to run at or near it regularly, accumulating quality time without overstressing yourself. Here are some effective sessions:
Continuous tempo runs
Hold a pace slightly below your threshold for 20‑40 minutes after a thorough warm‑up. This “tempo” effort raises both your aerobic and anaerobic thresholds. For example: 15 minutes easy + 30 minutes at a comfortably hard pace + 10 minutes easy.
Threshold intervals
Also called cruise intervals, these alternate 5‑10‑minute blocks at threshold pace with short recoveries (1‑2 minutes) of easy jog. Try 4 × 6 minutes with 1‑minute recovery, or 3 × 10 minutes with 2‑minute rests. This format lets you accumulate more total time at the target intensity without excessive fatigue.
Progressions and fartlek
Progression runs gradually increase pace until you hit threshold near the end. For example, a 40‑minute run where you speed up every 10 minutes, finishing the last 10 at threshold pace. Structured fartlek sessions can also include 5‑8‑minute blocks at threshold interspersed with easy jogging.
Double threshold days
Popularised by Ingebrigtsen, this approach involves two threshold workouts in a day (one in the morning and one in the afternoon) with moderate durations (e.g., 6 × 5 minutes in the morning and 4 × 8 minutes in the evening). It spreads 60 minutes of threshold work across the day and can be used sparingly during base periods by experienced runners.
Introduce these sessions gradually. Two threshold workouts per week are enough for most runners; your remaining mileage should be easy runs and strength or speed sessions. Remember that strength training, such as the exercises described in our strength training article, improves running economy and helps sustain threshold efforts.
Practical tips for threshold training
- Listen to your body: threshold workouts should feel demanding yet sustainable. If you need several days to recover, reduce the pace or duration.
- Don’t neglect easy mileage: aerobic base and easy runs enhance your ability to metabolise lactate. Keep at least 70 % of your weekly volume in comfortable zones.
- Include strength and mobility: strengthening your legs and core increases tendon stiffness and running economy, reducing lactate accumulation at high speeds.
- Mix up your sessions: alternate tempo runs, intervals and progressions to stimulate different adaptations. Avoid repeating the same workout every time.
- Use technology wisely: apps like SnapRace and smart watches provide heart‑rate zones and pace alerts. They help you stay in the right zone without overdoing it.
How SnapRace helps you train your threshold
Beyond acting as a social platform to compare times and join challenges, the SnapRace app includes advanced planning and tracking features. You can create custom threshold sessions, setting block durations, target paces and recovery intervals. The app offers real‑time pace and heart‑rate alerts to keep you in the right zone. After the workout it analyses your session and shows whether you spent too much time above threshold or hit the desired pace. Over time these metrics let you see how your ability to hold faster paces without fatigue improves.
On top of that, SnapRace training plans include strength workouts, easy runs and rest days, ensuring an integrated approach that maximises progress and reduces injury risk. Download the app and start leveraging your lactate threshold to run faster, longer.
Ready to discover your lactate threshold and take your training to the next level? Download SnapRace and start planning your threshold sessions today.