Demystifying Tempo Runs and Lactate Threshold

What are Tempo runs (also known as Lactate threshold (LT) runs)?

Tempos runs are faster than marathon pace and slower than interval pace. It is often expressed as 85% of maximum heart rate or 75% of maximum oxygen intake.

Another way of looking at tempo pace should be just within the aerobic range of activity, it should be a “comfortably hard” pace that you can sustain for around an hour in race conditions. (Lactic acid, or lactate, is a chemical by-product of anaerobic respiration — the process by which cells produce energy without oxygen around.)

Tempo runs in a runner's trainig pace continuum

Why should we do tempo runs?

The lactate threshold (LT) represents the highest intensity (or pace) we can manage before the body begins to exponentially accumulate lactate. Better the LT, it will help us to run in an aerobic state longer.

As runners, we tend to run initial miles of long runs very strong, because legs are fresh and a good recovery from the previous workout. However, our pace drops as the miles increase. This is where adding Tempo runs to our training comes handy.

• Tempo runs improve our lactate threshold (LT) which helps us maintain higher paces and in turn efficiency for long-distance running
• When we train at paces faster than our current lactate-threshold pace, lactate accumulates rapidly and we reach our VO2 max quickly. We aren’t giving enough time for our muscles to work hard without accumulating lactate. The more time spent close to the lactate-threshold pace, the greater the stimulus for improvement.
• Tempo runs also improve in oxygen uptake capacity (VO2 max)

The chart below shows the blood lactate levels of trained and untrained athletes at varying exercise intensities. As seen in the chart, trained athletes can run at a much higher intensity, before they reach their LT. Untrained athletes reach their LT at a much lower effort as a percentage of their VO2max.

Lactate Threshold in trained vs. untrained athletes

Training to Improve Lactate Threshold

By feel, Tempo runs should feel “comfortably hard”. One can know if they are running faster than their tempo pace when they start breathing too hard, and it’s time to slow down. Also when you train faster than the current lactate-threshold pace, you feel the “burn” of lactate accumulation in your muscles.

The most effective way to improve the Lactate Threshold is to run at the current lactate-threshold pace or a few seconds per kilometer faster. It is good to keep the distance at 800mts, 1km, 1mile to start with, and then progressively increase run duration. Below is a beginner Tempo workout.

• Begin with 3*1 km repeat with 2 mins rest interval
• Give yourself 2 weeks before you increase the tempo distance and mileage

If you are preparing for a half marathon with a weekly mileage of 40-45km, the distribution of runs w.r.t. Endurance, Tempo, and Intervals should be, Endurance runs - 50%-60%, Tempo runs - 20%-30% and Intervals 10%-20% in a training cycle. Here is an example distribution of mileage across different types of runs that I used in my training cycle as a run-up to the half-marathon race I was training for.

Calculating pace for Tempo Runs

The training pace for Tempo runs is typically between 10k and half-marathon race pace. If you have run a recent 10k time trial or a half-marathon, you can use those as a reference point for your tempo training pace.

Here is a sample pace chart for different levels of runners based on their finish time targets.

Measuring LT is best done using blood lactate test. Lactate levels in blood are measured at different times during a strenuous workout to find LT. GPS watches can help you find your approximate LT pace. Garmin GPS watch along with chest HR strap, you can perform LT test.

References:

Science of Running: Analyse your Technique, Prevent Injury, Revolutionize your Training; Napier, Chris

Aditi Pandya is an avid runner, a writer and a fitness enthusiast. She is second runners up at Airtel Hyderabad Marathon 2019, Vadodara International Marathon 2020 in Women half-marathon open & veteran categories respectively. She blogs at NarrativesByMe.com and can be reached on Insta narrativesbyme.

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