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How to calculate your Lactate Threshold

Updated: Apr 13, 2020

We have recently published the training program for the 2016 African X Trail run and we have decided to incorporate a little bit of heart rate (HR) training. A lot of people are fairly new to this but we will try and ease you into it so that you can gain the most out of the 2016 Training Program.

What is Lactate Threshold (LT)?

The lactate threshold (LT) (or lactate inflection point (LIP) or anaerobic threshold (AT)) is the exercise intensity at which lactate (more specifically, lactic acid) starts to accumulate in the blood stream. The reason for the acidification of the blood at high exercise intensities is two-fold: the high rates of ATP hydrolysis in the muscle release hydrogen ions, as they are co-transported out of the muscle into the blood via the MCT— monocarboxylate transporter, and also bicarbonate stores in the blood begin to be used up. This happens when lactate is produced faster than it can be removed (metabolized) in the muscle. When exercising at or below the LT, any lactate produced by the muscles is removed by the body without it building up.

With a higher exercise intensity the lactate level in the blood reaches the anaerobic threshold (AT), or the onset of blood lactate accumulation (OBLA).

The lactate threshold is a useful measure for deciding exercise intensity for training and racing in endurance sports (e.g. long distance running, cycling, rowing, swimming and cross country skiing), but varies between individuals and can be increased with training.

The method we will recommend you to follow to determine your LT is as follows:

  1. Warm up for a good 15 minutes, very easy and light running – remember to wear your heart rate monitor

  2. Then lap your watch and start a full 30 minute time trial, yes 30 minutes of running as hard as your body can handle.

  3. You can run up, down, flat – whatever suits you just run hard and ensure you last the full 30 minutes (this is going to be very uncomfortable)

  4. In the 30 minutes you want to lap your watch for the last 10 minutes, i.e after 20 minutes (continue running flat out/hard as possible)

  5. Then lap your watch again after the full 30 minutes or the 10 minutes of lap 2 of the 30 minutes

  6. Then cool down for 10 minutes

  7. You can then pull an average HR for the first 20 minutes and the second 10 minutes of the 30 minutes run

  8. Your LT is the average of your HR for the last 10 minutes.

Then you want to calculate your zones, we use the following 5 zones:

We can take John as an example, who has just completed his 30 minute LT test. He achieved an average HR of 160 over the final 10 minutes of his 30 minute test. Thus in brackets below are his HR training zones.

Zone 1 – Low Aerobic – 75 to 80%   (120 – 128)

Zone 2 – Moderate Aerobic – 81 to 89%   (129 – 142)

Zone 3 – Threshold – 96 – 100%   (153 – 160)

Zone 4 – VO2 Max – 102 – 105%   (163 – 168)

Zone 5 – Speed – 106+%   (169+)

If you are interested in reading more, get your hands on the 80/20 running book by Matt Fitzgerald

In this book they talk about 80% of your running must be done preferably in Zone 1 and Zone 2 and that 20% in the other Zones. It ensures that your easy runs are in fact easy.

We hope this will help you achieving your goal.

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