LTHR test – How far can you run in 30 min?

 In Running

How far can you run in 30 min? Today I did a time trial. Not to see how far I could go, rather to determine my Lactate Threshold Heart Rate. Or at least try to. No fancy equipment. A pair of running shoes and a GPS watch.

If you’ve followed me you know that I am a focused runner but never obsessed about numbers or time trials. I am however a big believer of training in heart beats and zones. It’s a good way to listen (first of all get to know!) to your body as sleep, nutrition, stress etc. affects heartbeats. Also, by training in all zones one creates a harmony in heartbeats and this has made me a better runner.

I have never done an official lactate reading from my blood, but known more or less where my zones have been. More or less. Today my coach in this ultra training, Sarah Seads, scheduled a LTHR field test. Its not as accurate as a blood test. Can be far from it. But if you do it in the right way, with the right conditions and able to push yourself it can give you accurate indications.


Heart Rate training is a way of monitoring the intensity of your workouts. Together with power or pace it is a powerful tool to learn to listen to signals & signs your body is giving you.  It varies over time, your heart rate limits. Depending on many factors.

Why I’m a keen zone runner is because this is my indication on training sessions and when racing. I seldom look at time or speed. It’s the heartbeats. I have learned to know how long I can push or not push in the different zones. But to know your zones… Well, the LTHR field test is a way.


This is what coach Sarah Seads instructed me to do. Find a flat course. Warm up 15-20 min. Run as far as you can for 30 min. 10 min into these 30 min start measuring your heartbeats. Take the average bpm during these 20 min. That is your Lactate Threshold Heart Rate. The tricky part running on your own is being able to push yourself hard enough. I gave it a go. It went utterly wrong. I think!


I was nervous! Didn’t feel strong or ready. Are you ever? But hang on, this wasn’t a competition. It was about finding out my heart beats in order to help adjust my zones when training for this ultra. What bothered me was the worry if I would be able to push myself hard enough. Time trial is always a time trial. And I am a competitive person. So I warmed up and off I went. It went utterly wrong. My flat course was dirt tracks 49m up and 35m down. BPM on my watch was showing 112 and then 203. This distracted me and I have no idea if my watch is wonky or my heartbeats so unpredictable. It hasn’t showed 203, ever. Then! I was going as fast as I could, but still holding back knowing I had to last for 30 min. Ugh! 4:42, 4:20 4:06 but never under 4 – until the last hundred meters! This was a huge blow on my running ego. I had to remind myself that for the past 11 months I’ve been maintaining (in a snowy wintry outdoor) fitness level not racing mountain marathons month after month. Maybe not improving. And shit, short distances are not easier than half marathons! Harder. However, be kind to yourself Sarah. Some weeks back, when I was race ready for TransGrancanaria I did 21k on ice in 1:38h including a shoe change! You see, thrills and “racing” fires this engine. So I knew there was potential. And! I had an image in my head. My fastest km ever in training has been 3:47min and that is after have run 10k dirt trails in a summery Lanzarote. Maybe my body does perform better in heat. Or I’m just hard on myself. Today’s fastest km was 4:10min. This is the reason I try not to obsess over times and speed, because I am never satisfied. I love to run with feeling. That way I find I never lose the joy.

So, how did I feel? Legs were fine, breathing harder. I ran just under the “feeling pukey” limit, you know when you start burping. Just didn’t feel harmony between body and breathing or the feeling of running free. Awkward is the right word!

Anyway. How far did I run in 30 min? 6.79km. Thats an average 4:25min/km My LTHR? Well the average on the 30min was 162bpm (that sounds low?), I still need to calculate the average on the last 20min. Would be fun to do a proper clinical LTHR test on a flat, non dirt track surface. With a GPS I know is wonky free. The good news is after 2 min recovery I could have done another 20km (not fast) and I guess that’s a nice boost for this aspiring ultrarunner. Bring on tomorrows zone 1 running! 

Ps. Pics with todays results. For the number freak. This is according to “old” zones.

Trailrunning 30 min





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