Lactate threshold in Suunto Run
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Hi,
In the Suunto Run the CTL widget shows me a very different lactate threshold (152bpm) than ZoneSense does (166 bpm).
Which one should I use to set my HR training zones?
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@Pep-Carbonell only accurate method is a professional lactate measurement on a treadmill.
If you can not do that or you don’t want to spend the money, a field test like a 10km Time-Trial/Race or 1h all-out is the most accurate you can go.
The average HR for the last 20 min is in the ball park of ±3 BPM of your lactate threshold. If you do that 2 or 3 times over the next months to reduce daily influences you will be able to quite accurately narrow down your HR at the lactate threshold.Formulas like 90% of HRmax are way to inaccurate and can be ±20 BPM off. ZoneSense is already more accurate but can still have around ±10 BPM inaccuracy as scientific works could show.
A deviation of 10 BPMs is quite good compared to the other calculation methods but it’s still huge if you want to train correctly in the zones. -
@brave_dave thank you so much, I see…
My last 20 minutes of a 10k race and my Zonesense anaerobic thershold are quite similar (+/-2bpm).
But then, there’s the widget on Suunto Run (the watch) that tells me that my lactate thershold is 12 or 14 bpm lower than the other methods and this confuses me, I guess it’s wrong.
Anyway, thanks again.
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@Pep-Carbonell yes, the values measured by SZ can be correct and can be closer or further away from time to time but it is hard to know when it is accurate and when not. Scientific papers could show that DDFA is correlated with the lactate threshold but even under perfect conditions/set-up on a treadmill, it is hard to detect the correct value. A publication from May 2025 (it’s actually from the scientific partners from Suunto from Tampere University) showed that the DDFA method indeed performs better than the estimations from HFmax. DDFA showed on average a deviation of ±10 BPMs from the actual value in 58 subjects…±10 though is usually bigger than the difference in HR between 10k and Marathon Pace. 10k is normally well above threshold and Marathon well below. At +10 BPM above my threshold I’m almost dead why -10 feels really easy :D. So it works in principle but is it accurate enough? A good race-based estimation will probably be on average a lot closer than ±10 BPM.
(Here is the publication of you are interested https://physoc.onlinelibrary.wiley.com/doi/10.14814/phy2.70241)
Of note: the accuracy of detecting the aerobic threshold was with ±12 BPMs even worse. -
@brave_dave great answer! thank you so much, especially this final note about the often forgotten aerobic thershold.
In the end, I guess RPE is more important than it seems.
Regards!
