Suunto ZoneSense

Brad_Olwin

I have stated this before and it is clearly presented in the Suunto videos. ZS is not a tool to set HR values. ZS is a tool to assess efforts for longer intervals and during exercise replacing HR values.
For training ultras where a mix of speed work, tempo and steady-state intervals are done, the general agreement is that HR is a poor indicator of effort. Running on trails presents difficulties not encountered on pavement that include rocks, sand, roots, mud, snow, ice and massive variations in grade accompanied by rocks, roots, sand, mud, snow, ice. For gauging effort in training most individuals use RPE and breathing tests. For short intervals (anything less than about 6 min for me) I don’t pay attention to ZS but anything longer I do knowing that ZS is not instantaneous.
On a Steady State interval of 30 min, which I have today I will keep ZS in the yellow as much as possible, which typically aligns well with my breathing test (on steady state I can say a short sentence or two).
A lot of comments here are too concerned with HR zones and I think for training you can focus on either but not both. (I rarely paid attention to my zones anyway but now I wish all I had for the outer ring was ZS.) Too many comments here are asking about adjusting HR zones with ZS, which I see as meaningless. ZS is most useful in real time, assessing how ZS sets your zones will depend on your recovery, your stress levels, probably food intake and likely others. As @Francesco-Pagano reported I see huge fluctuations in my AT from 120 to 145bpm. It will be interesting to see fluctuations in my LT as I soon have a block of intense intervals coming up. I do not adjust my HR zones because I believe it doesn’t matter.
This is my experience and my opinion from using ZS since last summer and not the opinion of Suunto.

borgelkranz

@flo7z Your screenshot shows the 5 Zones model. As far as I know, Z1 and Z2 in this model are below the Aerobic threshold, which is green in Zonesense.

ZE and Z4 are above Aerobic but below Aerobic threshold. This is yellow in Zonesense.

Z5 is above the Anaerobic threshold. Red in Zonesense.

I never trained for a marathon but I suspect that it should mostly be aerobic. So green in Zonesense.

As @Brad_Olwin stated: Zones and Zonesense are not the same. Use what helps you most.

I can also confirm that the thresholds reported by Zonesense do vary. Across different sports and even across different days.

For example in indoor rowing my Aerobic Threshold is at around 150, while in commuting by bike it is at around 136.

flo7z

That’s exactly my point, it seems there is a big difference between the HR and ZS zones.
I understand you cannot directly compare HR and ZS but at the end of the day, you want to know if you are in aerobic or anaerobic.
As I prepare marathons, I do big volumes and I have observed that difference on several runs and indoor biking sessions.

flo7z

@Brad_Olwin by running marathons i know my paces and HR zones by heart, and the terrain does not play a role in this case.
if we are not supposed to compare HR and ZS zones, then why is the SA doing it as on my screenshot?

A Former User

@flo7z You can compare, but assuming a correlation and immediately dismissing ZoneSense as ineffective is misguided. ZoneSense relies on HRV during activities to measure intensity and fatigue, and reducing it to just heart rate oversimplifies the multiple factors involved in its calculation. For example, after a good night’s sleep, the same pace and HR might indicate an aerobic effort, whereas after poor sleep, that same pace and HR could shift into anaerobic territory. This makes pace and HR unreliable—and for me, obsolete—when it comes to targeting training effectively.

A little perspective about the factors involved in ZoneSense calculations:

Heart Rate Variability (HRV) is influenced by several physiological, environmental, and behavioral factors:

Physiological and Biological Factors
• Autonomic Nervous System: The balance between the sympathetic (stress, action) and parasympathetic (rest, recovery) nervous systems is the primary regulator of HRV.
• Age: HRV naturally decreases with age.
• Sex: Women tend to have slightly higher HRV than men before menopause.
• Genetics: Some individuals naturally have higher or lower HRV.
• Physical Fitness: Better cardiovascular fitness is generally associated with higher HRV.
Lifestyle Factors
• Physical Exercise: Regular training improves HRV in the long term, but intense exercise can temporarily lower it.
• Sleep: Poor sleep quality or insufficient sleep reduces HRV.
• Hydration: Dehydration can lower HRV.
• Diet: A balanced diet low in inflammatory foods supports better HRV.
Environmental Factors
• Temperature and Altitude: Extreme cold and high altitude can affect HRV.
• Air Quality and Pollution: Exposure to toxins or poor air quality can lower HRV.
Psychological and Emotional Factors
• Stress and Anxiety: Chronic stress reduces HRV by increasing sympathetic nervous system activation.
• Relaxation and Meditation: These practices enhance HRV by activating the parasympathetic nervous system.
Medical and Hormonal Factors
• Chronic Diseases: Conditions like hypertension, diabetes, and heart disease reduce HRV.
• Inflammation: Chronic inflammation is associated with lower HRV.
• Hormonal Fluctuations: Cortisol (stress hormone) lowers HRV, while melatonin and testosterone may increase it.
• Substance Use: Caffeine, alcohol, nicotine, and certain medications can alter HRV.
Circadian and Temporal Factors
• Time of Day: HRV is typically higher at night due to parasympathetic dominance.
• Circadian Rhythms: Jet lag and disruptions to biological rhythms affect HRV.

Mattg576

I’ve been using ZoneSense since it’s release on my race.
I love the idea of it & really want to base all my training around it but continuously see random stuff like this going on.
Is this just highlighting the interval “limitations” discussed above or something else going on ?

Cheers
Matt

Brad_Olwin

@flo7z said in Suunto ZoneSense:

@Brad_Olwin by running marathons i know my paces and HR zones by heart, and the terrain does not play a role in this case.
if we are not supposed to compare HR and ZS zones, then why is the SA doing it as on my screenshot?

Your HR zones are going to change daily as judged by ZS. That at is the point.

Brad_Olwin

@Mattg576 how long are the intervals? Likely too short. I would not use ZS for any less than 6 min and even then ZS will have a 1 to 2 min delay.

Mattg576

@Brad_Olwin
They’re not intervals Brad, just some small hills on a tempo run.

Brad_Olwin

@Mattg576 How long? Looks too short as the downhills push ZS low and not enough sustained effort to go higher. On trails I cannot run downhill fast enough for ZS to show actual effort. That’s why I rely on RPE as well.

2b2bff

@Brad_Olwin @Mattg576 to extend on that, in the ZoneSense videos it is said that you don’t want to look at the actual curve of ZoneSense but only on the color. So, a downvard curve within green means nothing, it is just green…

Mattg576

@Brad_Olwin I don’t know what you mean by how long or looks too short, the whole run or the small hills ?

Mattg576

@2b2bff I understand the principles of Zonesense but by that logic my work effort got easier while I ran those hills (which it didn’t, it got harder).

I also understand there isn’t a direct correlation between ZS & HR BUT surely as the work effort increases it would push you up further into the anaerobic state - not nose dive back into low aerobic…

2b2bff

@Mattg576 as @Brad_Olwin said, ZoneSense always needs a couple of minutes to catch up. I remember from the videos that there are physiologic factors (30 seconds) and factors of calculation (2 minutes). So, if your intervals are shorter than those two minutes you won’t see any meaninful effects.

Here I had a run with 3 minute intervals and you can see how ZoneSense had a hard time to catch up, but it reached yellow at the end of the interval…

Brad_Olwin

@Mattg576 The small hills, how long was the uphill, it looks to be short only 3 minutes or so?

Brad_Olwin

@2b2bff A perfect example! I don’t use live ZS for less than 6 min. I just use RPE. I will look back at my zones out of curiosity.

Brad_Olwin

@Mattg576 said in Suunto ZoneSense:

@2b2bff I understand the principles of Zonesense but by that logic my work effort got easier while I ran those hills (which it didn’t, it got harder).

I also understand there isn’t a direct correlation between ZS & HR BUT surely as the work effort increases it would push you up further into the anaerobic state - not nose dive back into low aerobic…

The uphills are too short, it is simply green because the hard efforts were not long enough. Have you watched the videos or read the material on ZS. Those explain what you see.

Brad_Olwin

@iterum-tenta A great summary! I think to all forum users here…do not equate HR and ZS values or try to force them to fit together. Suunto has extensive information that explains 99% of the issues raised here. It is a substantial time commitment to view all of the videos.

Mattg576

@Brad_Olwin said in Suunto ZoneSense:

The uphills are too short, it is simply green because the hard efforts were not long enough

What mystifies me though is that I was already in an anaerobic state & my workload increased (confirmed by RPE - I was hanging out my ar#e) yet ZS suggests the complete opposite for nearly 10 minutes, I’ve experienced the same many times before…

I have read & watched some of the material but granted not all of it, the answer must in the bits I haven’t watched yet.

Thanks for your reply Brad.

ChrisA

@Brad_Olwin said in Suunto ZoneSense:

…do not equate HR and ZS values or try to force them to fit together.

That’s it in one sentence! I think that’s the main problem, the main mistake, made when using ZS at first, since it seems so obvious and somehow it seems like a paradigm change at first. I would also recommend watching the very good videos.