Let's hope for something as good as ZoneSense??

_Running_

The past week I've done 5 running sessions and 2 swimming (or rather 1.5 of those). I slightly increased the previous week's "20 minutes easy Out&Back" to 2 km Out and 2 km Back, on the least undulating path in the area (ca 12 metres Asc/Desc). Effort, expressed by RPE (1-10), Avg HR (Max HR), Avg Pace/km (mile) and ZoneSense detected "Aerobic HR threshold":

4 143(159) 6:22(10:15) 150 bpm
3 136(152) 6:14(10:02)
4 144(159) 6:16(10:05) 151 bpm
3 140(154) 6:09(9:54)
3 132(148) 6:04(9:46)

These are short ca 25 minutes steady pace runs using Polar H10. ANT+ connecting Garmin (3.1-0.0 Training Effect in FR955) and BLE for ZoneSense (ZS), which remains silent the first 10 minutes - waiting for the body to reach homeostasis:

www.webmd.com/.../what-is-homeostasis
"Homeostasis refers to any automatic process that a living thing uses to keep its body steady on the inside while continuing to adjust to conditions outside of the body, or in its environment. The body makes these changes in order to work the right way and survive. 18 jan. 2023"

After that, we have a dial to show live effort. The SuuntoPlus Sports App for ZS, that their modern watches can use, was wild during my first run. Lacking any previous data it swung mostly between RED (VO2Max) and YELLOW (Anaerobic) but also dipped down to GREEN (Aerobic). However, post run in the phone SA the graph was all GREEN, the data having been further analysed - whether at Suunto servers or in the app itself, I don't know. The phone SA also is the only place where a detected Threshold, Ae or/and An is shown. Analysis only done for the first 60 minutes of an activity since they want to avoid fatigued results.

The live effort dial during the four later runs got more and more stable as the watch established a baseline for my body. The SA graphs were GREEN overall and only had a couple of YELLOW peaks during the third run (where AeT was measured at 151 bpm). Also, the final run was done with an updated S+ ZS app which had a few bugs fixed and made quicker to react to effort changes.

During the first four runs I reached the breath-indicated LT1 of 149-150 during the latter part, from a few minutes up to about 10 minutes before the end. But observe how ZS only tagged my body as having reached the Aerobic Threshold during the runs I myself judged to be harder efforts, at an RPE of 4. And that is indicative of how ZS works. It is NOT a simple mapping between Heart Rate (Zones) and intensity. At the Suunto forum (in the almost 500 posts thread concerning ZS) one Moderator, who had betatested the app, described how he had 'run' "3 4300 m peaks one day after another for 3 consecutive days" where the post analysis measured AeT, from day one to day three, had dropped 22 beats (!) due to fatigue. Another user showed a graph where Heart Rate was stable but the ZS graph had him enter the AeT effort due to exiting woods and being exposed to brutal sunshine.

_Swimming_

The Suunto videos about ZS emphasises that it can be used for any activity, and swimming is especially mentioned by the presenter of "Training Lecture Series EP4: Suunto ZoneSense". I think he also brought it up in the "Training Lecture Series EP5: Suunto ZoneSense webinar with Monicardi". What I failed to reflect upon was the place where he swam; in a lake. So I ordered their "Smart Heart Rate Belt" (MOVESENSE) along with the SRS watch because it has internal memory, which syncs seamlessly to the watch whenever both are above the water. My use case is Pool Swimming indoors. Bare upper body, as opposed to the probable wetsuit used in the Finnish lake.

I quickly found out that in spite of being only 37 mm in diametre (French spelling...) [Polar H10 is 34x65 mm] it would flip over when pushing off from the pool side, and threaten to do so with every breaststroke. That 0.5 swim session I mentioned before was an experiment with my normal cotton T-Shirt to keep the HR belt from flipping. Swimming idly 5x50m while ZS took it's 10 minutes pause and then doing 5x50 backstroke to give it some data. The T-Shirt was heavy, flailed about and did not work well as an improvised wetsuit top. But the session was tiring and ZS showed some YELLOW peaks. Post processing gave a Measured 127 bpm as Aerobic Threshold. Cool! [I later found out that Pool rules forbade cotton clothes, only Tech Fabric was allowed].

For my next swimming session I had cut off the arms of a running T-Shirt and made it end above the navel - reducing the weight from ca 120 grams to 70. It worked for push offs, flip turns, freestyle and breaststroke. Riding up towards the belt now and then though. Backstroke was less of a success. I now contemplate some elastic strips arrangement at the bottom - but am afraid that it would then ride up and stay high on the stomach reducing the suction down pressure on the belt.

This final swim test was very tiring. 20x50 metres had a lot of YELLOW peaks - though no AeT was detected. And in this scenario with short intervals, ZS showed a similar lag to running intervals. 40-50 seconds activity with 30 seconds rest is simply to short a pair for good measurements. Both Suunto and ordinary users talk about a minimum of 2 to 4 minutes for the active phase. However, I could certainly tell from the live YELLOW periods on the ZS app that I was heading towards exhaustion. And that is all I need really. An objective reason to push the brake.

Swimming for me is to a large extent a social event. I try to meet with a childhood friend (and Swim Club team member when we were 11 to 18) twice weekly. We both retain the good technique and water position necessary for fast laps, but at 64 the muscles have withered. So we moan: "Inget puder i kroppen!" [No powder in the body!] when we can't keep our youth times, but still swim too fast. It would be worth the whole watch plus HR belt cost if I could convince both myself and my friend that slowing down is the way forward - even if it feels like just doing technique drills, not 'real' swimming.

And talking about drills, the SRS does not have such a mode. Furthermore, the style recognition is abysmal. Whatever style I chose, the watch listed it as freestyle in the interval list post session. Yet, I don't care. I bought it for ZS. Outside drills the lap count was even better than what the FR955 provided. Like in running I can swim with two watches. Both the FR955 and the Coros Pace 2 have drill mode and recognise the styles.

Hi soptunna!

Many thanks for Your time and great review!

I just remembered, that I was using AI Endurance for few months about year or two ago. It´s also based on DFA alpha1 analysis. It analyse many previous runs and cycling (with HRV records), count the HR zones, thresholds and makes the user defined training plan. You surely know that platform...

It sets my "tempo" runs to much lower intensity than Garmin suggested workouts, who makes me suffer during this sessions. So since I was using AI Endurance, my training sessions became much easier, I even started to enjoy them a lot and the most interesting part was, that my fitness level started to rise like never before! This confirmed to me, that one does not have to suffer to see results and the most important thing is maximum light training and proper rest. At least for my body.

I have some heart problems, got second ECG monitor implanted so that´s the reason too, why I´m trying to train in low zones. If I´m tired or push it much higher, my heart starts skipping (extrasystols) and after that, it beat a lot faster for a while to compensate the oxygen lost. I see also another coincidences, but that is long story and for another forum :-). So I´m trying to do most runs and cyling in Z1+Z2 and time to time some intervals in higher tempo if I feel good. I skipped sprints completely, last high effort intervals on Tacx cause the irregular heartbeat after last interval..

Thanks again and have a nice base building session!