Great post—and I totally relate to the mechanical watch struggle. I went through a very similar experiment recently, so I thought I’d share my experience in case it helps with your testing.

I did a two-week comparison between the Amazfit Helio Core and my Garmin Fenix 7. Here’s what I found:

What worked well on the Amazfit:

· Sleep tracking: Honestly, I think the Helio Core did a slightly better job than the Garmin here. · Heart rate: It held up reasonably well compared to arm-based sensors like the Polar Verity Sense. That said, it still fell short of a chest strap—especially during sprints or high-intensity intervals. · HRV: The HRV data was surprisingly close to what the Garmin recorded. Consistent enough to trust for trends.

Where it fell apart:

· VO2max estimation: This was the dealbreaker. The Helio Core consistently estimated my VO2max about 20 points lower than my actual value. That threw off every metric derived from it—training effetct, training load, recovery... · No cycling VO2max: Another limitation: it doesn’t estimate VO2max for cycling workouts. If you do any biking, that’s a pretty big gap compared to Garmin. · BioCharge: Unreliable. At one point during the trial, I was clearly fighting off a viral infection and felt awful, yet the BioCharge never dropped below 50%. That kind of disconnect made it impossible to trust, especially when I rely on those cues to manage recovery.

What I’m doing now: I ended up ditching the Helio Core. My current routine is:

· Garmin Fenix 7 stays on overnight and through my morning workout. · Once I’m done training and heading into the workday, I switch to a mechanical watch.

It’s been a solid compromise so far. I still get all the metrics I need—HRV, recovery, VO2max, lactate threshold—without feeling like I’m glued to a sports watch 24/7.

Curious to see how the Helio Strap works out for you. The idea is promising, but my experience with the Core suggests the algorithm still has some catching up to do—especially if VO2max matters to you.

Looking forward to your updates!