Since I have somewhat of a scientist’s ethos and realised that the Suunto HR belt with module could be used in four different combinations, I felt that I also had to provide data for all of them, to prove or disprove the warning in this topic’s heading; “Beware module orientation”.
The belt itself can be worn ‘correctly’ with the closing hook and loop on the left side of the torso (hook going down through the loop), or upside down on the right side of the torso with the hook going up through the loop. On my belt there are no markings at the electrode ‘snap-in holes’ other than the in-between text “MOVESENSE”.
The ‘correct’ belt position still feels awkward to me after half a year of usage since I’ve had so many years with both Garmin and Polar belts, which both close on the right side of the torso…
On this belt then, the module can be snapped in correctly, with the SUUNTO logo pointing upwards (red triangle above text) aligning with the reading of the MOVESENSE text orientation, or be flipped into an incorrect position upside down. The module has markings of L and R at the electrodes but, as said, nothing corresponding on my belt.
Calling ‘correct’ position Up and incorrect Down I have logged the following results:
BeltUp-ModuleUp
(Pulse OK, HRV OK)
BeltUp-ModuleDown
(Pulse OK, HRV Not-OK)
BeltDown-ModuleUp
(Pulse OK, HRV OK)
BeltDown-ModuleDown
(Pulse Not-OK, HRV Not-OK)
In my opening postings of this subject I included screenshots from the first two combinations. Looking at the third and fourth results, where one had OK pulse while the other had massive misreadings might be a fluke with either one, OR the last combination really do exacerbate the position problem. No way to know without doing a large number of experiment sessions.
I’ll skip screenshots from the BeltDown-ModuleUp (Pulse OK, HRV OK) session Wed 30/7 since it was so clean in both areas. I’m using the OHR of a Garmin FR955 with the old Firmware 19.18 as control - normal result is +1 to +2 bpm against both a Polar H10 and the Suunto belt at all kinds of running efforts (my skin/wrist really agrees with OHR, also on the Race S).
Instead I will end this posting with data from yesterday Fri 1/8 BeltDown-ModuleDown (Pulse Not-OK, HRV Not-OK) and a closing BeltUp-ModuleUp (Pulse OK, HRV OK) from today Sat 2/8 to really underscore that my belt is A-OK in a correct position. Not worn out, and locked to a constant length by a safety pin at the adjustment point.
Fri 1/8 BeltDown-ModuleDown (Pulse Not-OK, HRV Not-OK):
[image: 1754147758046-1000008639.jpg]
[image: 1754147816494-1000008640.jpg]
[image: 1754147848503-1000008641.jpg]
Sat 2/8 BeltUp-ModuleUp (Pulse OK, HRV OK):
[image: 1754147943930-1000008642.jpg]
[image: 1754147990362-1000008643.jpg]
The only conclusion I can draw is that some sensor inside the module interferes with the HRV and possibly HR data when not in an imagined ‘correct’ position. This then would most probably be a software problem. But since I am not offered any method to upload a new SW version, it might as well be called a hardware defect.
