What does Intensity in FIT Monitoring mean

Hi,

In FIT SDK, there is a message type called monitoring.The attached image is an example of monitoring file. In the monitoring file, there is a field called intensity. I want to ask 1) what does intensity mean and 2) how is intensity calculated.

1) In the monitoring file, intensity is an integer that is in the range [0, 7]. At first, I thought larger intensity represented more vigorous movement. In other words, 0 meant stationary and 7 meant the most vigorous movement. However, after reading some post and the code in FIT SDK, it seems that intensity is an enumerate type. And these values may represent rest, active, cooldown, etc. So my first question would be what does intensity really mean?

2) How is intensity calculated for different activity types? Suppose I have some (unknown) movement in a certain time interval. Then what criteria are used in order to determine the intensity of the movement in this particular time interval?

Thank you in advance!

0 Jason Brisbane over 3 years ago

Profile.xlsx in the SDK has this information:

Activity type is:

activity_type	enum
		generic	0
		running	1
		cycling	2
		transition	3
		fitness_equipment	4
		swimming	5
		walking	6
		sedentary	8

Intensity is:

intensity	enum
		active	0
		rest	1
		warmup	2
		cooldown	3
		recovery	4
		interval	5
		other	6

0 Jason Brisbane over 3 years ago

I'd actually love a bit of clarification on this one.

It would appear that the intensity field is UINT8 field and that the scale ranges from 0-10. Is there additional calculation that needs to be done similar to the timestamp_16 field in order to get a meaningful value?

When dealing with sleep/sedentary, are the numbers meant to be indicative of the different sleep stages?

0 9021638 over 3 years ago in reply to Jason Brisbane

Hi Jason,

Thank you for your answers. I think the intensity highlighted in the screenshot in my question is different from the one in Profile.xlsx. Actually I was able to contact Garmin Tech Team months ago and here are the answers from them.

What does intensity mean? The meaning is variable and depends on context. For walking and running messages (messages with steps) – intensity is a measure of average cadence over the minute. For non-step minutes (sedentary, generic) – it’s the base 2 logarithm of a signal feature we call “motion intensity. Basically – the higher that number the more someone is moving their wrist around without getting steps. There’s a caveat here as well – for non-step intensity values we only write new values to the monitoring file when they change between zero and non-zero. Meaning, if you have the following values for some group of minutes: 0, 0, 1, 2, 0, 0 – we’d write the first zero, then the 1, then the third zero.
How is intensity calculated? Intensity always is derived from the wrist motion – either cadence or “motion intensity” as mentioned earlier. It does not (currently) come from any other sources including other sensors that may compute cadence (i.e., no footpods or HRM straps). It is always the average intensity over that minute.

Hope this will be helpful.

0 Jason Brisbane over 3 years ago in reply to 9021638

Awesome!

Thanks for that, that was sort of my working theory. Makes complete sense!