Best Answer@hovdeo I spin with the Fitbit on my ankle and a different HR monitor on my wrist. I try to make sure they are reading similar heart rate before I get on the bike. The device does seem to be more sensitive to positioning on the ankle than the wrist. I really struggled with that initially and it was very frustrating.
I don't bother trying to compare Active Zone Minutes and Cardio Load. They are measuring things differently and it's rare for them to be similar. For instance, here's a spin ride I did over the weekend.
Amanda | Wyoming, USA
Pixel Watch 4, Inspire 3, Sense | Android
The Cardio Load is an implementation of TRIMP (Training Impulse). TRIMP, in its simplest format, is Time x Intensity. I have read several papers measuring TRIMP but they all seem to have different ways of figuring the intensity factor. Some implementations have a "scaling factor" based on the exercise you are engaged in.
Fitbit is woefully neglect in providing any detail onto how they calculate exercise intensity. It's clear they use some kind exercise scaling factor to calculate their score. Whatever algorithm they use, it appears to undervalue spinning. (I get more points sitting in a chair cooling down than I get for a rigorous spin.) I sure wish Fitbit would at least make their measurement algorithm known so I can understand why this disparity occurs and how I could correct for it.
Cardio Load targets and monitoring are totally crap on Charger 6. I get targets like 202 - 229 (= today) and others way over my safe active HR zone - I'm 78 YEARs OLD with a minimal exercise lifestyle and chronic CVD. Besides, my exercise sessions always show having had a Cardio Load 0, even when my session has been intence, showing having peak HR minutes in the Heart Rate monitoring and Activity!!!
Best AnswerThis still seems to be an issue. I can only imagine steps are somehow incorporated into the calculation for Cardio Load.
I can do two equivalent workouts spinning vs running (in terms of heart rate) and the run will have up to five times the cardio load the spin does.
Today I did 5x5 mins at 300W with HR 160s during the reps and 120s in recover, warmup, and cool down. Averaged high 130s. It took until past 30 minutes until it registered a cardio load of 1. I ended at 40 minutes with a cardio load of 11.
Yesterday I went for a slow 7km run with heart rate in the 140s for 35 minutes. Cardio Load of 71.
I've noticed people say wearing the watch on the ankle solves this - again I wonder if steps are somehow incorporated into cardio load. Seems ridiculous given how popular spinning is.