Getting a handle on Cardio Load

[YachatsMike]

I just got my first Cardio Load zone today.  Fitbit calculated 42 -66.  I guess that's about right for a 76-year-old guy whose goal is Maintain Fitness.

I looked at my exercises over the last couple of days:
Yesterday
-  Spinning for 40 minutes at 120 bps,  (78% of HRmax by Tanaka formula)
-  7.5 Mets, 408 Calories
-  Cardio Load 18  (way below range)

Today
-  Rowing Machine for 40 minutes at 127 bps (83% of HRmax by Tanaka formula)
-  8.5 Mets 461 Calories
-  Cardio Load 73 (way above range)

Something looks fishy here.  I know I worked harder today but the difference seems way out of scale.

[alexthecat]

@YachatsMike what were your Readiness Scores on those days? It takes a lot more effort to reach your Cardio Load Target on days when your Readiness Score is higher. Cardio Load is not like Active Zone Minutes, where the app just does basic arithmetic with time and heart rate. 

Also, it takes a few weeks for Cardio Load to fully calibrate. During that time, the numbers it gives you can seem really arbitrary. It may make more sense to do what you normally would and let the Fitbit app figure that out. 

[6down3togo]

I agree that there is something off.

I've found my Cardio Load to be very low and I think it is related to my resting heart rate being about 48 to 52 bpm.

I have a low resting heart rate, not because I am a star athlete, but because I am a survivor of a cardiac event that damaged my heart.  Even when I'm walking very fast, my HR seldom goes over 100.  On a recent day that I put in a solid 45 minutes of intervals on my stationary bike, keeping my HR between 105 and 125 bpm, along with another 45 minutes of core exercises, I had a Cardio Load of 11.  I've yet to go over 38.

Meanwhile, my walking companion who has just started to deal with Graves disease and the high HR's that come with thyroid malfunction, is getting Cardio Loads in excess of 100.  Her resting HR has been varying between 70 & 90 bpm.  She does not wear her Fitbit watch as snugly as I do which could also be an issue.

I bought my Sense watch for measuring steps, to have real time HR outside the gym,  its' ECG function (which has been useful), and that it was easy to read.  I use a Polar H9 chest strap when working out.

I feel that people with cardiac issues, whether it be a higher or lower than typical HR, should be very careful with this new metric.

Most of my cardiac rehab group wore some kind of Fitbit device.   Does Fitbit need to add some kind of compensator parameter for users with these issues?

.

[YachatsMike]

I think it's the Spinning app.  I rode 40 minutes at over 80% HRmax and 420 Calories, yesterday.  18 Cardio points.  Today I walked back and forth to the garage a couple of times doing a one hour carpentry job at home, 15 Cardio points.

Really?

[AndrewZach]

I have noticed the same story of thing. I tried using the sport selection instead of spinning on my Versa today and my 15 minute warmup on the stationary bike gave me 15 points where my last warmup generated 2 points. I guess I will be using sport instead of spinning going forward if I need the points.

[Jonesy1977]

This is totally not the same thing but just thought I'd at my experience of cardio load. Today, it's telling me I need to up the ante to because I'm in danger of not maintaining my fitness levels but I'm in the middle of recovering from covid and so shouldn't be doing my usual amount of cardio! When I was really ill with it, the app was able to recognise my readiness levels were low but now I'm getting back to feeling better, it's telling me (not in these specific words) that  ready but don't appear to be pushing myself at all. I wish I could tell it to ****** off! 😄 

[YachatsMike]

You can and I have.  The only thing use from the app are Zone Minutes (they're directly measured and the standards come from HHS) and my exercise heart rate graph.  Everything else is voodoo math.

[BadBetty81]

Same! I find the cardio load interesting, but I do not wear my bit like a freak on a leash 😆 I literally use it for workouts, seeing my HR, maybe caring about how quick my HR recovers, distance covered, active minutes. I wear it at work just to see how many steps I clock on different days. 

[RiekoC]

Hello @YachatsMike , @BadBetty81 , @Jonesy1977 , @AndrewZach , @6down3togo 

FYI - I saw a Moderator post from 07 Jan 2025 stating that there's an app update rolling out soon that includes fixes for the Cardio Load & Cardio Target Load general issues. That said, some users have reported that they got the latest update this week to version 4.34.

The app updates tend to rollout in waves. So keep a watch on the Play Store and install the update when it's available to you.

Hopefully, the update will fix the inconsistencies we've been seeing and we'll get more reasonable Target Loads.

[AndrewZach]

Hey, thanks for the info

Andrew

[jjreason]

My understanding is that spinning/stationary bike exercises are not being read properly by the fitbit due to the device being largely stationary during the session. One user posted that they switched to wearing it on their ankle for spinning - won't work for everyone. 

[YachatsMike]

The Fitbit information on Cardio Load says it's a measure of heart exercise.  I would like to understand how 38 minutes of exercise in my Vigorous zone spinning would yield just 18 points while 29 minutes of rowing in the same heart rate zone yields 3x as many.

[jjreason]

The fact that it wouldn't be based on respiratory & heart beat rates is beyond me. 

[Adnich82]

I'm getting in the 100s. 178 last week and although my job involves lugging some music equipment around it's not that strenuous