Cardio load is nonsense in my opinion

[Dom123456]

I believe this has replaced the daily readiness, i'm not finding this new feature very intuitive, the goal keeps changing I have no idea how to gauge how much or little exercise is needed, weather a rest day or not basically, the only gist I get is that I need to do some sort of cardio exercise everyday, well I know that, it's good that it can be removed from the home screen.

Moderator edit: updated subject for clarity

[Bill_209]

Fitbit grew up to be Google in 2021.

[JoshuaDoc]

Cardio Load is nonsense! I have daily readiness telling me that I am at risk of overtraining and cardio load telling me that I am missing my target for cardio MAINTENANCE on the same day. Yesterday I did an intense 30 minute core routine followed by a 50 minute VERY intense circuit class. Got home and walked 6,000 steps +/- on the treadmill and it tells me that I am not maintaining. Wake up to a HIGHER load for today and and readiness telling me to slow down. In part this is because the HRM was flakey and saying my heart rate while walking was 30 BPM higher than actual. Suddenly the HRM is working correctly so doing the same workouts I am not "in zone". I am working out 5-7 days a week and averaging over 10k steps. I don't run anymore (knee issues) and don't have the time to give more than 2 hours a day working out... but the conflict between readiness and load targets is perplexing.

[RiekoC]

Hello @JoshuaDoc 

My apologies if you're already reviewed this info.

This help page explains how Cardio Load and Cardio Target Load are calculated (<-- click link). After the Cardio Load algorithm gets sufficient data and based on your fitness goal, you'll get a recommended range each day.

This help page explains how the updated Daily Readiness score is calculated (<-- click link). The Daily Readiness score changed and now lets you know how well your body has recovered from the previous day's activities.

There shouldn't be a conflict between the Daily Readiness score and the suggested Cardio Target Load. You can have a High Readiness score but a lower Cardio Target Load range based on where your dot is on the Cardio Load bar graph & what your fitness goal is - Maintain or Improve. If your Daily Readiness score is low, you'll get a lower Cardio Target Load range since your sleep data indicates your body needs rest & recovery.

It helps to understand that the Cardio Target Load range is a recommendation as stated on the help page. If you miss hitting the suggested range on a day or two, you won't experience a significant health issue. At least that's been my experience.

[YachatsMike]

I look at the Cardio Load and Target Load from time to time.  I have to admit they are pretty confusing.  I've had low load scores for long exercises at my Anaerobic Threshold and high load scores for just doing chores.  Likewise I've had my Target bounce from over 100 to less than 10 for no compelling reason.  I just don't understand the algorithm for either the score or the target.  I wish they would publish a couple of formulas so I could really comprehend how it works.

[TotoVIP]

While exercise is undeniably valuable, it's only as effective as the fuel you provide your body. Think of it this way: your body is like a high-performance engine, and nutrition is the premium fuel that powers every cellular process. Without a balanced intake of macro and micro nutrients, even the most rigorous workouts might not yield the desired benefits. Essentially, managing your daily nutrient intake lays the foundation for overall health and optimal performance—making it arguably more critical than obsessing over metrics like cardio load alone.

[kayakmac08]

Cardio Load doesn't seems to take into account the bigger picture, which creates three problems for the user from what I've experienced.

• First, its recommended load for a given day doesn't seem to account for how hard you've been training lately, which can easily lead to overtraining. I'll have 500 zone minutes racked up by Fri but it'll push me to hit 100 on Sat, and I can tell I'm overtrained.
• Second, it will increase your load if your sleeping heart rate spiked for some reason the night before (such as alcohol before bed, stress, small children), as though that one night indicates a sudden drop in your cardio fitness. I've seen it change it's mind overnight regarding whether I'm improving or maintaining fitness. 
• Third, it treats HRV the same way. If your nightly HRV jumps or drops suddenly, the load adjusts with it. Myopic, bro. Just myopic.

And one more thing. When you have a training program you follow, the Cardio Load gets downright irritating because it's trying to set your rest days for you and tries to evenly distribute your cardio effort over the week. That's just a major flaw right there; no one operates like that. 

And another thing 😂: Right now, my training program is working. I'm getting much faster and my VO2 max, as estimated by speed and time, has improved prob 2-3 points over the last couple months. Yet Cardio Load has never given me credit for improving my cardio fitness for even 1 day during that time. It's a babe lost in the woods, who thinks it's your coach. Nonsense.

[kayakmac08]

Oh, and I forgot about this point: Cardio Load doesn't seem to consult your sleep data to decide whether you're overtrained. Common red flags of overtraining, such as disrupted REM and deep sleep and difficulty falling asleep, which plague me whenever I push too hard for a few consecutive days, seem to do nothing to its calculus. 

[Bill_209]

The Cardio Load Target appears to use the Daily Readiness Score (HRV, Sleep and RHR) to help determine training status.

"Daily readiness: Daily readiness determines your target load by checking how well your body has recovered from previous workouts and the stressors of everyday life. If your readiness is low, you’ll receive a lower target load that guides you to balance rest and recovery."

[hovdeo]

i love it when it says "take it easy, you have been training hard, limit your cardio load to x to y" and then you do so. just to wake up the next day to see "you have been slacking, to get back on track you with improving your endurance, aim for 279 to 323". not even a "you took it easy and you should be recharged and ready for....."

[kayakmac08]

Yes, I get this all the time.

[kayakmac08]

I'm curious how the algorithm uses the sleep data, because I can have a night of restless, short sleep, with no more than 45 min of combined REM and deep sleep --because I just did 150 zone minutes on each of the previous 2 days and am basically a walking bag of lactate and cortisol--and my Daily readiness score will be 75 and Cardio Load is 90 to 120. If I followed this instruction every time it was given me, rather than doing the exact opposite (listen to my body), I'd have Afib or simply be dead. The strongest correlation I've noticed between my sleep data and readiness score is my sleeping HRV and HR; I can have sleep stage ratios and overall sleep duration that scream overtraining--especially when compared to my normative numbers--but only see a very slight correlation in my Readiness score or Cardio Load.

[KF32]

I've been getting above my cardio load for over a week, then today it says I'm suddenly at risk of undertraining, when 3 days ago I was apparently really overtraining,  and I was maintaining for the last 2 days 🙄.

[kayakmac08]

Yes, I've had this, too! In some cases, I think this is just a testament to the simple-mindedness of Cardio Load, where it interprets a transient, non-exercise related fluctuation in RHR or HRV as an indication that you need to modulate your training effort. Once again, this is myopic and simplistic, and could easily get a person hurt if they put actual stock in it. Fortunately, people are usually smarter than their glorified pedometers. 

Also... I can't resist adding: Have you ever noticed how Cardio Load is absolutely loathe to ever recognize that you're actually improving your Cardio Fitness? I'm pretty much perpetually either overtrained or undertrained if you ask Cardio Load, with maybe 1 or 3 days per month that I'm supposedly "on track" to improve cardio fitness. Doesn't matter whether my weekly Zone minutes are 200 or 600, the only rule is that I can't get it right. Tell that to my mile time. 😂

[KF32]

Hopefully they improve it with the next update!

[kayakmac08]

Now that I think about it more, here's yet another factor behind why Cardio Load is so ineffective (and it's really an issue with Readiness, or more precisely, with how Fitbit uses your RHR data): Fitbit seems to calculate your daily RHR based on an average of all your "sedentary" HR readings taken over a 24 hour period -- that is, it samples your HR across all the times during the day when you're sitting still for awhile--and averages them out, whether that sedentary time was spent actually resting or, I dunno, doing something stressful, such as your freaking job lol. For some people, like myself, this leads to an "official" RHR that's misleadingly high. What Fitbit should do instead, is to try and control for things like, I dunno, working at a desk on a complex project for 2 hours straight where you're "RHR" is 70 because your mind is racing, or being in a meeting where you're sitting still but talking to your team and your "RHR" is 75. We're busy, stressed people who are often sitting still because we're working, not resting. Your true RHR is when you're reading a book on the couch for 30 min, or watching TV, or lying in bed waiting to fall asleep. Fitbit could easily control for this by selecting from among your daytime RHR samples only those samples that are at the lower end -- the ones that probably occurred when you were actually resting. As it is, though, Fitbit doesn't seem to distinguish this, which is why my official RHR is 59 this week, whereas it's 52 when I'm relaxed on the couch. And because my "RHR" was 58 earlier this week and thus has climbed (because work was extra stressful yesterday), Cardio Load has decided that I'm losing ground in my fitness and "need to get back on track". Dude, I just PRd on my Norwegian 4x4 two days ago. No. Shut up, Cardio Load. You don't know what you're talking about, and this RHR thing seems like a  easily avoidable oversight playing into it.

[Kurrjur]

I completely agree. I do approximately 80 minutes of the zone one and zone two cardio 5 days a week, and resistance training 4 days a week, but it rarely says my cardio load for the day is over 20 to 30.

[hovdeo]

a bit of a broken record here but oh well.

yesterday, did a 34 min easy walk, 23 zone mins, 26 cardio load, avg HR 109bpm. 

just completed a 96' vo2 session 5x5' with 2' fast start P:3' & 1x15' LT1 which by all measures would be a hard session, TSS came in at 113, 1103kj (power meter), max HR 165bpm, average 136bpm. 150 zone mins but only 76 cardio load.

how can it be that an easy walk has a relatively higher cardio load (1:1 with zone mins) whilst a hard session has a cardio load of 2:1 with zone mins?

but, most important - i feel good irrespective of what cardio load says about my training efforts!

[kayakmac08]

Thanks for sharing! It's relatable, a bit reassuring for others who are confused by their Cardio Load, and who knows--maybe one the designers will catch wind if we all make enough stink about the ineptitude of this feature. 😛

[Lurker1234567]

This! I have no idea what it means! I want it to tell me to spend 10 minutes with my heart rate in a higher zone today. Something I can understand 

[hovdeo]

yesterday, i was told to have a cardio load of 110 - 150 or so, which i did not achieve. in my simple mind, i would have thought this would mean i took it a bit too easy for cardio load. today, i was told to aim for 33 - 78 to keep on track to achieve fitness target (improve endurance). seems a bit counter intuitive to me being told to aim for a lower cardio load the day after having "failed" to meet the target the day before. Daily readiness score was about the same, a bit down today in spite of having failed to meet target and i slept better this night than the night before.

today i had a 3x(13x(30/15)) vo2 + 2x12' LT1. cardio load came in at 95, a fair bit above target, 158 zone minutes. From trainingpeaks - TSS 123, 1252kj, max HR 166, avg HR 139.

just curious to see cardio load message tomorrow morning when i be hitting the gym.