Is Cardio Fitness Score Solely Improved with Runs?

[StarryAtari]

I've been doing a lot of indoor cycling lately and know I have definitely improved my cardio fitness. I don't believe my Resting Heart Rate is going to go much lower than it already is and I've stopped seeing improvement in my Cardio Fitness Score. I know Fitbit recommends improving the accuracy with an outdoor run with GPS tracking, but I want to confirm it's not drawing data from my cycling. I have an accurate reading of my output over time from my Peloton bike through Strava so I don't see why a VO2 max couldn't be drawn from my 200+ rides.

I'm not sure what to do if running is the only metric. I hate running and have horrible form. I don't think a 10+ minute run would be an accurate representation of my VO2 max to fix my heart rate zones for more effective workouts on the bike. 

[WavyDavey]

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@StarryAtari wrote:

I've been doing a lot of indoor cycling lately and know I have definitely improved my cardio fitness. I don't believe my Resting Heart Rate is going to go much lower than it already is and I've stopped seeing improvement in my Cardio Fitness Score. I know Fitbit recommends improving the accuracy with an outdoor run with GPS tracking, but I want to confirm it's not drawing data from my cycling. I have an accurate reading of my output over time from my Peloton bike through Strava so I don't see why a VO2 max couldn't be drawn from my 200+ rides.

I'm not sure what to do if running is the only metric. I hate running and have horrible form. I don't think a 10+ minute run would be an accurate representation of my VO2 max to fix my heart rate zones for more effective workouts on the bike. 

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Hi @StarryAtari,

Yes, you're correct--the cardio fitness score is updated on the 10 minute run (on a flat surface). Other exercise modes, such as Spin, etc. aren't used in the calculation.  It will estimate a range for the score, but again it's the run that triggers it.

My understanding from some research is that running is fairly standard in terms of measurement and oxygen consumption. And to measure Vo2Max would require specially calibrated and very expensive treadmill and bike equipment. Let's be clear Fitbit isn't going to have a measurement to that degree.

You can do the 10 minute run periodically, or settle on the range that comes without the run. Those are the only options I know of.

[LZeeW]

@StarryAtari   I have a slightly different answer for you, one that comes from a background in human physiology and what Fitbit means by your Cardio Fitness Score (CFS).

Your CFS is an estimate of your VO2max, technically, the maximal rate of oxygen consumption during incremental exercise.  Fitbit estimates this by using your age, weight, resting heart rate, and heart rate response to exercise.  Resting heart rate is only part of the equation.  And it is part heart and part lungs, as some lung diseases interfere with oxygen delivery to the blood.

The estimate is a given as a range and all forms of exercise go in to calculating this estimate.  Fitbit provides your CFS as a single number after a GPS connected run because it has developed an algorithm to estimate your VO2max doing this one specific exercise.  You have data, but Fitbit doesn't have the means to convert it to a single number estimate.

Running is not the only way to improve your VO2max.  If you have been doing steady state biking on your Peloton, then try adding some high intensity intervals.

If you are serious about having an accurate VO2max measurement done, they are available.  There are "store front" businesses like Composition ID and Dexa Fit, which provide these services for a fee.  Some universities with exercise physiology labs offer them to the public, again for a fee.  The going rate for a VO2max test is about $150.  And it can be done cycling.

[Colinm39]

@StarryAtari  I'm like you, and running is not for me... 80 next birthday.  But I have tested Fitbit's Cardio Score against my Pulse Oximeter ($60). I gave up waiting for Fitbit to release their SPo2 feature.  I like to know if the Fitbit results are valid..

My RHR has averaged 54 for the last 12 months and moving between 51 and 55, my sleeping HR gets down to 41... and my weight ios stable and the SPo2 reading moves up and down by 1 point over the year..

I like to know what my baselines are, and fortunately I'm genetically born to have a reasonable oxygen uptake. as measured by my Cardiologist Cardio stress tests.  On my last test the specialist asked me if I felt OK because he wanted to keep the treadmill test running longer to analyse how/why my body was uptaking extra oxygen.. in the end... Genetics. 

The images below show that the Cardio score and my Pulse Oximeter score equates.. THis deviced links to your computer via the USB cable and stores your tests.

This link gives you more information, and I have done the Rockport Walking test and it also backs up Fitbit's Cardio Score.

[dbmemphis]

Ok, please FitBit or someone, who believes their cardio fitness score is accurate, explain this to me...

About 3 weeks ago my CFS was hovering around 54-55. As I am preparing for couple of upcoming events, I have stepped up my training routine and my score creped up to 59. I run with GPS, wear my versa all the time, RHR is consistent 52-54 ... all that stuff. So the day before yesterday (Sunday) I did probably the toughest workout routine where I beat some of my PBs: ran my fastest 5mile, climbed 180 stories under 30 mins, crap load of other lifting and Tabata style workout results. 2hr 15 min workout session with 29 mins in my peak heart rate zone (that's above 170bpm). The score goes up to 60, which was expected and explainable. And than Monday afternoon, as I am hobbling around all sore, my score drops to 55?! WTF? How? How does this make any sense whatsoever? How do gain score in 1 point increments and than loose the next day in 5 point chunks?!

So yesterday, out of frustration, and thinking it was just a glitch, I repeated the Sunday workout routine beating my 5mile time by 13 sec! plus matching Sunday times/reps on everything else. Does my score goes back TO 60... - nope. 55! How is this explainable? Its like I have not even trained for last 3 weeks.

And no, I don't need a watch to tell me how fit I am and absolute number is not the point here. The number by itself will always be wrong as its just a estimate. But these are metrics designed to gauge your relative progress, and give your relative measure of comparison to others (that scale, Ryan Hall, etc). And given FitBit trackers are already very limiting and primitive training tools that don't offer much in proper training metrics and indicators, measurements like this just destroy any kind of credibility FitBit trackers have left.

So if anyone has an explanation, I am listening!

[Andrew321Go]

Regarding the Walk Test, I'm wondering if you really can't jog or run for any of it. For example, VeryWellFit .com says you cannot speed walk or power walk, but then they give a sample calculation involving an 11:30 mile, which is 5.2 mph. My Fitbit score is only just getting into average but I can't imagine going that speed as a standard walk. Maybe it'll come with time.

I've been thinking about getting a pulse oximeter with USB data - what kind of information can be determined using data from the chart on the bottom of your computer screenshot (the one that looks like it shows your rhythm and perhaps strength of beat)?

Thanks