Cardio Fitness Score accurate?

[emmasawr]

Hi there! I've had the Charge 2 for a few months now (got it back in December) and I've been wondering how accurate the Cardio Fitness score is, and how exactly it is calculated. I currently have a 33 (which is poor for my age) but I don't think I have poor fitness. I'm 19 y/o female and I exercise regularly, as I'm a pretty avid runner. I'm also currently in college living on a big campus, so on a regular day I take at least 10K steps without exercise, and up to 30k with exercise. I run 4-5 times a week, running 3-10 miles per day depending on my training schedule, usually averaging out to 20-35 miles per week. I know the score is based on VO2 max, however, and I do have exercise-induced asthma. My HR to get pretty high during exercise, especially when running up hills (I take a couple of puffs of my inhaler before I go out for runs). Thanks for any insight! 🙂

[JoeC657]

I’m sorry to hear of your health issues, but that is just what they are, health issues. Make exceptions for this or that and everything, next thing you know everyone has a fitness score of 100. I have a blood issue that keeps me from running for any speed over 5-6 mph for more than a minute. Biking is limited to about 17-18 mph on flats. But, I can go all day if speeds are kept below that level. My cardio fitness score is 53-57 and I’m 71 years old. Why? I have a naturally low resting heart rate, likely inherited. Another curious thing, high elevations (10,000 feet plus) have little affect on me. Skiing and hiking at those elevations are no different than 1,000 feet.

We are all different. And stop trying to use these Fitbit date to compare yourself with others. That is not its purpose. Keep motivated to exercise. Try to improve your numbers, other than fitness score, and eat well. You mart already know this, but exercising at high (anaerobic) heart rates, other than controlled very short intervals, is actually damaging to your body. If you don’t know this, you may be exercising all wrong.

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[OldMike]

What’s your resting heart rate? This seems to be something the program takes into account. My resting heart rate is 54 averaged over the last year. My cardio fitness score is 50.

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[JoeC657]

My resting rate is anywhere between 48 and 54, depending on my current daily stress level. Right now I have a lot going on and it up to 54. Relaxing in Florida for the winter, down to 48. I’ve actually seen it down to 41 during relaxation exercises. Resting rate is a major factor in Fitbit’s calculation of cardio fitness.

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[AukeL]

These parameters can be used to calculate heart condition. It would be of interest for Fitbit to see if they can calculate VO2max accurately based on HR data over the day. I did an attempt and with some more effort that should be possible. I will keep you posted if I manage.

Regards

Moderator edit: personal info removed

[JoeC657]

I really doubt that O2 uptake can be measured with any accuracy through heart beat. For that you would need a blood test of some type. That would make a better measurement of physical fitness and I would likely fail miserably even though I am very fit physically except for my limited ability to get O2 into my blood.

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[FBMum]

I am still not 100% convinced that I am really as fit as the Charge 2 would have me believe, but I do think that an increasing cardio score must mean I am doing something positive.  I am not young, so my scores are portrayed against my age and therefore won't look as high as some that are reported here, but I've been trying to run for about 6 weeks and my score has gone from 33.6-33.9-34 (Excellent - yay!) - 35 (last night's change).  The interesting thing in the last change is that there has been no change in my rate or the exercise I have been doing night on night, but the score has increased.  My resting heartbeat has consistently been on the lower side of normal in the last week, but there has been no huge change there.  I use my phone GPS connected to the Charge 2 for the distance part of the run and sometimes the distance varies when it shouldn't, though not by much, but I did notice that last night it had reported a slightly higher distance than normal and I did wonder if the distance that you run has any bearing on the cardio score.  According to Google maps the run should be 4.01Km, sometimes it logs as low as 3.97Km, and last night it logged as high as 4.58Km (which it can't have been!)  I always set of end the run in the same place and turn on the top of the same man-hole cover!  The fact that the increase in cardio figure occured on a night with a log that exceeded 4.5Km!  I just wondered if the distance logged had anything to do with the suddenly increased figure?

[JCall]

I thought I was doing everything right too, yet another week has gone by where I've recorded a weight loss as well as improved times and distances in my runs, my resting heart rate has lowered 1 point, and my HR is reaching my expected peak during training, yet my cardio fitness score has reduced again by 1 point.

I feel fitter and lighter, and that is reflected in my improvements when I run. Not sure where Fitbit is deciding my cardio fitness has reduced.

I should probably just ignore it. It seems nonsense to me. 

[JoeC657]

One thing that I know for sure about your variance in distance is due to the minor inaccuracy of GPS over small distances. + or – 50 to 100 feet over hundreds of mile is virtually zero, however, over the small distance you run and the small area covered the inaccuracy can adds up. Don’t be concerned with these minor variances. I tried using my Charge 2 for interval training (walk/run) based on maintaining an average pace. It was impossible because the varying distance in time significantly affected the pace. One interval would add distance to my course and another would take it away. Just when you think that you are ahead of pace and start to slow down, you then find yourself way behind pace while walking at the same pace!

Resting heart is a major factor, not the only one, in calculating your fitness score. The score is also a 4-point range, not a specific number, at least on my Charge 2. And, what do you expect for $100? It takes tens of thousands of dollars of equipment to actually measure your physical fitness and putting a number on it would be no better than pulling it out of a hat. There are a lot of shades of gray in deciding who is physically fit and who is not and to what degree.

Resting heart is a major factor, not the only one, in calculating your fitness score. The score is also a 4-point range, not a specific number, at least on my Charge 2. And, what do you expect for $100? It takes tens of thousands of dollars of equipment to actually measure your physical fitness and putting a number on it would be no better than pulling it out of a hat. There are a lot of shades of gray in deciding who is physically fit and who is not and to what degree.

As for fitness score, it’s just an approximation of relative “fitness” based on typical or average numbers for the general populous. Resting heart rate is a major factor. The other factors can only be derived from the data you entered about yourself; age, weight, etc. Try reentering your age to say, 20, and see how fit you are relative to a person your “age” (20). Again, take these data with a grain of salt and use the Fitbit as a motivator and progress indicator. After all, that’s all it was designed to do. For a real fitness measurement, see your doctor and ask for a total fitness stress test. I doubt your insurance will pay for it.

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Moderator edit: merged replies

[JCall]

I think I have found out what is going on, as after more weight loss, improved running performance and lowered resting heart rate, I am now down to 41 for my cardio fitness, when I'd originally got it up to 48.

It seems there's an issue with my Fitbit connecting to GPS. It cuts out intermittently. When I check the run stats, my times are fine but the distances are off. The map shows gaps, and the total distance is much less than expected. I even did a walk this morning and it only recorded a distance of 1.5 miles over the course of 50 minutes, when it's just about a 3 mile route. I then did a run with Endomondo and there was no intermittent connection there and it tracked the full distanxe, so it's likely an issue with the device. My Fitbit is a few years old now...

[JoeC657]

Sounds like a GPS tracking issue. I know that when I run with my iPhone tracking the route I have to shut off the screen so that nothing can touch the screen and stop the tracking. The voice cues still tell me my pace every mile or I have to re-open the screen to see the details at any point on the course.

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[Gatorjoe74]

It's almost always related to resting hr. When mine goes down, the score goes up.

[JoeC657]

Yes, exactly. That’s because your age (another factor) didn’t change and I believe weight may factor in also. Go into your personal stats and change your age 10-20 or more years older and/or younger and see what happens to your fitness score.

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[OldMike]

So I adjusted my age down to 18 and it said I was of average to good fitness. I’m 68 so I feel pretty good about having the average fitness of an 18 year old. I wonder if that’s a soccer playing 18 year old or junk food scarfing playing video games in parents basement 18 year old 😉

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[JoeC657]

Pretty much the same for me too. I’m 71 and still in relatively good shape (same weight as when I was 20 going into the service). However, I know I’m not as strong, I used to work heavy construction before the Navy, so some muscle was lost and replaced by fat. No big deal. As for fitness… I’m still vertical.

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[Tifayyc]

I have tried going on flat terrain tracked runs as recommended in the post and my cardio score is 22 (pretty much the worst score). I cant seem to get the score to change at all.

I am a 26 yr old with a resting heart rate of 62 which is excellent. I am a weight lifter so my BMI score is never accurate even though I am lean because I am fairly muscular. I do cardio training by trail running but it doesn't affect my score.

Any other recommendations that might help me out? I am disappointed that this is a function that just doesnt seem to work for me on my charge 3.

[JoeC657]

Check your personal statistics again and completely for accuracy. Weight lifting does not help cardio fitness much. 62 is a good resting heart rate, but not for young, really fit (cardio) athletes. Your resting heartrate is key in lowering your score and many factors, not related to physical cardio fitness, can raise it. Stress is a major contributor to raising heart rate. Heredity is also another factor. A good balanced diet, not fad diet or what the doctors and the food industry are pushing as “healthy”; do your research.

To improve your score you will need to do proper cardio training, preferably with a qualified cardio coach or research the subject. Most exercise clubs employ people with minimal technical training, if at all, to work their shops. What I’ve experienced over the years are people who will gladly help you ruin your health and do more damage than good.

Finally, DON’T compare yourself with others (as in the score, relative to “averages”) and look to improve your own number over time through proper cardio training. It will take time to increase the size and strength of your heart and efficiency of your overall cardio-vascular system, but it should be possible. Best wishes and keep up with trying to improve your health. You will appreciate the effort in your later years.

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[OldMike]

 My average resting heart beat is 52 and my max is 190 which equates to a VO2 max 56 which would be good for a 28 year old However I’m age 68. Now I may be lucky genetically but I have been doing martial arts training for the last 27 years in a style that includes that equates to a lot of high intensity interval training ( lots of kicks, lots of Kata or poomse for Korean styles). Assuming you don’t end up at a McDojo, that might help. 

[JoeC657]

Great job staying fit! What did you use to get your heart rate to 190? I used slalom water skiing to get mine up to 180 a few years ago. I wore a Polar heart rate monitor for this test. Running can also get my rate up there. My resting rate ranges between 48 and 56, depending upon my stress or activity level for the day. Lowest recorded heart rate ever, through meditation, was 41. I tried for 30’s but never made it. I’m 71 and still moving along quite well.

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[OldMike]

To answer your question, martial arts training which has a lot of kicks. For those, you are using the major muscle mass of your legs. You are going for speed so after a year or so your body adapts, sort of like body building for your cardio vascular system.

I was fortunate to have had a 9th degree black belt instructor who had 35 years of training people and was a former inspector for training for the Korean army.


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[Paddymaree]

My impression is that it bases it a lot on weight and so it's not very
accurate for weightlifters. I actually found the function completely
useless. I now have a Garmin which is much more accurate.