cardio fitness vs VO2 max

[andyv1]

I'm unsure what to make of my cardio fitness score. It has me down as 48-52 which is classed as excellent for my age, yet my true VO2 max as measured with a mask on and reading my respiratory gases was recently given as 13 mg/kg/min, which is really poor. My resting HR is 52 which is what I think gives such a good cardio fitness score, but when I go for a run it's very difficult to avoid my heart rate going straight into the peak zone, so my speed and/or duration is somewhat restricted. Also my maximum rate is quite a bit above the predicted 220-age formula.

I've tried running at a steady pace as the Fitbit info says the score will adjust as it gets more data during exercise, but nothing is happening.

I have mild COPD which is what I think causes my HR to rise rapidly during exercise, but by keeping the pace down I can now run much further than I've managed in a long time. Can anybody offer any insight into the validity of the fitness score?

[FerdinandFitbit]

Hi there @andyv1. Great to see you in Fitbit Community Forums! 🙂

When it comes to how your cardio fitness score is calculated, it is determined by your resting heart rate, age, gender, weight, and other personal information. For best results, make sure your weight is correct in your Fitbit profile. Also, wear your tracker or watch to sleep for a better resting heart rate estimate.

When you track your activities (runs specifically), make sure to connect your tracker to GPS because  this way, your tracker can provide a more precise estimate of your score using the relationship between pace and heart rate during your runs. This is because individuals with higher VO2 Max have a lower heart rate while running at the same pace compared to individuals with lower VO2 Max.

Now, about the COPD, this could be a factor that affects your overall score but you might want to verify this with your doctor.

If you're running with GPS, try the following tips for the best estimate:

• Go for long runs (at least 10 minutes long) on flat terrain.
• Complete multiple runs to help improve accuracy.
• Run at a faster pace if you’re able to do so. You don’t have to run at maximum speed but higher-intensity runs provide a more accurate estimate.

Hope this helps and anything else you may need, I'm here to help!

[andyv1]

Thanks for responding Ferdinand. Can I just ask for clarification on one more point. Is it important to run at a steady pace to get the cardio data?

What I’ve been doing is roughly 50 steps walk then 150 steps run. This is how I keep out of the peak zone and get the distance. I began just 50/50 a month ago so I am improving and hopefully I can eventually avoid walking. I track this on GPS. But does Fitbit have problems registering this correctly for cardio fitness purposes?

[alavarre]

As for the high heart rate, that is how I discovered I have atrial fibrillation. Ask the doc.

I was out for my daily run on a sunny day with a pretty lady and all of a sudden the HR is 175 instead of the normal 115. This was with and older (Garmin) HRM. I figured it was acting up and ignored it. But when it happened again the next day I went to the doc. 

That was in 2010 and I stopped running. But I missed the runs (and the pretty ladies) so asked the cardio doc what it would take to get back in. He gave a stress test, they stopped before I even started to get winded. Then an ECG stress test, got the green flag.

So now  back in at a 12 minute mile every other day... Slow, but infinitely faster than all the people on the sidelines...

As for VO2Max vs Fitbit: The American College of Sports Medicine gives a simple calculation:

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3743617/

        VO2max= (0.2 · Speed) + (0.9 · Speed · Grade) + 3.5

which in my case averages ~28 for my slow trots, while FitBit gives a Cardio Fitness score of 50. So they are not the same. 

Maybe I'll track  down the FibBit equation IDC...

[andyv1]

Many thanks Alavarre. Since asking the question, I've kind of got used to some of the anomalies in Fitbit. My HR still goes way up, though not so high as it once used to, maxing at 160. I still find I'm running largely in the peak zone, even though I've reset my age to make it think I'm younger. (I'm 72 but it thinks I'm 60)

I had a pretty comprehensive medical about 2 years ago and after follow ups my doctors now don't think there is a great deal to be concerned about - in particular the max HR formula is way off. Some research says 208 - (0.7Xage) is better and even then this can be out by 10 bpm, and almost all the tests have been done on younger people.

My speed hasn't increased much though my distance is better.

[Voldemoo]

I went through this analysis as well when my hr went way above the 220-age equation. What I found in my internet scouring was that max hr is not equally distributed, but rather randomly distributed amongst the population. You get what you get and really can't influence it much if you're reasonably fit. Mine's up around 185 and I'm in my late 60's.

[Beemrdon]

Agreed. The formula is not accurate by any means. I am 68 and have had my HR into the high 180's many times.

[Voldemoo]

I'm of the opinion that the "VO2 Max" as presented does not reflect the accepted way of calculating it. It seems to be much inflated. It should probably be renamed "fitness score" or something like that.