I complete the same exercise, but different calorie burn recorded. Why?

[SunsetRunner]

Hi, Ive been using the Fitbit Blaze for 6 or so weeks now. Over that time Ive had some weird errors I dont understand but the main one is in regard to Calorie burn for the same exercise being wildly different.

I ride my bike on a set course regulalry. 31 kms and it takes me about 75 minutes to complete. (Give or take 1 to 2 minutes) When I set out I start the Tracker to record the ride under "Exercise" 

Distance and route travelled is identical each time.

Total time recorded for the activity is within 1 to  minutes of each other, so betweeen 75 and 77 minutes each time, so I am fairly consistent.

Average speed is within 0.2kms per hour each time (always average around 23.5 kph - wothin 0.2 kph each ride) 

However Calories burned is vastly different from ride to ride

For example

 (26th December) it says I averaged 4 Calories per minute for my ride or 478 overall calorie burn
23rd December the same ride and average speed  3 days ago shows 12 calories per minute for a totoal of 905 calories burned

22nd December same ride shows 13 calories per minute for 1043 total burned

Now I can accept maybe a variance of 10% from ride to ride but I can not see how one ride is 478 and the other is over 1000! 

Can anyone shed some light? Is my tracker faulty?

Thanks in advance.

[Rich_Laue]

If you would like help, you will need to post screen shots of the calories detail screens slurring the 2 rides. 

[SunsetRunner]

Hi, Here you go, Screen shots from Dashboard of difference of same ride one on 22nd December and one today on 26th of December. 

Ride 1 Cal's logged

Ride 2 Cal's logged

Ride 1 speed and Distance Summary

Ride 2 Speed and Distance summary

Ride 1 Total Calories logged from rideRide #2 Total Calories logged from ride

[SunsetRunner]

Anyone ?

[Rich_Laue]

I see the distance and times are close, but the second ride clearly shows way more calories burnt across the whole time. 

My guess the second ride will also have an increase in the average Heart Rate. 

Could the first ride have not captured a true HE reading! 

[SunsetRunner]

Hmm interesting. I have had some funny HR readings when exercising (Saying my HR is lower than a gentle walk when I am sweating and puffing away) 

If Fitbit takes into account HR in their Calorie calculation this could be it as looking back the ride that was low on Calorie burn had a very low average heart rate (Lower than I normally get walking) 

Are Fitbits a bit flaky when it comes to HR? 

[SunsetRunner]

The Blaze will absolutely use HR to calculate calories while biking. I'll take a wager that your low calorie ride shows a low HR. I have found that while biking, if my tracker is struggling to lock on a real HR removing / re securing the watch and making sure it is secure seems to fix it. 

[SunsetRunner]

Thanks all for the feedback. checking the stats on my HR for the low Calorie burn ride it shows a low average. (Too low for what I would expect based on my exercise history) 

At least I know now, why this occurs.

How to get the Blaze to track HR accurately I guess will be a bit of trial and error. 

Cheers