Strava fitness graph frequently drops 2 points in one day

[brushi]

Most of the time the Strava fitness graph drops 1 point on days without activities. When reading about the way the Strava fitness graph works this 1 point drop per day is the way it should behave.

However: a few times per month the score drops 2 points in a single day. And this seems "unfair" 😉. 

Does anyone know why this 2 points drop might happen? 

[anchskier]

@BryanC - I think the fitness graph relies at least in some part on things like heart rate.  Could it be that you are using a heart rate monitor when biking, but not when you are walking the dog or swimming?  

[BryanC]

I wear an Apple Watch so it always records heart rate

[brushi]

This is not the case. I don't use a heart monitor at any time.

[anchskier]

@brushi - I was asking BryanC, not you, about the heart rate monitor.  He was saying that his drops with certain types of activities, but not others, so just trying to help troubleshoot what might be contributing to it.

[BryanC]

On this topic I’d be interested in knowing more about the calculation.  A hard ride and it can jump upwards by 7 points.  I walk my dog daily and it still goes down, I swim and it still goes down.  Is the rate of decline related to Relative Effort?   It would make sense to do that (IMHO).  

[brushi]

Thanks, anchskier!

[anchskier · Accepted solution]

It could be that the amount it is dropping is actually more than a single point in a day, but due to rounding, you only see 1 point most days, but 2 every once in a while when the total gets high enough to round to 2.  Just speculating though.