Heart rate gauge red arrow?

Did a run today, ran a course that I saved from my last run. I have not changed any data fields. The first field which shows heart rate in different colors and zones have a black indicator. But today there was also a red triangle/arrow going up and down on the pulse scale. What does this indicate? 

There was also a red triangle on the edge of the screen, but that was something with navigation I think, perhaps pointing north?

Thanks!