Now that I have gathered heart rate statistics for a while, I see a recurring pattern in almost all of my heart rate diagrams. In the beginning of the run the heart rate is rather stable at a value, but suddenly there is a threshold and the heart rate jumps to a stable significantly higher pace.
I think it makes perfectly sense that the heart rate increases during running, but I find that steep rise a bit odd and therefore wonder what could cause it. I suspect that my wrist becoming sweaty after a while can play a role in this, but still, I think that wouldn't show up as that steep in the diagram.
This season I mostly have been running 5 km runs and haven't been doing any warm-up before starting running.
Here are other diagrams.
This diagram looks more what I would suspect most of the diagrams would look like, but its kind is rare for me.
A seven km run with a jump from 120 to 170+ at around 3 km.
A five km run with a jump from 140 to 170 at around 3,5 km.
A five km run with a jump from 120- to 160+ at around 1 km.
So, it this anything that looks familiar to you? In that case, any idea what causes the steep rise?