But also those are professional athletes that train 2*day all their lives, with elite trainers and perfect nutrition, in their mid 20s, not 40+ year old overweight and under-trained cardiovascularly software developers. No offense. Effort is relative.
Anyway, what i am trying to say is that for every level and sport, putting effort makes heart rate rise.
And then you can see that even for pro athletes the variation is +-10 , so for the same level and effort someone has 150 average , someone else 170.
But I won't insist more, i see you don't want to accept any argument that i give, either it is showing my own heart rate at 180+ for 2 hours at 50 years old, or pro bball players study for this exact topic.
Its perfectly fine though. Most important and im out, if you feel your heart function doing something is abnormal, 1) stop doing it immediately and 2) go see a doc ASAP.
pc