This was an interesting rowing session with respect to the way HR responded to rowing effort. It seems to be confirmation that I have the heart of a 'competitive rower' and it 'wants' to row hard before it will increase its BPM. I don't know what is the dividing line between what it considers hard and easy but at less than 'hard' the HR tends to be very low because it is getting the extra assistance it needs for pumping blood, from the contraction/relaxation of the other muscles in the body as they are used for rowing each stroke.