Yes lots of people have said that to me but the people doing 10's in 18 -19 minutes dont go into the red .Not sure why you would do this on a 10. Your HR should be nailed to the red line for pretty much the whole distance. In fact, as others have said, just don't even look at it, as it is a poor guide to high effort anyway.
Ive been more interested in 25's this season so only really taken the thinking into the tens a few times . Got a PB though .