I train with a hr monitor keeping my hr < LT 80% of the time. But during a race, my 3rd 1/2 ironman, should i be as concerned. When do I disreguard the monitor? Go by feel? How far can one go in the 90% of max. Is this common practice. Any help would be great. Not looking to qualifying, just an age grouper out for the weekend trying to stay in shape for 3 young boys at home.