This program is a beginner plan to bridge you from an a Half Ironman to Ironman using a HRM with the confidence that you can complete the race without difficulty.
Highly trained athletes can maintain a specific HR longer than a newbie without much creeping; their endurance is greater—thus able to keep pace efficiently and without much additional increase in HR.
My doctor says 140bpm HR is my max, but that feels like a walk in the park... I don't know what to do, how to train, and my motivation is waning. Any suggestions?