R,
Thanks for using our plans and welcome to the 80/20 family!
For a novice, using Pace or Power over HR is even more important. The variability of HR is more pronounced in a new runner. It takes time and experience for HR to “settle down” and become more reliable as your aerobic fitness matures. Even then, HR will always be unreliable.
HR for a novice reminds me of a newborn baby. At first, the sleep schedule is…no schedule at all. Totally unreliable. After a few months, a relatively stable schedule takes place, but there will still be a few 2am feedings that throw things off.
But, I’m obligated to always ask athletes when they bring up the delta between HR and Pace: how and when did you establish your LTHR and threshold pace? If not done correctly, HR and Pace will never align. If done correctly, HR and Pace will sometimes align. Our protocols for finding LTHR and threshold pace are listed in Intensity Guidelines for Running.
David