In this entry, I'm going to document my calculation for a Target Heart Rate which is defined via Wikipedia as follows:
"The Target Heart Rate (THR), or Training Heart Rate, is a desired range of heart rate reached during aerobic exercise which enables one's heart and lungs to receive the most benefit from a workout." link
There is a wide array of sometimes conflicting information given to the beginning-level althlete; and the available formulas rely on variables that are themselves fuzzy. For example, the most common maximum heart rate formula, attributed to Fox and Haskell, is to subtract your age from 220. Being 44, this would imply that my maximum heart rate is 176. This is somewhat disquieting, since I have recorded 185 on the treadmill and hit 180 or 181 probably a half dozen times. This formula for maximum heart rate is known to have an error of 7 to 11 beats per minute. But without trying to pin it down exactly, for the moment let's assume my maximum heart rate is between 176 and 185.
Over the past week or so, I've been measuring my resting heart rate and it's pretty much always between 66 and 74.
The Karvonen method for calculating aerobic heart training zones relies on both maximum heart rate and resting heart rate. It suggests a zone between 50% and 85%. I'm going to pick a more focused zone between 70% and 80%. The procedure is to subtract the rest rate from the maximum rate, multiply that result with the zone value, and then add back the resting heart rate. For example, if my maximum heart rate is 176, my resting heart rate is 74, and the zone value is 70% we would get (176-74)*0.7 + 74 = 145.4.
Allowing for plenty of uncertainty in both maximum heart rate and rest pulse I have constructed the table below:
The high number that works despite the uncertainty is 154.0.
The low number that works despite the uncertainty is 151.7.
This suggests that I can get a good aerobic benefit with a heart rate in the low 150s. I did this walking at 3.3 mph with a 7% incline on Valentine's Day. It didn't seem overly tough, and it's my target for future non-running "cardio workouts".