There is the concept of heart rate based training, where you push yourself just enough, but not too much, to reach a new goal. Roughly speaking, the typical maximum heart rate is 220 - age, which in my case would be 220-57 = 163.
from Polar’s web site:
- LIGHT: 70-80% (98 - 114)
- MODERATE: 70-80% (114 - 130) “especially effective for improving the efficiency of blood circulation in the heart and skeletal muscles”
- HARD: 80-90% (130 - 146)
But according to my Helix Apps Heart Analyzer app, my actual Max heart rate is 177.
If so, then my ideal training “zone” would be between 125 and 140.