From a WikiHow article.
1. Resting heart rate (calculated with the excellent Android heart rate monitor)
62
2. Maximum heart rate = 220 - 37
183
3. Heart rate reserve = step2 - step1
121
4. Lower THR is 60% of step3 = 121 * 0.6 + step1
134.6
5. Upper THR is 80% of step3 = 121 * 0.8 + step1
158.8
So my target heart rate is 134.6 at the fat-burning end, to 158.8 at the cardio end.
