Maximum Heart Rate = 220 – Your Age
Anaerobic Threshold = Maximum Heart Rate * 0.65
So for a 50 year old:
220 – 50 = 170
170 * 0.65 = 110.5
Work out at this level for 3 days a week for 45 – 60 minutes
Work out at 0.85 for 30 minutes on the other 3 days.
or you can also do:
Workout at .85 for 1 minute and then .65 for 2 minutes continuing it for at least 30 minutes
Remember intensity is not the key to fat loss but consistency is.