MAF is the Maximum Aerobic Function training method developed by Phil Maffetone. The goal is to train at a particular rate in order to build up your cardio base. This level of training is done at a particular heart rate that creates maximum fat burning and minimum reliance on carbohydrate stores in the body (glycogen).
The ideal heart rate for this training is derived from your age.
- Minimum heart rate = 170 – age
- Maximum heart rate = 180 – age
There are also adjustments for training and other health considerations but for this example suppose you are 50 years old. You would train at a heart rate between 120 and 130.
At this range, if you are fat adapted (keto or low carb diet) then you are burning the most fat possible and the least carb stores possible. This is about equivalent to a fast walk when you start where you can keep up a conversation without running out of breath.
This pace quickens as your fitness increases. Soon you will be running and not walking. The trick is to not push it even if you feel like you can do more. That extra beyond your MAF heart rate doesn’t come from body fat anyway.