You’ve probably heard both sides of the argument. Some say you should train at 65% of your max heart rate because this is the “fat burning zone”. Others will say you should train at 85% of your max heart rate.
While it is true you burn a higher percentage of fat calories in the 65% zone, working out at an elevated intensity will burn more calories, including fat calories, than working out in the “fat burning zone”.
|Low Intensity – 60-65% MHR||High Intensity – 80-85% MHR|
|Total Calories expended per min.||4.86||6.86|
|Fat Calories expended per min.||2.43||2.7|
|Total Calories expended in 30 min.||146||206|
|Total Fat calories expended in 30 min.||73||82|
|Percentage of fat calories burned||50%||39.85%|
From The 24/5 Complete Personal Training Manual, 24 Hour Fitness, 2000
If the chart above confuses you, keep this in mind – at 65%, less “other calories” are burned, therby upping the percentage of fat calories burned in comparison. This sometimes creates the illusion that more fat calories are burned. Working out at 85% burns “other calories” in addition to fat calories. This is why the percentage of fat calories burned at 85% is lower, yet the overall number of fat calories burned is higher.
What is your target heart rate?
220 – 23 (age) = 197
197 – 65 (resting heart rate) = 132
132 * 65% (low end of heart rate) OR 85% (high end) = 85.8 OR 112.2
85.8 + 65 (resting heart rate) = 150 112.2 + 65 (rhr) = 177
The target heart rate zone for this person would be 150 to 177
This person would need to work at 150 bpm or less to stay in the “fat burning zone”. To work in the cardio zone, this person would need to work closer to 177 bpm.