ok can u guys tell me if this is true and what it means, i have heard that for heart rate you take 220 minus your age and that is 100% intensity of your heart rate, and to be in fat burning when running you should be around 60-70% of that intensity, is this true????? so lets say im 16, i would do 220-16=204 and use 60% of that when running=122.4 beats per min, is this right???????