The traditional formula for calculating maximum heart rate — the fastest your heart can pump — is 220 minus your age. Trainers often suggest that people doing moderate-intensity activity work out at a THR of 50 percent to 70 percent of their maximum heart rate, while those doing high-intensity activity work at 70 percent to 85 percent of their max. Pushing harder is generally considered inadvisable, and shouldn't actually feel good since your heart can't go full speed ahead for very long.
"The standard '220 minus age' is not accurate," he says. "It produces numbers that are very low."
He says the following, more complicated formula is better:
220 - Age = Theoretical Max Heart Rate
Theoretical Max Heart Rate - Resting Heart Rate = Range
Range x .5 + Resting Heart Rate = 50 percent intensity
Range x .6 + Resting Heart Rate = 60 percent intensity
Range x .7 + Resting Heart Rate = 70 percent intensity
Range x .8 + Resting Heart Rate = 80 percent intensity
