220 is the estimate of our maximum heartrate, at birth.

Each year this decreases by one beat. At 20, our age-predicted maximum heartrate is 200. At 30, it's 190. At 67, it's 153. Simple, right? Now to complicate it. Some references cite 227 as a woman's age-predicted maximum heartrate, at birth. That increases your potential exertion level a bit, doesn't it? So, ladies, if you want to, and you're fit, substitute 227 for 220 when determining your maximal heart rate. Men, use 220 in your formulas.

In deternining your individual aerobic training range always take into account your current physical condition and your particular goals. Training at 65% to 85% of your Maximum Heart Rate just because a formula dictates that as the optimal range for your age makes little sense. Successful and safe fitness training and sports performance are quite subjective and dependent on an athlete's day by day abilities. Personalize your workouts for the safest and most effective results.