While resting heart rate is determined mostly by how fit you are, and is usually in the 50-80 range, maximal heart rate is generally a factor of your age. The a

While resting heart rate is determined mostly by how fit you are, and is usually in the 50-80 range, maximal heart rate is generally a factor of your age. The accepted formula for maximal heart rate is (210 - age). Most workouts are at 60-75% of maximal heart rate (depending on workout intensity), so a 20% increase during workout is not likely (or at least, you wouldn't call it a workout).