Answer:
Maximum heart rate
Step-by-step explanation:
Your heart rate is measured in "beats per minute" (BPM), which counts the number of times your heart beats in a minute. The word "maximum" means the most.
Subtracting your age from 220 will give you the most times your heart should beat in a minute.
Example:
If you are 19 years old, you subtract 19 from 220.
220 - 19 = 201
A 19 year-old's maximum heart rate is 201 BPM.
This formula is often used to measure the intensity of exercise. You should aim to increase your heart rate to 55% to 85% of your maximum heart rate. Your maximum heart rate would be 100%.
Example:
For someone who is 19 years old:
55% of max. HR = 0.55(201) = 110.55
85% of max. HR = 0.85(201) = 170.85
They would aim for between 110 and 170 BPM.