The Maximum Heart Rate is the maximum number of times your heart can safely beat per minute. This figure will decreases with your age. Your heart rate can be measured by using two fingers on your pulse (either at the neck, or on the wrist). Use a watch or stopwatch and count the number of beats over 15 seconds – then multiply by 4. This will give you your heart rate BPM.
Some exercise & cardio machines calculate heart rate but often they are far from accurate. The best way to measure your heart rate is to use a Heart Rate Monitor or (Pulse Oxigen Meter) PulseOx.