Close-up of a pulse oximeter on the finger of an adult, showing readings within the normal range for an athlete or extremely fit person. A pulse oximeter, also known as a blood oxygen meter, measures the heart rate and oxygen concentration of the blood. It measures the oxygen concentration by analysing the absorption of light as it passes through the fingertip. For most adults, a healthy resting heart rate is 60-100 beats per minute, but in athletes and very fit people it can be 40-60 bpm. Normal blood oxygen saturation is between 95 and 100 per cent.