Oxygen saturation in exercise

Our red blood cells carry oxygenated blood throughout our entire body. In healthy adults, the red blood cells that pass through the lungs are between 97 and 99 percent saturated with oxygen. Each red blood cell is capable of carrying four molecules of oxygen. Oxygen saturation is the measure of how much oxygen each red blood cell is carrying. It is also expressed as Sp02.  There are two methods for oxygen saturation.

Invasive Method

A blood gas analysis is one direct method to measure oxygen levels. During this invasive test a small amount of blood is drawn out of an artery (not like most lab test when blood is drawn from a vein). The radial artery on the wrist is the most common site for an arterial blood gas draw. Sometimes an earlobe is used.


Non-invasive Method

This non-invasive method is by using a pulse oximeter. An oximeter is a clip, normally placed on the finger, that emits a light on one side. When placed on the finger, the light is measured as it comes through the other side of the finger. It works on the principle that oxygen saturated cells absorb light in a different manner than those that are not. The oximeter gives out a digital reading of the estimated blood oxygen level. Measuring oxygen saturation may be important for patients with chronic respiratory conditions, such as asthma. If the medical condition interferes with the amount of oxygen taken into the body, a pulse oximeter can monitor a patient's oxygen levels to ensure safety.


Activity Response

Normal oxygen levels 97 and 99 percent allow the proper pressure within the body to allow the oxygen to be absorbed into the muscles. If the levels at rest are in the normal range, that also allows for a small supply of oxygen to be stored in the muscles. Once the exercise is started, the rate and depth of respiration increases to help meet the increase in oxygen demands. A normal response in regards to oxygen saturation is a probable drop of only 2 to 3 percent. Ideally, that level will stay above 92 percent during exercise to keep the proper pressure of oxygen in the blood.  Athletes may wear a pulse oximeter during exercise simply to monitor their oxygen levels during strenuous workouts. You may also wish to wear a pulse oximeter while exercising in a high-altitude area, such as in the mountains. To ensure adequate oxygenation, people with respiratory conditions and patients recovering from a recent illness or surgery might also want to wear a pulse oximeter during exercise.

Practical Advice

If your hands become sweaty while exercising, the pulse oximeter may slip off your finger. Additionally, people with unusually small or large fingers may also have a difficult time keeping the device on the finger. If necessary, wrap a small amount of medical tape around the device and finger to keep it securely in place. If your workout requires extensive use of your hands, such as during basketball or weightlifting, attach the pulse oximeter to your earlobe. Again, a small amount of tape may be necessary to hold it in place.



Low blood oxygen levels, or hypoxemia, are those below 90 percent. Several medical conditions can cause hypoxemia. These include COPD, emphysema, anaemia, pulmonary embolism, sleep apnoea, shock or pneumonia, to name a few.


Fun Fact

A study carried out in 2010 concluded that if you ingest wheatgrass prior to exercising, it’ll improve your oxygen saturation during exercise.