During exercise, you breathe more heavily and more rapidly and your heart rate increases to supply muscles with needed oxygen. A pulse oximeter can be used during exercise to measure the oxygen saturation of your blood.

Your pulse oximeter measurement naturally lowers during exercise because of changes that occur in oxygen-binding properties of red blood cells. Specific measurements vary depending on your health situation and exercise intensity.


A pulse oximeter is a non-invasive piece of equipment, often used in a health-care setting, typically placed on the end of your finger to measure your blood’s oxygen saturation. The device uses red and infrared lights to measure the percentage of haemoglobin, which carries oxygen throughout your body. Measuring this way is possible because haemoglobin is a different colour with and without oxygen, and absorbs different amounts of light depending on oxygen level.

Normal readings are between 95 and 100 percent. A reading below 90 percent is too low and may indicate hypoxemia, or low blood oxygen.


Haemoglobin is the component of red blood cells that binds to oxygen and carries it throughout the body; it is thus very dependent on the level of oxygen available. 

Your body typically adapts to different levels of oxygenation during physical activity by increasing your breathing rate. If your body is not getting enough oxygen during exercise, your breathing will become laboured and you will likely not be able to continue.


An exercise pulse oximeter measures the level of oxygen in your blood during exercise and is a useful tool for serious athletes and people with health problems. For example, athletes routinely engaging in vigorous exercise, particularly at high altitudes, may wear pulse oximeters to ensure adequate oxygenation.


Measuring oxygen levels during exercise has many benefits, but can also be problematic. According to a study published in the February 2002 issue of the “Journal of Exercise Physiology,” an oxygen saturation level that decreases 4 percent or more from resting levels during exercise may be the result of movement and is possibly inaccurate. If there are questions about a person’s oxygen saturation during exercise, another form of measurement may be necessary.

An arterial blood gas test, for example, provides accurate information about oxygenation levels during movement.