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 of oxygen saturation during exercise vary depending on your health situation and exercise intensity.
Read more: What Is a Good Exercise Heart Rate?
How It Works
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 hemoglobin, which carries oxygen throughout your body. Measuring this way is possible because hemoglobin is a different color with and without oxygen, and it absorbs different amounts of light depending on oxygen level.
The difference between the amount of absorption provides a fairly accurate level of your oxygen saturation. Normal readings are between 95 percent and 100 percent. A reading below 90 percent is too low and may indicate hypoxemia, or low blood oxygen.
Hemoglobin During Exercise
Hemoglobin is the component of red blood cells that binds to oxygen and carries it throughout the body; it is thus dependent on the level of oxygen available. Your oxygen levels will likely fall during exercise because physical activity lowers the amount of oxygen that is able to bind to hemoglobin due to changes occurring in properties of the blood.
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 labored and you will likely not be able to continue.
Read more: Athletes Vs. Non-Athletes Heart Rate
Benefits of Measurement During Exercise
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. Those with respiratory illnesses or recovering from surgery, meanwhile, may find wearing an exercise pulse oximeter during exercise useful for monitoring oxygen levels.
Things to Consider
Measuring oxygen saturation during exercise has many benefits, but it can also be misleading. According to a 2013 study of oxygen saturation in soccer players published by the Australian Journal of Basic and Applied Sciences, oxygen saturation initially drops during exercise as the body works to meet the demands of working muscles. 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.
When to See a Doctor
In some cases, hypoxemia is caused by heart issues or defects, or lung conditions, such as bronchitis, asthma or emphysema, according to Cleveland Clinic. Low blood oxygen can also be a side effect of some medications, or occur from sleep apnea. See a doctor if you experience frequent symptoms of hypoxemia with exercise or at rest.