Blood oxygen saturation, or SpO2, is a measure of the percentage of hemoglobin in the blood carrying oxygen from the lungs to the rest of the body. A normal range for a healthy person typically falls between 95% and 100%. The WHOOP device, a wearable technology primarily focused on recovery and strain management, has incorporated this measurement into its health tracking suite. The WHOOP 4.0 model and all subsequent versions are equipped with the necessary hardware to track SpO2 levels.
WHOOP’s Blood Oxygen Tracking Function
The WHOOP system integrates SpO2 data into its comprehensive daily recovery assessment. The device does not offer on-demand, real-time blood oxygen readings like some other consumer wearables. This measurement is primarily taken throughout the night while the user is asleep and relatively still. The WHOOP 4.0 hardware is set to sample data for about 30 seconds, repeating this measurement approximately every 20 minutes during the sleep cycle. In the morning, users can view their SpO2 data within the Health Monitor feature, which provides a single, consolidated figure representing the average blood oxygen saturation level recorded during that night’s sleep.
The Technology Behind the Measurement
Pulse oximetry is implemented in the device using an advanced sensor configuration. The WHOOP 4.0 hardware includes five LEDs, utilizing a combination of red and infrared lights for this function. These lights are directed through the skin and into the underlying capillary beds. Oxygenated blood and deoxygenated blood absorb these two wavelengths of light differently. Hemoglobin, the protein in red blood cells responsible for carrying oxygen, changes its light absorption properties depending on whether it is bound to an oxygen molecule. By analyzing the amount of red and infrared light that is reflected back to the device’s photodiodes, the WHOOP sensor can calculate the ratio of oxygenated to deoxygenated hemoglobin. This ratio is then translated into the percentage figure known as SpO2.
Health Significance of Tracking SpO2
Tracking blood oxygen levels provides a direct window into the efficiency of the body’s respiratory function and its recovery status. Low SpO2 values, which fall below the typical 95% range, can sometimes be an early indication of underlying respiratory or circulatory strain. For instance, a persistent drop in nighttime SpO2 levels may suggest the presence of sleep-disordered breathing. Consistently low blood oxygen saturation, a condition known as hypoxemia, can hinder the body’s ability to recover fully from training or illness. For athletes, tracking this metric is relevant when training at high altitudes, where the reduced oxygen availability naturally causes a temporary drop in SpO2. Monitoring this trend helps a user understand how their body is adapting to environmental or physiological stress. The WHOOP Health Monitor uses these readings alongside other metrics like respiratory rate to identify deviations from an individual’s established baseline.
Understanding Accuracy and Limitations
The SpO2 measurement provided by a consumer device like WHOOP is intended for wellness and informational purposes only. The device is not classified as a medical-grade pulse oximeter, and its readings should not be used as a basis for medical diagnosis or treatment decisions. Wearable technology functions as a tool for self-awareness and tracking personal trends. The accuracy of the measurement can be influenced by various external factors, despite the system’s reliance on measurements taken during stillness. Poor sensor contact, excessive movement during sleep, or even extreme cold can interfere with the light-based reading. Consequently, while the data is useful for tracking personal health trends, any concerning or persistently low readings should prompt a consultation with a healthcare professional.