I was wondering why Garmin (FitBit competitor) was proeminently displaying the disclaimer below on their Web site.
Now I know why..
Activity Tracking Accuracy
Garmin activity trackers are intended to be tools to provide you with information to encourage an active and healthy lifestyle. Garmin activity trackers rely on sensors that track your movement and other metrics. The data and information provided by these devices is intended to be a close estimation of your activity and metrics tracked, but may not be completely accurate, including step, sleep, distance, heart rate and calorie data. Garmin activity trackers are not medical devices, and the data provided by them is not intended to be utilized for medical purposes and is not intended to diagnose, treat, cure, or prevent any disease. Garmin recommends you consult your doctor before engaging in any exercise routine.
Accuracy of Wrist-based Heart Rate (Elevate)
The optical wrist heart rate (HR) monitor for Garmin wearables is a valuable tool that can provide an accurate estimation of the user’s heart rate at any given point in time. The optical HR monitor is designed to attempt to monitor a user’s heart rate 24 hours a day, 7 days a week. The frequency at which heart rate is measured varies, and depends on the level of activity of the user. When you start an activity with your Garmin optical HR device, the optical HR monitor provides feedback more frequently as the optical sensor is on all of the time and is trying to measure heart rate on a continuous basis during a given activity period. The intent is to provide the user with a more frequent and accurate heart rate reading during a given activity.
While our wrist HR monitor technology is state of the art, there are inherent limitations with the technology that may cause some of the heart rate readings to be inaccurate under certain circumstances. These circumstances include the user’s physical characteristics, the fit of the device and the type and intensity of the activity as outlined above. The HR monitor data is not intended to be used for medical purposes, nor is it intended to diagnose, treat, cure or prevent any disease or condition.