Just How Accurate Is Your Fitness Tracker?

May 12, 2022

For anyone who has worn a fitness tracker, there’s probably one question they have in the back of their minds: just how accurate are they?

Long story short, say the experts, they can help indicate when you should go see a doctor, but they aren’t a substitute for a trained medical professional.

“There is nothing that is a substitute for a well-experienced cardiologist in a hospital setting with their hospital grade equipment,” said IEEE Member Carmen Fontana, who began using the earliest heart rate monitors as a college athlete in the ‘90s, and now uses a fitness watch to monitor a genetic heart condition discovered in recent years. “These devices we wear on our wrists now are pretty darn good. Where they are beneficial to you and your cardiologist is it allows continuous monitoring. You can’t be in the lab 24/7. While they might not be medical grade, they do a great job of being a first line of defense.”

A handful of fitness trackers are marketed as ECG watches –– ECG standing for electrocardiogram. The distinction between a fitness tracker and an ECG watch is that the latter has received a level of regulatory clearance to monitor for certain conditions. In the U.S., for example, that’s usually the Food and Drug Administration.

But the clearance may not extend to all cardiac conditions. The most common conditions that ECG watches are cleared to monitor for is a type of irregular heartbeat known as atrial fibrillation. But the watches are not approved to monitor for other conditions. That means that the patient will still require further testing by a medical professional using a 12-lead professional ECG in a hospital.

“The traditional 12-lead ECG can measure the overall magnitude of the electrical potentials of the heart,” said IEEE Member Eros Pasero, “Some smartwatch models can provide important information about atrial fibrillation and other important cardiovascular diseases. This information can require an additional full ECG.”

The question of accuracy in smartwatches and fitness trackers, however, continues to draw continued research interest, with hundreds of trials using some of the most popular fitness devices. The most reliable answers, as reported in IEEE Pulse, are systematic reviews that examine multiple assessments.

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Engineers and technologists are exploring numerous ways to integrate smartwatches and other wearable devices into mission-critical applications for health and safety. In IEEE, the world’s foremost researchers provide several examples, including detecting when people are too sleepy to drive, and when workers in healthcare or food preparation have or haven’t washed their hands properly.