Fitness trackers

Smartwatch fitness trackers don’t work as well for people with darker skin, study finds

Smartwatches are less effective at tracking the health of people with darker skin, according to a new study. Joggers and other fitness enthusiasts are increasingly turning to trendy devices to measure their heart rate and pace during exercise and to monitor their overall health.

But measurements may be less accurate in people with darker skin, according to the latest findings based on a systematic review of 10 previously published studies involving more than 460 participants. The research is the first to pool numbers from multiple studies to look specifically at how skin tone can affect the accuracy of heart data in wearable devices.

Study co-lead Dr Daniel Koerber said: “People should be aware that there are some limitations for darker-skinned people when using these devices, and the results should be taken with a grain of salt.” Algorithms are often developed in homogeneous white populations, which can lead to results that are not as generalizable as we would like.

“Ongoing research and development of these devices should focus on including populations of all skin tones so that the algorithms developed can better adapt to variations in the innate light absorption of the skin. skin.”

The research team identified 10 studies, from 622 scientific papers, that reported heart rate and rhythm data for consumer wearable technology based on a participant’s race or skin tone. Of these studies, four found that heart rate measurements were “significantly less accurate” in darker-skinned people compared to lighter-skinned people or measurements from validated devices, such as heart rate monitors. chest strap or electrocardiograms.

One study reported that although there was no difference in heart rate accuracy, wearables recorded “significantly fewer” data points for people with darker skin tones. Dr. Koerber explained that most wearable devices detect heart rate and rhythm by directing a beam of light at the wrist and then detecting the amount of light absorbed.

Greater absorption of light indicates a greater volume of blood flowing through the veins under the skin. He said the study results suggest the signaling process might not work as well on darker skin that contains more melanin, which absorbs light.

In addition to the growing use of wearables to monitor physical activity and sleep patterns, interest in using consumer wearables for medical research and even early detection of heart problems has increased in recent years. years. Dr Koerber, a resident physician at the University of Alberta in Edmonton, Canada, said: “There are a lot of claims that these devices can detect heart rhythm problems like tachycardia, bradycardia and even atrial fibrillation.

“We want to be able to inform healthcare providers about the reliability of these data collection sources in all patients, regardless of skin tone.”

According to Dr. Koerber, the study underscores the importance of ensuring that technology meets the needs of diverse populations, especially when aimed at improving health. He said recent studies have reported that other devices — such as pulse oximeters used to measure the amount of oxygen in the blood — don’t work as well for people with darker skin, which can lead to serious health consequences if the problems are not detected. .

Dr. Koerber added: “It is important to explore alternative options to ensure that we can create a fairer solution in healthcare and not just in the consumer industry. For example, there is evidence to suggest that certain wavelengths of light, particularly green light, are more accurate in people of all skin tones.”

He is due to present the findings at the American College of Cardiology’s annual conference in Washington DC next month.