Runners and other fitness enthusiasts are increasingly turning to smartwatches or fitness bands to measure their heart rate during exercise and for general health monitoring. However, in black or dark-skinned people it may not work properly.
A recent study from the University of Alberta in Canada found that trendy devices are less effective at tracking the health of people with darker skin tones. The study suggests this may be because the signaling process , which uses light beams to detect heart rate and rhythm, might not work as well in black people who contain more melanin, as it absorbs more light.
However, the algorithms that power these devices are often developed and tested on homogeneous white populations, which can mean problems are not identified before launch.
They are only tested on white skin
It is the first to pull together figures from multiple studies to specifically examine how skin tone can affect the accuracy of cardiac data on wearable devices. People should be aware that there are some limitations for people with darker skin tones when using these devices, and the results should be taken with a grain of salt.
Algorithms are often developed on 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 emphasize the inclusion of all skin tones so that the algorithms developed can better accommodate variations in the skin’s innate light absorption.
Of those studies, some 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 chest strap monitors or EKGs.
Most wearable devices detect heart rate and rhythm by aiming a beam of light at the wrist and then detecting how much light is absorbed. Greater light absorption indicates a greater volume of blood flowing through the veins under the skin. The signaling process might not work as well on darker skin that contains more melanin and absorbs light.
Oximeters are also not effective
In addition to the growing use of wearable devices to monitor physical activity and sleep patterns, interest in the use of wearable consumer devices for medical research and even early detection of heart problems has increased in recent years.
Other recent studies have reported that some devices, such as pulse oximeters used to measure the amount of oxygen in the blood, also do not work well in black people. This can have serious health consequences if problems go undetected. However, there is some evidence to suggest that certain wavelengths of light, particularly green light, are more accurate in people of all skin tones.
