Fitness Trackers Can Detect Early Signs of Illness

What happens when you program wearable technology to track the metrics of fitness with diagnostics that can detect signs of disease? In a new study, a team of researchers from Stanford University have investigated the use of such devices, finding that fitness trackers may be able to detect early signs of illness.

Fitness trackers— health monitoring devices worn like watches– have built-in sensors to monitor the wearer’s activities and measure the number of steps taken each day, heart rate, skin temperature, calories consumed and burned, and other indicators of fitness. The trackers can sync with a computer and store data to build a picture of the user’s health. These devices have become a popular gadget for those looking to understand and improve their physical activity and overall wellness. Wearable fitness bands continue to grow in popularity, according to a recent report from the International Data Corporation, with sales of such devices continuing to rise while smartwatch sales decline.

In a recent study published in the journal PLOS Biology, a team lead by Stanford University researchers studied how the biosensors on wearable fitness devices can measure not only basic information on the wearer’s physical health, but can give us early warning signs of illness. Worn regularly, fitness trackers can offer continuous measurement and recording of these health indicators, but are typically collected in the context of monitoring exercise and general fitness. When physiological parameters such as heart rate, blood pressure, or body temperature go up, it can be a sign of cardiovascular disease, pathogen infection, or pulmonary disease.

Considering the capabilities of these wearable devices, the Stanford research team investigated their potential broader use in health care. Their study included 18 participants between the ages of 28 and 72, to analyze the effects of air travel on their levels of peripheral capillary oxygen saturation (SpO2), which offers an estimate on the amount of oxygen in the blood. In addition, the study included the physical monitoring of 43 participants ages 35 to 70 who had no chronic inflammatory conditions or major organ diseases, each for up to 11 months. With a combination of seven different fitness tracking devices, the researchers recorded more than 250,000 daily measurements based on heart rate, SpO2, skin temperature, sleep, daily activity, and total gamma and X-ray radiation exposure. Included in their findings, the researchers noted that airline travel led to increased radiation exposure and decreased peripheral capillary oxygen saturation. In addition, the study team found that devices were also able to distinguish physiological differences between insulin-sensitive and insulin-resistant individuals, and could establish a baseline range of health-related measurements that could then be used to detect deviations indicating illness or a change in environmental conditions.

During the investigation period, study author Michael Snyder, PhD, was even able to catch his own early warning signs of Lyme disease while on a flight to Norway. “I had elevated heart rate and decreased oxygen at the start of my vacation and knew something was not quite right,” said Dr. Snyder in a recent press release from PLOS Research News. As a study participant himself, the researcher was wearing eight biosensors and explained in an interview with Stanford Medicine how the devices played an important role in detecting the infection. “Wearables helped make the initial diagnosis.”

The researchers hope their findings support the use of wearable fitness trackers as a cost-effective tool for monitoring and managing health for everyone, not just those training for marathons.