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The Doctor's In: How Health Smart Are Smartwatches?

Sure, smartwatches are state-of-the-art and snazzy, but what do they really tell us about our health? Do their growing reams of data on us impress or carry clout with actual health care professionals? Let’s dive into watches, from start to future.

The Past
Watches have come a long way since their humble beginnings in the 15th century. Back then, they were nothing more than miniature clocks worn around the neck or kept in a pocket. It wasn't until the 16th century that a Swiss watchmaker invented the wristwatch, primarily for women to wear as a fashionable accessory. Wristwatches gained popularity among men in the late 19th century, thanks in part to soldiers using them during the Boer War in South Africa for timing military operations.

During the next century, watches continued to evolve with innovations like the electric watch and quartz watch; it wasn't until the 21st century that the watch indeed became “smart.” With the advent of Bluetooth and touchscreens, watches incorporated features like notifications, GPS, and fitness tracking. Now, smartwatches are more than just a way to tell time; they're mini computers we wear on our wrists. So, after almost 600 years of technological advancements, how “smart” are our watches today? How smart are our watches at telling us about our health?

The Present
Smartwatches are the latest technological innovation in the world of health and fitness. These wrist-bound devices are jam-packed with features that make tracking your health and wellness easier than ever. Engineers have designed sensors for smartwatches to measure a wide range of metrics, from basic activity tracking to more advanced biometrics like heart rate, blood oxygen levels, and even electrocardiograms (ECG). Let's take a closer look at some of the most common sensors.

• The accelerometer is one of the essential sensors found in smartwatches, which measures your body's movement and helps track your steps and distance throughout the day. Other sensors include a gyroscope, which measures your wrist's rotation, and a magnetometer, which measures the earth's magnetic field and helps determine your orientation. Combining these sensors enables a watch to detect your activity, whether it’s walking, running, cycling, etc.
• The heart rate monitor is another ubiquitous smartwatch feature. These sensors use photoplethysmography (PPG) technology to detect changes in your blood flow, allowing them to measure your heart rate. That green light that periodically lights up on your watch? That’s a PPG measurement. Keeping track of your heart rate allows your watch to estimate patterns like stress levels, calories burned, and sleep quality.
• Blood oxygen sensors are also becoming common in smartwatches. These sensors use pulse oximetry to measure the oxygen saturation levels in your blood. A smartwatch with a blood-oxygen sensor can provide users a better understanding of how their oxygen levels fluctuate throughout the day and night. Algorithms can then use this data to estimate restfulness and help avoid overtraining.

There are some newer features on the way as well. Some smartwatches can incorporate temperature sensors, which measure the skin's temperature on your wrist. These sensors can detect changes in your body temperature and are primarily used for tracking women’s health.

Smartwatches also have apps and digital solutions that act like a one-stop shop for all the health data recorded by your smartwatch. Within these apps, powerful algorithms can combine data from various sensors to provide in-depth analysis and long-term monitoring of health trends.

The Future
With the introduction of ECG sensors, smartwatches began to blur the lines between wellness tracking and medical-grade instrumentation. Now, some watches can detect arrhythmias or regular heartbeats and notify you to visit a doctor.

Building off the successful implementation of ECG, smartwatch designers have circled blood pressure and glucose monitoring as the next major innovative features, promising critical new tools for patients with diabetes and high blood pressure. Who knows? Maybe someday they will analyze our blood (looking at you, Theranos) or tell us whether we have contracted COVID-19. Either way, the future of smartwatches is so bright that it even outshines those green PPG sensors.

It's important for users to remember, however, smartwatches are not hospital-grade equipment, and tech companies are quick to note their products are not intended to make a medical diagnosis. It doesn’t mean the data is useless, but users should know that some doctors might scrunch their noses at smartwatch data.

The sophistication of health-tracking features in smartwatches is evolving rapidly. Medical instrumentation that once was confined to hospitals or clinics is now finding a new home in smartwatches. These devices provide users with unprecedented insight into their health and wellness, allowing them to make better informed decisions about their lifestyle and seek medical treatment when necessary. As technology advances, smartwatches will become even more valuable tools for doctors and patients alike, helping us to live happier, healthier lives. Say what you will about how smart our watches are today; they have certainly come a long way from the humble pocket watch.

This column originally appeared in the May 2023 issue of PCB007 Magazine.