How accurate are smart watches in measuring health indicators?
The world's first smartwatch was released in 1998, the Seiko Roboter, which was able to connect to a computer. By 2014, brands like Samsung and Apple had their own versions of smartwatches. In the last few years, smartwatches and other wearable devices have become popular, and are worn by all groups, from children and young people to the elderly.
Smart watches provide multiple features for measuring health and fitness indicators, and many people have come to rely on them to monitor their health. The companies that manufacture these watches are constantly competing to add new health features so that their watches become the first choice for users who are interested in constantly tracking health indicators. But the important question is, how accurate are these watches in measuring health indicators, and are they always accurate?
Some experts and studies indicate that it is not always accurate, and we will explain the details in this article.
First: Smart watches can save your life:
The smartwatch's uses go beyond just telling you the time. It can tell you how many calories you've burned and how many steps you've taken. You can also make a phone call through it in the event of an accident. For example, in May 2024, a woman in Delhi survived a serious accident because of her Apple Watch. The watch's heart rate monitoring feature detected an abnormally high heart rate and alerted her.
In 2023 , Robert Naess, an investment manager in Norway, slipped while jogging and was seriously injured, but thanks to the emergency contact feature built into the Apple Watch, he was able to quickly call emergency services, saving his life.
There are other similar cases where smartwatches have saved people’s lives; this is due to their ability to monitor a variety of health and fitness indicators, such as heart rate, steps, calories burned, and even sleep patterns. They also include some advanced features such as monitoring blood oxygen levels (SpO2), electrocardiogram (ECG), and stress level estimates based on heart rate variability, respiration rate, body temperature, and blood pressure. Women can also track their menstrual cycles with these watches.
Second: How accurate are smartwatches and other wearable devices?
In a recent comprehensive review , experts examined a range of scientific studies examining the accuracy of wearable devices, including smartwatches, in measuring health indicators such as heart rate, calories, sleep tracking, and step counts. The review found that the accuracy of these devices is good.
The review showed that wearable devices are able to measure heart rate with an error rate of about 3%, depending on factors such as skin color, type of exercise, and the presence of tattoos. They are also good at detecting heart rhythm problems and estimating heart muscle strength, especially during exercise.
In terms of measuring other indicators, these devices tend to underestimate the number of steps taken by about 9%, and there are significant errors in tracking calories burned, ranging from 14.76% to 21.27%. In terms of sleep tracking, wearables often overestimate total sleep time and quality by more than 10%, and underestimate the amount of time it takes a person to relax before actually falling asleep and when waking up after sleeping.
Many experts agree with the review’s findings. Dr. Shrey Kumar Srivastav, a general practitioner at Sharda Hospital in India, says the accuracy of wearables, especially fitness trackers, can vary depending on the quality of the device, how it’s used, and the sensors built into it. Examples include:
- Some wearables rely on optical sensors that measure blood flow through the skin to monitor heart rate. This method can be inaccurate if the watch is not tight enough, if you have dark skin, if you have tattoos, or during intense activity.
- Wearable devices often estimate sleep based on movement and heart rate that may not always match the results of clinical sleep studies, may treat resting times as sleep times, or may fail to identify different sleep stages.
- It can be difficult to calculate calories burned accurately because it depends on many individual factors, such as metabolic rate, fitness level, and type of exercise.
Third: What should be considered before purchasing wearable devices?
Before purchasing a wearable device, you should consider the following to ensure you get a good device that can measure health indicators with high accuracy:
1- Choose reliable brands, and avoid wearable devices from unknown brands, as in addition to being inaccurate in measuring health indicators, their use may lead to other problems such as:
- Potential exposure of health data, as these devices may not provide strong data and privacy protection.
- They may provide misleading health metrics because they use inaccurate sensors.
- The device may have a short lifespan, may not provide good integration with different applications, and may not support software updates.
2- Determine why you want a wearable device, whether you want to track workouts, monitor health indicators, or just track notifications. Knowing your goals helps you narrow down your choices.
3- Check that the device integrates with the applications you usually use, such as health tracking applications installed on your phone.
4- Check how the device manufacturer handles user data, especially if you are tracking sensitive health information.