The first clock was invented in the 1500s by a locksmith named Peter Henlein from Nuremberg, Germany. From then on, the race to make watches more compact, smarter and accurate began. The watch on your hand gradually transformed into a machine that can not only tell you the time but also keep track of your heart rate. Analog became digital and soon digital became high-tech.

The first smartwatch was the Seiko Rupeuter, which was launched in 1998 and could run applications and connect to a PC. By 2014, brands such as Samsung and Apple had created their own versions. Today, wearables or smartwatches have become common and are no longer restricted to athletes.

In India, you can find these smartwatches even on the roadside for as low as Rs 100 or Rs 150, making them more common.

A smartwatch that saves lives

• Smartwatches can do more than just tell the time. They can tell you how many calories you’ve burned, how many steps you’ve taken, and even make a phone call in case of an accident.
• For instance, recently, in May 2024, a Delhi woman and her Apple Watch made headlines after she nearly escaped what doctors termed as a “narrow” death.

• This happened when her Apple Watch’s heart rate feature detected her “abnormally high” heart rate and alerted her.
• A similar case occurred last year, when Norwegian investment director Robert Naess accidentally slipped while running and was seriously injured in July 2023.
• Thanks to the Apple Watch’s calling feature, he was able to call for emergency services, saving his life.

Today, there are many other cases where smartwatches have saved lives. These wearable devices such as smartwatches and fitness trackers can monitor a variety of health and fitness metrics.

• These devices can track heart rate, step speed, calories burned, distance traveled, and even sleep patterns including deep and REM sleep stages.
• Advanced features include blood oxygen level monitoring (SpO2), electrocardiogram (ECG) to track heart health, and stress level estimation based on heart rate variability.
• Some wearable devices measure respiratory rate, body temperature, and even blood pressure.
• For fitness enthusiasts, wearable devices provide detailed workout metrics for activities like running, cycling, and swimming.
• Women can track their menstrual cycles, and some wearable devices even monitor their posture.
• Additionally, GPS functionality allows for tracking outdoor routes.
• These devices have become essential companions for both health monitoring and fitness tracking.

But are your wearable devices really as accurate as they’re marketed? Read on to find out.

In a recently published umbrella review (a systematic review of systematic reviews), experts examined the scientific literature to see whether consumer wearable devices can accurately measure metrics such as heart rate, aerobic capacity, energy expenditure, sleep and step count. The review found that at a basic level, the accuracy of the devices is good.

The study found that wearable devices can measure heart rate with about a 3% error, depending on factors such as ‘skin tone and type of exercise and if you have a tattoo.’ They also do a good job at detecting heart rhythm problems and estimating cardiorespiratory fitness, especially during exercise.

But

• They underestimate step counts by about 9%.
• There are large errors in tracking calories burned, ranging from 21.27% to 14.76%.
• When it comes to sleep, wearable devices often overestimate total sleep time and efficiency by more than 10%, while underestimating the time it takes to fall asleep and the time to wake up after sleep, with errors ranging from 12% to 180% compared to standard sleep studies.

Experts seem to agree with this analysis.

Dr Shrey Kumar Srivastava, general physician at Sharda Hospital, says the accuracy of wearable devices, especially fitness trackers, can vary widely depending on the quality of the device, the sensor technology and the way it is used. He gives some examples:

Heart rate monitoring: Some wearable devices rely on optical sensors, which measure blood flow through your skin. This method can be inaccurate if the wearable isn’t tight enough, if you have dark skin or tattoos, or during intense activities.

Sleep Tracking: Wearable devices often estimate sleep based on movement and heart rate, which may not always match the results of clinical sleep studies. They may misinterpret periods of rest as sleep or fail to identify different stages of sleep.

calories burned: This metric is particularly difficult to track accurately because it depends on many individual factors, including metabolism, fitness level and type of exercise.

Talking about wearables, you might have also come across the latest types of wearables that can do all the functions of a smartwatch, but they are much smaller.

Yes, we are talking about smart rings. Rings sound good as a fitness accessory, but Dr. Tushar Tayal, Consultant of Internal Medicine at CK Birla Hospital, Gurugram, says that even though rings are becoming popular due to their small size, they have small sensors, which can affect accuracy compared to watches.

“Like other wearable devices, the quality of the data depends on the brand and technology used,” says Dr. Tayal.

Avoid cheap versions

If wearing wearables is something you are interested in, choose brands you trust and not cheap street finds or brands you have never heard of, because apart from being wrong, these can lead to other problems as well.

Dr. Tayal says that this can lead to the following problems:

1. Health metrics are misleading because they use less accurate sensors.
2. The risk of your health data being compromised is high, as cheap wearable devices do not have strong security or privacy protection.
3. The device may have a limited lifespan, and may not provide reliable app integration, software updates, or customer support, especially in times of need.

What to consider before buying wearables

Think about why you want a wearable device. Is it to track workouts, monitor health metrics, or just receive notifications? Knowing your goals helps you narrow down your choices.

Research, review and study how accurate a wearable device is for the parameters that are important to you (e.g., heart rate, sleep or GPS tracking).

Make sure the wearable integrates with the apps and platforms you already use, such as health apps on your phone.

Pay attention to how the company handles your data, especially if you’re handling sensitive health information.

Memorization

While wearable devices can provide valuable health information, their accuracy varies. When it tells you something is wrong with your heart, believe it, but for other things like your step count or calories burned in a day, take it with a grain of salt. Keep in mind that it’s important to invest in a trusted brand and consider your needs carefully before making a purchase.