Why our devices are not very smart, yet.

The problem with wearables

Wearable devices such as the smartwatch and activity tracker are mobile devices connected to the Internet of Things. Devices such as the Apple Watch and Fitbit are designed to help us track fitness-related metrics (e.g. physical activity, calorie consumption, heartbeat, mood and sleep quality). Potentially sparking the kind of behaviour change we need to guide us towards healthier habits and disease prevention. Another potential benefit of wearables is their ability to enable web-based data sharing/collaboration between devices and people without requiring human intervention.

Despite their potential, current wearables are affected by data quality issues. According to a recent report by Stanford University School of Medicine, devices that measure calories are particularly poor. Researchers evaluated 7 devices (Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn and Samsung Gear S2) with 60 volunteers and found that:

• Not all wearables are created equal. The Apple Watch was a clear winner in both heart rate and energy expenditure, while Samsung’s device reported the highest error rates.
• The devices were consistently terrible at tracking energy expenditure, with the most accurate device off by an average of 27 percent. Ashley said the error rate should be less than 10 percent when these devices are used in non-medical settings.
• Heart rate measurements have improved over the years. He described some of the early wearables as “random number generators.” Ashley said that users can rely on this data-point.
• The devices were better at measuring data collected during cycling than walking.
• Errors also tended to be more common in men versus women, those with a greater body mass index, and with a darker skin tone.

The reason wearable devices are so inaccurate is that human behaviour and related biological function are incredibly varied: e.g. some people walk smoothly, while others take rigorous strides. People also respond differently to motivational cues. Yearlong studies by Patel et al. (2016) found that even when people have access to their activity levels or get paid to stay active, wearables don’t persuade them to exercise more, with almost half of respondents ditching devices within the first 6 months.

Based on this evidence, people should avoid investing in wearables, at least until devices are more personalised to user needs. Tech companies that develop more responsive devices are likely those that will create more clinically effective and economically sustainable products.

Until then, our advice is invest your well-earned money in an effective personal trainer to motivate you, and a convenient gym membership to build positive reinforcement and social support.