Wearables can motivate and mislead. Results of a 5-month test

August 1, 2022
Ads promise that so-called wearables help manage health, modify unhealthy behaviors, motivate and even make it possible to detect certain diseases at an early stage. It is also a dynamically developing market dominated by big tech giants like Apple, Samsung, Fitbit, Garmin, Huawei and Xiaomi. 45% of Americans already wear smartwatches. In 2021, 533 million wearables units were shipped globally, 20% more than in 2021. But how much truth is in what their manufacturers promise? To find it out, I decided to verify what fitness bands and smartwatches really offer. Here are the results of my test.

Complicated health math

I won't reveal the brand of my watch to avoid being suspected of advertising. It's a fitness smartwatch that costs around 250 EUR. Every physical activity – running, swimming, biking, walking – is registered, including parameters such as route, average speed, and heart rate. Based on this data, the watch calculates sports performance and presents it in the form of a chart. A day without sport and the decreasing bar in the chart becomes mathematically calculated proof of laziness. And this brings us closer to feeling guilty, which can actually be motivating. The device counts every step, even those during a day spent entirely at home. It turns out that walking between our desk and kitchen can generate several thousand steps, sometimes as much as 25% of the recommended exercise dose of 8000 steps. Not bad. The most important data is visible on the watch face (steps, heart rate), while more complex analyses are available in the mobile app. During the first days of wearing the watch, it is fascinating to discover the abundance of constantly changing data and colorful charts. They are transformed into trends over time. You can spend several dozen minutes a day delving into the analysis of lifestyle and health parameters. Unfortunately, most of it is only raw data which you have to interpret on your own. I don't know if an average heart rate of 60 is better than 58 or if a lower number of breaths per minute is good or bad. I understand, however, why the producers of this type of devices do not go one step further – to interpret the data based on medical knowledge or provide personalized advice. The reason is simple: in order to obtain reliable conclusions, tens or hundreds of other factors – neither measured by the watch nor other sensors – would have to be taken into account. The high level of stress calculated based on the resting heart rate or perspiration shows the effect, not the cause. The reason for this could also be a horror movie, not a hard day at work. Another question that arises: Is this already unhealthy stress or still an average adrenaline level? I can't find it out – raw data is not enough. Certain achievements, like more kilometres done at a higher speed, certainly provide personal satisfaction and boost your ego, which is motivating, at least for the first few weeks, before the data becomes repetitive, but the trends did not change much. An additional challenge is recording every physical activity. Otherwise, the data is incomplete and the calculated trends incorrect.

Surprising moments of truth

However, among all the information, some can be educational. An example is the effect of alcohol on the body. We tend to think of its harmful effects only when our body punishes us with a hangover the next day. But, in fact, the harmful effects are visible after only several dozen minutes. So how big was my surprise when after two seemingly innocent glasses of wine, my heart rate increased rapidly and the next day the sleep quality chart showed abnormally torn REM phases. This was one of the most exciting lessons I learned during the first weeks. Objective numbers appeal to the imagination and make one realize how moderate consumption of alcohol, which is often underestimated, can burden the body. I can imagine that if there are devices to monitor eating quality in the future, it could be a breakthrough in behaviour change. People tend to ignore facts which are uncomfortable for them. Therefore, raw data coming straight from one's body leave no doubt and can be convincing. When something is wrong with our body, it is not always manifested with clear symptoms.

Well-rested after a sleepless night

I also encountered some absurd situations. One of them took place after a hard night caused by coronavirus infection. Even though I had the impression that I had fallen asleep for only one or two hours, the next day I found out from the app that I had slept 9 hours, 40% of which were REM phases. Unfortunately, that I didn't sleep well was not a dream but a fact. My watch is not smart enough to verify and know that I was only lying in bed trying to fall asleep, using, among others, breathing exercises to induce sleep. Effect: the watch did not register any movements and my breathing and heart rate suggested sound and restful sleep. From that moment on, my confidence in measuring sleep quality dropped to zero. Calculations of REM phases or sleep quality indicators based on very limited data are burdened with significant errors. The device also did not inform me why my REM phases were sometimes shorter and light sleep phases dominated. Nevertheless, one of the features turned out to be working well. At the beginning of wearing the watch, the main data dashboard often showed that I was sleeping too little. It motivated me to go to bed earlier. This change became permanent. However, it is also easy to get false data here – lying in bed with a smartphone can also be interpreted as sleeping.

Navigation helps but workout features disturb

For me, sport is a form of taking care of my health. When running, which I try to do twice a week, I always choose the same route. It's about moving, not exploring the surroundings. Therefore, tips for new routes or suggestions for interval training, pauses and intensity were not helpful for me. These features are for those who exercise professionally and prioritize improving their achievements. While running, I listen to music or podcasts, which is also a form of relaxation. Therefore, messages telling me to stop and then to run very fast and then stop again began to annoy me over time. The navigation feature was useful during walks and bike trips, though. The routes can be directly uploaded to the watch. This helps especially in unfamiliar areas – instead of looking at the smartphone screen every few minutes, you can follow the navigation on your wrist. Some features quickly became favourites – for example, breathing exercises. So far, my attempts at meditation have always failed – after several dozen seconds of focusing on my breath, my thoughts quickly drifted away toward work. And then I discovered breathing training on my watch. Various techniques can be selected, for example, 4:4 (four seconds in, four seconds out). The watch vibrates, gently reminding me to breathe in or breathe out. This is very important as it makes it harder to forget about the rhythm of breathing. COVID-19 and the change of perspective By coincidence, in the 10th week of testing, I caught the COVID-19 infection, with a high fever, headaches and cough. My condition did not require hospitalization, but provoked considerable anxiety and uncertainty. I regretted that my watch did not have a feature to measure body temperature so that I could monitor it in real-time. However, I felt calmer when my blood oxygen saturation results remained unchanged at 95%. In this case, the data objectively confirmed that everything was fine. Did it matter that the increased heart rate triggered by infection was understood by the watch as an increased level of stress? Not really, because over time, I learned to interpret some of the calculations with a grain of salt, knowing that the device had its limitations. It also turned out that the watch has no mercy. When I stopped practising sports, it consistently reminded me that my achievements had reached the bottom. No matter, I could not get out of bed with a headache like never before. Using intelligent devices that measure health parameters requires a large dose of common sense and acceptance of the imperfections of technology. Its weakest point is a very selective analysis of data and an attempt to draw conclusions on this basis, for example, regarding physical condition or sleep quality. Today, I don't feel guilty any more when I don't reach my goal of 8000 steps. The watch does not know that I had good reasons for that. After a few weeks, the illusion of the power of data disappeared. Many measurements are helpful but require preliminary knowledge from the user to interpret them. I mean digital and health literacy. The data itself, though fascinating at the beginning, will not suffice. I knew beforehand that saturation at the level of 95% was good. The watch only gave a percentage value again, without any hints. Ultimately, however, I am convinced that measuring health parameters makes sense if we define our goal in advance. The numbers speak to reason better than assumptions, sometimes pulling us out of the bubble of our own misconceptions. In my case, the motivational impact on developing healthy habits worked well. Besides, it's a gadget that collects a lot of data and shows intriguing charts. Despite this, it will not take care of your health – this still remains the responsibility of the technology owner.