Smart rings have lots of advantages. They’re small, lightweight and convenient, making them much less obtrusive compared to many other forms of fitness trackers. This does raise the question, however, of how such a small device situated such a long way from the main parts of your body can accurately monitor anything (https://longevity.technology/lifestyle/fitness-tracker-rings-accurate-tools-or-just-trendy-gadgets/).
There are a few things that a fitness tracker can measure, but most will probably include your heart. Comparisons between your resting heart rate and the way it changes during different activities can be used to plan your exercise routine and evaluate its success. Resting heart rate isn’t too difficult. A smart ring uses something called photoplethysmography (PPG) to measure how your skin absorbs light, which alters every time your heart beats. When you’re moving rapidly, however, these readings can be interrupted and therefore unreliable.
Step counters are even trickier. An accelerometer can detect movement, but there needs to be an algorithm to figure out whether that movement constitutes a step. This is much easier for a tracker on your hip. On your finger, waving to someone, reaching out to pick something up, or even just gesticulating during a lively conversation could be misinterpreted as your whole body stepping forward.
Accelerometers and algorithms are used for sleep tracking, too. They can’t provide the same degree of precision as a controlled, clinical environment like in a sleep study conducted by professionals, but the most modern iterations can even distinguish between the stages of sleep (such as REM or non-REM) due to various physiological markers.
Calorie counting is difficult for any device because there are so many different factors that influence the results. Your personal data, such as height and weight, needs to be combined from the input form a range of sensors and won’t necessarily be keyed in to the subtle variations in each person’s individual metabolism. It’s a rough guide, not gospel.
You can get maximum accuracy from your ring by ensuring it is the right size for you, making sure data like your height and weight are up-to-date, and keeping an eye on your results to see whether particular activities lead to anomalies. Try to take a generalized long view rather than zeroing in on short-term fluctuations.
As technology improves, rings will probably become even more accurate, but always be pragmatic about any results.
