Smartwatches are very popular today for tracking fitness, sleep, and heart rate. However, researchers from the University of Michigan found that many health numbers are algorithmic estimates rather than direct measurements. The team published their findings in the scientific journal Sensors.
Modern smartwatches use optical sensors to monitor blood flow and motion sensors to track movement. Algorithms then calculate readable metrics for the user. Simple numbers, such as step counts and resting heart rate, are generally reliable. In contrast, complex metrics like burned calories, sleep stages, and hydration are much harder to measure accurately.
Several personal and environmental factors can also change the accuracy of these readings. For example, sweat, body movement, temperature, skin tone, and how tightly the watch fits all influence the data. Furthermore, different brands use different formulas, so results from different watches cannot easily be compared.
The researchers recommend that users focus on long-term personal trends. Watching your numbers change over weeks or months is much more meaningful than worrying about a single unusual reading.
Difficult words
- estimate — a guess or calculation of a value or sizeestimates
- measurement — the act of finding the exact size or amountmeasurements, measure
- metric — a standard of measurement used to track somethingmetrics
- accurate — correct and free from any mistakesaccurately
- influence — to have an effect on something
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you use a smartwatch or fitness tracker? If so, which health numbers do you check the most?
- Why do you think factors like sweat and skin tone can change the accuracy of smartwatch readings?
- Do you agree that looking at long-term trends is better than worrying about a single day's results? Why or why not?
Related articles
Clock disruption speeds breast cancer in models
New research finds that repeating disruption of the body’s 24-hour clock changes breast tissue, weakens immune defenses and leads to faster, more aggressive breast cancer in experimental models. The study links altered light–dark schedules to worse outcomes.
Mindfulness helps couples under financial stress
A University of Georgia study of over 400 couples with children found that higher mindfulness links to greater confidence the relationship will survive stress. Mindfulness also related to better relationship quality and stronger co-parenting.
Gene Variant Raises Heart Failure Risk After Myocarditis in Children
A study found that a cardiomyopathy gene variant is more common in children who develop dilated cardiomyopathy after myocarditis. Researchers describe a "double hit" model and advise genetic testing to identify higher risk.
