Wearable devices can count steps, estimate active minutes and record long periods of sitting. That makes them appealing for population health, where officials need to understand how movement patterns differ across age groups, regions and communities.
But a device that works well for an individual fitness goal is not automatically suitable for national surveillance. In November 2026, the World Health Organization opened a consultation on draft specifications for wrist-worn devices intended to measure physical activity and sedentary behaviour in population monitoring. The proposal highlights a basic public-health challenge: useful data must be accurate enough, comparable enough and accessible enough to work across very different settings.
Personal tracking and population monitoring are different jobs
A consumer may choose a wearable for convenience, battery life or a preferred app. A public-health programme has broader responsibilities. It needs measurements that can be interpreted consistently across thousands of people, clear documentation of what the device actually records and methods that remain usable when technology changes.
Population data also need context. A low activity count may reflect illness, disability, unsafe streets, extreme weather, demanding work or a lack of accessible public space. A device can record movement; it cannot explain every reason behind it.
Why objective measures are attractive
Surveys remain essential, but they depend on memory and interpretation. People may remember a workout while overlooking short walks, domestic tasks or long periods of sitting. A wrist-worn sensor can add continuous, time-stamped information and may reveal patterns that are difficult to capture with a questionnaire alone.
That does not make wearable data perfectly objective. Different devices use different sensors, algorithms and thresholds. A brisk walk, cycling, pushing a stroller or using a mobility aid may be classified differently. The same raw movement can produce different summaries depending on the software.
The equity test
For national or regional monitoring, cost and usability matter as much as technical performance. A device that is expensive, difficult to charge or dependent on a modern smartphone may exclude the very groups whose health opportunities are least visible.
Fit, comfort, accessibility and language support also affect whether people wear a device consistently. Skin contact, wrist size, disability and cultural preferences can influence data quality. If participation is uneven, a precise sensor can still produce a biased picture of the population.
Privacy cannot be an afterthought
Movement data can reveal routines, sleep windows and location-related patterns even when a programme is not designed to track individuals. Public-health systems therefore need clear limits on collection, retention, linkage and access. Participants should understand what is measured, why it is needed and whether it will be combined with other records.
Data minimisation is a practical safeguard: collect the information required for the stated public-health purpose and avoid retaining more detailed traces simply because the device can generate them.
What better standards could enable
Common minimum specifications could make studies easier to compare across places and over time. They could also help health agencies purchase devices based on documented requirements instead of marketing claims. That matters particularly in lower-resource settings, where a failed procurement can consume scarce funding and leave unusable data.
Better monitoring would not by itself make people more active. It could, however, show where safe walking, cycling, recreation and accessible public space are missing; identify which groups are being left behind; and help evaluate whether policies change everyday movement.
A measurement tool, not a diagnosis
Wearable estimates should not be treated as medical diagnoses or as a complete picture of a person’s health. Consumer devices vary in accuracy, and activity needs differ according to age, health status, disability and pregnancy. People with symptoms or medical concerns should seek individual advice from a qualified clinician.
The public-health value of wearables will depend less on producing the largest possible dataset and more on producing trustworthy, interpretable and equitable evidence. Standards are part of that work: they define what a device must do before its numbers are used to shape decisions for whole communities.
