BackgroundNew fitness trackers and smartwatches are released to the consumer market every year. These devices are equipped with different sensors, algorithms, and accompanying mobile apps. With recent advances in mobile sensor technology, privately collected physical activity data can be used as an addition to existing methods for health data collection in research. Furthermore, data collected from these devices have possible applications in patient diagnostics and treatment. With an increasing number of diverse brands, there is a need for an overview of device sensor support, as well as device applicability in research projects.ObjectiveThe objective of this study was to examine the availability of wrist-worn fitness wearables and analyze availability of relevant fitness sensors from 2011 to 2017. Furthermore, the study was designed to assess brand usage in research projects, compare common brands in terms of developer access to collected health data, and features to consider when deciding which brand to use in future research.MethodsWe searched for devices and brand names in six wearable device databases. For each brand, we identified additional devices on official brand websites. The search was limited to wrist-worn fitness wearables with accelerometers, for which we mapped brand, release year, and supported sensors relevant for fitness tracking. In addition, we conducted a Medical Literature Analysis and Retrieval System Online (MEDLINE) and ClinicalTrials search to determine brand usage in research projects. Finally, we investigated developer accessibility to the health data collected by identified brands.ResultsWe identified 423 unique devices from 132 different brands. Forty-seven percent of brands released only one device. Introduction of new brands peaked in 2014, and the highest number of new devices was introduced in 2015. Sensor support increased every year, and in addition to the accelerometer, a photoplethysmograph, for estimating heart rate, was the most common sensor. Out of the brands currently available, the five most often used in research projects are Fitbit, Garmin, Misfit, Apple, and Polar. Fitbit is used in twice as many validation studies as any other brands and is registered in ClinicalTrials studies 10 times as often as other brands.ConclusionsThe wearable landscape is in constant change. New devices and brands are released every year, promising improved measurements and user experience. At the same time, other brands disappear from the consumer market for various reasons. Advances in device quality offer new opportunities for research. However, only a few well-established brands are frequently used in research projects, and even less are thoroughly validated.

Wearable computing has long been described as the solution to many health challenges because of its ability to be ever present and accessible to patients. The market for these technologies is immature and is still developing, offering more possibilities for health management every year. In fact, benefits for diabetes management were recently cited in an editorial of Journal of Diabetes Science and Technology. 1 Through a feasibility study, our research group aimed to explore the interoperability and usability of a suitable wearable computing device in conjunction with a developed smartphone application, and initiate the evaluation of such systems for use in diabetes self-management. Review of current devices and platforms illustrates the context of this study. While monitoring systems such as continuous glucose monitors (CGMs) and insulin pumps are made widely available through the medical system, wearable computers have not yet reached such common status in the diabetes self-management market. Wearables include smart eyewear, such as Google Glass (Google Inc, Mountain View, CA), as well as wristbands and mobile phone apps, which offer more computing functionalities including sleep pattern analysis, elevation climbed, and goal tracking. Evaluation of Mobile Phones and Applications While all of these are expected to offer useful health applications, mobile phones and applications (apps), in particular, 567708D STXXX10.

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