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Wearable activity trackers are promising as interventions that offer guidance and support for increasing physical activity and health-focused tracking. Most adults do not meet their recommended daily activity guidelines, and wearable fitness trackers are increasingly cited as having great potential to improve the physical activity levels of adults.
The objective of this study was to use the Coventry, Aberdeen, and London-Refined (CALO-RE) taxonomy to examine if the design of wearable activity trackers incorporates behavior change techniques (BCTs). A secondary objective was to critically analyze whether the BCTs present relate to known drivers of behavior change, such as self-efficacy, with the intention of extending applicability to older adults in addition to the overall population.
Wearing each device for a period of 1 week, two independent raters used CALO-RE taxonomy to code the BCTs of the seven wearable activity trackers available in Canada as of March 2014. These included Fitbit Flex, Misfit Shine, Withings Pulse, Jawbone UP24, Spark Activity Tracker by SparkPeople, Nike+ FuelBand SE, and Polar Loop. We calculated interrater reliability using Cohen's kappa.
The average number of BCTs identified was 16.3/40. Withings Pulse had the highest number of BCTs and Misfit Shine had the lowest. Most techniques centered around self-monitoring and self-regulation, all of which have been associated with improved physical activity in older adults. Techniques related to planning and providing instructions were scarce.
Overall, wearable activity trackers contain several BCTs that have been shown to increase physical activity in older adults. Although more research and development must be done to fully understand the potential of wearables as health interventions, the current wearable trackers offer significant potential with regard to BCTs relevant to uptake by all populations, including older adults.
Physical inactivity contributes to an estimated 3.2 million deaths each year [
Sedentary behavior is an independent risk factor for chronic disease that is separate from physical inactivity. Sedentary behavior is defined as “any waking behavior characterized by an energy expenditure of < 1.5 metabolic equivalents while in a sitting or reclining posture” [
Wearable activity trackers are an emerging solution for motivating people to improve their physical activity levels and reduce sedentary behavior. Wearable trackers are activity monitors that track daily movement through sensors and companion smartphone or computer applications. As of 2015, at least half of consumers have heard of wearable activity trackers such as Fitbit or Jawbone and one in three have plans to purchase one [
One question that emerges is how well wearable activity trackers align with the evidence-based techniques that have been shown to increase physical activity levels. One approach to identifying the behavior change techniques (BCTs) present in new and emerging technologies is to use a taxonomy such as the Coventry, Aberdeen, and London-Refined (CALO-RE) taxonomy. First published in 2011, the CALO-RE taxonomy contains 40 techniques derived from behavior change theories. It was based on an earlier 26-item taxonomy developed in 2008 by Abraham and Michie [
Wearable activity trackers are being targeted at users of mobile apps as a way to promote physical activity [
We ran this study concurrently with another study examining the real and perceived acceptance of wearable activity trackers by older adults (aged more than 50 years) living with chronic illness [
Wearable fitness trackers. Top L-R: Jawbone UP24, Nike Fuelband, Polar Loop, Misfit Shine with sport band . Centre: Misfit Shine with action Clip. Bottom L - R: Withings Pulse, Fitbit Zip, Spark Activity Tracker.
We coded the wearable activity trackers using the CALO-RE taxonomy, which is a standardized tool for describing and comparing the BCTs used in lifestyle interventions [
We coded each technique using a dichotomous score of either 0 (not present) or 1 (present). For mobile apps and websites that had archives of information articles, we only coded a technique if the user was prompted to read a specific article or community post through an email alert or daily message. Upon installation of certain mobile apps, animations would prompt users to look at specific tabs and features or everything listed in the main menu. If any of these elements fit in with a BCT, it was also coded. We did not consider any information that was not immediately accessible or that was not presented through prompting.
We used descriptive statistics to summarize the CALO-RE ratings. We calculated interrater reliability using Cohen's kappa on SPSS Statistics (version 22, IBM). Cohen's kappa is used to describe the degree of interrater reliability between two raters and can be applied to dichotomous data [
Seven wearable activity trackers were rated by two independent raters using the 40-item CALO-RE taxonomy [
There were 15 techniques absent in all wearable activity trackers, as listed in
Behavior change techniques absent
Barrier identification or problem-solving
Set graded tasks
Prompting generalization of a target behavior
Environmental restructuring
Agree behavioral contract
Use of follow-up prompts
Prompt identification as role model or position advocate
Prompt anticipated regret
Fear arousal
Prompt self-talk
Prompt use of imagery
Relapse prevention or coping planning
Stress management or emotional control training
Motivational interviewing
General communication skills training
Most common behavior change techniques; with total number of devices found in.
The kappa scores for interrater reliability of the taxonomy for the seven wearable activity trackers ranged from .746 to 1 (
Interrater reliability of taxonomy per wearable activity tracker
Wearable activity tracker | Cohen's kappa (95% CI) |
Fitbit Flex | 1 (0.00) |
Jawbone UP24 | .899 (0.764-1.034) |
Misfit Shine | 1 (0.00) |
Nike+ FuelBand SE | .944 (0.836-1.052) |
Polar Loop | .881 (0.722-1.040) |
SparkPeopl Spark Activity Tracker | .746 (0.544-0.948) |
Withings Pulse | .899 (0.764-1.034) |
The mean number of BCTs incorporated in wearable activity trackers was 16.3/40 (SD 4.6), with Withings Pulse having the highest number at 23/40 and Misfit Shine having the lowest at 10/40 (
Behavior change technique content of wearable activity trackers, mean 16.3 (SD 4.6).
Wearable activity tracker | Number of behavior change techniques (N=40) | Possible behavior change techniques present (%) |
Withings Pulse | 23 | 57.5 |
SparkPeople Spark Activity Tracker | 21 | 52.5 |
Jawbone UP24 | 18 | 45.0 |
Fitbit Flex | 15 | 37.5 |
Nike+ FuelBand SE | 14 | 35.0 |
Polar Loop | 13 | 32.5 |
Misfit Shine | 10 | 25.0 |
Many of the newest generation wearable activity trackers include BCTs in the user interface. Results from the CALO-RE taxonomy ratings demonstrated that the devices tend to focus on techniques for goal setting, self-regulation, and social support. Techniques related to self-efficacy (such as planning, consequences, and knowledge) were present in less than half of the trackers or absent in all seven devices.
Our findings were similar to the ratings of activity trackers by Lyons et al [
In previous evaluations of physical activity interventions among adults aged 50 years and older, social support from peer mentors, families, and friends significantly increased initiation and maintenance of physical activity [
A 2014 systematic review by French et al [
Self-efficacy is an important predictor for starting and maintaining physical activity in adults aged more than 50 years [
The focus of wearable activity trackers on self-monitoring and self-regulation is to be expected. The main design and purpose of these devices is to monitor past, present, and future activity. A qualitative analysis of an 18-month physical activity intervention in older adults found that targeting self-regulation behaviors may support long-term increases in physical activity [
Although we had a high interrater reliability, the ratings may not represent the most current version of the wearable activity tracker and associated platforms because of frequent updates. We minimized these elements by ensuring that all notifications were enabled, saving screenshots and website links representing each technique, consulting an experienced tracker user when necessary, and downloading all updates as of August 8, 2014. This method of evaluating the physical tracker and downloaded platforms allowed us to identify more BCTs than if Web-based descriptions alone were used, which was the approach used by Conroy et al [
One challenge for studies of this nature is that there is no guarantee that the user will encounter a technique even if it is present. For example, if a user does not wish to use or does not have access to social media, then the user will not encounter any of the tracker's social support techniques. A further challenge for rating trackers is that they are complex tools with multiple features and different users are likely to have different experiences. For example, a user who wants to perform more physical activity may not use the device in the same way as a user who wants to be less sedentary. Similarly, a user who has a lower health or technology literacy may not explore the features as deeply as a health professional or expert technology user, regardless of age. As a result, this study should be considered a snapshot of the BCTs of wearable activity trackers and of the potential of how these trackers can relate to self-efficacy in the older user. By determining the similarities and differences between the overall population and the older adult population, there is great potential to develop wearable activity trackers and their affiliated apps to be the most broadly reaching.
Wearable activity trackers are a promising innovation for promoting physical activity behaviors in a wide age range of users, including the older adult population. They can easily be distributed across a wide population and integrated as a part of physical activity interventions through pharmacies and prescribers. Behavior change techniques most commonly found in the evaluated wearable activity trackers, such as self-monitoring and self-regulation techniques, are likely to appeal more to younger and middle-aged adults. To make wearable activity trackers more appealing to older adults, additional BCTs that are specific to older adult needs may be necessary, such as helping users find ways to overcome barriers to physical activity by problem-solving and modeling or demonstrating ways to increase physical activity. Future collaborations between tracker developers and health behavior change experts may enhance the potential to elicit behavior change.
CALO-RE Taxonomy Rating Data.
behavior change technique
Behavior Change Technique Taxonomy
Coventry, Aberdeen, and London-Refined
The authors wish to thank Joslin Goh, Statistical Consultant, University of Waterloo.
None declared.