Deconstructing Fitbit to Specify the Effective Features in Promoting Physical Activity Among Inactive Adults: Pilot Randomized Controlled Trial (Preprint)

Abstract

BACKGROUND Wearable activity trackers have become key players in mobile health practice as they offer various behavior change techniques (BCTs) to help improve physical activity (PA). Typically, multiple BCTs are implemented simultaneously in a device, making it difficult to identify which BCTs specifically improve PA. OBJECTIVE We investigated the effects of BCTs implemented on a smartwatch, the Fitbit, to determine how each technique promoted PA. METHODS This study was a single-blind, pilot randomized control trial in which 70 adults (44 women; mean age of 40.5 years; closed user group) were allocated to one of three BCT conditions: self-monitoring (feedback on participants’ own steps), goal setting (providing daily step goals), and social comparison (displaying daily steps achieved by peers). Each intervention lasted for four weeks (fully automated), during which participants wore a Fitbit and responded to day-to-day questionnaires regarding motivation. At pre- and post-intervention (in-person sessions), levels and readiness for PA as well as different aspects of motivation were assessed. RESULTS Participants showed excellent adherence (mean valid-wear time of Fitbit = 26.4 out of 28 days; 94.39 %), no dropout was recorded. No significant changes were found in self-reported total PA (dz < 0.27, Ps > .05). Fitbit-assessed step count during the intervention period was slightly higher in the goal-setting and social-comparison groups than in the self-monitoring group although the effects did not reach statistical significance (Ps = .052 and .057). However, more than half of the participants in the precontemplation stage (n = 27 out of 46) reported progress to a higher stage across the three conditions. Additionally, significant increases were detected for several aspects of motivation (i.e., integrated and external regulation), and significant group differences were identified for the day-to-day changes in external regulation; that is, the self-monitoring group showed a significantly larger increase in the sense of pressure and tension (as part of external regulation) than the goal-setting group (P = .039). CONCLUSIONS Fitbit-implemented BCTs promote readiness and motivation for PA although their effects on PA levels are marginal. The BCT-specific effects were unclear, but preliminary evidence showed that self-monitoring alone may be perceived demanding. Combining self-monitoring with another BCT (or goal setting, at least) may be important for enhancing continuous engagement in PA. CLINICALTRIAL https://osf.io/87qnb/?view_only=f7b72d48bb5044eca4b8ce729f6b403b