Fitness Trackers Increase Self-Monitoring but Do Not Lead to Increased Physical Activity

Introduction: Fitness trackers have become an increasingly popular tool for individuals seeking to monitor and improve their physical activity and fitness levels. The wearability and easy use of these trackers have made them an appealing technological intervention in public health programs aimed at promoting physical activity. Initial research suggests that commercially available fitness trackers have adequate accuracy, however, more research is need to determine their efficacy in changing health behaviors (Evenson, Goto, & Furburg, 2015; Lewis, Lyons, Jarvis, & Baillargeon, 2015). Fitness trackers are hypothesized to increase users’ self-monitoring, a mechanism for behavior change. This study investigates the effects of fitness trackers on physical activity in individuals participating in a 26-week health education program focused on improving participants’ sleep, activity, and nutrition.

Methods: Participants in this study included 4,418 Soldiers assigned to 1 of 3 groups: comparison, health education only, or health education plus fitness tracker. Data on self-monitoring and health behaviors such as average minutes per week of physical activity and frequency of resistance training were collected at baseline, 3 months, and 6 months. Mixed model repeated measures ANOVAs were used to evaluate the differences between groups over time in self-monitoring and physical activity.

Results: Self-monitoring increased in all conditions over time (main effect F(2,8830)= 589.08, p<.001), however there was a significant interaction of group by time (F(4,8830)=324.59, p<.001), such that individuals in the group given fitness trackers reported significantly greater increases in self-monitoring over time compared to the other two groups. Conversely, the average minutes per week of physical activity decreased in all conditions over the 6-month period (main effect F(2,7572)=238.44, p<.001), and no significant interaction was observed, indicating that there was no effect of group membership (i.e., fitness trackers) on average minutes of physical activity. This same pattern was observed for reported number of days of resistance training.

Conclusions: Results of this study indicate that fitness trackers are associated with an increase in self-monitoring, a key mechanism of behavior change. Despite an increase in self-monitoring behavior, individuals in the fitness tracker group did not differ from the other two groups in terms overall physical activity. These findings suggest that although fitness trackers are becoming an increasingly popular tool in the health and fitness industry they may have limited utility as a public health intervention aimed at increasing physical activity.

Lewis, Z. H., Lyons, E. J., Jarvis, J. M., & Baillargeon, J. (2015). Using an electronic activity monitor system as an intervention modality: A systematic review. BMC public health, 15(1), 1.

Evenson, K. R., Goto, M. M., & Furberg, R. D. (2015). Systematic review of the validity and reliability of consumer-wearable activity trackers. International Journal of Behavioral Nutrition and Physical Activity, 12(1), 159-181.