The purpose of this project was to design and test data collection and management tools that can be used to study the use of mobile fitness applications and social networking within the context of physical activity. This project was conducted over a 6-month period and involved collecting publically shared Twitter data from five mobile fitness apps (Nike+, RunKeeper, MyFitnessPal, Endomondo, and dailymile). During that time, over 2.8 million tweets were collected, processed, and categorized using an online tweet collection application and a customized JavaScript. Using the grounded theory, a classification model was developed to categorize and understand the types of information being shared by application users. Our data show that by tracking mobile fitness app hashtags, a wealth of information can be gathered to include but not limited to daily use patterns, exercise frequency, locationbased workouts, and overall workout sentiment.
KEYWORDSPhysical activity, Twitter, Mobile fitness apps, Online social network INTRODUCTION Technology, health, and physical activity As much as technology has enriched society and expanded global communication, it can be argued that it has also negatively affected overall global health by lowering opportunities for physical activity [1] and by contributing to an overall secular decline in physical activity participation rates [2]. At the same time, research also indicates that there is a potential for technologies to be used as a means for improving health and increasing physical activity [3].According to a report issued by mobihealthNews, more than 13,000 health and fitness apps were available via iTunes by August 2012 [4]. The use of smartphones in supporting health behavior change via mobile fitness apps is encouraging. Aside from expanded opportunities for users to access health information, mobile devices are becoming more persuasive behavior change tools, allowing for the facilitation of ongoing collection of personal data and the opportune timing of feedback and education to elicit a change in behavior [5]. The most recent health applications have been smartphone applications for