۱- Introduction

۲- Study 1: quantitative study

۳- Study 2: qualitative

۴- General discussion

References

Introduction 

Online social networking sites, such as Facebook (FB), are ubiquitous in society and have changed the way people interact. FB provides its 1.28 billion daily users (Facebook, 2017) with a personal profile and the ability to upload photos, access others’ profiles, accumulate friends, and interact with these friends through messaging, commenting on photos, status updates, wall posts and other applications. Adults aged 18-25 years encompass 23% of all FB users (Facebook, ۲۰۱۷) and a large proportion (32%) of undergraduate students spend over four hours a day on Facebook (Bicen & Cavus, 2011). Researchers have begun to investigate the potential for these changing interaction patterns to positively (or negatively) affect health behaviours of young adults, such as physical activity (PA). Regular PA is beneficial for health, physical and psychological wellbeing (Lee, Shiroma, Lobelo, Blair, & Katzmarzyk, 2012). The World Health Organization (2011) recommends that adults participate in 150 minutes of moderate PA per week, yet due to a decline in PA during the ages of 18 and 25 years young adults are not meeting PA guidelines (Kilpatrick, Hebert, & Bartholomew, 2005). One form of PA is exercise, which is planned, structured, and involves pursuit of a physical fitness objective(s) (Caspersen, 1985). Thus, an important focus within health psychology is to understand the factors that influence exercise motivation and behaviour, with recent interest growing in the potential role of social media, and FB in particular (e.g., Cavallo et al., 2014; Ellison, Steinfield, & Lampe, 2007; Mabe, Forney, & Keel, 2014). One framework to understanding the effects of FB use on exercise motivation is through Self Determination Theory (SDT; Deci & Ryan, 1985; Ryan & Deci, 2000), which examines the different types of motivation underlying exercise behaviour. First, SDT distinguishes between extrinsic and intrinsic motivation. Extrinsic motivation occurs on a continuum of less self determined (controlled) to more self-determined (autonomous) motivation.