Networked Social Influence: Online Social Network Physical Activity Interventions for Young Adults

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Doctor of Philosophy (PhD)
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Online Network
Physical Activity
Social Influence
Young Adults
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Sedentary lifestyle significantly increases the risks of chronic disease and all-cause mortality. Nevertheless, low levels of physical activity among young adults remain a serious nationwide problem, with 69% of Americans 18 to 24 years of age failing to meet the federal guidelines for both aerobic and muscle-strengthening activity in 2014. Among all the social and environmental factors affecting physical activity levels, interpersonal social networks are one of the most prominent targets for cost-effective interventions. In particular, online social networks are a highly attractive resource for large scale health initiatives given their capacity to disseminate interventions easily while simultaneously facilitating social influence dynamics. This dissertation examines online social networks’ efficacy and mechanisms in increasing physical activity among young adults. The dissertation comprises three experiment studies. The first study employed a 3-arm randomized controlled trial (RCT) to examine the effects of basic website, promotional media messaging, and web-based anonymous online networks in increasing exercise class enrollment. The results showed among 217 university graduate students anonymous online networks were more effective than the basic website in increasing exercise class enrollment. The second study built upon the first study and employed a 2 by 2 factorial RCT to compare the effects of supportive versus competitive interactions and individual versus team incentives through web-based online networks in increasing exercise class attendance. The results showed among 790 university graduate students, social comparison was more effective in increasing exercise class attendance than social support. There was no significant difference between individual and team incentives in increasing class attendance. The third study shifted the technological platform and employed a mobile application. It tested the efficacy of an online network mobile app intervention in increasing daily active minutes objectively recorded by a fitness tracking device (Fitbit zip) in comparison with a control condition where individuals used the app by themselves without any connection with other people. Results showed among 91 young African American women, the online networks did not impact the primary outcome, daily active minutes. Self-reported physical activity significantly increased after the intervention program irrespective of intervention arms. Online networks were effective in increasing daily engagement with the fitness tracking device and the mobile app in comparison with the control condition. In addition, descriptive analyses on theoretical variables indicated that young African American women perceived low levels of peer norm and social support on physical activity in general. Online networks entail great potentials in promoting physical activity for young adults. More research is needed to fully understand the long-term effects and mechanisms of online networks in promoting physical activity and in other health behavior domains.

John B. Jemmott
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