Background: During isolation, sharing physical activity experiences on social network sites (SNS) can enhance individual social connectedness. The objective of the present study was to examine the associations between sharing physical activity experiences on SNS, positive self-presentation, positive feedback, and social connectedness during isolation. Methods: Based on the Physical Activity Experience Sharing Scale, Social Connectedness Scale, Positive Self-Presentation Scale, and Online Positive Feedback Scale, we collected 460 questionnaires online from across 31 provinces, municipalities and autonomous regions in China. We used multiple linear regression models to investigate the relationship between variables, and used bootstrapping to test for mediation.. Results: During isolation, sharing physical activity experiences was positively associated with social connectedness (b = 0.308, p < 0.001), as well as with positive self-presentation(b = 0.956, p < 0.001)and positive feedback(b = 0.421, p < 0.001). In addition,we found that positive self-presentation showed a significant positive impact on positive feedback (b = 0.563, p < 0.001), and that positive self-presentation(b = 0.331, p < 0.001) and positive feedback(b = 0.311, p < 0.001) were positively associated with social connectedness. Finally, we found an effect on sharing physical activity experiences indirectly through positive self-presentation (b = 0.316, 95% CI: [0.180, 0.463]),and positive feedback (b = 0.131, 95% CI: [0.063, 0.207]) and that the mediation chain between the two also had a significant impact on social connectedness (b = 0.167, 95% CI: [0.088, 0.251]). Conclusions: During the COVID-19 pandemic, sharing physical activity experiences on SNS can create a positive, healthy, and energetic personal image, gain recognition from others, and establish new interpersonal relationships.

Introduction: Prevention of the health risk of amateur marathon runners is of great significance for the sustainable development of marathon. To reduce the psychological burden of amateur marathon runners and improve the participation experience, the current study used the health belief model to study the relationship among health beliefs, attitude to preventative behavior, self-efficacy, and health values of amateur marathon runners. Methods: A total of 342 data were collected, and using the PROCESS (analytical procedures developed for mediating and moderating effects tests based on SPSS and SAS). A series of multiple linear regression models were established to study the relationship between variables, and the bootstrap confidence interval was selected to test the mediating and moderating effect. Results: The results showed that perceived health threat (b = 0.463, p < 0.05), health behavior expectations (b = 0.373, p < 0.001), self-efficacy (b = 0.322, p < 0.001), and behavioral attitudes (b = 0.230, p < 0.001) can be regarded as antecedent variables for predicting preventative behaviors. In addition, the results also show that health behavior expectations, self-efficacy, and behavioral attitudes play chain-mediating role between perceived health threat and preventative behaviors. Health values appear to play a moderating role in the direct/indirect effects of perceived health threat on preventive behavior through a number of mediating variables. Discussion: This study emphasizes that the amateur marathon runners must improve their health concept and take effective preventive measures before participating in the competition. According to this research, it is the responsibility of the event parties, public health officials and relevant departments of the host city to provide rich health information and risk education to amateur marathon runners. More public service advertisements or educational materials are needed to be placed on runners to enhance their awareness of the necessity and importance of taking preventive measures.