Latent Profiles of Informal Social Contact and Their Associations with Physical Exercise Participation Among Young Adults in China.

Physical inactivity remains a major public health concern worldwide, including among young adults. Drawing on data from the 2021 China General Social Survey (CGSS), this study examined heterogeneous patterns of informal social contact and their associations with exercise frequency among an analytic sample of young adults aged 18-35 years in China. A total of 1853 respondents were included in the analysis. Latent profile analysis identified four distinct informal social contact profiles: a generally low-contact profile, a relative-oriented and low-neighbor contact profile, a neighbor-oriented profile with approximately average friend contact, and a broadly high-contact profile. Multinomial logistic regression was used to examine associations between exercise frequency, sociodemographic characteristics, and profile membership. The BCH method with Holm-Bonferroni correction was used to compare exercise frequency across profiles. The results showed that rural respondents were more likely to belong to the broadly high-contact profile, whereas respondents who never exercised were more likely to belong to the generally low-contact profile. After correction for multiple BCH comparisons, only the difference between the relative-oriented, low-neighbor contact profile and the neighbor-oriented, average-friend contact profile remained statistically significant, with the former reporting higher exercise frequency. These findings highlight heterogeneity in informal social contact within the analytic sample and suggest that different configurations of everyday contact with relatives, friends, and neighbors are associated with exercise frequency.