A study showed that adolescents who engage in physical activity for more than one hour a day are less likely to feel lonely and depressed than those who do not. There are suggestions that an institutional foundation for adolescents' physical activity should be established. According to the academic world on the 13th, a research team led by Professor Kim Jae-yeop of Yonsei University's Department of Social Welfare published the results of a study analyzing the correlation between adolescents' physical activity, smartphone use, loneliness, etc. in the international journal 'Child and Adolescent Social Work Journal'. The World Health Organization (WHO) recommends an average of at least one hour of physical activity per day to promote adolescents' health and prevent diseases. The results of the study showed that adolescents who engaged in physical activity for less than 1 hour a day were 1.3 times more likely to belong to the group that felt lonely than adolescents who engaged in physical activity for more than 1 hour, and the probability of belonging to the opposite group was low. Additionally, it was confirmed that the more physical activity one did, the more effective it was at alleviating loneliness even if one had experienced emotional abuse.