Abstract
BACKGROUND: The internet is highly convenient and has become an indispensable part of daily life. However, its widespread use also has notable disadvantages, such as the risk of internet addiction. Still, increased internet use may enhance eHealth literacy, and online health information seeking may contribute to health promotion. In Hong Kong, internet addiction and low physical activity among adolescents are growing concerns, underscoring the need to address internet use to better support the health and well-being of youth. OBJECTIVE: This study aimed to investigate the effects of internet use, eHealth literacy, and internet addiction on adolescents' physical activity in Hong Kong. METHODS: An online cross-sectional study was conducted in Hong Kong between June 2023 and August 2023. Secondary school students aged 12 to 18 years were recruited. Data were collected using the eHealth Literacy Scale, the International Physical Activity Questionnaire, the Chen Internet Addiction Scale, and a questionnaire assessing demographic characteristics and the use of eHealth technologies. Spearman ρ correlation and mediation analyses were performed to examine the relationships among variables. RESULTS: A total of 117 participants were included. Participants reported an average internet use of 5.28 (SD 3.50) hours per day, and the mean eHealth literacy score was 31.15 (SD 4.04). Correlation analyses revealed that internet use was positively correlated with internet addiction (r=0.33; P<.001) but negatively correlated with physical activity (r=-0.21; P=.02), and internet addiction was negatively correlated with physical activity (r=-0.26; P=.005). In addition, the mediation analysis demonstrated that both internet use and eHealth literacy had a direct effect on internet addiction (B=1.53, P<.001 and B=-0.91, P=.002, respectively). Internet addiction had a direct effect on physical activity (B=-43.94, P=.02). In contrast, eHealth literacy had no significant direct effect on physical activity and did not mediate the relationship between internet use and physical activity. CONCLUSIONS: The findings highlight the importance of eHealth literacy in reducing internet addiction. However, future research should further examine factors that mediate the relationship between eHealth literacy and physical activity or other health-related behaviors. This study sheds light on the benefits of promoting eHealth literacy among adolescents to prevent internet addiction and offers practical insights for teachers and parents.