An Examination of Longitudinal Changes in Korean Middle School Students’ Psychological Health According to Their Body Mass Index and Weekly Exercise Hours

Background : It is necessary for adolescents to maintain proper body mass index (BMI) and regular exercise for proper growth, development, and psychological health. Existing studies have demonstrated the significant positive effect of regular physical activity or exercise on preventing socio-psychological problems and cognitive body image issues in adolescents. This study aimed to investigate the longitudinal changes in psychological health factors of mental health, self-concept, self-esteem, and self-efficacy according to BMI and weekly exercise hours among Korean middle school students. Methods : Cohort data were obtained from the Gyeonggi Institute of Education for three years (2015–2017), and a total of 16,027 data points were analyzed. We performed a repeated-measures analysis of variance (3 grades × 4 body mass index groups × 5 weekly exercise hours groups) using SPSS software (version 21.0, IBM Corp., Armonk, NY, USA) for data analysis. Results : The results obtained through the analysis are as follows. As school grades rose among Korean middle school students, psychological health factors such as mental health, self-concept, self-esteem, and self-efficacy decreased. And the deterioration of psychological health factors showed lower positive results for normal and underweight students than for over-weight and obese students. Students with a lot of exercise time every week showed a lower decrease in psychological health factors. Conclusions : The results suggest that education for health promotion, considering body mass index and daytime exercise, is necessary to prevent the deterioration of psychological health factors in Korean middle school students.