Physical activity trajectories of different grade levels of male adolescents in association of academic performance and mental health.

Regularly performed daily moderate to vigorous physical activity (PA) is recommended to promote physical and mental health in adolescents. However, sedentary behavior has been reported with ever-increasing demand for competition without clear understanding of the relationship between PA and mental health and academic performance. Therefore, this study observed the changes in the amount PA in 6 grade levels in relation to mental health and academic performance. This study analyzed the amount of moderate and vigorous PA, sedentary time, mental health, and academic performance in male adolescents of 6 middle to high school grade levels by sedentary group (SG: 2 or less min/wk) and physical activity group (PG: 3 or more min/wk) groups depending on the days of weekly PA. The most weekly moderate and vigorous PA duration significant reduced by 29.4% (*P<0.01) and -43.8% (*P<0.01) for H2 in comparison to M1 in SG. The greatest increase in sitting duration 744.95±470.27 min/wk (*P<0.01) was shown by SG. Significant increase in loneliness degree was shown throughout the grade levels of M3 to H3 (2.41±1.08 to 2.50±1.06, *P<0.01) in SG. Degree of stress also significantly increased from M3 to H3 (2.69±0.98, *P<0.01 to 2.90±0.96, *P<0.01) in SG. Finally, perceived academic performance by the days of PA did not show clear difference between SG and PG. In conclusion, regularly performed PA male adolescents showed greater duration of moderate and vigorous PA without negatively influencing mental health and academic performance. Moreover, well controlled academic performance and sitting duration were shown.