Aerobic running at different intensities produces distinct temporal patterns of improvement in depression, anxiety, and stress among adolescents with problematic internet use

Objective: To examine the effects of low-, moderate-, and high-intensity aerobic running on depression, anxiety, and stress among adolescents with problematic internet use (PIU). Methods: = 30 per group). The intervention lasted 12 weeks. Exercise intensity was defined according to percentages of maximal heart rate (HRmax): low intensity, 40-49% HRmax; moderate intensity, 50-59% HRmax; and high intensity, 60-69% HRmax. Depression, anxiety, and stress were assessed at pretest, midtest, and posttest using the Depression Anxiety Stress Scales-21 (DASS-21). Repeated-measures mixed-effects models were fitted for each outcome, followed by Bonferroni-adjusted simple-effects analyses. Results: Significant main effects of group and time, as well as significant group × time interactions, were observed for depression, anxiety, and stress. Compared with the control group, all three exercise conditions showed lower depression, anxiety, and stress scores at posttest. No statistically significant posttest differences were found among the three intervention groups. However, the temporal patterns of improvement differed across exercise intensities. Moderate-intensity running showed a more continuous pattern of change across the intervention period, high-intensity running showed earlier improvement, particularly at midtest, and low-intensity running also produced significant benefits, although its effects emerged later. Conclusion: Aerobic running can reduce depression, anxiety, and stress among adolescents with PIU. The findings suggest that intensity-related differences are better understood in terms of timing and trajectory of emotional change rather than endpoint superiority across exercise conditions. These findings provide intensity-specific evidence to inform more targeted exercise prescriptions for adolescents with PIU.