Maintain your original lifestyle without engaging in regular physical exercise. Participants were contacted every two weeks via WeChat or in person to monitor their conditions and ensure no extra exercise or medication use.

The Tai Chi group practiced 24-form simplified Tai Chi for 12 weeks, 3 times/week, 60 minutes/session (including 5-minute warm-up and 5-minute cool-down) at our university's track, under professional coaching, from 8:00-9:10 AM. The first 4 weeks were for learning, and the next 8 for consolidation. Then, we will observe all participants for an additional 4 weeks (Week 16) as a follow-up.

The Tai chi group practiced 24-form simplified Tai Chi for 12 weeks, 3 times/week, 60 minutes/session (including 5-minute warm-up and 5-minute cool-down) at our university's track, under professional coaching, from 8:00-9:10 AM. The first 4 weeks were for learning, and the next 8 for consolidation.

The CIAS, tailored to Chinese college students' psychological traits, was used. It has 26 items across five dimensions: compulsive symptoms, withdrawal symptoms, tolerance symptoms, interpersonal and health problems, and time management problems. It's a 4-point self-report Likert scale (1="extremely disagree" to 4="extremely agree"). The scale has good reliability and validity, with factor consistency coefficients of 0.70-0.82 and internal consistency of 0.9446[21]. The total CIAS score is the sum of all items, with higher scores indicating greater dependence and addiction risk. The CIAS was administered at baseline, week 12, and week 16 for both groups.

At baseline, week 12, and week 16, 2 ml of fasting venous blood was collected from participants between 7:00-8:00 AM. Serum dopamine levels was measured using radioimmunoassay on a Beckman DXC800 autoanalyzer, with reagents from IBL (Germany). All steps followed the kit instructions, and absorbance was measured at 450 nm to calculate concentrations.