Author(s): LIU, H., KIM, S.H., Institution: KOREA UNIVERSITY, Country: KOREA, SOUTH, Abstract-ID: 677

INTRODUCTION:
Anxiety is common in adults and often co-occurs with depressive symptoms and poor sleep. It may relate to HPA-axis dysregulation reflected in the cortisol awakening response (CAR). Exercise is a safe, low-cost option, but many adults struggle to fit continuous aerobic sessions into their schedules. Accumulated aerobic exercise delivered in short bouts may lower this barrier, yet short-term evidence—especially for CAR—is limited. We conducted a 4-week pilot RCT to assess feasibility, adherence, and acceptability, and to estimate preliminary effects on anxiety, depression, sleep, and CAR.
METHODS:
Adults aged 18–44 with mild-to-moderate anxiety (GAD-7 5–14) were recruited online. After e-consent, 20 participants were randomized 1:1 to accumulated aerobic running (EX, n=10) or control (CON, n=10; usual activity). The 4-week program was 3 days/week: 3×10-min bouts/day (≥2 h apart) at Borg CR10 RPE 3–4, logged via a smartphone app with researcher feedback. Primary outcome was GAD-7; secondary outcomes were PHQ-9, PSQI, and CAR. CAR was assessed at baseline and post-intervention (saliva at awakening, +30, +45, +60 min); awakening cortisol (C0), AUCg, and AUCi were calculated. Feasibility included recruitment/retention, adherence (≥10/12 exercise days), assessment completion, and adverse events; acceptability used a 4-item Likert scale. Effects were analyzed using Bayesian linear mixed-effects models (group×time), reporting posterior mean differences (95% CrI).
RESULTS:
Twenty participants were randomized (EX=10; CON=10). Follow-up completion was 95% (19/20); one EX participant withdrew for a non-study-related health reason, and no adverse events occurred. Adherence among EX completers was 100% (≥10/12 exercise days). Acceptability was high (accumulated exercise: 8.22±1.39/10; remote supervision: 8.78±0.97/10). Compared with CON, EX showed greater reductions in GAD-7 and PSQI (GAD-7: −0.68, 95% CrI −1.13 to −0.20; PSQI: −0.51, 95% CrI −0.96 to −0.06). The between-group effect for PHQ-9 was directionally favorable but uncertain (−0.59, 95% CrI −1.28 to 0.10). CAR indices showed small directional shifts, but between-group effects were uncertain with all 95% CrIs including 0 (C0: −0.14, −1.38 to 1.07; AUCg: 0.25, −1.03 to 1.52; AUCi: 0.26, −1.19 to 1.63). Across 0–60 min post-awakening, cortisol increased to ~45 min on average and group profiles largely overlapped (wide CrIs).
CONCLUSION:
Remotely supervised accumulated aerobic running appears feasible, safe, and acceptable, with preliminary improvements in anxiety and sleep. Effects on depression and CAR were uncertain (95% CrIs crossed 0); a larger RCT is needed to confirm effects and examine mechanisms.