Feasibility and Effects of High-Intensity Interval Training in Older Adults with Mild to Moderate Depressive Symptoms: A Pilot Cluster-Randomized Controlled Trial

Abstract Background and aims: Older adults with mild-to-moderate depressive symptoms (MMDS) are at high risk to develop severe depression along with mortality and disability. The aim of this study was to investigate the feasibility and effects of high intensity interval training (HIIT) in older adults with MMDS. Methods Three elderly centers involving 24 older adults with MMDS were randomized into: 1) HIIT (n = 8); 2) moderate-intensity continuous training (Baduanjin Qigong) (MICT-BDJ) (n = 8); or 3) recreation workshop (RW) control (n = 8) for a 16-week (32 session) intervention. Feasibility was assessed using retention rate, session attendance rate, exercise intensity adherence, acceptability, and safety. Self-reported depressive symptoms and objectively measured physical fitness (PF) were assessed at baseline and post-intervention. Results 20 participants completed data collection twice. The retention rate was 87.5% (7/8), 87.5% (7/8), 75% (6/8) for HIIT, MICT-BDJ, and RW, respectively. 87.5% (7/8) of HIIT participants completed at least 75% of exercise sessions. 81.4% of HIIT participants achieved the pre-designed intensity (≥ 80% maximum heart rate) during the high-intensity intervals. All HIIT (7/7) participants were satisfied with their group allocation. More HIIT (6/7) than MICT-BDJ (5/7) participants found the exercise enjoyable. Two mild adverse events were reported in the HIIT group. HIIT improved depressive symptoms more than MICT-BDJ (d = -1.02) and RW (d = -1.32). Both HIIT (d = 1.26) and MICT-BDJ (d = 1.39) improved PF more than RW. Conclusion HIIT was feasible and effective in improving the depressive symptoms and PF for older adults with MMD. Trial registration: This study was registered on the ClinicalTrials Registry (NCT06014294).