Real-time feedback-based personalized moderate-intensity aerobic brisk walking intervention using wrist-worn...

To evaluate the effectiveness of personalized moderate-intensity aerobic brisk walking intervention based on real-time feedback from wrist-worn photoplethysmography (PPG) in improving mild-to-moderate depressive symptoms. Using an N-of-1 randomized crossover trial design, 33 patients with mild-to-moderate depression (PHQ-9 scores 10-19) completed a 6-week trial consisting of three personalized PPG feedback periods (Period A) and three standardized exercise prescription periods (Period B), each lasting 7 days with 2-day washout periods between phases. The personalized group dynamically adjusted exercise intensity based on real-time heart rate variability (HRV) monitoring (40-59% heart rate reserve), while the standardized group adopted fixed intensity parameters (walking speed 5-6 km/h). The primary outcome was change in PHQ-9 depression scale score, with secondary outcomes including heart rate variability, 6-minute walking distance, serum BDNF, and inflammatory cytokine levels. Compared to standardized prescription, personalized intervention additionally reduced PHQ-9 scores by 2.8 points (95% CI: 1.9-3.7, P < 0.001) with an effect size of 0.73; HRV RMSSD increased by 8.7 ms versus 4.3 ms (P < 0.001), and HRV improvement predicted subsequent symptom relief (β = -0.42); exercise adherence rate in the personalized group was 87.3% compared to 82.1% in the standardized group (P = 0.029); BDNF increased by 28.4% versus 18.7% (P = 0.018); participants with baseline HRV < 25 ms derived greater benefit from personalized intervention (additional improvement of 3.8 points versus 2.1 points, P = 0.008). Both intervention conditions produced clinically meaningful within-group PHQ-9 improvements, though the between-group difference of 2.8 points did not reach the minimal clinically important difference (MCID) threshold of 5 points. Both personalized and standardized moderate-intensity walking interventions substantially improved mild-to-moderate depressive symptoms. Personalized exercise intervention based on real-time PPG monitoring provided statistically significant additional benefits over standardized prescriptions, with advantages in physiological adaptation, exercise adherence, and biomarker improvement. The incremental benefit of personalized monitoring was most pronounced among individuals with impaired autonomic function, providing evidence for precision exercise medicine approaches in depression management.