Objective: Physical activity and training are associated with positive effects on heart rate variability (HRV). This study investigated how exercise therapy in hospitalized patients with major depressive disorder affects HRV.
Methods: 15 patients (8 male, 7 female; age 52.5 ± 8.7 years, weight 76.7 ± 15.6 kg, height 173.4 ± 12.2 cm, body mass index-BMI 25.4 ± 3.5 kg/m²) completed an electrocardiography (ECG) at rest and an incremental cycle ergometry test, to detect the HRV at the beginning and at the end of their hospital stay. Patients were divided into control group (CG) obtaining standard therapy, and experimental group (EG) with additional exercise therapy sessions 4 times a week.
Results: The overall group showed a significant reduction in the Beck Depression Inventory (BDI) score of 25.8 ± 8.1 to 11.3 ± 8.3. There was a significant reduction in the BDI of the EG from 26 ± 5.4 to 12.3 ± 8.7, but insignificant in the CG (from 24.7 ± 10.2 to 9 ± 8.2). The root mean square of successive differences (RMSSD) demonstrated resting values in the pre-test of 12.9 ± 8.2 ms (CG) and 24.4 ± 19.3 ms (EG) and in the post-test of 15.4 ± 2.9 ms (CG) and 16.0 ± 7.1 ms (EG). The HRV data of the cycle ergometry showed no significant differences between the groups. However, significant changes were shown in the pre to post comparison of the SD2 parameters of the time domain analysis. A significant increase was observed in the pre to post comparison in the experimental group at an intensity of 80% and a significant decrease in the control group at an intensity of 100%. In the frequency domain, a significant reduction in low frequency/high frequency (LF/HF) power (%) was found in the control group.
Conclusions: Depression patients present a reduced HRV when admitted to an acute care clinic. The regulation of HRV during physical work is very different from normal physiological behaviour. Exercise therapy interventions can induce a tendency of improved sympathovagal balance. The results should be verified in a similar setting in a larger cohort of patients.
Key words: Antidepressants, bipolar disorder, clinical psychiatry, exercise therapy