Acute effects of Rajyoga meditation on heart rate variability in older trained practitioners and younger novices: A quasi-experimental repeated measures study

Objectives: Engaging in meditation contributes to both mental and physical well-being. This quasi-experimental repeated measures Study aimed to investigate the impact of Rajyoga meditation (RM) on acute, reproducible changes in heart rate variability (HRV) markers, reflecting enhanced parasympathetic activity in trained and untrained individuals. Materials and Methods: This study included 45 participants, comprising 21 healthy trained meditators (10 females/11 males) and 24 healthy untrained individuals (5 females/19 males). The trained group ( n = 21), who practiced RM daily for at least 1 year (30–60 min/session, 7 days/week, with ≥90% adherence), was recruited from the Brahma Kumaris Meditation Centre in Durgapur, India, and the untrained group ( n = 24, no prior meditation experience), the electrocardiogram (ECG) was recorded for 30 min in 3 phases, 10 min before, 10 min during and 10 min after meditation for both the trained and untrained participants. Relative risk (RR) intervals were extracted from the ECG for the analysis of HRV. The Bonferroni test was employed as a post hoc analysis following a non-parametric Friedman test to assess statistical differences among the phases. Results: During meditation, a significant increase in HRV parameters, including the standard deviation of RR intervals (SDNN), low-frequency component, total power and long-term variability (SD 2 ) was observed compared to pre- and post-meditation phases in both trained and untrained individuals (Friedman test with Bonferroni correction, P < 0.01). Post hoc analysis confirmed that for these parameters, values during meditation were significantly higher than both pre- and post-meditation values ( P < 0.01), while no significant difference was found between pre- and post-meditation phases ( P > 0.01), indicating a reversible effect. Conversely, a significant decrease in the inverse average length of acceleration/deceleration segments and the percentage of short segments was observed during meditation compared to before and after meditation in both groups ( P < 0.01), with values returning to baseline post-meditation. The secondary analysis, using Quade’s nonparametric analysis of covariance to control for the significant age difference between the trained and untrained groups, using age as a covariate, revealed that the magnitude of change (Δ) in HRV from pre- to during-meditation was significantly greater in the trained group across nearly all key HRV parameters. Most notably, trained practitioners exhibited a 154.6% greater increase in root mean square of successive differences (Trained: Δ = 10.57 ± 4.36 ms; Untrained: Δ = 4.15 ± 1.84 ms; P < 0.001) and a 54.7% greater increase in SDNN (Trained: Δ = 14.24 ± 2.70 ms; Untrained: Δ = 9.20 ± 2.55 ms; P < 0.001), indicating a significantly enhanced parasympathetic and overall autonomic response to meditation. This pattern of greater responsiveness among trained participants was consistent across the majority of parameters, including SD1 (154.5% greater increase) and SD2 (43.6% greater increase). Conclusion: These results suggest that RM promotes a shift in sympathovagal balance towards parasympathetic dominance, highlighting its potential benefits for autonomic regulation.