European Journal of Cardiovascular Medicine

Autonomic function is a cornerstone of human physiology, governing the body's ability to maintain internal balance through its sympathetic and parasympathetic branches. This delicate interplay regulates cardiovascular, respiratory, and metabolic processes, ensuring survival in a dynamic environment. However, the increasing prevalence of stress, sedentary lifestyles, and unhealthy habits has led to widespread autonomic dysregulation, which is implicated in the pathogenesis of cardiovascular diseases, metabolic syndrome, and mental health disorders1,2. As modern medicine seeks holistic approaches to mitigate these issues, yoga and, specifically, yogic breathing practices have emerged as promising non-pharmacological interventions. Yogic breathing, or pranayama, involves consciously regulating the respiratory rhythm to influence autonomic function. Scientific evidence highlights its ability to enhance parasympathetic activity, reduce sympathetic overdrive, and restore autonomic balance3. Techniques such as alternate nostril breathing (Nadi Shuddhi), diaphragmatic breathing (Kapalabhati), and slow rhythmic breathing have demonstrated significant reductions in resting heart rate and blood pressure, coupled with improvements in heart rate variability, a marker of autonomic health4,5. Moreover, regular practice of pranayama has been linked to better stress resilience, attributed to its effects on the hypothalamic-pituitary-adrenal (HPA) axis and neuroplasticity in brain regions like the prefrontal cortex and insula6,7. The neurophysiological mechanisms underlying these benefits are a subject of active research. It is hypothesized that pranayama enhances Vagal tone through slow, deliberate breathing patterns, which increase baroreflex sensitivity and promote efficient gas exchange. Furthermore, these practices may downregulate the amygdala’s activity, reducing the physiological markers of stress and anxiety8. The integration of yogic breathing into daily routines not only offers physiological advantages but also fosters mental well-being, emphasizing its potential in holistic healthcare approaches9.

Despite the growing body of evidence, there is a lack of rigorous studies examining the effects of short-term yogic breathing interventions on autonomic function in young adults. Most existing research either focuses on long-term practice or combines yoga with other modalities, making it challenging to isolate the impact of pranayama. This study addresses this gap by investigating the effect of a structured, five-week yogic breathing intervention on autonomic function in healthy young adults. By employing comprehensive autonomic reactivity tests, this research aims to elucidate the physiological changes induced by pranayama and contribute valuable insights to the field of integrative medicine.

Ethical Statement

The study was conducted after obtaining approval from the Institutional Ethics Committee of NIMS University, Jaipur. Written informed consent was obtained from all participants before enrollment, ensuring adherence to ethical principles for research involving human subjects.

Participants

This randomized controlled study involved 37 participants aged 18 to 34 years, recruited from NIMS University. Inclusion criteria required participants of all genders who were willing to engage in a structured yogic breathing program for five weeks. Exclusion criteria included a history of cardiovascular, respiratory, or chronic systemic diseases; regular yoga practice (defined as practicing more than once a week); current engagement in structured stress-reduction programs; pregnancy or planning to conceive during the study; physical impairments or musculoskeletal disorders; and the use of medications affecting autonomic, cardiovascular, or respiratory functions.

Procedure

The study was conducted over 18 months in the Department of Physiology, NIMS Medical College. Participants were assessed both before and after a five-week yogic breathing intervention. The pre-intervention assessment involved baseline autonomic function tests, conducted in a quiet, temperature-controlled laboratory under standardized conditions. Resting parameters, including resting heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP), were measured. Parasympathetic reactivity was evaluated using the expiration-inspiration (E:I) ratio and the 30:15 ratio, which reflects R-R interval variability during positional changes. Sympathetic reactivity was assessed through SBP and DBP responses to standing. Participants were instructed to fast for two hours before testing and to abstain from physical exertion, caffeine, and nicotine for 24 hours to ensure the accuracy of results.

Yogic Breathing Intervention

Participants engaged in a structured yogic breathing program for five weeks, with daily 15-minute sessions supervised by a trained yoga instructor. Practices included Nadi Shuddhi, Kapalabhati, Bhastrika, Sheetali, and OM chanting, conducted in a noise-free environment. The duration of each practice is summarized in Table 1.

Table 1. Types of Yogic Breathing Practices and Duration

Post-Intervention Assessment
After five weeks, the same autonomic function tests was repeated under identical conditions to evaluate the effects of the intervention.

Data Analysis

The data collected were analyzed using paired t-tests to compare pre- and post-intervention values for autonomic function parameters. Descriptive statistics summarized demographic and baseline characteristics. Statistical significance was set at a p-value < 0.05. Graphical and tabular representations were used to illustrate findings.

A total of 37 participants underwent autonomic function testing before and after yogic breathing techniques. The results demonstrated significant improvements in key parameters, indicating enhanced autonomic regulation and cardiovascular adaptability as shown in Table 2 and bar diagram 1.

Table 2.  Comparison of Autonomic Function Test Parameters Before and After Yogic breathing

Bar diagram 1: Comparison of Autonomic Function Test Parameters before and after the different Yogic Breathing techniques.

Resting heart rate decreased from 89.27 bpm to 82.68 bpm (p = 0.0118), SBP response to hand grip dynamometer reduced from 122.35 mmHg to 118.11 mmHg (p = 0.002), and SBP response to standing decreased from 116.59 mmHg to 109.97 mmHg (p = 0.016). Other parameters, such as resting SBP, DBP, and E:I ratio, showed minor, non-significant changes.

Yogic breathing techniques, also known as pranayama, have long been an integral part of traditional Indian practices, known for their potential to improve mental clarity and physical health. The physiological effects of these techniques are increasingly being studied in the context of stress reduction, autonomic function regulation, and cardiovascular health. The present study aimed to assess the effects of a 4-week intervention of yogic breathing on autonomic function parameters in healthy individuals, focusing on heart rate, blood pressure responses, and respiratory ratios. This investigation is significant, as it seeks to provide scientific evidence for the potential use of yogic breathing as a non-pharmacological tool to manage stress and enhance cardiovascular function, which is particularly relevant given the rise in lifestyle-related diseases and stress-induced health conditions.

Our findings reveal several important results that align with previous studies, while also contributing new insights into the benefits of yogic breathing. The significant reduction in resting heart rate (p = 0.0118) is consistent with previous research indicating that regular practice of pranayama can enhance parasympathetic tone and reduce sympathetic dominance (Pal et al., 2004; Telles et al., 2013)10,11. In our study, the mean resting heart rate decreased from 89.27 bpm to 82.68 bpm, suggesting that even a 4-week intervention can lead to noticeable improvements in autonomic regulation. This is in line with findings by Telles et al. (2013)11, who demonstrated that practicing pranayama for a duration of 6 weeks resulted in significant reductions in heart rate, further supporting the idea that yogic breathing enhances Vagal activity. Furthermore, our study showed significant changes in SBP response to hand grip dynamometer (HGD) and standing. SBP during HGD decreased from 122.35 mmHg to 118.11 mmHg (p = 0.002), and SBP response to standing decreased from 116.59 mmHg to 109.97 mmHg (p = 0.016), indicating improved cardiovascular adaptability. These findings are supported by studies from Kosinski et al. (2009)12 and Vempati et al. (2009)13, who observed similar reductions in blood pressure responses to stress after practicing yogic breathing for several weeks. The improvement in cardiovascular responses, particularly to stress-induced stimuli, suggests that yogic breathing could be a powerful tool for mitigating the effects of acute stress on the cardiovascular system, as supported by Sharma et al. (2013)14, who reported significant reductions in both systolic and diastolic blood pressure after 8 weeks of yoga practice. The mechanisms by which yogic breathing exerts these effects can be understood through the modulation of the autonomic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. Studies suggest that controlled breathing techniques can enhance parasympathetic activity and reduce sympathetic dominance by stimulating the Vagus nerve and modulating baroreceptor sensitivity (Mohan et al., 2011; Brown & Gerbarg, 2005)15,16. Yogic breathing practices, particularly those involving slow, deep, and rhythmic breathing patterns, activate the vagal pathways, which in turn reduce heart rate and blood pressure (Pal et al., 2004). Moreover, pranayama has been shown to lower cortisol levels, a hormone associated with stress, which further helps in reducing the physiological impacts of stress (Brown & Gerbarg, 2005; Varambally et al., 2012)16,17. Additionally, regular practice of pranayama can improve baroreceptor sensitivity, leading to better regulation of blood pressure, particularly in response to postural changes and stress (Telles et al., 2013; Sharma et al., 2013)11,14. These physiological changes are likely responsible for the significant improvements observed in the current study.

However, not all parameters showed significant changes. For instance, while the resting SBP decreased from 117.78 mmHg to 114.78 mmHg, and DBP from 82.38 mmHg to 81.84 mmHg, these changes were not statistically significant (p = 0.129 and p = 0.781, respectively). Similarly, the E:I ratio showed no significant difference, with values remaining nearly identical before and after the intervention. This could be attributed to the short duration of the intervention (4 weeks), as longer-term studies have often observed more pronounced changes (Kosinski et al., 2009; Vempati et al., 2009)12,13. Additionally, individual variability in autonomic function and the presence of other confounding factors, such as lifestyle and diet, may have influenced these results.

The outcomes of this study suggest that a 4-week yogic breathing intervention can significantly improve autonomic function, particularly in heart rate modulation and cardiovascular responses to stress. These findings reinforce the potential of yogic breathing as an accessible, non-invasive, and effective tool for promoting cardiovascular health and managing stress. Future studies with longer interventions, larger sample sizes, and more diverse populations are needed to further explore the sustained benefits and underlying mechanisms of yogic breathing practices.

A 4-week yogic breathing intervention significantly improves autonomic function, particularly by reducing resting heart rate and enhancing systolic blood pressure responses to stress. These findings suggest that yogic breathing can be an effective, non-invasive tool for managing stress and promoting cardiovascular health. Further research with longer interventions and larger samples is needed to confirm and expand upon these results.

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