Immediate effect of Kaki Mudra on pupillary light reflex among healthy individuals – A study protocol of a Randomized control trial

Velan Arumugam; Arthi Balakrishnan; Gayathri Annamalai; Sankaralingam Thirupathy Venkateswaran; Maheshkumar Kuppusamy

doi:10.1515/ohe-2023-0032

Article Open Access

Immediate effect of Kaki Mudra on pupillary light reflex among healthy individuals – A study protocol of a Randomized control trial

Velan Arumugam , Arthi Balakrishnan , Gayathri Annamalai , Sankaralingam Thirupathy Venkateswaran and Maheshkumar Kuppusamy

Published/Copyright: June 11, 2024

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From the journal Open Health Volume 5 Issue 1

Abstract

Background

Kaki Mudra is a yogic gesture that involves nasikagara drishti focusing on the nose tip without the eyes blinking and pursing the lips, which form beaks during inhalation, and exhaling slowly through the nose. However, there is a lack of evidence on the impact of kaki mudra on cardiovascular changes and autonomic function using pupillary light reflex (PLR).

Methods

A randomized control study design will be adopted for this study with 80 healthy participants with more than 18 years of age, will be recruited. Subjects will be randomly divided into the study (n = 40) and control groups (n = 40). The study group will be advised to practice Kaki Mudra for 20 min, whereas the control group will be asked to relax in sitting posture for 20 min.

Results

The baseline and post-assessment will be immediately evaluated for all the individuals; five leads to ECG for heart rate variability (HRV) and dynamic pupillometry for PLR.

Discussion

The immediate effect of kaki mudra is an effective and simple technique that might improve HRV and PLR variable, which may improve overall health and enhance parasympathetic dominance among healthy participants. The study is prospectively registered in the Clinical Trial Registry of India (CTRI/2024/05/067289).

Keywords: Kaki Mudra; pupillary light reflex; clinical trials; yoga; dynamic pupillometry; heart rate variability; autonomic nervous system

1 Background

Mudras, encompassing hand, body, or eye positions, have long been integral to various spiritual and meditative practices, particularly in the realm of yoga. These intricate gestures are designed to channel energy flows within the body, influencing specific states of consciousness and mental well-being [1]. Widely employed during meditation and pranayama, mudras play a role in directing energy flow and symbolizing a range of emotions and feelings [2].

In the context of yoga philosophy, mudras extend beyond mere symbolic gestures, actively stimulating designated brain regions by applying gentle pressure to specific areas of the hand [3]. Previous studies have indicated the potential health benefits associated with practicing yoga hand mudras. For instance, specific mudras have been linked to significant reductions in both systolic and diastolic blood pressure [4]. Additionally, lifestyle education programs incorporating mudras have demonstrated positive effects on risk factors for cardiovascular disease and diabetes mellitus, showcasing metabolic benefits and reductions in blood pressure, heart rate, and stress [5].

One such mudra, Kaki Mudra, involves the concentration of gaze on the nosetip without blinking, coupled with pursing of the lips during inhalation and exhalation. While this mudra is believed to enhance concentration, focus, and induce a sense of calmness and grounding, there is a dearth of scientific evidence regarding its specific health benefits.

It is essential to acknowledge that Kaki Mudra is often integrated into broader lifestyle modifications and practices such as yoga and meditation, both of which have demonstrated positive impacts on blood pressure and overall health. Given this context, this study protocol aims to investigate the immediate effects of Kaki Mudra intervention on heart rate variability (HRV) and pupillary changes in healthy individuals, contributing to a deeper understanding of the potential physiological benefits associated with this specific mudra.

2 Methodology

2.1 Study design and study settings

The study is a randomized, controlled trial aimed at assessing the immediate effect of Kaki Mudra on pupillary light reflex (PLR) among healthy individuals (Figure 1, Trial profile). This study will be conducted at Chengalpattu’s International Institute of Yoga & Naturopathy Medical Sciences (IIYNMS). The study has been approved by the institutional ethics committee (IEC-IIYNMS/Approval/051/2023), and it is prospectively registered in the Clinical Trial Registry of India (CTRI/2024/05/067289).

Figure 1

Trial profile of the study.

2.2 Sample size

The sample size was calculated using online open epi software as 80 (Kaki mudra = 40; Control = 40). The effect size taken was 0.60 from previous studies and fixing α = 0.05 and a 1:1 allocation; a total sample of 80 participants is estimated [6].

2.3 Recruitment

A total of 80 healthy individuals between the ages of 18–35 will be enrolled in the study after screening for eligibility criteria. Informed consent will be obtained from each participant prior to their inclusion in the study.

2.4 Eligibility and screening

Participants will be screened for psychiatric illness, systemic illness, surgical history, refractive error, medication, or allergies that may interfere with the study protocol. The screening process will ensure that only eligible and suitable participants are included in the study, maintaining the integrity and validity of the research findings.

2.5 Randomization and blinding

All selected participants will be randomly allocated to either an intervention (n = 40) or a control group (n = 40) with a ratio of 1:1. Computer randomization will be done using software version 1. Allocation concealment will be carried out using the sequentially numbered opaque sealed envelope method, maintained by a person who is not directly involved in the project, and handed over the sealed opaque envelopes to the participants. The selected list will remain private and unblinded for withdrawal or any adverse events.

2.6 Preparation and procedure

Subjects will be advised to sit in a comfortable asana with a straight head and spine, and hands resting on knees. The practice involves closing the eyes and relaxing the body, performing nasikagra drishti (nose tip gazing), and pursing the lips to deeply inhale and exhale air through nose. The tongue should be relaxed, and the practice should be repeated five times. The Kaki Mudra is done at a frequency of 6 breaths/min, followed by a 2-min rest. The process should be repeated for 20 min [7]. The subjects in the control group will be advised to concentrate on their breathing in a sitting (sukasana) position for 20 min.

3 Outcome parameters

3.1 Primary outcome variables

Dynamic pupillometry will be used to monitor the quantitative assessment of PLR, which will be categorized into parameters such as reflex latency, minimum pupil diameter, baseline pupil diameter, maximum constriction velocity, maximum redilation velocity, absolute constriction amplitude, absolute dilation amplitude, and duration of constriction [8,9,10,11].

3.2 Secondary outcome variables

The HRV test will be conducted in the morning after an hour of light breakfast. Subjects are allowed to urinate before starting the recording. After 5 min of rest in a supine position on a couch, to be taken with the AD converter [12]. This study used a linear model to analyze HRV in the time and frequency domains.

3.3 Pupillometry assessment

A PC-based infra-red pupillometer was developed using a web camera and virtual reality box to assess sympathetic and parasympathetic activity based on pupillary responses [13]. The system uses infrared light, LEDs, and a microcontroller for continuous illumination, analyzing images to measure pupil dimensions, detect margins, and eliminate LED reflections. It also analyzes pupil outlines to accurately determine pupil size [8]. The reactivity of the pupil can be used to assess autonomic nervous system function. Dynamic pupillometry shows various parameters such as Reflex Latency, Minimum Pupil Diameter, Baseline Pupil Diameter, Maximum Constriction Velocity, Maximum Redilation Velocity, Absolute Constriction Amplitude, Absolute Dilation Amplitude, Duration of Constriction, and Duration of Dilation. Measurements will be taken in full darkness, requiring less than 30 s for each eye, and averaged data were recorded. All measurements will be performed in complete darkness, just before the CA assessment, and averaged values from both eyes of the individual patient [14].

3.4 Statistical analyses

Statistical analyses will be conducted to determine the significance of the data collected before and after the intervention. Descriptive statistics such as means and standard deviations will be calculated for each variable measured by the pupillometer and HRV. Additionally, inferential statistics such as t-tests will be performed to compare the PLR measurements between intervention and control groups. The level of significance will be set at p ≤ 0.05. Any outliers or missing data points will be carefully addressed and handled accordingly.

4 Discussion

Cardiac autonomic function is most commonly assessed by using HRV. Previous research indicates that individuals with lower HRV are at higher risk of future cardiovascular diseases and are also more likely to experience increased morbidity and mortality [15,16]. Debate surrounds the accuracy of HRV due to conflicting indicators like high and low frequency parameters [17]. The LF/HF ratio in HRV denotes sympathetic or parasympathetic dominance, but interpretation challenges persist [18]. Recognizing the complexity, PLR gains importance as a potential alternative to HRV in assessing autonomic nervous system dynamics [19].

While yoga asanas and pranayama techniques have been widely studied for their benefits on cardiac autonomic function [20,21,22], the specific impact of mudras on this aspect of the nervous system is still being explored [23]. Mudras are believed to work by stimulating specific energy channels in the body, known as nadis, and redirecting the flow of prana, or life force energy [24]. This subtle manipulation of energy is thought to have a profound effect on the autonomic nervous system, which regulates involuntary bodily functions such as heart rate, blood pressure, digestion, and breathing [25]. Earlier studies suggested that mudras have been found to connect the nervous system, stimulate energy pathways, and increase blood circulation, thereby managing stress, depression, and anxiety and improving mental health [26,27]. Based on this research, the present study aimed to explore the immediate effects of kaki mudra, on PLR and HRV. The findings of this study will contribute to the growing body of evidence supporting the positive impact of mudra practices on both physical and mental health, emphasizing the potential of simple techniques to promote overall well-being.

The limitation of this study is the short duration of the study may not capture the long-term effects of kaki mudra on PLR and HRV. Future research with larger sample sizes and longer durations could provide more evidence of the benefits of kaki mudra practices on health outcomes.

5 Conclusion

The observations of this study ascertain the improvement in PLR and HRV variables among healthy individuals. This study will also explore high-quality clinical evidence on the potential benefits of kaki mudra on the sympathovagal balance among healthy participants.

Funding information: Authors state no funding involved.
Author contributions: All authors have accepted responsibility for the entire content of this manuscript and consented to its submission to the journal, reviewed all the results and approved the final version of the manuscript. VA, AB, and MK were involved in the study design, and drafting of the article, GA and STV provided critical revisions and supervised the manuscript.
Conflict of interest: Authors state no conflict of interest.
Data availability statement: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Ethical approval: The research related to human use has been complied with all the relevant national regulations, institutional policies and in accordance the tenets of the Helsinki Declaration. The host institutional Ethics committee approval was obtained for this protocol (No. IEC-IIYNMS/Approval/051/2023).

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Received: 2024-01-27

Revised: 2024-04-27

Accepted: 2024-05-07

Published Online: 2024-06-11

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

https://doi.org/10.1515/ohe-2023-0032

Keywords for this article

Kaki Mudra; pupillary light reflex; clinical trials; yoga; dynamic pupillometry; heart rate variability; autonomic nervous system

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