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Review and analysis of applicable research is an important component to promoting health, wellbeing, and sustainable high performance. This is the first installment in the application of current research to the polyvagal informed paradigm.
An important element underlying The Practices of the Healthcare Athlete is that the recommendations and strategies are based upon the best available evidence. This promotes trust that there is a solid foundation underlying the skills and strategies that are developed in the promotion of health, wellbeing, and sustainable high performance. A new component to this article series will be review of current and pertinent evidence that contributes to the practices described within the polyvagal informed pursuit of these goals.
The first article for analysis within this new contribution to the series is that reported on the impact of various breathing patterns, compared to mindfulness meditation, on mood, anxiety, and physiological metrics. The study is reported by Balban et al (2022) from Stanford and the senior author listed on the paper is Andrew Huberman, PhD. This was a study of 108 participants randomized to one of four groups: mindfulness meditation, prolonged exhalation breathing training, box breathing training, or prolonged inhalation breathing training. The mindfulness group served as the control group for the differing breathing pattern groups. Each group participated in 5 minutes of practice over a duration of 1 month. The outcomes analyzed were changes in mood and anxiety, as determined by standard questionnaires, and physiological metrics, specifically respiratory rate, heart rate, and heart rate variability. The physiological data was obtained using a wrist based wearable device and were obtained as daily averages.
The authors reported improvements in mood and decreases in anxiety across all groups in the study. The prolonged exhalation group demonstrated a statistically significant improvement, compared to mindfulness mediation, with respect to positive affect. While the other breathing patterns demonstrated improvements relative to mindfulness, the increases in positive affect were not statistically significant. There was a greater decrease in respiratory rate with breathing training in comparison to mindfulness. There was no reported difference between any of the breathing training groups and the mindfulness group with respect to resting heart rate or heart rate variability. It is unclear from the paper whether or not there were differences in heart rate variability between the three breathing training groups.
There is important evidence provided by the study which fits within the polyvagal informed perspective of The Practices of the Healthcare Athlete. The findings reported in the study of improvement in mood and decrease in anxiety associated with a prolonged exhalation breathing pattern fits within the paradigm predicted through application of Polyvagal Theory. As informed by the theory, such a breathing pattern would be expected to increase ventral vagal activation, with an associated shift towards the ventral vagal physiological state. As this state is associated with increased connection to self and others, as well as other characteristics, described in further detail in past articles, it would be predicted that individuals more predominantly within this state would have improved mood and reduced anxiety.
The study also encountered an increase in positive affect and decrease in anxiety with the other breathing patterns compared to mindfulness meditation although to a lesser degree than the prolonged exhalation group. While it would be expected that mindfulness would result in similar changes, the explanation for these reported findings may reflect either the time horizon of the study or the fact that there was no true control group for comparison. Given the one month time horizon of the study it is possible that the benefits of mindfulness may require a longer duration of time to become apparent. With respect to the control group, it is possible that had a different group been utilized as a control, specifically one in which the training would not be expected to impact mood, anxiety, or physiological parameters, that a significant improvement with the other breathing patterns may have been demonstrated. The explanation for this is that it would be expected that with mindfulness training there would be some degree of improvement in these parameters, thereby decreasing the incremental benefit of the breathing training.
Interestingly, the study did not demonstrate improvement in heart rate variability within the prolonged exhalation group. Given the predicted increase in ventral vagal activation, according to Polyvagal Theory principles, it would be expected that this group would have demonstrated an increase in heart rate variability. The absence of this finding may reflect that there was no comparison of the prolonged exhalation group to the other breathing patterns, which would not be expected to be associated with increased ventral vagal activation and, therefore, increased heart rate variability. Alternatively, the absence of the expected increase in heart rate variability may reflect the measurement of this metric as a daily average rather than during and immediately following the breathing practice. Perhaps a longer duration of time than 1 month of training is necessary in order to encounter a reflection in the average daily heart rate variability, whereas there may be a measurable change in heart rate variability both during and immediately following breathing training.
On the basis of the review and in consideration of the study within the polyvagal informed paradigm, there are several areas for future study that would be of interest. A direct comparison of the different breathing patterns and their respective impact on heart rate variability would be informative. Based upon the principles of Polyvagal Theory, it would be expected that prolonged exhalation would lead to increased heart rate variability, box breathing with little change in variability, and prolonged inhalation with decreased variability. This could be directly tested, particularly if heart rate variability data were obtained during and immediately following the training timeframe. It would also be beneficial to investigate whether or not a longer training duration, greater than 1 month, may result in a greater magnitude of change than that which was encountered in this study. As mindfulness and breathing are skills that can be trained, it may be the case that additional training time results in further improvements. It would also be helpful to obtain the physiological metrics during and immediately following the respective training times in addition to the daily averages in order to determine if there is a latency before which the training impacts the physiological parameters over the course of an entire day. Finally, inclusion of a control group for which there would be no expected benefit in mood, anxiety, or physiological metrics is necessary in order to provide further information regarding the magnitude of benefit provided by mindfulness and the breathing training.
By analyzing and integrating the best available and current data, it is possible to ensure that the mind-based and body-based skills and strategies incorporated within the polyvagal informed perspective of The Practices of the Healthcare Athlete are evidence-driven. If the evidence were to lead to differing recommendations, this would be reflected in the skills and strategies promoted within this perspective to promote health, wellbeing, and sustainable high performance. The article reviewed above further strengthens the scientific basis for the breathing training incorporated within these practices.
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REFERENCE
Balban MY, Neri, E, Kogon MM, Weed L, Nouriani B, Jo B, Holl G, Zeitzer JM, Spiegel D, Huberman AD. Brief Structured Respiration Practices Enhance Mood and Reduce Physiological Arousal. Cell Reports Medicine (2022), https://doi.org/10.1016/j.xcrm.2022.100895.
