Heart rate variability biofeedback training can provide many important physical and psychological health benefits. This strategy is being more commonly integrated in the promotion of health and wellbeing.
Heart rate variability (HRV) describes the differential timing between successive heartbeats. While there are many metrics which describe various aspects of HRV, for the purpose of this article, it will be considered as a single metric. The significance of HRV is that it is currently the most widely available metric that provides a measure of the degree of recovery within our nervous system. There are numerous wearable devices which provide measures of HRV and by using these devices, the impact of various training regimens can be followed and tracked over time.
While it is possible to measure both current HRV and changes over time, it should be emphasized that improvements in HRV are not the end goal of biofeedback and polyvagal informed training. Rather this measure provides information regarding our state of recovery and function of the autonomic nervous system. Improvements in HRV metrics are associated with improved recovery and enhanced ventral vagal activation. The secondary effects of this include improved emotional control, physical wellbeing, and cognitive function.
Tinello et al (2022) studied the impact of HRV biofeedback training on executive functioning across various age groups and populations. The components of executive functioning which were studied included inhibition, working memory, and cognitive flexibility. The paradigm upon which the study was based was that described by Thayer et al (2009). Specifically, the neurovisceral integration model was utilized, describing the relationship between prefrontal cortical function and cardiovascular function with the finding that dysregulation of HRV has a negative effect on executive function.
Tinello et al (2022) conducted a systematic review of 16 studies, of which 9 demonstrated increased executive functioning following HRV biofeedback training. The strongest association was amongst domains of attention, inhibition, and working memory. The findings of the study suggested that HRV training was most beneficial amongst those individuals experiencing greater stress, those with lower baseline cognitive function, and amongst older adults. Interestingly, the impact of HRV biofeedback did not seem to be associated with either frequency or intensity of training. The authors did note that substantial heterogeneity in the analyzed data limited the robustness of the results. The contributors to heterogeneity included the type of biofeedback devices, varying effect sizes utilized across studies, target population, and method of measurement of executive function. One important limitation of the study was an inability to distinguish between short-term and long-term effects of HRV training.
The evidence provided by the study does lead to several potential areas for future research. It is important to evaluate the effects of more specific HRV biofeedback training methods. The short-term and long-term effects of this training should be better investigated. There would be benefit from more specific and consistent measures of HRV and executive functioning. It would also be highly informative to include, in future studies, assessments of self-perceived stress and wellbeing in order to analyze the impact of HRV biofeedback on these parameters. In addition, it is not readily evident whether or not the increase in HRV is the cause of the improvement in executive function or if these two metrics improve in parallel in response to a change in another variable. For example, could the biofeedback training lead to an increase in ventral vagal complex activation with resulting improvements in both HRV and executive function? These are all important and contributory considerations for future research.
It is also informative to consider the results of the study from a polyvagal informed perspective. Within this paradigm, HRV is considered a surrogate marker for the extent of activation of the ventral vagal complex. Improvements in HRV are a reflection of greater autonomic nervous system resilience on account of enhanced ventral vagal function. Given the biological characteristics of the ventral vagal state, in particular in the context of the psychological attributes, this increased ventral vagal complex activation would be expected to be associated with improved attention, working memory, and emotional regulation and control. Decreased HRV, as would be encountered within sympathetic and dorsal vagal states, would be anticipated to be associated with reciprocal changes in these characteristics. Taken as a whole, the polyvagal informed perspective of the evidence provided by Tinello et al (2022) would reinforce the importance of polyvagal informed training of mind-based and body-based strategies with the integration of HRV biofeedback training and metric measurement as an indicator of the results of such training.
The polyvagal informed paradigm of The Practices of the Healthcare Athlete incorporates the development of mind-based and body-based skills and strategies in the promotion of health, wellbeing, and sustainable high performance. HRV biofeedback training in conjunction with the development of these strategies is an integral component of this perspective. Through the measurement of HRV metrics we are able to objectively determine the impact of this approach and correlate these changes with our subjective experience.
REFERENCES
Tinello D, Kliegel M, Zuber S. Does Heart Rate Variability Biofeedback Enhance Executive Functions Across the Lifespan? A Systematic Review. J Cognitive Enhancement 2022; 6: 126-142.
Thayer JF, Hansen AL, Saus-Rose E, Johnsen BH. Heart Rate Variability, Prefrontal Neural Function, and Cognitive Performance: The Neurovisceral Integration Perspective on Self-Regulation, Adaptation, and Health. Ann Behav Med 2009; 37(2): 141-153.
