Professor Richard Gevirtz is one of the world’s foremost authorities on Heart Rate Variability Biofeedback (also known as Heart Rate Coherence biofeedback). Last week he visited the UK and delivered a two day training seminar focusing on the applications of HRV biofeedback. I was in attendance and like the other delegates was (re-)inspired by the power and potential of this technique. I wanted to devote this blog post to summarising some of the main themes.
Professor Gevirtz is both a researcher and practising clinician. His grasp of the research evidence in the field of HRV biofeedback is probably second to none, and he showed us how HRV biofeedback offers so much promise in a range of conditions including chronic pain, IBS, anxiety, depression, PTSD and asthma.
HRV biofeedback builds greater adaptive capacity in the Autonomic Nervous System (ANS). Professor Gevirtz drew on the modern understanding of the ANS as a heirarchical system of mind-body regulation (a theory known as polyvagal theory). The most primitive and evolutionarily oldest level is the old parasympathetic system which works to shut down the body. It’s probably responsible for fainting, for example. For most of us it’s not that relevant – at least hopefully not as it seems to be maladaptive for our species.
The next level is the sympathetic nervous system, which generally cranks up the body’s arousal level, preparing us for “fight or flight” as the well-known phrase has it. For example the SNS increases heart rate and blood pressure and channels blood and resources away from the digestive system and towards our skeletal muscles.
It used to be thought that the sympathetic response was quite generalised, triggering a number of effects all at once, and only differing in degree. More recent evidence suggests it can be much more selective and varies across individuals.
At the highest level is the new parasympathetic system, which counteracts the sympathetic and calms us down. It evolved in mammals and is key to many social behaviours and also self-soothing. In our normal state of affairs the new vagal system is active, as a kind of brake on the sympathetic system. This brake is necessary to allow our repertoire of social behaviours to come to the fore.
The heirarchical nature of the ANS is key to the modern understanding of stress. The old view is that stress equals sympathetic activation equals generalised fight-or-flight response. The sympathetic and parasympathetic systems were seen as reciprocal, like the two arms of a set of scales. The new view is that stress is not just some monolithic effect, rather different stressors can produce quite specific effects, and can affect different people in different ways. A lot of stress in our culture is not classic fight or flight but is more like mild but insistent worries (for example financial worries). These don’t necessarily activate the sympathetic nervous system but are more likely to trigger withdrawal of the “new vagal brake”, perhaps for an extended period of time. When this happens we tend to lose access to our social resources, and might get stuck in a hyper-vigilant state, feeling wary and on edge. This may be different from outright anxiety but over time can wear us down, perhaps leading to depression.
Heart Rate Variability gives us a good way to measure the state of the new vagal system. It can tell us something (but less) about the sympathetic system, and really nothing about the old vagal system.
HRV biofeedback training gives us a way to exercise and thus to strengthen the vagal brake. That’s why it’s so powerful with so many applications – withdrawal of the vagal brake is common and a key effect of stress.
The vagus nerve is the pathway by which the parasympathetic influences are conducted from brain to body, but it also carries information back in the opposite direction. (In fact more traffic goes from the body to the brain – the brain is listening in to the body.) So the in-bound signals coming to the brain via the vagus nerve can change brain state.
In fact a modern surgical technique takes advantage of this. In vagal stimulation, an implant electrically stimulates the vagus nerve to boost this signal in some way. It’s been shown to be effective in for example epilepsy and intractable depression.
It could be that HRV biofeedback confers some of its benefit by a similar mechanism – in other words it trains both the out-bound and in-bound vagal signals. This could be an important part of the story of why HRV biofeedback is so effective with depression. What is not in doubt is that it is effective – several studies have shown it now, and some of them are quite remarkable.
Professor Gevirtz gave a very powerful account of the physiology behind certain types of chronic pain. Again HRV biofeedback has shown efficacy in research, with chronic pain, and I think it can offer some hope to a lot of people. I’ll devote a separate blog piece to this story – coming soon!