I was looking into research around physical therapy and the autonomic nervous system, and I came across the review below. It triggered me to look deeper into some of things mentioned, and I’m sharing some information here to help you look in more depth if you’d like to. The review I’ve included below looked at whether or not joint mobilisation techniques lead to changes in the body related to the autonomic nervous system.
Some background information…
The autonomic system “regulates involuntary physiologic processes including heart rate, blood pressure, respiration, digestion, and sexual arousal.” (Read more here). This is as opposed to the somatic nervous system, which is “associated with the voluntary control of the body movements via the use of skeletal muscles. It is responsible for all the functions we are aware of and can consciously influence, including the movement of our arms legs and other parts of our body.” (Read more here). Basically we use the somatic nervous system (SNS) to create movement, and the autonomous nervous system (ANS) to regulate bodily functions.
The autonomic nervous system can then be divided into three sections, the sympathetic, parasympathetic, and enteric. The sympathetic and parasympathetic control sensory (feeling) and motor (movement) information that travels to and from between the central nervous system (brain and spinal cord) and the rest of the body. The enteric nervous system deals with everything else. The sympathetic nervous system activates the ‘fight or flight’ response, the parasympathetic nervous system activates the ‘rest and digest’ response. (Read more here).
It’s difficult to measure immediate changes in the autonomic nervous system, and so researchers have discovered a way of measuring changes in the skin that indicate potential changes in the rest of the autonomic nervous system. You can read more about this here. That’s the technique that was noted in the results section in this review.
The results of the review were fairly inconclusive, in my opinion. The conclusion states that “Some types of mobilizations probably produce an immediate and short-term, statistically significant increase in skin sympathetic nerve activity when compared to a sham procedure”. To give an idea of just how hard it is to find high quality evidence on the subject, only “twenty-nine of 2267 studies were included” once the reviewers applied their inclusion criteria. I think this just goes to show how hard it is to figure out which research to take notice of.
Even though the review found limited evidence of changes in the autonomic nervous system created by joint mobilisation techniques, they did find that “Mobilizations (oscillatory technique) probably produce an immediate and short-term, bilateral increase in skin sympathetic nerve activity”. For those of you who have watched me treat your horse, you may have noticed that I use oscillatory techniques a lot in my work. I find that they are very effective in reducing pain and improving range of movement, they are well accepted by the horses, and they are (mostly) gentle both on my body and on the horse. If you’d like to watch it, there’s a useful video on oscillatory techniques, specifically what’s called ‘Maitland mobilisations’ here.
Background: The autonomic nervous system (ANS) interests many chiropractors and manual therapists, because joint manipulative techniques (JMT), e.g. high velocity low amplitude (HVLA) manipulations and mobilizations, appear to produce acute changes in ANS mediated physiology. The complexity of this issue justifies a systematic critical literature review.
Objective: To review the literature comparing the acute changes in markers of ANS activity between JMT applied on spinal or peripheral joints and a sham procedure in healthy or symptomatic subjects.
Method: We searched PsycINFO, PEDro, PubMed, Cochrane library, EMBASE, and Medline up to December 2017. We updated the search with PubMed, Cochrane library, EMBASE, and Medline including July 2018. Inclusion criteria were: randomized sham-controlled trials assessing the effect of JMT on markers of ANS activity; manually applied JMT, regardless of technique, applied on either healthy or symptomatic humans; outcome measurements recorded at baseline and repeated during and/or after interventions. Selection of articles and data extraction were performed independently by two reviewers. The quality of studies was assessed using the Cochrane 'risk of bias' tool and a technical check-list. Results were reported narratively with some meta-analyses. The Cochrane GRADE approach was used to assess the certainty of evidence.
Results: Twenty-nine of 2267 studies were included in the synthesis. Mobilizations (oscillatory technique) probably produce an immediate and short-term, bilateral increase in skin sympathetic nerve activity (reflected by an increase in skin conductance) regardless of the area treated (moderate-certainty evidence). It is uncertain whether the sympathetic arousal also explains an increase in respiratory rate (very low-certainty evidence). Our evaluation of the literature suggests that spinal sustained apophyseal glides (SNAGs) mobilization and HVLA manipulation of the spine may have no acute effect on the studied markers of ANS activity (very low- to low-certainty evidence).
Conclusion: Some types of mobilizations probably produce an immediate and short-term, statistically significant increase in skin sympathetic nerve activity when compared to a sham procedure, whereas spinal SNAGs and spinal HVLA techniques may have no acute effect on the studied markers of ANS activity. No region-specific results were noted. The literature suffers from several shortcomings, for which reason we strongly suggest further research.
Picchiottino M, Leboeuf-Yde C, Gagey O, Hallman DM. The acute effects of joint manipulative techniques on markers of autonomic nervous system activity: a systematic review and meta-analysis of randomized sham-controlled trials. Chiropr Man Therap. 2019 Mar 12;27:17. doi: 10.1186/s12998-019-0235-1. PMID: 30911373; PMCID: PMC6413458.
You can find this study online here.
© Sue Palmer, The Horse Physio, 2021
Treating your horse with care, connection, curiosity and compassion