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ABSTRACT
Background: Spinal manipulation (SM) has been hypothesized to influence the autonomic nervous system (ANS). Further, it has been proposed that the effects may vary depending on the segment manipulated. The aim of this systematic review was to synthesize the current level of evidence for SM in influencing the ANS in healthy and/or symptomatic population. Methods: Various databases (n = 8) were searched (inception till May 2023) and 14 trials (n = 618 participants) were included in the review. Two authors independently screened, extracted and assessed the risk of bias in included studies. The data were synthesized using standard mean differences and meta-analysis for the primary outcome measures. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of the body of evidence for each outcome of interest. Results: Overall, there was low quality evidence that SM did not influence any measure of ANS including heart rate variability (HRV), oxy-hemoglobin, blood pressure, epinephrine and nor-epinephrine. However, there was low quality evidence that cervical spine manipulation may influence high frequency parameter of HRV, indicating its influence on the parasympathetic nervous system. Conclusion: When compared with control or sham interventions, SM did not alter the ANS. Due to invalid methodologies and the low quality of included studies, findings must be interpreted with great caution. Future studies are needed which employ rigorous data collection processes to verify the true physiological implications of SM on ANS.
Abbreviations
| ANS | = | autonomic nervous system |
| BP | = | blood pressure |
| CCT | = | controlled clinical trial |
| ELPCT | = | edge light pupil cycle time |
| GRAPH | = | Guidelines for Reporting Articles on Psychiatry and Heart rate variability |
| HF | = | high frequency |
| HRV | = | heart rate variability |
| HVLA | = | high velocity, low amplitude |
| LF | = | low frequency |
| MSNA | = | muscle sympathetic nerve activity |
| NIRS | = | near infrared spectroscopy |
| O2Hb | = | oxygenated hemoglobin |
| PNS | = | parasympathetic nervous system |
| RCT | = | randomized controlled trial |
| rMSSD | = | root mean square of consecutive RR intervals |
| SDNN | = | standard deviation of NN intervals |
| SM | = | spinal manipulation |
| SNS | = | sympathetic nervous system |
| TOI | = | tissue oxygenation index |
Disclosure statement
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/10669817.2023.2285196
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Notes on contributors
Kesava Kovanur Sampath
Kesava Kovanur Sampath is a Principal Academic Staff Member in the Centre for Health and Social Practice at Waikato Institute of Technology in New Zealand. He is the chair of the osteopathic research steering committee in New Zealand. He is part of the leadership team at the Duke Centre of Excellence in Manual and Manipulative Therapy. He is also a visiting research fellow at the University of Technology, Sydney. Kesava’s research specialties include neurophysiological outcomes, spinal manipulation, manual therapy practice and education.
Steve Tumilty
Steve Tumilty is one of the few clinician scientists in Physiotherapy Worldwide and one of the few Registered Physiotherapy Specialists in New Zealand. The majority of his clinical experience has been in the outpatient musculoskeletal practice setting in UK, Germany and New Zealand. He also has experience in professional sports and Occupational Health Physiotherapy. In 2002 he came to work at the School of Physiotherapy, Otago University and he has developed and coordinated the specialist Masters degree for Sports and Orthopaedic Manipulative Therapy for which he provides teaching and clinical expertise. He is the author or co-author on 125 research outputs in the field of Physiotherapy and Orthopaedic Manipulative Therapy for musculoskeletal conditions and has been invited to present at international conferences. He has taught manual therapy seminars in New Zealand and Japan. Associate Professor Tumilty’s research interests are in Tendinopathy, modulation of the Hypothalamus-Pituitary Axis using manual interventions, and the influence of the autonomic nervous system on musculoskeletal pain and healing.
Liana Wooten
Liana Wooten is an Assistant Professor and Assistant Director Admissions at Tufts University, Phoenix. Her research/Areas of Interest includes Applied Physiology, Clinical Exercise Physiology, Scholarship of Teaching and Learning.
Suzie Belcher
Suzie Belcher is an Academic Staff Member and a physiotherapist with a passion for sports rehabilitation, injury prevention, biomechanical analysis and performance conditioning. Suzie has worked with international athletes from the UK and NZ, in Winter and Summer sports up to Olympic/Paralympic level. She recently completed a PhD ‘Improving the Design and Implementation of New Zealand’s NetballSmart Injury Prevention Programme’.
Gerard Farrell
Gerard Farrell is a PhD candidate at the Center for Health, Activity and Rehabilitation Research, School of Physiotherapy at the University of Otago. His research interests include the neuroendocrine mechanisms of manual therapy, the part a dysfunctional stress response has to play in the development and maintenance of persistent post-concussion symptoms, and the role manual therapy plays in the treatment of persistent post-concussion symptoms.
Angela Spontelli Gisselman
Angela Spontelli Gisselman is an assistant professor at Tufts University School of Medicine. Her main research interests are in the role of health metrics, such as heart rate variability (an index of the autonomic nervous system), and their ability to influence decision making in rehabilitation, such as post-concussion rehabilitation. In addition to this line of research, other areas of interest include heart rate variability and temporomandibular disorders; the use of thermal imaging in tendinopathy; examination and management of shoulder injuries; load monitoring technology and post-operative rehabilitation.