Posts

Dr. Steven Passmore

Chiropractic Science Podcast with Dr. Steven Passmore

Dr. Dean Smith will be hosting a podcast interview with Dr. Steven Passmore this Thursday, September 24th at 2 pm (EST).

Passmore Headshot 2012Steven Passmore, DC, PhD.  Dr. Passmore is Assistant Professor in the Faculty of Kinesiology & Recreation Management at the University of Manitoba. His expertise deals with human perceptual learning and motor control.  Dr. Passmore utilizes his theoretical and applied background in perceptual motor behaviour to explore performance-based outcome measures in an attempt to objectively determine population characteristics, movement outcomes and sustainability of interventions.  We will discuss Dr. Passmore’s chiropractic and performance related research. To hear the podcast live, go to chirocredit.com/chiropracticscience and login for instructions (Not a member? Create an account for free).

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Chiropractic Adjustments Reduce Fatigue and Increase Neural Drive

chiropractic adjustmentOver the last decade, research has demonstrated that spinal manipulation can change various aspects of nervous system function, including muscle reflexes, cognitive processing, reaction time, and the speed at which the brain processes information. One research group from New Zealand (Haavik Taylor et al) has hypothesized that the joint dysfunction part of the chiropractic clinical construct, the vertebral subluxation, results in altered afferent input to the central nervous system (CNS) that modifies the way in which the CNS processes and integrates all subsequent sensory input. This processing (i.e., sensorimotor integration) is a central nervous system (CNS) function that appears most vulnerable to altered inputs.  Many studies show that chiropractic adjustments result in changes to sensorimotor integration within the central nervous system.

A new study sought to investigate possible neural plastic changes with spinal manipulation by measuring H-reflexes and V-waves.  The H-reflex is an electrically evoked response that operates via the same neuronal circuitry as stretch reflexes.  The H (Hoffmann) reflex may be useful to assess motoneuron excitability in vivo while also reflecting presynaptic inhibition of Ia afferent synapses.  The so-called V-wave, which is an electrophysiological variant of the H-reflex, can be recorded during maximal voluntary motor contractions. The elicited V-wave response may be used to reflect the level of efferent neural drive from spinal α-motoneurons during maximal voluntary contraction (MVC).

Results of the study:

  • the threshold to elicit the H-reflex significantly decreased by 8.5% in the spinal manipulation group
  • the SEMGs showed a significant drop in the power spectrum after controls but there was no fatigue demonstrated in the power spectrum after spinal manipulation
  • for study 1: maximal voluntary contraction as determined by SEMG increased significantly by 59.5% after spinal manipulation and decreased significantly by 13.3% after control
  • for study 2: maximal voluntary contraction increased significantly by 16.1% after spinal manipulation and decreased significantly by 11.4% after control
  • the V-wave amplitude (V/Mmax ratio) increased significantly by 45% after spinal manipulation and reduced significantly by 23% after control

Key Points

  • This study is the first to indicate that chiropractic adjustments can induce significant changes in the net excitability for the low-threshold motor units/and or alters the synaptic efficacy of the Ia synapse
  • the improvements in maximal voluntary contraction following spinal manipulation are likely attributed to the increased descending drive and/or modulation in afferents
  • spinal manipulation prevents fatigue
  • these results suggest that spinal manipulation may be indicated as part of the treatment for the patients who have lost tonus of their muscle and/or are recovering from muscle dysfunction such as stroke or orthopedic operations
  • These findings will also be of interest to athletes and perhaps the general public

 

Podcast

Dr. Heidi Haavik

Brain Adjustments with Dr. Heidi Haavik

HeidiHaavik
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Learn what happens in your brain when a chiropractor adjusts your spine.  Dr Heidi Haavik is a chiropractor and a neurophysiologist who has worked in the area of human neurophysiology for over 15 years. Heidi has a PhD in human neurophysiology from the University of Auckland. Her work has been instrumental in building the base of scientific evidence demonstrating the efficacy of chiropractic care in improving people’s health and wellbeing. As a researcher, she has investigated the effects of chiropractic adjustments of dysfunctional spinal segments (vertebral subluxations) on somatosensory processing, sensorimotor integration and motor cortical output.

Dr Haavik is the Director of Research at the New Zealand College of Chiropractic where she has established the Centre for Chiropractic Research. Dr Haavik is also an Adjunct Professor at the University of Ontario, Institute of Technology in Oshawa, Canada and is a member of the World Federation of Chiropractic’s Research Council. Dr Haavik has received numerous research awards and has published a number of papers in chiropractic and neurophysiology journals. She has presented her work to both chiropractic and neuroscience communities around Australasia, North America and Europe. She is on the Editorial Board of the Journal of Manipulative and Physiological Therapeutics and Journal of Chiropractic Education. She was named Chiropractor of the year in 2007 by both the New Zealand Chiropractic Association and the New Zealand College of Chiropractic Alumni Association.  She is also the author of a textbook – The Reality Check which describes in easy to understand language what happens in the brain when a chiropractor adjusts dysfunctional segments in your spine.

Read about Dr Haavik at her website, and get her book and posters at heidihaavik.com.  Subscribe to Dr Haavik’s research service at haavikresearch.com to get great evidence-informed marketing material for chiropractic practices including among other things, videos for your website that explain how chiropractic works.  Interested in donating toward her research efforts?  Contact her at haavikresearch.com.

HeidiDean2015

Dr. Haavik and Dr. Smith at the Ohio State Chiropractic Association Convention, 2015

reality check

Dr. Haavik’s book: The Reality Check

Dr. John Srbely

Myofascial and Chiropractic Research with Dr. Srbely

Dr. John Srbely
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Listen to this great interview with Dr. John Srbely as we talk about his research interests in chiropractic, myofascial pain, myofascial trigger points and central sensitization.  Dr. Srbely is a researcher and Assistant Professor at the University of Guelph in the Department of Human Health and Nutritional Sciences.  He studies the physiologic mechanisms of myofascial trigger points and their role in the clinical expression and treatment of pain and joint/muscle dysfunction in chronic disease. A core theme to his research is the study of central sensitization which is a fundamental neuradaptive process associated with the pathophysiology of pain and disease.

Dr. Srbely’s research expertise and interests lie in the fields of clinical biomechanics and neurophysiology. He has a specific interest in the study of pain and joint function associated with aging and chronic disease such as osteoarthritis, myofascial pain and fibromyalgia. To this extent, he studies the physiologic mechanisms of myofascial trigger points and their role in the clinical expression and treatment of pain and joint/muscle dysfunction in chronic disease. A core theme to his research is the study of central sensitization. Central sensitization is a fundamental neuradaptive process associated with the pathophysiology of pain and disease, however, the impact of central sensitization on the physiologic expression of chronic myofascial pain and human mechanics/pathomechanics in chronic degenerative diseases such as osteoarthritis is poorly understood. Dr. Srbely’s research initiatives aim to develop novel/enhance existing treatment approaches in clinical pain management (diagnosis and treatment) and musculoskeletal biomechanics/pathomechanics associated with chronic diseases and aging.