We recently published a paper in the journal ‘Experimental Brain Research’1 and demonstrated that following a full spine chiropractic adjustment session there was an increase in the subjects’ ability to maximally voluntarily contract one of their leg muscles. We found an increase in the electrical activity readings from that muscle of almost 60% and a 16% increase in absolute force measures. There was also a 45% increase in the drive from their brain to their muscle (the degree to which the brain can activate that particular muscle) and a small, but significant, shift in the H reflex curve (a neurophysiological measure of spinal cord excitability). For those of you who understand neuroscience, this study is the first to indicate that chiropractic adjustments of the spine can actually induce significant changes in the net excitability for the low-threshold motor units, and/or alter the synaptic efficacy of the Ia synapse with these low-threshold homonymous motoneurons.
In simpler language these results indicate that the subjects were better able to use their muscles (they were actually stronger and better able to activate their leg muscle) after their subluxations were adjusted. The results of the study also indicate that spinal adjustments can prevent fatigue, which meant we were able to recommend that chiropractic care could potentially enhance the outcomes for patients seeking medical treatment for lost tonus of their muscles or are recovering from muscle degrading dysfunction such as with stroke or orthopaedic operations. The results suggest that the improvements in maximum voluntary contractions following the chiropractic adjustment session are likely attributed to the increased descending drive (i.e. from the brain to the spinal cord) and/or modulation in afferent input. These results may also be of interest to sports performers! Do you know a sports performer who would like to be 16% stronger for at least ½ hour ☺ We obviously need to run some follow-up studies now to see how long these changes last and whether we have the same effect in a sports population, or for those who have suffered a stroke or in a post-operative population.
These remarkable findings come from a study that was funded by a combination of donations to the Centre and a recent grant partnership between Spinal Research (formerly Australian Spinal Research Foundation), The New Zealand Hamblin Trust and the New Zealand College of Chiropractic.
This study involved a collaboration between the Centre for Chiropractic Research and a world-renowned neurophysiologist, Professor Kemal Türker, from the School of Medicine at Koҫ University in Istanbul, Turkey. To be able to continue this work we need more funding! For that reason we have come up with several new clever ways you can benefit from the work we are doing while you are supporting us financially to do more of this important work, hence the launch of our new evidence informed patient education videos now available.
1. Niazi IK, Turker KS, Flavel S, Kinget M, Duehr J, Haavik H. Changes in H-reflex and V-waves following spinal manipulation. Experimental Brain Research. 2015; 233(4):1165–1173.