Changes in H-reflex and V-waves following spinal manipulation
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This study investigates whether spinal manipulation leads to neural plastic changes involving cortical drive and the H-reflex pathway. Soleus evoked V-wave, H-reflex, and M-wave recruitment curves and maximum voluntary contraction (MVC) in surface electromyography (SEMG) signals of the plantar flexors were recorded from ten subjects before and after manipulation or control intervention. Dependent measures were compared with 2-way ANOVA and Tukey’s HSD as post hoc test, p was set at 0.05. Spinal manipulation resulted in increased MVC (measured with SEMG) by 59.5 ± 103.4 % (p = 0.03) and force by 16.05 ± 6.16 4 % (p = 0.0002), increased V/M max ratio by 44.97 ± 36.02 % (p = 0.006), and reduced H-reflex threshold (p = 0.018). Following the control intervention, there was a decrease in MVC (measured with SEMG) by 13.31 ± 7.27 % (p = 0.001) and force by 11.35 ± 9.99 % (p = 0.030), decreased V/M max ratio (23.45 ± 17.65 %; p = 0.03) and a decrease in the median frequency of the power spectrum (p = 0.04) of the SEMG during MVC. The H-reflex pathway is involved in the neural plastic changes that occur following spinal manipulation. The improvements in MVC following spinal manipulation are likely attributed to increased descending drive and/or modulation in afferents. Spinal manipulation appears to prevent fatigue developed during maximal contractions. Spinal manipulation appears to alter the net excitability of the low-threshold motor units, increase cortical drive, and prevent fatigue.
KeywordsH-reflex V-wave Spinal manipulation Maximal voluntary contraction Evoked potentials Neural adaptations
The authors would like to acknowledge the following organizations for support and funding Australian Spinal Research Foundation, Hamblin Chiropractic Research Fund Trust, New Zealand College of Chiropractic and Koç University. KST is a Fellow of the Turkish Academy of Sciences Association.
- Gandevia SC (2001) Spinal and supraspinal factors in human muscle fatigue. Psychol Rev 81:1725–1789Google Scholar
- Haavik Taylor H, Murphy B (2007b) Transient modulation of intracortical inhibition following spinal manipulation. J Aust Chiropr Assoc 37:106–116Google Scholar
- Haavik Taylor H, Holt K, Murphy B (2010) Exploring the neuromodulatory effects of the vertebral subluxation and chiropractic care. J Aust Chiropr Assoc 40:37–44Google Scholar
- Herzog W (1996) Mechanical, physiologic, and neuromuscular considerations of chiropractic treatment. In: Lawrence DJ, Cassidy JD, McGregor M, Meeker WC, Vernon HT (eds) Advances in chiropractic. Mosby-Year Book, New York, pp 269–285Google Scholar