Physiological Responses to Spinal Manipulation Therapy: Investigation of the Relationship Between Electromyographic Responses and Peak Force (original) (raw)
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The effect of spinal manipulation impulse duration on spine neuromechanical responses
The Journal of the Canadian Chiropractic Association, 2014
Spinal manipulation therapy (SMT) is characterized by specific kinetic and kinematic parameters that can be modulated. The purpose of this study is to investigate fundamental aspects of SMT dose-physiological response relation in humans by varying SMT impulse duration. Twenty healthy adults were subjected to four different SMT force-time profiles delivered by a servo-controlled linear actuator motor and differing in their impulse duration. EMG responses of the left and right thoracic paraspinal muscles (T6 and T8 levels) and vertebral displacements of T7 and T8 were evaluated for all SMT phases. Significant differences in paraspinal EMG were observed during the "Thrust phase" and immediately after ("Post-SMT1") (all T8 ps < 0.01 and T6 during the thrust ps < 0.05). Sagittal vertebral displacements were similar across all conditions (p > 0.05). Decreasing SMT impulse duration leads to a linear increase in EMG response of thoracic paraspinal during and fol...
BMC Complementary and Alternative Medicine, 2016
Background: Neuromechanical responses to spinal manipulation therapy (SMT) have been shown to be modulated through the variation of SMT biomechanical parameters: peak force, time to peak force, and preload force. Although rate of force application was modulated by the variation of these parameters, the assumption that neuromuscular responses are modulated by the rate of force application remains to be confirmed. Therefore, the purpose of the present study was to evaluate the effect of a constant rate of force application in neuromechanical responses to SMT in healthy adults. Methods: Four SMT force-time profiles presenting different time to peak force and peak force, but with a constant rate of force application were applied on 25 healthy participants' T7 transverse processes. Muscular responses were recorded through surface electromyography electrodes (T6 and T8 levels), while vertebral displacements were assessed through pasted kinematic markers on T6 to T8 spinous processes. Effects of SMT force-time profiles on neuromechanical responses were assessed using repeated-measures ANOVAs. Results: There was no main effect of SMT force-time profile modulation on muscular responses (ps > .05) except for the left T8 (F (3, 72) = 3.23, p = .03) and left T6 (F (3, 72) = 2.94, p = .04). Muscular responses were significantly lower for the lowest peak force condition than the highest (for T8) or second highest (for T6). Analysis showed that increasing the SMT peak force (and concomitantly time to peak force) led to a significant vertebral displacement increase for the contacted vertebra (F T7 (1, 17) = 354.80, p < .001) and both adjacent vertebras (F T6 (1, 12) = 104.71, p < .001 and F T8 (1, 19) = 468.68, p < .001). Conclusion: This study showed that peak force modulation using constant rate of force application leads to similar neuromuscular responses. Coupled with previous investigations of SMT peak force and duration effects, the results suggest that neuromuscular responses to SMT are mostly influenced by the rate of force application, while peak force modulation yields changes in the vertebral displacement. Rate of force application should therefore be defined in future studies. Clinical implications of various SMT dosages in patients with spine related pain should also be investigated. Trial registration: ClinicalTrials.gov NCT02550132. Registered
The Neuromuscular Response to Spinal Manipulation in the Presence of Pain
Journal of manipulative and physiological therapeutics, 2016
The purpose of this study was to evaluate differences in muscle activity in participants with and without low back pain during a side-lying lumbar diversified spinal manipulation. Surface and indwelling electromyography at eight muscle locations were recorded during lumbar side-lying manipulations in 20 asymptomatic participants and 20 participants with low back pain. The number of muscle responses and muscle activity onset delays in relation to the manipulation impulse were compared in the 2 pain groups using mixed linear regressions. Effect sizes for all comparisons were calculated using Cohen's d. Muscle responses occurred in 61.6% ± 23.6% of the EMG locations in the asymptomatic group and 52.8% ± 26.3% of the symptomatic group. The difference was not statistically significant but there was a small effect of pain (d = 0.350). Muscle activity onset delays were longer for the symptomatic group at every EMG location except the right side indwelling L5 electrode, and a small effe...
Spinal Reflex Attenuation Associated With Spinal Manipulation
Spine, 2000
Study Design. This study evaluated the effect of lumbosacral spinal manipulation with thrust and spinal mobilization without thrust on the excitability of the alpha motoneuronal pool in human subjects without low back pain. Objectives. To investigate the effect of high velocity, low amplitude thrust, or mobilization without thrust on the excitability of the alpha motoneuron pool, and to elucidate potential mechanisms in which manual procedures may affect back muscle activity. Summary of Background Data. The physiologic mechanisms of spinal manipulation are largely unknown. It has been proposed that spinal manipulation may reduce back muscle electromyographic activity in patients with low back pain. Although positive outcomes of spinal manipulation intervention for low back pain have been reported in clinical trials, the mechanisms involved in the amelioration of symptoms are unknown. Methods. In this study, 17 nonpatient human subjects were used to investigate the effect of spinal manipulation and mobilization on the amplitude of the tibial nerve Hoffmann reflex recorded from the gastrocnemius muscle. Reflexes were recorded before and after manual spinal procedures. Results. Both spinal manipulation with thrust and mobilization without thrust significantly attenuated alpha motoneuronal activity, as measured by the amplitude of the gastrocnemius Hoffmann reflex. This suppression of motoneuronal activity was significant (P Ͻ 0.05) but transient, with a return to baseline values exhibited 30 seconds after intervention. Conclusions. Both spinal manipulation with thrust and mobilization without thrust procedures produce a profound but transient attenuation of alpha motoneuronal excitability. These findings substantiate the theory that manual spinal therapy procedures may lead to short-term inhibitory effects on the human motor system.
Journal of manipulative and physiological therapeutics, 2014
Previous studies have identified preload forces and an important feature of skillful execution of spinal manipulative therapy (SMT) as performed by manual therapists (eg, doctors of chiropractic and osteopathy). It has been suggested that applying a gradual force before the thrust increases the spinal unit stiffness, minimizing displacement during the thrust. Therefore, the main objective of this study was to assess the vertebral unit biomechanical and neuromuscular responses to a graded increase of preload forces. Twenty-three participants underwent 4 different SMT force-time profiles delivered by a servo-controlled linear actuator motor and varying in their preload forces, respectively, set to 5, 50, 95, and 140N in 1 experimental session. Kinematic markers were place on T6, T7, and T8 and electromyographic electrodes were applied over paraspinal muscles on both sides of the spine. Increasing preload forces led to an increase in neuromuscular responses of thoracic paraspinal muscl...
Journal of Manipulative and Physiological Therapeutics, 2013
Objective: The main objective of this report is to present an innovative research tool that will provide the opportunity to study fundamental aspects of the spinal manipulation dose-physiological response relation in humans. Methods: A servo-controlled linear actuator motor was developed to simulate spinal manipulative therapy. Coefficient of multiple correlations was calculated to assess the degree of similarity between each measured force curves, whereas precision was obtained by comparing resulting peak force and time-to-peak force to the target curves. Results: The coefficient of multiple correlations calculations showed that repeatability was very high with all correlation values over 0.98. Precision was also very high with average differences in peak force and time-to-peak force of less than 3 N and less than 5 milliseconds. Conclusion: The tool was designed to optimize precision, repeatability, and safety in the delivery of force to the spine in humans. It offers a unique opportunity to study dose-response relationship for several spinal manipulation parameters such as peak force, time-to-peak force, and preload.
Effects of biomechanical parameters of spinal manipulation: A critical literature review
Journal of Integrative Medicine, 2022
Spinal manipulation is a manual treatment technique that delivers a thrust, using specific biomechanical parameters to exert its therapeutic effects. These parameters have been shown to have a unique dose-response relationship with the physiological responses of the therapy. So far, however, there has not been a unified approach to standardize these biomechanical characteristics. In fact, it is still undetermined how they affect the observed clinical outcomes of spinal manipulation. This study, therefore, reviewed the current body of literature to explore these dosage parameters and evaluate their significance, with respect to physiological and clinical outcomes. From the experimental studies reviewed herein, it is evident that the modulation of manipulation's biomechanical parameters elicits transient physiological responses, including changes in neuronal activity, electromyographic responses, spinal stiffness, muscle spindle responses, paraspinal muscle activity, vertebral displacement, and segmental and intersegmental acceleration responses. However, to date, there have been few clinical trials that tested the therapeutic relevance of these changes. In addition, there were some inherent limitations in both human and animal models due to the use of mechanical devices to apply the thrust. Future studies evaluating the effects of varying biomechanical parameters of spinal manipulation should include clinicians to deliver the therapy in order to explore the true clinical significance of the dose-response relationship.
Journal of Manipulative and Physiological Therapeutics, 2000
Objective: The objective of this study was to determine whether mechanical force, manually-assisted (MFMA) spinal manipulative therapy (SMT) affects paraspinal muscle strength as assessed through use of surface electromyography (sEMG). Design: Prospective clinical trial comparing sEMG output in 1 active treatment group and 2 control groups. Setting: Outpatient chiropractic clinic, Phoenix, AZ. Subjects: Forty subjects with low back pain (LBP) participated in the study. Twenty patients with LBP (9 females and 11 males with a mean age of 35 years and 51 years, respectively) and 20 age-and sex-matched sham-SMT/control LBP subjects (10 females and 10 males with a mean age of 40 years and 52 years, respectively) were assessed. Methods: Twenty consecutive patients with LBP (SMT treatment group) performed maximum voluntary contraction (MVC) isometric trunk extensions while lying prone on a treatment table. Surface, linear-enveloped sEMG was recorded from the erector spinae musculature at L3 and L5 during a trunk extension procedure. Patients were then assessed through use of the Activator Methods Chiropractic Technique protocol, during which time they were treated through use of MFMA SMT. The MFMA SMT treatment was followed by a dynamic stiffness and algometry assessment, after which a second or post-MVC isometric trunk extension and sEMG assessment were performed. Another 20 consecutive subjects with LBP were assigned to one of two other groups, a sham-SMT group and a control group. The sham-SMT group underwent the same experimental protocol with the exception that the subjects received a sham-MFMA SMT and dynamic stiffness assessment. The control group subjects received no SMT treatment, stiffness assessment , or algometry assessment intervention. Within-group analysis of MVC sEMG output (pre-SMT vs post-SMT sEMG output) and across-group analysis of MVC sEMG output ratio (post-SMT sEMG/pre-SMT sEMG output) during MVC was performed through use of a paired observations t test (POTT) and a robust analysis of variance (RANOVA), respectively. Main Outcome Measures: Surface, linear-enveloped EMG recordings during isometric MVC trunk extension were used as the primary outcome measure. Results: Nineteen of the 20 patients in the SMT treatment group showed a positive increase in sEMG output during MVC (range,-9.7% to 66.8%) after the active MFMA SMT treatment and stiffness assessment. The SMT treatment group showed a significant (POTT, P < .001) increase in erector spinae muscle sEMG output (21% increase in comparison with pre-SMT levels) during MVC isometric trunk extension trials. There were no significant changes in pre-SMT vs post-SMT MVC sEMG output for the sham-SMT (5.8% increase) and control (3.9% increase) groups. Moreover, the sEMG output ratio of the SMT treatment group was significantly greater (robust analysis of variance, P = .05) than either that of the sham-SMT group or that of the control group. Conclusions: The results of this preliminary clinical trial demonstrated that MFMA SMT results in a significant increase in sEMG erector spinae isometric MVC muscle output. These findings indicate that altered muscle function may be a potential short-term therapeutic effect of MFMA SMT, and they form a basis for a randomized, controlled clinical trial to further investigate acute and long-term changes in low back function.
Spinal manipulation causes variable spine kinematic and trunk muscle electromyographic responses
Clinical Biomechanics, 2001
Study design. Analytic cohort with a convenience sample in a research clinic.Objectives. To determine the influence of a spinal manipulation on trunk kinematics and associated trunk myoelectric activity.Summary of background. While the mechanism of spinal manipulation is unknown, it has been theorized to influence spinal range of motion and trunk muscle activity.Methods. Trunk kinematics were measured in low back pain patients (n=14) during simple range of motion tasks in three planes, while trunk muscle electromyogram signals were recorded bilaterally from paraspinal and abdominal musculature. Kinematics and electromyogram signals were assessed pre–post manipulation. Electromyogram activity was also assessed pre–post manipulation during quiet stance.Results. While no consistent kinematic or electromyographic changes occurred following manipulation across the population, individual changes were observed. The largest changes (>6°) in range of motion occurred in the sagittal plane of three patients experiencing the greatest amount of pain. During quiet stance 17 muscles across all subjects exhibited changes in muscle activity following manipulation. Sixteen of those changes were decreases in muscle amplitude.Conclusions. This study offers some preliminary data on the short-term effects of manipulation on lumbar range of motion and dynamic electromyogram. The findings suggest that the response to manipulation is variable and dependent on the individual, with no change in some to the largest changes seen in the more pained patients.RelevanceBasic science investigations into the mechanisms and biomechanical influences of spinal manipulation are few. This study attempts to address issues of measureable functional change with manipulative therapy.