Evaluation of the effect of postural perturbation on motoneuronal activity following various methods of lumbar spinal manipulation

The effect of lumbar spinal manipulation on biomechanical factors and perceived transient pain during prolonged sitting: a laboratory-controlled cross-sectional study

BACKGROUND

Spinal manipulation has been shown to affect muscle activity, posture, and pain. To date, no studies have examined the effect of manipulation on biomechanical factors during sitting. Therefore, the purpose of this study was to investigate the immediate effect of lumbar spinal manipulation on trunk muscle activation, spine posture and movements, and perceived ratings of transient pain in asymptomatic adults during prolonged office sitting.

METHODS

Twenty healthy adults were recruited for a single laboratory session that included a standardized office sitting/data entry protocol (120 min total, 3 blocks of 40 min). Data were collected between July and August 2012. The first block (baseline) was immediately followed by two experimental blocks. Prior to the start of each experimental block, participants were transferred to a therapy plinth and placed side lying (right side down), and a random presentation of either a control or high velocity low amplitude thrust directed at L4/L5 was delivered. Continuous measures of muscle activity, spine posture, and spine movements were recorded throughout the sitting trials. Perceived transient pain was measured by visual analogue scale at 10-min intervals (including immediately before and after the randomized maneuvers).

RESULTS

There were no significant differences in spine or pelvic posture or perceived back pain following either the manipulation or control maneuvers. Significantly reduced muscle activity and increased shifts of the lumbar spine angle were identified in the block following manipulation compared to both baseline and post control blocks.

CONCLUSIONS

Spinal manipulation does not appear to have an immediate impact on spine or pelvic posture in healthy adults but does appear to reduce muscle activity and increase spine movement during sitting. Future work should replicate this study with a larger population in a field setting. It may be worthwhile to explore the implication of reduced muscle activation and increased spine movements during prolonged sitting for office workers that receive manipulations or mobilizations during their workday.

The passive voice and comprehensibility of biomedical texts: An experimental study with 2 cohorts of chiropractic students

OBJECTIVE:

Authors in the health sciences are encouraged to write in the active voice in the belief that this enhances comprehensibility. Hence, the purpose of this study was to compare objectively measured and subjectively perceived comprehensibility of texts in which one voice or the other was highly prevalent.

METHODS:

Objectively rated comprehensibility was obtained by presenting 161 2nd-year chiropractic students with questions pertaining to 2 methods sections of biomedical articles, each presented in its original form with high prevalence of the passive voice, and in a manipulated form with all main verbs in the active voice. The difficulties and sensitivities of questions were compared for the 2 forms of each text. Comprehensibility was obtained by asking students to rate the comprehensibility of authentic sentences from biomedical manuscripts and matched manipulated form in which the voice of the main verb had been changed. Differences in comprehensibility between the 2 texts were assessed with a dependent t test.

RESULTS:

There were no significant differences in the difficulties or sensitivities of questions pertaining to the 2 original texts written in the passive voice versus the active voice ( p > .35 for all comparisons). Students rated sentences written in the passive voice as marginally more comprehensible than sentences written in the active voice ( p = .003 per 2-tailed paired t test).

CONCLUSION:

The texts written in the active voice were not more comprehensible than texts written in the passive voice. The results of this study do not support editorial guidelines that favor active voice over passive voice.

Motor Neuron Excitability Attenuation as a Sequel to Lumbosacral Manipulation in Subacute Low Back Pain Patients and Asymptomatic Adults: A Cross-Sectional H-Reflex Study

OBJECTIVE

The purpose of the study was to compare a time series of tibial nerve H-reflex trials between patients with subacute low back pain (LBP) and asymptomatic adults using pre and post high-velocity, low-amplitude (HVLA) spinal manipulation (SM) and control procedures.

METHODS

Asymptomatic adults (n = 66) and patients with subacute LBP (n = 45) were randomized into 3 lumbosacral procedures: side-posture positioning, joint preloading with no thrust, and HVLA SM. A time series of 40 H_max/M_max ratios at a rate of 0.1 Hz were recorded in blocks of 10 trials at baseline and after the lumbosacral procedures at time points corresponding to immediately after, 5 minutes after, and 10 minutes after the procedure. Descriptive time series analysis techniques included time plots, outlier detection, and autocorrelation functions. A mixed analysis of variance model (group × procedure × time) was used to compare the effects of lumbosacral procedures on H_max/M_max ratios between the patients with subacute LBP and asymptomatic participants.

RESULTS

The time series analysis and the significant lumbosacral × time interaction term (P < .05) indicated that inhibition of the H_max/M_max ratios at the 10-second postlumbosacral procedure time point was greatest after the HVLA SM procedure. The effects of lumbosacral procedures on H_max/M_max ratios were similar between patients with subacute LBP and asymptomatic participants.

CONCLUSIONS

Although nonspecific effects of movement or position artifacts on the H_max/M_max ratio were present, a reliable and valid attenuation of the H_max/M_max ratio occurred as a specific aspect of HVLA SM in both asymptomatic adults and patients with subacute LBP.

Grade-IV inferior glenohumeral mobilization does not immediately alter shoulder and scapular muscle activity: a repeated-measures study in asymptomatic individuals

OBJECTIVES

To assess: (1) the presence of any carry-over effect between interventions; (2) the immediate effects of inferior shoulder mobilization on shoulder and scapular muscle activity; and (3) to compare muscle activity response between the control and mobilization conditions. Repeated measures, cross-over, pre-post intervention study with sample of convenience.

METHODS

Twenty-two asymptomatic individuals performed 10 repetitions of shoulder abduction before and after the control and mobilization, with a dosage of three sets of 30-s duration, with grade-IV. The order of intervention was randomized. Surface electromyography was used for recording activity of upper and lower trapezius; anterior, middle and posterior deltoids; supraspinatus; infraspinatus; and serratus anterior. Repeated measures mixed-model analysis of variance was used to assess immediate changes in muscle activity levels following inferior shoulder mobilization. Statistical parametric mapping (SPM) was used for comparing muscle activity waveforms between control and mobilization conditions throughout the range of motion.

RESULTS

No systematic changes in muscle activity levels were found between: (1) baseline and follow-up for each condition, at the concentric and eccentric phases of shoulder abduction; (2) control and mobilization conditions during the concentric and eccentric phases of shoulder abduction. SPM results suggested no differences in muscle activity pattern between conditions.

CONCLUSIONS

Inferior shoulder mobilization did not produce immediate effects on shoulder and scapular muscle activity. It is possible that the dose used was insufficient to generate an immediate neuromuscular response to the mobilization.

Characteristics of Paraspinal Muscle Spindle Response to Mechanically Assisted Spinal Manipulation: A Preliminary Report

OBJECTIVES

The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices.

METHODS

L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAM thrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included (a) the time required post-thrust until the first action potential, (b) differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and (c) the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM.

RESULTS

Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required >6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in <6 seconds after MAM. Nonparametric comparisons between the 22 N and 44 N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF.

CONCLUSION

Short duration (<10 ms) MAM thrusts decrease muscle spindle discharge with a majority of afferents requiring prolonged periods (>6 seconds) to return to baseline MF activity. Physiological consequences and clinical relevance of described MAM mechanoreceptor responses will require additional investigation.

Chiropractic Identity: A Neurological, Professional, and Political Assessment

OBJECTIVE

The purpose of this article is to propose a focused assessment of the identity of chiropractic and its profession, triangulating multiple viewpoints converging upon various aspects and definitions of neurology, manual medicine, and alternative or mainstream medicine.

DISCUSSION

Over 120 years since its inception, chiropractic has struggled to achieve an identity for which its foundations could provide optimal health care. Despite recognition of the benefits of spinal manipulation in various government guidelines, advances in US military and Veterans Administration, and persistently high levels of patient satisfaction, the chiropractic profession remains underrepresented in most discussions of health care delivery. Distinguishing characteristics of doctors of chiropractic include the following: (1) they embrace a model of holistic, preventive medicine (wellness); (2) they embrace a concept of neurological imbalance in which form follows function, disease follows disturbed biochemistry, and phenomenology follows physiology; (3) they diagnose, and their institutions of training are accredited by a body recognized by the US Department of Education; (4) they manage patients on a first-contact basis, often as primary care providers in geographical areas that are underserved; (5) the spine is their primary-but not exclusive-area of interaction; (6) they deliver high-velocity, low-amplitude adjustments with a superior safety record compared with other professions; and (7) they use a network of institutions worldwide that have shown increasing commitments to research.

CONCLUSION

This article provides an overview of chiropractic identity from 6 points of view: (1) concepts of manual medicine; (2) areas of interest beyond the spine; (3) concepts of the chiropractic subluxation; (4) concepts of neurology; (5) concepts of mainstream or alternative health care; and (6) concepts of primary care, first-contact provider, or specialist.

Fibular taping does not alter lower extremity spinal reflex excitability in individuals with chronic ankle instability

OBJECTIVE

To determine changes in spinal reflex excitability of the soleus and fibularis longus muscles before and after fibular taping intervention.

METHODS

Twenty-one individuals (age = 23.4 ± 2.7 y, height = 171.0 ± 12.8 cm, mass = 69.7 ± 11.8 kg) with chronic ankle instability (CAI) and at least 5° ankle dorsiflexion asymmetry volunteered for this randomised crossover design study. Each participant received a fibular taping with tension or fibular taping without tension during separate sessions. Spinal reflex excitability of the soleus and fibularis longus was determined by obtaining maximum values for H-reflex (Hoffmann reflex) and maximum compound muscle action potential (Mmax), which was expressed as a ratio (H/M ratio). Measures were obtained immediately before and after a fibular taping intervention.

RESULTS

The application of tape to the fibula, regardless of tension, did not produce a change in spinal reflex excitability for the soleus (F1,39 = .01, P = .91) or fibularis longus (F1,39 = .001, P = .99).

CONCLUSIONS

Fibular taping with and without tension did not result in an immediate change in spinal reflex excitability of the soleus or fibularis longus in individuals with CAI. Although fibular taping has been shown to reduce recurrent ankle sprains in individuals with CAI, the mechanism of effectiveness may not involve an immediate increase in spinal reflex excitability.

Immediate changes after manual therapy in resting-state functional connectivity as measured by functional magnetic resonance imaging in participants with induced low back pain

OBJECTIVE

The purposes of this study were to use functional magnetic resonance imaging to investigate the immediate changes in functional connectivity (FC) between brain regions that process and modulate the pain experience after 3 different types of manual therapies (MT) and to identify reductions in experimentally induced myalgia and changes in local and remote pressure pain sensitivity.

METHODS

Twenty-four participants (17 men; mean age ± SD, 21.6 ± 4.2 years) who completed an exercise-injury protocol to induce low back pain were randomized into 3 groups: chiropractic spinal manipulation (n = 6), spinal mobilization (n = 8), or therapeutic touch (n = 10). The primary outcome was the immediate change in FC as measured on functional magnetic resonance imaging between the following brain regions: somatosensory cortex, secondary somatosensory cortex, thalamus, anterior and posterior cingulate cortices, anterior and poster insula, and periaqueductal gray. Secondary outcomes were immediate changes in pain intensity, measured with a 101-point numeric rating scale, and pain sensitivity, measured with a handheld dynamometer. Repeated-measures analysis of variance models and correlation analyses were conducted to examine treatment effects and the relationship between within-person changes across outcome measures.

RESULTS

Changes in FC were found between several brain regions that were common to all 3 MT interventions. Treatment-dependent changes in FC were also observed between several brain regions. Improvement was seen in pain intensity after all interventions (P < .05) with no difference between groups (P > .05). There were no observed changes in pain sensitivity, or an association between primary and secondary outcome measures.

CONCLUSION

These results suggest that MTs (chiropractic spinal manipulation, spinal mobilization, and therapeutic touch) have an immediate effect on the FC between brain regions involved in processing and modulating the pain experience. This suggests that neurophysiologic changes after MT may be an underlying mechanism of pain relief.

Feasibility of using the patient-reported outcomes measurement information system in academic health centers: case series design on pain reduction after chiropractic care

OBJECTIVE

The purpose of this study was to test the utility of Patient-Reported Outcomes Measurement Information System (PROMIS) as a resource for collecting data on patient-reported outcomes (PRO) within academic health centers at a chiropractic college; and, to describe changes in PRO following pragmatic chiropractic care incorporating instrument-assisted soft tissue mobilization (IASTM) on pain symptoms.

METHODS

This was a pre-post intervention design without a control group (case series) involving 25 patients (14 females and 11 males; 40.5 ± 16.39 years, range 20-70 years) who completed their chiropractic care and their baseline and post-treatment pain assessments. The pragmatic chiropractic care intervention included both spinal manipulation and IASTM to treat pain symptoms. PRO's were collected using PROMIS to measure pain behavior, pain interference and pain intensity.

RESULTS

The average pre-post assessment interval was 33 ± 22.5 days (95% CI, 23-42 days). The durations of treatments ranged from one week to 10 weeks. The median number of IASTM treatments was six. Pre-post decreases in T-scores for pain behavior and pain interference were 55.5 to 48.4 and 57.7 to 48.4, respectively (P < .05). Only 12 patients had a baseline T-score for pain intensity greater than 50. The pre-post decrease in pain intensity T-scores for these 12 patients was from 53.4 to 40.9.

CONCLUSION

Within the limitations of a case series design, these data provide initial evidence on the utility of PROMIS instruments for clinical and research outcomes in chiropractic patients.

Manual therapy directed at the knee or lumbopelvic region does not influence quadriceps spinal reflex excitability

Manual therapies, directed to the knee and lumbopelvic region, have demonstrated the ability to improve neuromuscular quadriceps function in individuals with knee pathology. It remains unknown if manual therapies may alter impaired spinal reflex excitability, thus identifying a potential mechanism in which manual therapy may improve neuromuscular function following knee injury.

AIM

To determine the effect of local and distant mobilisation/manipulation interventions on quadriceps spinal reflex excitability.

METHODS

Seventy-five individuals with a history of knee joint injury and current quadriceps inhibition volunteered for this study. Participants were randomised to one of five intervention groups: lumbopelvic manipulation (grade V), lumbopelvic manipulation positioning (no thrust), grade IV patellar mobilisation, grade I patellar mobilisation, and control (no treatment). Changes in spinal reflex excitability were quantified by assessing the Hoffmann reflex (H-reflex), presynaptic, and postsynaptic excitability. A hierarchical linear-mixed model for repeated measures was performed to compare changes in outcome variables between groups over time (pre, post 0, 30, 60, 90 min).

RESULTS

There were no significant differences in H-reflex, presynaptic, or postsynaptic excitability between groups across time.

CONCLUSIONS

Manual therapies directed to the knee or lumbopelvic region did not acutely change quadriceps spinal reflex excitability. Although manual therapies may improve impairments and functional outcomes the underlying mechanism does not appear to be related to changes in spinal reflex excitability.

Effects of thrust amplitude and duration of high-velocity, low-amplitude spinal manipulation on lumbar muscle spindle responses to vertebral position and movement

OBJECTIVE

Mechanical characteristics of high-velocity, low-amplitude spinal manipulations (HVLA-SMs) can vary. Sustained changes in peripheral neuronal signaling due to altered load transmission to a sensory receptor's local mechanical environment are often considered a mechanism contributing to the therapeutic effects of spinal manipulation. The purpose of this study was to determine whether variation in an HVLA-SM's thrust amplitude and duration alters the neural responsiveness of lumbar muscle spindles to either vertebral movement or position.

METHODS

Anesthetized cats (n = 112) received L6 HVLA-SMs delivered to the spinous process. Cats were divided into 6 cohorts depending upon the peak thrust force (25%, 55%, 85% body weight) or thrust displacement (1, 2, 3 mm) they received. Cats in each cohort received 8 thrust durations (0-250 milliseconds). Afferent discharge from 112 spindles was recorded in response to ramp and hold vertebral movement before and after the manipulation. Changes in mean instantaneous frequency (∆MIF) during the baseline period preceding the ramps (∆MIFresting), during ramp movement (∆MIFmovement), and with the vertebra held in the new position (∆MIFposition) were compared.

RESULTS

Thrust duration had a small but statistically significant effect on ∆MIFresting at all 6 thrust amplitudes compared with control (0-millisecond thrust duration). The lowest amplitude thrust displacement (1 mm) increased ∆MIFresting at all thrust durations. For all the other thrust displacements and forces, the direction of change in ∆MIFresting was not consistent, and the pattern of change was not systematically related to thrust duration. Regardless of thrust force, displacement, or duration, ∆MIFmovement and ∆MIFposition were not significantly different from control.

CONCLUSION

Relatively low-amplitude thrust displacements applied during an HVLA-SM produced sustained increases in the resting discharge of paraspinal muscle spindles regardless of the duration over which the thrust was applied. However, regardless of the HVLA-SM's thrust amplitude or duration, the responsiveness of paraspinal muscle spindles to vertebral movement and to a new vertebral position was not affected.

Understanding inhibitory mechanisms of lumbar spinal manipulation using H-reflex and F-wave responses: a methodological approach

The purpose of this research was to characterize unique neurophysiologic events following a high velocity, low amplitude (HVLA) spinal manipulation (SM) procedure. Descriptive time series analysis techniques of time plots, outlier detection and autocorrelation functions were applied to time series of tibial nerve H-reflexes that were evoked at 10-s intervals from 100 s before the event until 100 s after three distinct events L5-S1 HVLA SM, or a L5-S1 joint pre-loading procedure, or the control condition. Sixty-six subjects were randomly assigned to three procedures, i.e., 22 time series per group. If the detection of outliers and correlograms revealed a pattern of non-randomness that was only time-locked to a single, specific event in the normalized time series, then an experimental effect would be inferred beyond the inherent variability of H-reflex responses. Tibial nerve F-wave responses were included to determine if any new information about central nervous function following a HVLA SM procedure could be ascertained. Time series analyses of H(max)/M(max) ratios, pre-post L5-S1 HVLA SM, substantiated the hypothesis that the specific aspects of the manipulative thrust lead to a greater attenuation of the H(max)/M(max) ratio as compared to the non-specific aspects related to the postural perturbation and joint pre-loading. The attenuation of the H(max)/M(max) ratio following the HVLA SM procedure was reliable and may hold promise as a translational tool to measure the consistency and accuracy of protocol implementation involving SM in clinical trials research. F-wave responses were not sensitive to mechanical perturbations of the lumbar spine.

Lumbopelvic joint manipulation and quadriceps activation of people with patellofemoral pain syndrome

CONTEXT

Quadriceps weakness and inhibition are impairments associated with patellofemoral pain syndrome (PFPS). Lumbopelvic joint manipulation has been shown to improve quadriceps force output and inhibition, but the duration of the effect is unknown.

OBJECTIVE

To determine whether quadriceps strength and activation are increased and maintained for 1 hour after high-grade or low-grade joint mobilization or manipulation applied at the lumbopelvic region in people with PFPS.

DESIGN

Randomized controlled clinical trial.

SETTING

University laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty-eight people with PFPS (age = 24.6 ± 8.9 years, height = 174.3 ± 11.2 cm, mass = 78.4 ± 16.8 kg) participated.

INTERVENTION(S)

Participants were randomized to 1 of 3 groups: lumbopelvic joint manipulation (grade V), side-lying lumbar midrange flexion and extension passive range of motion (grade II) for 1 minute, or prone extension on the elbows for 3 minutes.

MAIN OUTCOME MEASURE(S)

Quadriceps force and activation were measured using the burst superimposition technique during a seated isometric knee extension task. A 2-way repeated-measures analysis of variance was performed to compare changes in quadriceps force and activation among groups over time (before intervention and at 0, 20, 40, and 60 minutes after intervention).

RESULTS

We found no differences in quadriceps force output (F(5.33,101.18) = 0.65, P = .67) or central activation ratio (F(4.84,92.03) = 0.38, P = .86) values among groups after intervention. When groups were pooled, we found differences across time for quadriceps force (F(2.66,101.18) = 5.03, P = .004) and activation (F(2.42,92.03) = 3.85, P = .02). Quadriceps force was not different at 0 minutes after intervention (t(40) = 1.68, P = .10), but it decreased at 20 (t(40) = 2.16, P = .04), 40 (t(40) = 2.87, P = .01) and 60 (t(40) = 3.04, P = .004) minutes after intervention. All groups demonstrated decreased quadriceps activation at 0 minutes after intervention (t(40) = 4.17, P < .001), but subsequent measures were not different from preintervention levels (t(40) range, 1.53-1.83, P > .09).

CONCLUSIONS

Interventions directed at the lumbopelvic region did not have immediate effects on quadriceps force output or activation. Muscle fatigue might have contributed to decreased force output and activation over 1 hour of testing.

Comparison of the effectiveness of three manual physical therapy techniques in a subgroup of patients with low back pain who satisfy a clinical prediction rule: a randomized clinical trial

STUDY DESIGN

Randomized clinical trial.

OBJECTIVE

The purpose of this randomized clinical trial was to examine the generalizability of 3 different manual therapy techniques in a patient population with low back pain that satisfy a clinical prediction rule (CPR).

SUMMARY OF BACKGROUND DATA

Recently a CPR that identifies patients with LBP who are likely to respond rapidly and dramatically to thrust manipulation has been developed and validated. The generalizability of the CPR requires further investigation.

METHODS

A total of 112 patients were enrolled in the trial and provided demographic information and completed a number of self-report questionnaires including the Oswestry Disability Questionnaire (ODQ) and the Numerical Pain Rating Scale (NPRS) at baseline, 1-week, 4-weeks, and 6-months. Patients were randomly assigned to receive 1 of the 3 manual therapy techniques for 2 consecutive treatment sessions followed by exercise regimen for an additional 3 sessions. We examined the primary aim using a linear mixed model for repeated measures, using the ODQ and NPRS as dependent variables. The hypothesis of interest was the group by time interaction, which was further explored with pair-wise comparisons of the estimated marginal means.

RESULTS

There was a significant group x time interaction for the ODQ (P < 0.001) and NPRS scores (P = 0.001). Pair-wise comparisons revealed no differences between the supine thrust manipulation and side-lying thrust manipulation at any follow-up period. Significant differences in the ODQ and NPRS existed at each follow-up between the thrust manipulation and the nonthrust manipulation groups at 1-week and 4-weeks. There was also a significant difference in ODQ scores at 6-months in favor of the thrust groups.

CONCLUSION

The results of the study support the generalizability of the CPR to another thrust manipulation technique, but not to the nonthrust manipulation technique that was used in this study. In general, our results also provided support that the CPR can be generalized to different settings from which it was derived and validated. However, additional research is needed to examine this issue.

Effects of lumbopelvic joint manipulation on quadriceps activation and strength in healthy individuals

Lumbopelvic joint manipulation has been shown to increase quadriceps force output and activation, but the duration of effect is unknown. It is also unknown whether lower grade joint mobilisations may have a similar effect. Forty-two healthy volunteers (x+/-SD; age=28.3+/-7.3 yr; ht=172.8+/-9.8 cm; mass=76.6+/-21.7 kg) were randomly assigned to one of three groups (lumbopelvic joint manipulation, 1 min lumbar passive range of motion (PROM), or prone extension on elbows for 3 min). Quadriceps force and activation were measured using the burst-superimposition technique during a seated isometric knee extension task before and at 0, 20, 40, and 60 min following intervention. Collectively, all groups demonstrated a significant decrease (p<0.001) in quadriceps force output without changes in activation (p>0.05) at all time intervals following intervention. The group that received a lumbopelvic joint manipulation demonstrated a significant increase in quadriceps force (3%) and activation (5%) (p<0.05) immediately following intervention, but this effect was not present after the 20 min interval. Since participants in this study were free of knee joint pathology, it is possible that they did not have the capacity to allow for large changes in quadriceps muscle activation to occur.

Motor-evoked potentials recorded from lumbar erector spinae muscles: a study of corticospinal excitability changes associated with spinal manipulation

OBJECTIVE

The purpose of this study was to determine if high-velocity, low-amplitude spinal manipulation (SM) altered the effects of corticospinal excitability on motoneuron activity innervating the paraspinal muscles. In a previous study using transcranial magnetic stimulation (TMS), augmentation of motor-evoked potentials (MEPs) from the gastrocnemius muscle after lumbar SM was reported. To date, there is no known report of the effect of SM on paraspinal muscle excitability.

METHODS

The experimental design was a prospective physiologic evaluation of the effects of SM on corticospinal excitability in asymptomatic subjects. The TMS-induced MEPs were recorded from relaxed lumbar erector spinae muscles of 72 asymptomatic subjects. The MEP amplitudes were evaluated pre-SM and post-SM or conditions involving prethrust positioning and joint loading or control.

RESULTS

There was a transient increase in MEP amplitudes from the paraspinal muscles as a consequence of lumbar SM (F([6,414]) = 8.49; P < .05) without concomitant changes after prethrust positioning and joint loading or in control subjects (P > .05). These data findings were substantiated by a significant condition x time interaction term (F([12,414]) = 2.28; P < .05).

CONCLUSIONS

These data suggest that there is a postsynaptic facilitation of alpha motoneurons and/or corticomotoneurons innervating paraspinal muscles as a consequence of SM. It appears that SM may offer unique sensory input to the excitability of the motor system as compared to prethrust positioning and joint loading and control conditions.

The 2005 Conference on the Biology of Manual Therapies

A historic and critically important scientific workshop for all professions involved with manual therapies was held at the National Institutes of Health (NIH) on June 9 and 10, 2005. The conference was jointly sponsored and organized by the NIH and the Canadian Institutes of Health Research and was the first ever national or international research conference to focus on the biologic mechanisms that underlie a broad range of interventions, which can be described as "manual therapies." Leading scientific experts from North America and Europe presented their latest findings and theories related to 5 different areas of science relevant to manual therapies: neuroscience, biomechanics, endocrinology, imaging, and immunology. During the conference, breakout groups composed of scientists, physicians and therapists, and patient advocates were formed in the relevant disciplines. These groups developed consensus statements on key unanswered research questions, which were then submitted back to the conference for comment and approval. The outcomes of this workshop have subsequently been incorporated into a new initiative by the NIH and Canadian Institutes of Health Research for funding research on the biology of manual therapies. This editorial includes presentation summaries and 13 key consensus recommendations relating to mechanisms of action for manual therapies.