Comparison of tibial nerve H-reflex excitability after cervical and lumbar spine manipulation

Electromyographic Responses of Neck, Back, and Limb Outlet Muscles Associated With High-Velocity, Low-Amplitude Manual Cervical and Upper Thoracic Spinal Manipulation of Individuals With Mild Neck Disability: A Descriptive Observational Investigation

OBJECTIVES

The purpose of this study was to investigate the extent of electromyographic responses associated with manual high-velocity, low-amplitude (HVLA) spinal manipulation systematically applied to the upper and lower cervical and upper thoracic spines in a cohort with mild neck disability.

METHODS

The study was a descriptive observational investigation, with all participants receiving the same interventions. Nineteen participants with mild neck disability received 6 manual HVLA manipulations to the cervical and upper thoracic spine. Bipolar surface electromyography electrode pairs were used to measure responses of 16 neck, back, and limb outlet muscles bilaterally. The number of electromyographic responses was then calculated.

RESULTS

Electromyographic responses associated with cervical and thoracic manipulation occurred in a median of 4 of the 16 (range: 1-14) recorded muscles. Cervical spinal manipulation was associated with the highest rates of electromyographic responses in neck muscles, whereas responses in back muscles were highest after upper thoracic manipulation.

CONCLUSION

Cervical spinal manipulation was associated with the highest rate of electromyographic responses in muscles of the cervical spine (sternocleidomastoid and splenius cervicis), whereas responses in back muscles (upper and middle trapezius, latissimus dorsi, and longissimus thoracis) were highest after upper thoracic manipulations. This result suggests that electromyographic muscular responses associated with spinal manipulation primarily occur locally (close to the target segment) rather than distally.

Short-Term Effects of Global Pelvic Manipulation on Knee Joint Position Sense in Asymptomatic Participants: A Double-Blind Randomized Controlled Trial

OBJECTIVE

The purpose of this study was to evaluate short-term effects of the global pelvic manipulation (GPM) on knee joint position sense (JPS).

METHODS

This randomized, controlled double-blind trial included 26 asymptomatic participants (X¯± 25.3; standard deviation ± 4.4 years) who were randomly allocated into 2 groups. Sixteen participants were allocated into the experimental group, in which GPM was performed, and the rest of the participants (n = 10) were included in the control group, which received sham ultrasound therapy. Each participant attended 1 session only, and the evaluations were assessed pretreatment and 5 minutes posttreatment through an isokinetic dynamometer (Biodex Medical Systems), in which the data regarding knee JPS ipsilateral to the manipulated sacroiliac joint were collected. Mann-Whitney and Wilcoxon tests were used, with a 95% significance level.

RESULTS

There were no statistically significant differences between the groups concerning active and passive JPS at 30° and 60° (P > .05). The results showed a lack of significant differences between the moments in both groups (P > .05).

CONCLUSION

This investigation demonstrated that GPM, with high-velocity low-amplitude thrust, has no effect on knee JPS, suggesting that this manipulative technique does not have a relative effect on muscle spindles and Golgi tendon organ activation in asymptomatic participants.

The Immediate Effect of Spinal Manipulation on Ball Velocity and Neuromuscular Function During an Instep Kick in Former Varsity Soccer Players: A Feasibility Study

Corso, M, Liang, L, Tran, S, Howitt, S, Srbely, J, and Mior, SA. The immediate effect of spinal manipulation on ball velocity and neuromuscular function during an instep kick in former Varsity soccer players: a feasibility study. J Strength Cond Res XX(X): 000-000, 2020-Spinal manipulation (SM) has been shown to increase ball velocity (BV) in soccer players. Evidence suggests that SM modulates responses at spinal or cortical levels to enhance force production in asymptomatic populations. No studies have explored the underlying neuromuscular mechanisms contributing to changes in BV post-SM in soccer players. We assessed the feasibility of measuring change in BV and neuromuscular function after SM in former Varsity level soccer players with a pre-post study design. Three to 5 maximal instep kicks were performed before and after SM at the L3-5 level. Ball velocity was measured using high-speed camera. Activation of lower limb and trunk musculature was recorded with electromyography. Outcomes included ease of recruitment, scheduling and data capture, as well as expectation and perception of SM effect and adverse events (AE). Fifteen potential subjects were recruited over 1.5 months. Eleven were scheduled (24-31 years; 8 females, 3 males). Two subjects reported mild AE after maximal voluntary isometric contraction testing. A significant increase in BV (mean change: 1.75 m·s [95% confidence interval: 0.5-3.0]) and a trend to increased peak-activation of knee extensors (90.7%) were observed post-SM. Findings suggest that our recruitment strategy and methodology are feasible in a larger trial with some modifications. Our preliminary findings support previous research by suggesting that increased BV may be mediated through increased activation of knee extensors during the kick. Our findings may offer additional insight into the underlying neuromuscular mechanisms contributing to immediate change in BV post-SM.

A global view on how local muscular fatigue affects human performance

There is a growing interest in scientific literature on identifying how and to what extent interventions applied to a specific body region influence the responses and functions of other seemingly unrelated body regions. To investigate such a construct, it is necessary to have a global multivariate model that considers the interaction among several variables that are involved in a specific task and how a local and acute impairment affects the behavior of the output of such a model. We developed an artificial neural network (ANN)-based multivariate model by using parameters of motor skills obtained from kinematic, postural control, joint torque, and proprioception variables to assess the local fatigue effects of the abductor hip muscles on the functional profile during a single-leg drop landing and a squatting task. Findings suggest that hip abductor muscles' local fatigue produces a significant effect on a general functional profile, built on different control systems. We propose that expanded and global approaches, such as the one used in this study, have great applicability and have the potential to serve as a tool that guarantees ecological validity of future investigations.

Reflex Responses of Neck, Back, and Limb Muscles to High-Velocity, Low-Amplitude Manual Cervical and Upper Thoracic Spinal Manipulation of Asymptomatic Individuals-A Descriptive Study

OBJECTIVE

The purpose of this research was to determine the extent of reflex responses after spinal manipulative therapy (SMT) of the cervical and upper thoracic spine.

METHODS

Eleven asymptomatic participants received 6 commonly used SMTs to the cervical and upper thoracic spine. Bipolar surface electromyography electrodes were used to measure reflex responses of 16 neck, back, and proximal limb muscles bilaterally. The percentage of occurrence and the extent of reflex responses of these muscles were determined.

RESULTS

Reflex responses after cervical SMT were typically present in all neck and most back muscles, whereas responses in the outlets to the arm and leg were less frequent. This trend was similar, although decreased in magnitude, after thoracic SMT.

CONCLUSION

Reflex responses were greatest after upper cervical SMT and lowest with thoracic SMT.

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.

Acute electromyographic responses of deep thoracic paraspinal muscles to spinal manual therapy interventions. An experimental, randomized cross-over study

This single group, randomized, cross-over study explored whether manual therapy alters motor tone of deep thoracic back muscles by examining resting electromyographic activity (EMG) after 2 types of manual therapy and a sham control intervention. Twenty-two participants with thoracic spinal pain (15 females, 7 males, mean age 28.1 ± 6.4 years) had dual fine-wire, intramuscular electrodes inserted into deep transversospinalis muscles at a thoracic level where tissues appeared abnormal to palpation (AbP) and at 2 sites above and below normal and non-tender to palpation (NT). A surface electrode was on the contralateral paraspinal mass at the level of AbP. EMG signals were recorded for resting prone, two 3-s free neck extension efforts, two 3-s resisted maximal voluntary isometric contractions (MVIC), and resting prone before the intervention. Randomized spinal manipulation, counterstrain, or sham manipulation was delivered and EMG re-measured. Participants returned 1 and 2 weeks later for the remaining 2 treatments. Reductions in resting EMG followed counterstrain in AbP (median decrease 3.3%, P = 0.01) and NT sites (median decrease 1.0%, P = 0.05) and for the surface electrode site (median decrease 2.0%, P = 0.009). Reduction in EMG following counterstrain during free neck extension was found for the surface electrode site (median decrease 2.7%, P < 0.01). Spinal manipulation produced no change in EMG, whereas counterstrain technique produced small significant reductions in paraspinal muscle activity during prone resting and free neck extension conditions. The clinical relevance of these changes is unclear.

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 Care of a 10-Year-Old Boy With Nonorganic Gait Disorder: A Case Report

OBJECTIVE

The purpose of this case report is to describe the multidisciplinary management of a boy with nonorganic gait disorder.

CLINICAL FEATURES

A 10-year-old boy presented to a chiropractic clinic having had a concussion 1 week prior. He presented with lower limb muscle weakness and ataxia while weight bearing. He was referred immediately to the emergency department, from which he was sent to a neurologist at a children's hospital. The neurologist's diagnosis was nonorganic gait disorder.

INTERVENTION/OUTCOME

Treatment consisted of physiotherapy, occupational therapy, and a psychiatric assessment. Chiropractic care including manipulative therapy was initiated 6 months after diagnosis. After 1 year, the gait disorder was resolved.

CONCLUSION

The addition of chiropractic care to conventional treatment may have been supportive in the recovery process for this patient. The condition required 1 year to resolve, with questions remaining as to whether the symptom resolution was a result of treatment or natural history.

Manual and Instrument Applied Cervical Manipulation for Mechanical Neck Pain: A Randomized Controlled Trial

OBJECTIVE

The purpose of this study was to compare the effects of 2 different cervical manipulation techniques for mechanical neck pain (MNP).

METHODS

Participants with MNP of at least 1 month's duration (n = 65) were randomly allocated to 3 groups: (1) stretching (control), (2) stretching plus manually applied manipulation (MAM), and (3) stretching plus instrument-applied manipulation (IAM). MAM consisted of a single high-velocity, low-amplitude cervical chiropractic manipulation, whereas IAM involved the application of a single cervical manipulation using an (Activator IV) adjusting instrument. Preintervention and postintervention measurements were taken of all outcomes measures. Pain was the primary outcome and was measured using visual analogue scale and pressure pain thresholds. Secondary outcomes included cervical range of motion, hand grip-strength, and wrist blood pressure. Follow-up subjective pain scores were obtained via telephone text message 7 days postintervention.

RESULTS

Subjective pain scores decreased at 7-day follow-up in the MAM group compared with control (P = .015). Cervical rotation bilaterally (ipsilateral: P = .002; contralateral: P = .015) and lateral flexion on the contralateral side to manipulation (P = .001) increased following MAM. Hand grip-strength on the contralateral side to manipulation (P = .013) increased following IAM. No moderate or severe adverse events were reported. Mild adverse events were reported on 6 occasions (control, 4; MAM, 1; IAM, 1).

CONCLUSION

This study demonstrates that a single cervical manipulation is capable of producing immediate and short-term benefits for MNP. The study also demonstrates that not all manipulative techniques have the same effect and that the differences may be mediated by neurological or biomechanical factors inherent to each technique.

Preliminary findings on the use of osteopathic manipulative treatment: outcomes during the formation of the practice-based research network, DO-Touch.NET

CONTEXT

Few studies have assessed the use of osteopathic manipulative treatment (OMT) and subsequent patient-reported outcomes.

OBJECTIVE

To assess the current use of OMT and associated patient-reported outcomes.

DESIGN

A retrospective medical record review and a prospective observational study.

SETTING

Two university-based sites and their clinics associated with the practice-based research network DO-Touch.NET.

PARTICIPANTS

Patients aged 18 years or older who received OMT.

MAIN OUTCOME MEASURES

Medical records from 2007 were retrospectively reviewed to identify conditions being managed with OMT. From 2008 to 2010, patients were recruited before seeing their physicians. Questionnaires were distributed to patients and physicians, and information including demographics, chief complaints, symptom severity, current and past treatments, interference of symptoms with quality of life, physical examination findings, diagnoses, OMT performed, and immediate patient response to OMT was collected. A subset of patients provided data on symptom severity and frequency and other treatments daily for the 7 days after OMT. On day 7, symptom interference with quality of life was reassessed.

RESULTS

Retrospective data were collected from 2569 office visits, and prospective data were collected from 299 office visits (patient age range, 18-93 years). In the medical record review, 17 of the top 25 diagnoses (68%) were related to musculoskeletal conditions. In the prospective study, 18 of the top 24 medical diagnoses (75%) were related to musculoskeletal conditions. Immediately after OMT, patients at 271 of 296 office visits (92%) felt better or much better; those at 5 (<2%) felt worse. After 7 days, patients at 126 of 175 office visits (72%) felt better or much better, and those at 10 (6%) felt worse. Average and worst symptom severity decreased until post-OMT days 4 and 5, respectively, when severity leveled off. There was decreased interference of symptoms with quality of life from before OMT to 7 days after OMT in usual/general activities, sleep, mood, and relationships (all P≤.05).

CONCLUSION

These preliminary results suggest that for adults, OMT is predominantly used for managing musculoskeletal pain conditions and is effective for short-term symptom relief. Continued surveillance of DO-Touch.NET member practice outcomes may help identify priorities for osteopathic research and define evidence-based standards for OMT practice and training.

A regional interdependence model of musculoskeletal dysfunction: research, mechanisms, and clinical implications

The term 'regional interdependence' or RI has recently been introduced into the vernacular of physical therapy and rehabilitation literature as a clinical model of musculoskeletal assessment and intervention. The underlying premise of this model is that seemingly unrelated impairments in remote anatomical regions of the body may contribute to and be associated with a patient's primary report of symptoms. The clinical implication of this premise is that interventions directed at one region of the body will often have effects at remote and seeming unrelated areas. The formalized concept of RI is relatively new and was originally derived in an inductive manner from a variety of earlier publications and clinical observations. However, recent literature has provided additional support to the concept. The primary purpose of this article will be to further refine the operational definition for the concept of RI, examine supporting literature, discuss possible clinically relevant mechanisms, and conclude with a discussion of the implications of these findings on clinical practice and research.

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.

The effect of muscle energy technique on corticospinal and spinal reflex excitability in asymptomatic participants

The aim of the current study was to investigate, using a controlled, repeated measure design, the neurophysiological responses following an acute bout of muscle energy technique (MET). Transcranial magnetic stimulation elicited motor evoked potentials using a 110 mm double cone coil placed over the motor area of the brain, while Hoffman reflexes (H-reflex) were measured from the posterior tibial nerve using electrical stimulation. Responses were measured using surface electromyography electrodes placed over the lateral head of the gastrocnemius muscle in 12 asymptomatic volunteers. An MET aimed at the lumbosacral joint was performed bilaterally. Data were collected pre-intervention, after a control intervention, and after the MET intervention. A significant increase was found in evoked potential silent period (SP) duration (F2,22 = 7.64; p = 0.03) over time following MET, but not the control intervention. A significant decrease was found in H-reflex (F1.3,14.4 = 13.8; p = 0.01) over time following the MET intervention. MET applied to the lumbosacral joint produced a significant decrease in corticospinal and spinal reflex excitability, suggesting overall decreased motor excitability.

The effects of thoracic spine manipulation in subjects with signs of rotator cuff tendinopathy

STUDY DESIGN

Controlled laboratory study.

OBJECTIVES

To assess scapular kinematics and electromyographic signal amplitude of the shoulder musculature, before and after thoracic spine manipulation (TSM) in subjects with rotator cuff tendinopathy (RCT). Changes in range of motion, pain, and function were also assessed.

BACKGROUND

There are various treatment techniques for RCT. Recent studies suggest that TSM may be a useful component in the management of pain and dysfunction associated with RCT.

METHODS

Thirty subjects between 18 and 45 years of age, who showed signs of RCT, participated in this study. Changes in scapular kinematics and muscle activity, as well as changes in shoulder pain and function, were assessed pre-TSM and post-TSM using paired t tests and repeated-measures analyses of variance.

RESULTS

TSM did not lead to changes in range of motion or scapular kinematics, with the exception of a small decrease in scapular upward rotation (P = .05). The only change in muscle activity was a small but significant increase in middle trapezius activity (P = .03). After TSM, subjects demonstrated decreased pain during performance of the Jobe empty-can (mean ± SD change, 2.6 ± 1.1), Neer (2.6 ± 1.3), and Hawkins-Kennedy (2.8 ± 1.3) tests (all, P<.001). Subjects also reported decreased pain with shoulder flexion (mean ± SD change, 2.0 ± 1.5; P<.001) and improved shoulder function (force production, 2.5 ± 1.4 kg; Penn Shoulder Score, 7.7 ± 9.4; sports/performing arts module of the Disabilities of the Arm, Shoulder and Hand questionnaire, 16.4 ± 13.2) (all, P<.001).

CONCLUSION

Immediate improvements in shoulder pain and function post-TSM are not likely explained by alterations in scapular kinematics or shoulder muscle activity. For people with pain associated with RCT, TSM may be an effective component of their treatment plan to improve pain and function. However, further randomized controlled studies are necessary to better validate this treatment approach.

LEVEL OF EVIDENCE

Therapy, level 4.

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.

Spinal manipulative therapy has an immediate effect on thermal pain sensitivity in people with low back pain: a randomized controlled trial

BACKGROUND

Current evidence suggests that spinal manipulative therapy (SMT) is effective in the treatment of people with low back pain (LBP); however, the corresponding mechanisms are unknown. Hypoalgesia is associated with SMT and is suggestive of specific mechanisms.

OBJECTIVE

The primary purpose of this study was to assess the immediate effects of SMT on thermal pain perception in people with LBP. A secondary purpose was to determine whether the resulting hypoalgesia was a local effect and whether psychological influences were associated with changes in pain perception.

DESIGN

This study was a randomized controlled trial.

SETTING

A sample of convenience was recruited from community and outpatient clinics.

PARTICIPANTS

Thirty-six people (10 men, 26 women) currently experiencing LBP participated in the study. The average age of the participants was 32.39 (SD=12.63) years, and the average duration of LBP was 221.79 (SD=365.37) weeks.

INTERVENTION AND MEASUREMENTS

Baseline demographic and psychological measurements were obtained, followed by quantitative sensory testing to assess temporal summation and Adelta fiber-mediated pain perception. Next, participants were randomly assigned to ride a stationary bicycle, perform low back extension exercises, or receive SMT. Finally, the same quantitative sensory testing protocol was reassessed to determine the immediate effects of each intervention on thermal pain sensitivity.

RESULTS

Hypoalgesia to Adelta fiber-mediated pain perception was not observed. Group-dependent hypoalgesia of temporal summation specific to the lumbar innervated region was observed. Pair-wise comparisons indicated significant hypoalgesia in participants who received SMT, but not in those who rode a stationary bicycle or performed low back extension exercises. Psychological factors did not significantly correlate with changes in temporal summation in participants who received SMT.

LIMITATIONS

Only immediate effects of SMT were measured, so the authors are unable to comment on whether the inhibition of temporal summation is a lasting effect. Furthermore, the authors are unable to comment on the relationship between their findings and changes in clinical pain.

CONCLUSIONS

Inhibition of Adelta fiber-mediated pain perception was similar for all groups. However, inhibition of temporal summation was observed only in participants receiving SMT, suggesting a modulation of dorsal horn excitability that was observed primarily in the lumbar innervated area.

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.

Basic Science Research Related to Chiropractic Spinal Adjusting: The State of the Art and Recommendations Revisited

OBJECTIVE

The objectives of this white paper are to review and summarize the basic science literature relevant to spinal fixation (subluxation) and spinal adjusting procedures and to make specific recommendations for future research.

METHODS

PubMed, CINAHL, ICL, OSTMED, and MANTIS databases were searched by a multidisciplinary team for reports of basic science research (since 1995) related to spinal fixation (subluxation) and spinal adjusting (spinal manipulation). In addition, hand searches of the reference sections of studies judged to be important by the authors were also obtained. Each author used key words they determined to be most important to their field in designing their individual search strategy. Both animal and human studies were included in the literature searches, summaries, and recommendations for future research produced in this project.

DISCUSSION

The following topic areas were identified: anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system. A relevant summary of each topic area and specific recommendations for future research in each area were the primary objectives of this project.

CONCLUSIONS

The summaries of the literature for the 6 topic sections (anatomy, biomechanics, somatic nervous system, animal models, immune system, and human studies related to the autonomic nervous system) indicated that a significant body of basic science research evaluating chiropractic spinal adjusting has been completed and published since the 1997 basic science white paper. Much more basic science research in these fields needs to be accomplished, and the recommendations at the end of each topic section should help researchers, funding agencies, and other decision makers develop specific research priorities.

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

BACKGROUND AND CONTEXT

One basic physiologic response to spinal manipulation (SM) is a transient decrease in motoneuronal activity, as assessed by the Hoffmann reflex (H-reflex) technique. However, questions of appropriate control procedures when using the H-reflex technique to study the basic physiologic mechanisms of SM still exist. The identification of appropriate control procedures may allow us to better differentiate among the specific and nonspecific aspects of SM.

PURPOSE

The purpose of the research was to determine the contributions of postural perturbations on the attenuation of motoneuronal activity following spinal manipulative thrusts and spinal joint preload procedures applied to the lumbar spine.

STUDY DESIGN/SETTING

H/M(max) ratios, recorded from the gastrocnemius muscle, were measured before and after lumbar spinal procedures. The experimental designs for the laboratory data collection protocols were repeated measures and between-subjects.

PATIENT SAMPLE

The subjects were asymptomatic, young, healthy volunteers.

OUTCOME MEASURE

H/M(max) ratios recorded from the gastrocnemius muscle.

METHODS

In Experiment 1, the administration of prone lumbar procedures involved either manual assist to more fully shear the lumbar zygapophyseal joints or no manual assist. One set of subjects (n=17) received assisted joint preload force and manipulation, whereas a second set of subjects (n=17) received unassisted joint preload force and manipulation. In a second laboratory experiment, one set of subjects (n=10) received a L5-S1 side-posture SM, whereas a second set of subjects (n=10) were just positioned into side-posture.

RESULTS

There was a H/M(max) ratio attenuation of 18.2% after assisted spinal manipulation, whereas H/M(max) ratio attenuation was only 9.5% after unassisted spinal manipulation. Decreases of H/M(max) ratios by 8.5% and 7.5% were observed after assisted and unassisted joint preload forces, respectively. The amount of H/M(max) ratio attenuation was significantly greater immediately after the L5-S1 SM procedure (28.4%) as compared with a side-posture positioning maneuver (15.3%).

CONCLUSION

SM may provide procedure-specific sensory input that appears to vary, based upon the various types of vertebral loading applied to the lumbar spine.

Pressures Generated During Spinal Manipulation and Their Association With Hand Anatomy

BACKGROUND CONTEXT

The role of the variation in the application manipulation itself is largely unknown. A greater understanding of its input parameters is necessary to better understand spinal manipulation outcomes.

PURPOSE

The objective of this study is to determine if pressures generated during manipulation are altered by hand configuration.

DESIGN/SETTING

Paired comparison of 2 different variable groups.

METHODS

Sixteen chiropractors provided 2 manipulations to a rigid surface using 2 hand configurations used commonly in clinical practice: arched and flat. Interposed between the hand and the rigid surface was a pressure sensor array and radiographic cassette. For each manipulation, pressures were recorded and a radiographic image was captured. Two radiologists then located the osseous features of the hand with respect to the sensor array.

RESULTS

In 15 of 16 cases, arched configurations produced peak pressures that corresponded to the radiographic location of the pisiform bone. In flat configurations, peak pressure migrated about the location of the hamate bone. Radiologists' agreement for bone position was high (kappa = 0.96). Measures of peak pressure, total pressure, and pressure distribution were statistically different between hand configurations.

CONCLUSIONS

The results of this study suggest that hand configuration influences the magnitude, location, and distribution of pressure generated by the hand during manipulation. This knowledge may have importance in understanding the relation among application parameters of manipulation, therapeutic benefit, and patient safety.

Paraspinal muscles and intervertebral dysfunction: part two

BACKGROUND

One of the diagnostic characteristics of the manipulable spinal lesion--a musculoskeletal disturbance that is claimed to be detected with manual palpation and corrected with manipulation--is said to be altered segmental tissue texture. Little evidence for the nature of abnormal paraspinal tissue texture exists, but indirect evidence from experimental studies supports the plausibility of the concept of protective muscle spasm, although investigations of increased paraspinal electromyography (EMG) associated with low back pain suggests complex changes in motor control rather than simple protective reflexes.

OBJECTIVES

To review the literature for evidence that may support or refute proposed explanations for clinically observed altered paraspinal tissue texture associated with the manipulable spinal lesion. This review aims to highlight areas that require further research and make recommendations for future studies. Data Source MEDLINE and CINAHL databases were searched using various combinations of the keywords paraspinal, muscle, palpation, EMG, spine, low back pain, pain, myofascial, hardness, manipulation, reliability, and somatic dysfunction, along with searching the bibliographies of selected articles and textbooks. Data Extraction All relevant data were used.

RESULTS

Decreased paraspinal muscle activity and strength associated with low back pain is well established, and there is evidence of changes in muscle fiber composition and localized selective multifidus atrophy. Disturbances in microcirculation have been implicated in nonparaspinal muscle pain. The effect of spinal manipulation on paraspinal EMG activity is inconclusive but promising.

CONCLUSION

Little direct evidence exists to support the existence or nature of paraspinal tissue texture change that is claimed to be detected with palpation. The proposal of segmental reflex paraspinal muscle contraction was not supported, at least in association with low back pain. There appears to be a complex relationship between deep paraspinal muscle inhibition during dynamic activity and nonvoluntary guarding behavior during static activity. The relationship between these findings and palpable tissue change is speculative, but increased activity, decreased activity, or both may be responsible for paraspinal tissues detected as abnormal with palpation. Recommendations are outlined for future research.