The Effects of Spinal Manipulation on Motor Unit Behavior

Cervical manipulation accelerates recovery and further correction of cervical alignment in mechanical neck pain (MNP) patients with neck exercise: A randomized controlled trial

BACKGROUND

Mechanical neck pain (MNP) is often associated with changes in cervical sagittal alignment, causing pain and functional limitations.

OBJECTIVE

This study evaluated the additional effects of cervical manipulation in patients with MNP undergoing neck retraction exercise.

METHODS

Patients with MNP were randomly assigned to either the cervical manipulation plus neck retraction exercise group (CM + NRE) or the neck retraction exercise group (NRE). Both groups completed their respective regimens over an 8-week period. Primary outcomes include visual analogue scale (VAS) and cervical range of motion (CROM). Secondary outcomes include neck disability index (NDI), neck muscle strength, and cervical sagittal alignment (relative rotation angles [RRA]; absolute rotation angles [C2-7ARA]; cervical sagittal vertical axis [c2-7SVA]). The statistical analysis applied intention-to-treat (ITT) and per-protocol (PP) analyses.

RESULTS

In the ITT analysis, the CM + NRE group demonstrated more pronounced changes in VAS and CROM after the first treatment (VAS: d = 1.83, P = 0.001; CROM: d = 1.92, P = 0.001), at 4 weeks (VAS: d = 0.98, P = 0.001; CROM: d = 1.05, P = 0.001), 8 weeks (VAS: d = 1.05, P = 0.001; CROM: d = 0.93, P = 0.001), and at a 4-week follow-up (VAS: d = 1.16, P = 0.001; CROM: d = 0.91, P = 0.001). In the assessments of NDI, RRA, and C2-7ARA, the CM + NRE group showed significantly greater changes compared to the NRE group (p < 0.05). These results were consistent with the PP analysis.

CONCLUSION

Cervical manipulation enhances the effectiveness of neck retraction exercise, which promotes rapid recovery from neck pain and stiffness and further facilitates the correction of cervical sagittal alignment in patients with MNP.

The Impact of a Single Hip Manipulation on Quadriceps Activity and Performance: A Randomized Study

Background/Objectives: Optimal activation of the quadriceps femoris, particularly the vastus medialis, while minimizing excessive activation of the vastus lateralis, is crucial for treating knee injuries like ACL ruptures and patellofemoral pain syndrome. Restoring proper muscle balance may enhance rehabilitation outcomes, but effective strategies for modulating muscle activity remain unclear. High-velocity low-amplitude hip manipulation has shown potential to influence neuromuscular function, yet its impact on quadriceps activation during knee extension has not been well studied. Therefore, the main aim of this study is to examine the effects of a single session of high-velocity low-amplitude hip manipulation on quadriceps femoris muscle activation and maximum voluntary contraction during knee extension. Methods: This study utilizes a randomized controlled design. Thirty physically active men and women (mean age: 21.9 ± 1.7 years) were randomly assigned to either an experimental group (n = 15; receiving hip joint manipulation) or a control group (n = 15; undergoing a sham intervention). Participants in the intervention group received a treatment involving hip manipulation and short-duration traction. Muscle activity of the rectus femoris, vastus lateralis, and vastus medialis was assessed using surface electromyography before and after the intervention, while muscle performance was measured by evaluating isometric knee extension strength in the lower limb. The isometric strength test was conducted in a seated position with the knee flexed at 60 degrees in Biodex System 4. Results: This study finds that the experimental group had significantly higher vastus lateralis mean amplitude (p = 0.020; effect size = 0.186) and vastus medialis mean amplitude (p < 0.001; effect size = 0.577) of electromyography root mean square electromyography compared to the control group. The experimental group also showed greater vastus medialis max amplitude (p < 0.001; effect size = 0.435). No significant differences were noted for rectus femoris mean amplitude (p = 0.078; effect size = 0.110), vastus lateralis max amplitude (p = 0.363; effect size = 0.031), rectus femoris max amplitude (p = 0.069; effect size = 0.117), or median frequency of the raw electromyography signal across muscle groups. Conclusions: In conclusion, high-velocity low-amplitude hip manipulation significantly enhances vastus medialis activation, highlighting its potential to improve quadriceps balance. These findings support the incorporation of hip manipulation into rehabilitation protocols.

Neuromuscular Response to High-Velocity, Low-Amplitude Spinal Manipulation-An Overview

The clinical use of spinal manipulation to treat musculoskeletal conditions has nearly tripled in the United States since 1980, and it is currently recommended by most global clinical guidelines as a conservative treatment for musculoskeletal pain, despite a lack of knowledge concerning its mechanisms of action. This overview highlights evidence of direct neuromuscular responses to high-velocity, low-amplitude spinal manipulation (HVLA-SM) as delivered by chiropractic, osteopathic, and physical therapy clinicians, with an intent to foster greater interprofessional dialogue and collaborative research to better address current gaps in mechanistic knowledge of the neuromuscular response to HVLA-SM. Three databases (PubMed, CINAHL Ultimate (EBSCO), EMBASE (Elsevier)) were searched from 2000 to December 2024 with specific search terms related to thrust HVLA-SM and the neuromuscular response. To focus strictly on neuromuscular responses related to HVLA-SM, this literature overview excluded articles using non-HVLA-SM manual therapy techniques (i.e., massage, non-thrust joint mobilization, and/or combined HVLA-SM with other forms of treatment such as exercise or non-thrust joint mobilization) and studies in which patient-centered outcomes (i.e., pain scores) were the primary outcomes of the HVLA-SM interventions. Pediatric studies, animal studies, and studies in languages other than English were also excluded. One-hundred and thirty six articles were identified and included in this overview. Neuromuscular findings related to HVLA-SM in the areas of electromyography (EMG), muscle thickness, muscle strength, reflexes, electroencephalogram (EEG), and evoked potential were often mixed; however, evidence is beginning to accumulate either in favor of or opposed to particular neuromuscular responses to HVLA-SM as larger and more scientifically rigorous studies are being performed. Recurrent limitations of many HVLA-SM-related studies are small sample sizes, leading to a lack of generalizability, and the non-standardization of HVLA-SM delivery, which has prevented researchers from arriving at definitive conclusions regarding neuromuscular responses to HVLA-SM. Discussions of future neuromuscular research needs related to HVLA-SM are included for clinicians and researchers inside and outside of the field of manual therapy, to advance this field.

Neuroplastic Responses to Chiropractic Care: Broad Impacts on Pain, Mood, Sleep, and Quality of Life

OBJECTIVES

This study aimed to elucidate the mechanisms of chiropractic care using resting electroencephalography (EEG), somatosensory evoked potentials (SEPs), clinical health assessments (Fitbit), and Patient-reported Outcomes Measurement Information System (PROMIS-29).

METHODS

Seventy-six people with chronic low back pain (mean age ± SD: 45 ± 11 years, 33 female) were randomised into control (n = 38) and chiropractic (n = 38) groups. EEG and SEPs were collected pre and post the first intervention and post 4 weeks of intervention. PROMIS-29 was measured pre and post 4 weeks. Fitbit data were recorded continuously.

RESULTS

Spectral analysis of resting EEG showed a significant increase in Theta, Alpha and Beta, and a significant decrease in Delta power in the chiropractic group post intervention. Source localisation revealed a significant increase in Alpha activity within the Default Mode Network (DMN) post intervention and post 4 weeks. A significant decrease in N30 SEP peak amplitude post intervention and post 4 weeks was found in the chiropractic group. Source localisation demonstrated significant changes in Alpha and Beta power within the DMN post-intervention and post 4 weeks. Significant improvements in light sleep stage were observed in the chiropractic group along with enhanced overall quality of life post 4 weeks, including significant reductions in anxiety, depression, fatigue, and pain.

CONCLUSIONS

These findings indicate that many health benefits of chiropractic care are due to altered brain activity.

Hip Manipulation Increases Electromyography Amplitude and Hip Joint Performance: A Double-Blind Randomized Controlled Study

(1) Background: Activation of the gluteus medius (GM) muscle while minimizing the involvement of the tensor fascia latae (TFL) is crucial in treating many lower limb and lumbar spine injuries. Previous studies have demonstrated the effectiveness of joint manipulations in regulating muscle activity. The main objective of this study was to evaluate the effects of hip joint manipulation (HJM) on the muscle strength and activity (GM and TFL) of hip abductors in asymptomatic young participants. (2) Methods: The study followed a double-blind randomized controlled design. Thirty healthy, physically active women and men, free from spinal and lower limb injuries, voluntarily participated. The participants were allocated to two groups: those allocated to the HJM intervention and those in the control group receiving a sham intervention. They were assessed before and after the intervention using surface electromyography to measure muscle activation (EMGRMS) of the GM and TFL during maximal voluntary isometric hip abduction. (3) Results: HJM resulted in a significant increase in EMGRMS amplitude solely within the GM muscle (p < 0.01); (4) Conclusions: This study suggests that HJM may increase EMGRMS amplitude in the GM muscle; however, the effects are neither statistically nor clinically significant when compared to the control group for most of the muscles analyzed.

Effect of manual manipulation on mechanical gait parameters

CONTEXT

A variety of manual manipulation techniques are utilized in clinical practice to alleviate pain and improve musculoskeletal function. Many manual practitioners analyze gait patterns and asymmetries in their assessment of the patient, and an increasing number of gait motion capture studies are taking place with recent improvements in motion capture technology. This study is the first systematic review of whether these manual modalities have been shown to produce an objectively measurable change in gait mechanics.

OBJECTIVES

This study was designed to perform a systematic review of the literature to assess the impact of manual medicine modalities on biomechanical parameters of gait.

METHODS

A master search term composed of keywords and Medical Subject Headings (MeSH) search terms from an initial scan of relevant articles was utilized to search six databases. We screened the titles and abstracts of the resulting papers for relevance and then assessed their quality with the Cochrane Risk of Bias Tool. Clinical trials that featured both a manual manipulation intervention and multiple mechanical gait parameters were included. Case reports and other studies that only measured gait speed or other subjective measures of mobility were excluded.

RESULTS

We included 20 studies in our final analysis. They utilize manipulation techniques primarily from osteopathic, chiropractic, massage, and physiotherapy backgrounds. The conditions studied primarily included problems with the back, knee, and ankle, as well as healthy patients and Parkinson's patients. Control groups were highly variable, if not absent. Most studies measured their gait parameters utilizing either multicamera motion capture systems or force platforms.

CONCLUSIONS

Twelve of 20 papers included in the final analysis demonstrated a significant effect of manipulation on gait variables, many of which included either step length, walking speed, or sagittal range of motion (ROM) in joints of the lower extremity. However, the results and study design are too heterogeneous to draw robust conclusions from these studies as a whole. While there are initial indications that certain modalities may yield a change in certain gait parameters, the quality of evidence is low and there is insufficient evidence to conclude that manual therapies induce changes in biomechanical gait parameters. Studies are heterogeneous with respect to the populations studied and the interventions performed. Comparators were variable or absent across the studies, as were the outcome variables measured. More could be learned in the future with consistent methodology around blinding and sham treatment, and if the gait parameters measured were standardized and of a more robust clinical significance.

The Neurophysiological Lesion: A Scoping Review

Objective

The purpose of this study was to examine the extent of the literature on the neurophysiological lesion as referenced in functional neurology.

Methods

A literature search was performed within the period from 2010 to March 2021. Search terms included central sensitization, central sensitivity syndrome, nociplastic pain, cold hyperalgesia, heat hyperalgesia, mechanical hyperalgesia, dynamic mechanical allodynia, temporal summation, spatial summation, and descending inhibition. A qualitative synthesis summarized the research findings, including clinical conditions and effect of spinal manipulation.

Results

There were 30 studies, which included 7 high-level studies (meta-analysis or systematic reviews), 22 randomized controlled studies, and 1 scoping review. The findings suggest the existence of the changes in the central integrated state of a population of neurons with various disorders, experimentally induced stimulation, and treatment. The current literature suggests plasticity of the central integrative state (CIS) with the onset of pathologies and the changes in the CIS with different conservative nonpharmacologic treatments.

Conclusions

This review suggests changes in the resting state of the CIS of a population of neurons that exist in the physiologic lesion may change in response to various therapies, including manipulative therapy. The findings from this review provide support of the hypothesis that nonpharmacologic conservative care may affect the neurophysiological lesion. However, studies were heterogeneous and evidence was lacking in the translation of targeting the therapies to distinct neuronal areas for clinical outcomes to treat specific disease states.

Effects of manual therapy on body posture: Systematic review and meta-analysis

BACKGROUND

Several clinical trials investigated the effectiveness of MT on body posture, but a systematic review grouping the results of these studies was not found in the literature.

RESEARCH QUESTION

Does manual therapy (MT) cause postural changes?

METHODS

Inclusion criteria were: randomized controlled trials in any population; studies in which the primary intervention was the use of any MT technique; studies that evaluated the immediate, short, medium, or long-term effects of interventions on body posture; and studies published in peer-reviewed scientific journals in any year and language. In March 2022, we conducted a search in the PUBMED, Cinahl, Embase, PEDro, and Cochrane Central databases that yielded 6627 articles, of which 38 including 1597 participants were eligible; of these, 35 could be grouped into 12 meta-analyses. The risk of bias was assessed using the PEDro scale and the certainty in the scientific evidence rated through the GRADE system.

RESULTS

The results allowed us to conclude with moderate certainty in the evidence that, when compared to no intervention or sham, in the short and medium term, MT reduced the forward head posture (14 studies, 584 individuals, 95%CI 0.38, 1.06), reduced thoracic kyphosis (5 studies, 217 individuals, 95%CI 0.37, 0.94), improved lateral pelvic tilt (5 studies, 211 individuals, 95%CI 0.11, 0.67) and pelvic torsion (2 studies, 120 individuals, 95%CI 0.44, 1.19) and increased plantar area (3 studies, 134 individuals, 95%CI 0.04, 0.74). With moderate certainty, there was no significant effect on shoulder protrusion (5 studies, 176 individuals, 95%CI -0.11, 0.61), shoulder alignment in the frontal plane (3 studies, 160 individuals, 95%CI -0.15, 0.52), scoliosis (2 studies, 26 individuals, 95%CI -1.57, 2.19), and pelvic anteversion (5 studies, 233 individuals, 95%CI -0.02, 0.51). With low certainty, MT had no effect on scapular upward rotation (2 studies, 74 individuals, 95%CI -0.76, 2.17). With low to very low certainty, it is possible to conclude that MT was not superior to other interventions in the short or medium term regarding the improvement of forward head posture (5 studies, 170 individuals, 95%CI -1.39, 0.67) and shoulder protrusion (3 studies, 94 individuals, 95%CI -4.04, 0.97).

SIGNIFICANCE

MT can be recommended to improve forward head posture, thoracic kyphosis and pelvic alignment in the short and medium term, but not shoulder posture and scoliosis. MT reduces the height of the plantar arch and this must be taken into account in physical therapy planning. PROSPERO registration number: CRD42021244423.

The Changes of Brain Function After Spinal Manipulation Therapy in Patients with Chronic Low Back Pain: A Rest BOLD fMRI Study

OBJECTIVE

To investigate the changes of regional homogeneity (Reho) values before and after spinal manipulative therapy (SMT) in patients with chronic low back pain (CLBP) through rest blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI).

METHODS

Patients with CLBP (Group 1, n = 20) and healthy control subjects (Group 2, n = 20) were recruited. The fMRI was performed three times in Group 1 before SMT (time point 1, TP1), after the first SMT (time point 2, TP2), after the sixth SMT (time point 3, TP3), and for one time in Group 2, which received no intervention. The clinical scales were finished in Group 1 every time before fMRI was performed. The Reho values were compared among Group 1 at different time points, and between Group 1 and Group 2. The correlation between Reho values with the statistical differences and the clinical scale scores were calculated.

RESULTS

The bilateral precuneus and right mid-frontal gyrus in Group 1 had different Reho values compared with Group 2 at TP1. The Reho values were increased in the left precuneus and decreased in the left superior frontal gyrus in Group 1 at TP2 compared with TP1. The Reho values were increased in the left postcentral gyrus and decreased in the left posterior cingulate cortex and the superior frontal gyrus in Group 1 at TP3 compared with TP1. The ReHo values of the left precuneus in Group 1 at TP1 were negatively correlated with the pain degree at TP1 and TP2 (r = -0.549, -0.453; p = 0.012, 0.045). The Reho values of the middle temporal gyrus in Group 1 at TP3 were negatively correlated with the changes of clinical scale scores between TP3 and TP1 (r = 0.454, 0.559; p = 0.044, 0.01).

CONCLUSION

Patients with CLBP showed abnormal brain function activity, which was altered after SMT. The Reho values of the left precuneus could predict the immediate analgesic effect of SMT.