The Effectiveness of Spinal Manipulation in Increasing Muscle Strength in Healthy Individuals: A Systematic Review and Meta-Analysis

Regional Sensorimotor Effects of Chiropractic Spinal Manipulation: Preliminary Results From an Experimental Study

OBJECTIVE

The purpose of this study was to assess the effects of different spinal manipulation (SM) techniques and target segments on a specific dermatome and myotome, when compared with a remote spinal cord segment that served as a control location.

METHODS

Twenty-nine healthy volunteers were randomized to receive instrumental (Activator IV, Activator Methods International Ltd) or manual SM at the C6, C1, and T4 vertebral segments in 3 independent sessions. Pressure pain thresholds (PPTs) and muscle strength were examined at the C6 (test) and L4 (control) dermatomes and myotomes, at baseline and after intervention. Linear mixed-effects models were used to analyze changes over time and interindividual variability.

RESULTS

Pressure pain thresholds significantly increased at both proximal and distal C6 dermatome locations (P < .05), irrespective of the technique and segment of application (P > .2). No significant changes were observed at the L4 dermatome. Muscle strength remained unchanged throughout the study. Multilevel modeling revealed significant associations between increased PPTs along the C6 dermatome (P < .001), whereas the combination of technique and target segment predicted PPT increases at the proximal C6 dermatome.

CONCLUSION

These findings support regional, rather than segmental mechanisms underlying the sensory effects of SM. Specifically, significant increases in PPTs along the C6 dermatome suggest localized effects on pain sensitivity, which may depend on the target spinal region. Further investigation is needed to better understand these regional changes of SM and their potential clinical implications.

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.

Manual therapy should not be on the sideline in the game of treating tendinopathy

Tendinopathy is a common but difficult condition to manage in the orthopedic and sports settings. Despite strong evidence supporting exercise and load-management, a substantial proportion of individuals with the condition do not achieve a satisfactory long-term outcome. Tendinopathy can be associated with a number of impairments, including mobility deficits, muscle performance impairments, pain, and possible altered central pain processing - all of which are indications for manual therapy. Manual therapy has not been well described in the management of tendinopathy, even though its indications match the impairments associated with the condition. In this clinical perspective, the role of manual therapy in the management of tendinopathy is explored, with the intention of expanding possible treatment strategies for this challenging condition.

The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function

Purpose

There is growing evidence that vertebral column function and dysfunction play a vital role in neuromuscular control. This invited review summarises the evidence about how vertebral column dysfunction, known as a central segmental motor control (CSMC) problem, alters neuromuscular function and how spinal adjustments (high-velocity, low-amplitude or HVLA thrusts directed at a CSMC problem) and spinal manipulation (HVLA thrusts directed at segments of the vertebral column that may not have clinical indicators of a CSMC problem) alters neuromuscular function.

Methods

The current review elucidates the peripheral mechanisms by which CSMC problems, the spinal adjustment or spinal manipulation alter the afferent input from the paravertebral tissues. It summarises the contemporary model that provides a biologically plausible explanation for CSMC problems, the manipulable spinal lesion. This review also summarises the contemporary, biologically plausible understanding about how spinal adjustments enable more efficient production of muscular force. The evidence showing how spinal dysfunction, spinal manipulation and spinal adjustments alter central multimodal integration and motor control centres will be covered in a second invited review.

Results

Many studies have shown spinal adjustments increase voluntary force and prevent fatigue, which mainly occurs due to altered supraspinal excitability and multimodal integration. The literature suggests physical injury, pain, inflammation, and acute or chronic physiological or psychological stress can alter the vertebral column’s central neural motor control, leading to a CSMC problem. The many gaps in the literature have been identified, along with suggestions for future studies.

Conclusion

Spinal adjustments of CSMC problems impact motor control in a variety of ways. These include increasing muscle force and preventing fatigue. These changes in neuromuscular function most likely occur due to changes in supraspinal excitability. The current contemporary model of the CSMC problem, and our understanding of the mechanisms of spinal adjustments, provide a biologically plausible explanation for how the vertebral column’s central neural motor control can dysfunction, can lead to a self-perpetuating central segmental motor control problem, and how HVLA spinal adjustments can improve neuromuscular function.

Effects of Chiropractic Care on Strength, Balance, and Endurance in Active-Duty U.S. Military Personnel with Low Back Pain: A Randomized Controlled Trial

Objectives: To investigate whether chiropractic care influences strength, balance, and/or endurance in active-duty United States military personnel with low back pain (LBP). Design: This study employed a prospective randomized controlled trial using a pragmatic treatment approach. Participants were randomly allocated to 4 weeks of chiropractic care or to a wait-list control. Interventions: Chiropractic care consisted of spinal manipulation, education, advice, and reassurance. Settings/Location: Naval Air Technical Training Center branch clinic at the Naval Hospital Pensacola Florida. Subjects: One hundred ten active-duty military personnel 18-40 years of age with self-reported LBP. Outcome measures: Isometric pulling strength from a semisquat position was the primary outcome. Secondary outcomes were single-leg balance with eyes open and eyes closed, and trunk muscle endurance using the Biering-Sorensen test. Patient-reported outcomes such as pain severity and disability were also measured. Outcomes were measured at baseline and 4 weeks. Linear mixed-effects regression models over baseline and 4 weeks were used for analysis. Results: Participants had mean age of 30 years (18-40), 17% were female, 33% were non-white, and 86% reported chronic LBP. Mean maximum pulling strength in the chiropractic group increased by 5.08 kgs and decreased by 7.43 kgs in the wait-list group, with a statistically significant difference in mean change between groups (p = 0.003). Statistically significant differences in mean change between groups were also observed in trunk muscle endurance (13.9 sec, p = 0.002) and balance with eyes closed (0.47 sec, p = 0.01), but not in balance with eyes open (1.19 sec, p = 0.43). Differences in mean change between groups were statistically significant in favor of chiropractic for LBP-related disability, pain intensity and interference, and fear-avoidance behavior. Conclusions: Active-duty military personnel receiving chiropractic care exhibited improved strength and endurance, as well as reduced LBP intensity and disability, compared with a wait-list control.