Claude Dugas

Learning Spinal Manipulation Skills: Assessment of Biomechanical Parameters in a 5-Year Longitudinal Study

OBJECTIVE Teaching spinal manipulation (SM) is a fundamental aspect of chiropractic training. Recent works have identified various biomechanical variables as indicators of SM performance and learning. However, only data from cross-sectional studies are available, limiting conclusions regarding the persistence of SM performance over the years. Therefore, the main objective of this investigation was to quantify the evolution of biomechanical parameters of SM over a 5-year learning period. METHODS Thirty-three students enrolled in a chiropractic program participated in the present study. They were tested each year at the beginning of each fall semester by performing 10 SMs on an instrumented manikin while standing on a force plate. The procedure allowed us to measure various force-time parameters. RESULTS Overall, significant time effects were noted for most dependent variables. The results indicated rapid improvement in the peak force applied and the rate of force production during the first 2 years. Time to peak force decreased drastically during the first year, whereas preload forces reached satisfactory levels during the third year. When various force-time requirements of bimanual task components were met, learners significantly reduced trial-to-trial variability of SM peak and preload forces, indicating automaticity of performance. Although global coordination improved in all learning processes, it was only in the later phase that learners reached values approaching those of experts. CONCLUSION Overall, these results highlighted the importance of considering learning principles in the development of didactic strategies related to SM motor skills.

Kinetic analysis of expertise in spinal manipulative therapy using an instrumented manikin

OBJECTIVE The goals of this study were to measure the kinetic profile of thrust in different groups of subjects with various levels of expertise and to quantify general coordination while performing thoracic spine manipulation. PARTICIPANTS A total of 43 students and chiropractors from the Chiropractic Department of the Université du Québec à Trois-Rivières participated in this study. METHODS Participants were asked to complete ten consecutive thoracic spine manipulations on an instrumented manikin. Peak force, preload force, time to peak force, time to peak force variability, peak force variability, rate of force production and unloading time were compared between groups. Hand-body delay obtained by calculating the temporal lag between the onset of unloading and the onset of peak force application was also compared between groups. RESULTS No group difference was observed for the peak force, peak force variability and preload force variables. However, group differences were present for variables like time to peak force, time to peak force variability, rate of force production, unloading time and hand-body delay. CONCLUSION This study demonstrates clear differences between groups of subjects with different levels of expertise in thoracic spine manipulation. This study also demonstrates the usefulness of a simple, instrumented manikin to analyze spinal manipulation and identify important parameters related to expertise.

Improving gross motor function and postural control with hippotherapy in children with Down syndrome: Case reports

The purpose of this case report is to describe the impact of an 11-week hippotherapy program on the gross motor functions of two children (respectively 28 and 37 months old) diagnosed with Down syndrome. Hippotherapy is a strategy that uses the horses motion to stimulate and enhance muscle contraction and postural control. The children were assessed by the Gross Motor Function Measure (GMFM) and accelerometry. The results indicate that both children improved on many dimensions of the GMFM. Power spectral analysis of the acceleration signals showed improvement in postural control of either the head or trunk, because the children adopted two different adaptative strategies to perturbation induced by the moving horse.

A randomised controlled trial of preventive spinal manipulation with and without a home exercise program for patients with chronic neck pain

BackgroundEvidence indicates that supervised home exercises, combined or not with manual therapy, can be beneficial for patients with non-specific chronic neck pain (NCNP). The objective of the study is to investigate the efficacy of preventive spinal manipulative therapy (SMT) compared to a no treatment group in NCNP patients. Another objective is to assess the efficacy of SMT with and without a home exercise program.MethodsNinety-eight patients underwent a short symptomatic phase of treatment before being randomly allocated to either an attention-group (n = 29), a SMT group (n = 36) or a SMT + exercise group (n = 33). The preventive phase of treatment, which lasted for 10 months, consisted of meeting with a chiropractor every two months to evaluate and discuss symptoms (attention-control group), 1 monthly SMT session (SMT group) or 1 monthly SMT session combined with a home exercise program (SMT + exercise group). The primary and secondary outcome measures were represented by scores on a 10-cm visual analog scale (VAS), active cervical ranges of motion (cROM), the neck disability index (NDI) and the Bournemouth questionnaire (BQ). Exploratory outcome measures were scored on the Fear-avoidance Behaviour Questionnaire (FABQ) and the SF-12 Questionnaire.ResultsOur results show that, in the preventive phase of the trial, all 3 groups showed primary and secondary outcomes scores similar to those obtain following the non-randomised, symptomatic phase. No group difference was observed for the primary, secondary and exploratory variables. Significant improvements in FABQ scores were noted in all groups during the preventive phase of the trial. However, no significant change in health related quality of life (HRQL) was associated with the preventive phase.ConclusionsThis study hypothesised that participants in the combined intervention group would have less pain and disability and better function than participants from the 2 other groups during the preventive phase of the trial. This hypothesis was not supported by the study results. Lack of a treatment specific effect is discussed in relation to the placebo and patient provider interactions in manual therapies. Further research is needed to delineate the specific and non-specific effects of treatment modalities to prevent unnecessary disability and to minimise morbidity related to NCNP. Additional investigation is also required to identify the best strategies for secondary and tertiary prevention of NCNP.Trial registrationClinicalTrials.gov: NCT00566930

Evaluation of a specific balance and coordination programme for individuals with a traumatic brain injury

The purpose of this study was to evaluate the effectiveness of an aerobic dancing training, designed to reduce postural imbalance and coordination deficits for individuals who had sustained a traumatic brain injury (TBI). A two group experimental design was conducted. A control group participated in a traditional muscular training (TMT) programme while participants in the experimental group were assigned to an aerobic dancing, Slide and Step training programme (specific training group (ST)). Participants were evaluated pre- and post-training. Balance was quantified using a force platform and coordination using a Peak Performance system to compare the velocity profiles of a modified Jumping jack test. Results showed that temporal variables were significantly different pre- and post-training for the ST group, but no changes were found in the TMT group. The results of the balance test indicated a significant reduction of postural sway area in the ST group but not in the TMT group. Overall, the combination workout with Step and Slide is more effective in reducing balance and coordination deficits when compared to muscular based training.

Physiological Responses to Spinal Manipulation Therapy: Investigation of the Relationship Between Electromyographic Responses and Peak Force

OBJECTIVE It is believed that systematic modulation of spinal manipulative therapy (SMT) parameters should yield varying levels of physiological responses and eventually a range of clinical responses. However, investigation of SMT dose-physiological response relationship is recent and has mostly been conducted using animal or cadaveric models. The main objective of the present study is to investigate SMT dose-physiological response relation in humans by determining how different levels of force can modify electromyographic (EMG) responses to spinal manipulation. METHODS Twenty-six participants were subjected to 2 trials of 4 different SMT force-time profiles using a servo-controlled linear actuator motor. Normalized EMG activity of paraspinal muscles (left and right muscles at level T6 and T8) was recorded during and after SMT, and EMG values were compared across the varying levels of force. RESULTS Increasing the level of force yielded an increase in paraspinal muscle EMG activity during the thrust phase of SMT but also in the two 250-millisecond time windows after the spinal manipulation impulse. These muscle activations quickly attenuated (500 milliseconds after spinal manipulation impulse). CONCLUSION The study confirmed the presence of a local paraspinal EMG response after SMT and highlighted the linear relationship between the SMT peak force and paraspinal muscle activation.

Standardization of spinal manipulation therapy in humans: development of a novel device designed to measure dose-response.

OBJECTIVE The main objective of this report is to present an innovative research tool that will provide the opportunity to study fundamental aspects of the spinal manipulation dose-physiological response relation in humans. METHODS A servo-controlled linear actuator motor was developed to simulate spinal manipulative therapy. Coefficient of multiple correlations was calculated to assess the degree of similarity between each measured force curves, whereas precision was obtained by comparing resulting peak force and time-to-peak force to the target curves. RESULTS The coefficient of multiple correlations calculations showed that repeatability was very high with all correlation values over 0.98. Precision was also very high with average differences in peak force and time-to-peak force of less than 3 N and less than 5 milliseconds. CONCLUSION The tool was designed to optimize precision, repeatability, and safety in the delivery of force to the spine in humans. It offers a unique opportunity to study dose-response relationship for several spinal manipulation parameters such as peak force, time-to-peak force, and preload.

The Role of Preload Forces in Spinal Manipulation: Experimental Investigation of Kinematic and Electromyographic Responses in Healthy Adults

OBJECTIVES Previous studies have identified preload forces and an important feature of skillful execution of spinal manipulative therapy (SMT) as performed by manual therapists (eg, doctors of chiropractic and osteopathy). It has been suggested that applying a gradual force before the thrust increases the spinal unit stiffness, minimizing displacement during the thrust. Therefore, the main objective of this study was to assess the vertebral unit biomechanical and neuromuscular responses to a graded increase of preload forces. METHODS Twenty-three participants underwent 4 different SMT force-time profiles delivered by a servo-controlled linear actuator motor and varying in their preload forces, respectively, set to 5, 50, 95, and 140N in 1 experimental session. Kinematic markers were place on T6, T7, and T8 and electromyographic electrodes were applied over paraspinal muscles on both sides of the spine. RESULTS Increasing preload forces led to an increase in neuromuscular responses of thoracic paraspinal muscles and vertebral segmental displacements during the preload phase of SMT. Increasing the preload force also yielded a significant decrease in sagittal vertebral displacement and paraspinal muscle activity during and immediately after the thrust phase of spinal manipulation. Changes observed during the SMT thrust phase could be explained by the proportional increase in preload force or the related changes in rate of force application. Although only healthy participants were tested in this study, preload forces may be an important parameter underlying SMT mechanism of action. Future studies should investigate the clinical implications of varying SMT dosages. CONCLUSION The present results suggest that neuromuscular and biomechanical responses to SMT may be modulated by preload through changes in the rate of force application. Overall, the present results suggest that preload and rate of force application may be important parameters underlying SMT mechanism of action.

Effects of Muscle Fatigue, Creep, and Musculoskeletal Pain on Neuromuscular Responses to Unexpected Perturbation of the Trunk: A Systematic Review

Introduction: Trunk neuromuscular responses have been shown to adapt under the influence of muscle fatigue, as well as spinal tissue creep or even with the presence of low back pain (LBP). Despite a large number of studies exploring how these external perturbations affect the spinal stability, characteristics of such adaptations remains unclear. Aim: The purpose of this systematic review was to assess the quality of evidence of studies investigating trunk neuromuscular responses to unexpected trunk perturbation. More specifically, the targeted neuromuscular responses were trunk muscle activity reflex and trunk kinematics under the influence of muscle fatigue, spinal creep, and musculoskeletal pain. Methods: A research of the literature was conducted in Pubmed, Embase, and Sport-Discus databases using terms related to trunk neuromuscular reflex responses, measured by electromyography (baseline activity, reflex latency, and reflex amplitude) and/or trunk kinematic, in context of unexpected external perturbation. Moreover, independent variables must be either trunk muscle fatigue or spinal tissue creep or LBP. All included articles were scored for their electromyography methodology based on the “Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM)” and the “International Society of Electrophysiology and Kinesiology (ISEK)” recommendations whereas overall quality of articles was scored using a specific quality checklist modified from the Quality Index. Meta-analysis was performed on reflex latency variable. Results: A final set of 29 articles underwent quality assessments. The mean quality score was 79%. No effect of muscle fatigue on erector spinae reflex latency following an unexpected perturbation, nor any other distinctive effects was found for back muscle fatigue and reflex parameters. As for spinal tissue creep effects, no alteration was found for any of the trunk reflex variables. Finally, the meta-analysis revealed an increased erector spinae reflex latency in patients with chronic LBP in comparison with healthy controls following an unexpected trunk perturbation. Conclusion: The literature provides some evidence with regard to trunk adaptions in a context of spinal instability. However, most of the evidence was inconclusive due to a high methodological heterogeneity between the studies.

Learning Spinal Manipulation: The Effect of Expertise on Transfer Capability

OBJECTIVE Transfer capability represents the changes in performance in one task that result from practice or experience in other related tasks. Increased transfer capability has been associated with expertise in several motor tasks. The purpose of this study was to investigate if expertise in spinal manipulation therapy, assessed in groups of trainees and experienced chiropractors, is associated with increased transfer capabilities. METHODS Forty-nine chiropractic students (fifth- and sixth-year students) and experienced chiropractors were asked to perform blocks of 10 thoracic spine manipulations in 3 different conditions: preferred position and table setting, increased table height, and unstable support surface. Spinal manipulations were performed on a computer-connected device developed to emulate a prone thoracic spine manipulation. Thrust duration, thrust force rate of force application, and preload force were obtained for each trial and compared across groups and conditions. RESULTS Results indicated that both expertise and performance conditions modulated the biomechanical parameters of spinal manipulation. Decreased thrust duration and increased rate of force application were observed in experienced clinicians, whereas thrust force and thrust rate of force application were significantly decreased when task difficulty was increased. Increasing task difficulty also led to significant increases in performance variability. CONCLUSION Overall, this study suggests that when instructed to perform spinal manipulation in a challenging context, trainees and experts choose to modulate force to optimize thrust duration, a characteristic feature of high-velocity, low-amplitude spinal manipulation. Given its known association with motor proficiency, transfer capability assessments should be considered in spinal manipulative therapy training.