The Role of the Rate of Force Application in Responses to Spinal Manipulation Therapy

Study Overview
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Brief Summary
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The objective of the present study is to determine if spinal manipulations with a constant rate of force application but with different peak force and time to peak force lead to similar responses in healthy adults.

Detailed Description
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Although there are indirect evidences that the rate of force application modulates neuromuscular responses to spinal manipulation therapy (SMT) through peak force or thrust duration modulations, such an assumption remains to be confirmed. Therefore, the objective of the present study was to determine if different SMT force-time profiles where a constant rate of force application would be maintained (through the modulation of the peak force and the time to peak force) lead to similar neuromechanical responses. Based on the available data relative to the effect of SMT biomechanical parameters modulation, it was hypothesized that neuromuscular responses would be similar across SMT force-time profiles, while vertebral displacements would increase as SMT peak force increases.

Official Title
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Neuromechanical Response to Spinal Manipulation Therapy: Effects of a Constant Rate of Force Application

Conditions
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Spinal Manipulation

Intervention / Treatment
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* Procedure: Spinal manipulation
* Device: Apparatus used to deliver spinal manipulations


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy adult Exclusion Criteria: Thoracic or lumbar pain History of back trauma or surgery Severe osteoarthritis Inflammatory arthritis Vascular conditions Contraindication to the use of SMT

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Participants<br>All volunteers will participate in an experimental session. Participants will be delivered four different spinal manipulations (SMT) at T7 with a rate of force application of about 2200 Newtons/seconds and a preload force of 25 Newtons (N). SMTs will differed in their time to peak force (ms) and peak force (N), respectively fixed as follow for each applied SMT: (1)57 ms / 150 N, (2)80 ms / 200 N, (3)102 ms / 250 N and (4)125 ms / 300 N. | Procedure: Spinal manipulation<br>* Participants will lie down during the 45-minute experimental session. Vertebral displacements (cm) and muscle response amplitude (RMS value) will be recorded through kinematic markers (on T6, T7 and T8 spinous processes) and surface electromyography electrodes (on the left and right erector spinae at T6 and T8 vertebra level). Each SMT (4 per participant) will be delivered at T7 transverse processes by an apparatus. Responses during the thrust phase (duration equal to twice the time to peak force) and after the thrust (1,5s duration) will be compared between SMTs.<br>* Other names: Manual therapy;Device: Apparatus used to deliver spinal manipulations<br>* An apparatus using a servo-controlled linear actuator motor (Linear Motor Series P01-48x360, LinMot Inc., Switzerland) will be used to deliver spinal manipulations.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Left T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Left T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T6 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Right T8 Normalized Root Mean Square (RMS) Value | Normalized amplitude (RMS) of surface electromyography response. The normalisation was achieved by dividing the obtained RMS by the RMS value before thrust application. | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Sixth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Seventh Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Eighth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 150N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Sixth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Seventh Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Eighth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 200N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Sixth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Seventh Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Eighth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 250N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Sixth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Seventh Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 
| Vertebral Displacement of the Eighth Thoracic Vertebra | Absolute posterior to anterior vertebral displacement during the spinal manipulation in centimeter | During the 300N spinal manipulation procedure, assessed up to 2 seconds following thrust onset | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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electromyography, biomechanical phenomena, dose-response relationship, musculoskeletal manipulations, spinal manipulation