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The Effects of Spinal Manipulation on Central Nervous System Activity Measured by Reflexive Calf Muscle Recruitment

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ClinicalTrials.gov Identifier: NCT02848456
Recruitment Status : Completed
First Posted : July 28, 2016
Last Update Posted : April 19, 2017
Sponsor:
Collaborator:
University of Kentucky
Information provided by (Responsible Party):
Grant Sanders, University of Kentucky

Brief Summary:
This study investigated the effects of spinal manipulation on central nervous system activity. The presence of postactivation potentiation, an increase in muscular force production following prior muscular contractions, was measured with electromyography and the muscular force production during electrically-induced calf muscle reflexes. It was hypothesized that significantly greater potentiation would be stimulated by a calf muscle contraction with spinal manipulation delivered immediately beforehand than the potentiation arising from the contraction only.

Condition or disease Intervention/treatment Phase
Subluxation of Joint of Lumbar Spine Procedure: Spinal Manipulation Procedure: Max Voluntary Isometric Contraction Procedure: SM+MVIC Not Applicable

Detailed Description:

A randomized, controlled, single-blind crossover study design was utilized, and the three independent variables were spinal manipulative therapy (SMT), a 10 second plantar flexion maximal voluntary isometric contraction (MVIC) or SMT immediately preceding the MVIC (SMT + MVIC). The treatment order was randomized for each of the three sessions before the tibial nerve Hmax/Mmax stimulation protocol.

Each of the four dependent variables were evoked during the tibial nerve H-reflex stimulation protocol at the conclusion of each session, and included the Hmax/Mmax ratio (%) of the gastrocnemius and soleus muscles and the isometric twitch torque occurring at Hmax and at Mmax. Hmax, the highest H-reflex amplitude, is an indication of the greatest possible reflex activation; as such, it is an estimate of the number of motor neurons a subject is capable of activating in a given state. Further increases in the stimulation intensity cause the subsequent M-wave to reach its highest amplitude, Mmax. Mmax is a compound muscle action potential (CMAP) which represents full muscle activation. Specific to the current investigation, Mmax indicated activation of the total volume of the gastrocnemius/soleus motor neuron (MN) pool.

Given that Hmax is an inference of the number of MNs being recruited, and Mmax constitutes the entire motor neuron pool, the proportion of the entire MN pool capable of being recruited can be estimated with the Hmax/Mmax ratio. The Hmax/Mmax ratio was determined by division of the EMG peak-to-peak amplitudes (mV) evoked at Hmax by the preceding Mmax EMG peak-to-peak amplitudes. Differences in each of the four dependent variables (Hmax/Mmax ratios of the gastrocnemius and soleus and the peak twitch torques evoked at Hmax and Mmax) following each treatment form of SMT, MVIC or SMT+MVIC delivered during the three data collection sessions on three separate days were determined with a two-way (treatment × time point) repeated measures ANOVA. Percent changes from baseline were also calculated for each of the dependent variables, and the same type of ANOVA was used to determine differences in the within-subjects effects of each treatment.


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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Single (Participant)
Primary Purpose: Basic Science
Official Title: The Effects of Spinal Manipulative Therapy on Postactivation Potentiation
Study Start Date : August 2014
Actual Primary Completion Date : October 2014
Actual Study Completion Date : October 2014

Arm Intervention/treatment
Active Comparator: Spinal Manipulation SM
In a repeated measures, crossover design, all subjects received one of three randomized treatments during three separate sessions: SM; a 10 second plantar flexion maximal voluntary isometric contraction (MVIC) or the manipulation immediately preceding the contraction (SM+MVIC).
Procedure: Spinal Manipulation
Manual, side-posture, high-velocity low-amplitude spinal manipulation targeting the lower lumbar spine and sacroiliac joints

Active Comparator: Max Voluntary Isometric Contraction MVIC
In a repeated measures, crossover design, all subjects received one of three randomized treatments during three separate sessions: SM; a 10 second plantar flexion maximal voluntary isometric contraction (MVIC) or the manipulation immediately preceding the contraction (SM+MVIC).
Procedure: Max Voluntary Isometric Contraction
A 10 second plantar flexion maximal voluntary isometric contraction

Active Comparator: SM+MVIC
In a repeated measures, crossover design, all subjects received one of three randomized treatments during three separate sessions: SM; a 10 second plantar flexion maximal voluntary isometric contraction (MVIC) or the manipulation immediately preceding the contraction (SM+MVIC).
Procedure: SM+MVIC
The spinal manipulation immediately preceding the maximal voluntary isometric contraction




Primary Outcome Measures :
  1. Changes in H-reflex amplitudes of the gastrocnemius and soleus muscles compared to baseline [ Time Frame: Data were collected at 17 time points during a 20-minute tibial nerve electrical stimulation protocol post-treatment: 20 seconds, 40 seconds, 1:00, 2:00, 3:00, 4:00, 5:00, 6:00, 7:00, 8:00, 9:00, 10:00, 12:00, 14:00, 16:00, 18:00 and 20:00 minutes ]
    Peak-to-peak EMG amplitudes (mV) at Hmax of the gastrocnemius and soleus were recorded before and immediately following the three separate treatments

  2. Changes in isometric twitch torques of the gastrocnemius and soleus muscles compared to baseline [ Time Frame: Data were collected at 17 time points during a 20-minute tibial nerve electrical stimulation protocol post-treatment: 10 seconds, 30 seconds, 50 seconds, 1:30, 2:30, 3:30, 4:30, 5:30, 6:30, 7:30, 8:30, 9:30, 11:00, 13:00, 15:00, 17:00 and 19:00 minutes ]
    Twitch torques (Nm) of the gastrocnemius and soleus at Mmax were recorded before and immediately following the three separate treatments



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Ages Eligible for Study:   20 Years to 35 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • At least one year of resistance training experience and current completion of at least three training sessions per week
  • Males needed to be able to back squat a minimum load of 1.5 x body weight
  • Females needed to be able to back squat 1 x body weight

Exclusion Criteria:

  • Any pain in the lower back, abdomen or legs and/or surgeries performed in these regions

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02848456


Locations
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United States, Kentucky
College of Education, Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY
Lexington, Kentucky, United States, 40506
Sponsors and Collaborators
Grant Sanders
University of Kentucky
Investigators
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Principal Investigator: Grant D Sanders, D.C., Ph.D. College of Education, Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY
Study Chair: James W Yates, Ph.D. College of Education, Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY

Publications:

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Responsible Party: Grant Sanders, Principal Investigator, University of Kentucky
ClinicalTrials.gov Identifier: NCT02848456     History of Changes
Other Study ID Numbers: 14-0507-F6A
First Posted: July 28, 2016    Key Record Dates
Last Update Posted: April 19, 2017
Last Verified: April 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Yes
Plan Description: Shared data include the subjects' reflexive EMG amplitudes and peak torques of the gastrocnemius and soleus during the Hoffmann Reflex electrical stimulation protocol at the conclusion of each data collection session. These raw data are available in Appendix K of the PI's dissertation, which may be obtained at http://uknowledge.uky.edu/khp_etds/27/
Keywords provided by Grant Sanders, University of Kentucky:
Manipulation, Spinal
H-Reflex
Muscle Contraction
Muscle Strength Dynamometer