François Nougarou1, Claude Dugas2, Michel Loranger3, Isabelle Pagé4, Martin Descarreaux5. 1. Post-doctoral fellowship, Département de Chiropratique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada. 2. Full professor, Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada. 3. Undergraduate student, Département de Chiropratique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada. 4. MSc student, Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada. 5. Full professor, Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada. Electronic address: Martin.descarreaux@uqtr.ca.
Abstract
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.
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.
Authors: Michel Loranger; Julien Treboz; Jean-Alexandre Boucher; François Nougarou; Claude Dugas; Martin Descarreaux Journal: J Chiropr Educ Date: 2015-08-13
Authors: William R Reed; Jamie T Cranston; Stephen M Onifer; Joshua W Little; Randall S Sozio Journal: Exp Brain Res Date: 2017-07-07 Impact factor: 1.972
Authors: William R Reed; Cynthia R Long; Gregory N Kawchuk; Randall S Sozio; Joel G Pickar Journal: Spine (Phila Pa 1976) Date: 2018-01-01 Impact factor: 3.241
Authors: François Nougarou; Isabelle Pagé; Michel Loranger; Claude Dugas; Martin Descarreaux Journal: BMC Complement Altern Med Date: 2016-06-02 Impact factor: 3.659