title: The effect of spinal manipulation impulse duration on spine neuromechanical responses.
abstract: BACKGROUND
  Spinal manipulation therapy (SMT) is characterized by specific kinetic and kinematic parameters that can be modulated. The purpose of this study is to investigate fundamental aspects of SMT dose-physiological response relation in humans by varying SMT impulse duration.
  
  
  METHODS
  Twenty healthy adults were subjected to four different SMT force-time profiles delivered by a servo-controlled linear actuator motor and differing in their impulse duration. EMG responses of the left and right thoracic paraspinal muscles (T6 and T8 levels) and vertebral displacements of T7 and T8 were evaluated for all SMT phases.
  
  
  RESULTS
  Significant differences in paraspinal EMG were observed during the "Thrust phase" and immediately after ("Post-SMT1") (all T8 ps < 0.01 and T6 during the thrust ps < 0.05). Sagittal vertebral displacements were similar across all conditions (p > 0.05).
  
  
  CONCLUSIONS
  Decreasing SMT impulse duration leads to a linear increase in EMG response of thoracic paraspinal during and following the SMT thrust.
authors.affiliation: Département des sciences de l'activité physique, Université du Québec à Trois-Rivières.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pagé
authors.affiliation: Département des sciences de l'activité physique, Université du Québec à Trois-Rivières.
authors.forename: François
authors.initials: F
authors.lastname: Nougarou
authors.affiliation: Département des sciences de l'activité physique, Université du Québec à Trois-Rivières.
authors.forename: Claude
authors.initials: C
authors.lastname: Dugas
authors.affiliation: Département des sciences de l'activité physique, Université du Québec à Trois-Rivières.
authors.forename: Martin
authors.initials: M
authors.lastname: Descarreaux
keywords: chiropractic; dose; impulse duration; manipulation; spine