title: Instantaneous rate of loading during manual high-velocity, low-amplitude spinal manipulations.
abstract: OBJECTIVE
  The objective of this study was to determine the instantaneous rate of loading during manual high-velocity, low-amplitude spinal manipulations (HVLA SMs) in the lumbar and thoracic regions and compare to the average rates of loading.
  
  
  METHODS
  Force-time profiles were recorded using a hand force transducer placed between the hand of a doctor of chiropractic and the subject's back during 14 HVLA SM thrusts on asymptomatic volunteers while 3 doctors of chiropractic delivered the spinal manipulations. Doctors also delivered 36 posterior to anterior thoracic manipulations on a mannequin. Data were collected at a sampling rate of 1000 Hz using Motion Monitor software. Force-time profile data were differentiated to obtain instantaneous rates of loading. The data were reduced using a custom-written MathCad program and analyzed descriptively.
  
  
  RESULTS
  The instantaneous rates of loading were 1.7 to 1.8 times higher than average rates of loading, and instantaneous rates of unloading were 2.1 to 2.6 times the average rates of unloading during HVLA SMs. Maximum instantaneous rates of loading occurred 102 to 111 milliseconds prior to peak load. Maximum instantaneous rates of unloading occurred 121 to 154 milliseconds after the peak load. These data may be useful for further understanding of HVLA SMs.
  
  
  CONCLUSIONS
  The instantaneous rates of loading and where they occurred may be useful data for understanding and describing HVLA SMs.
authors.affiliation: Associate Professor, Palmer Center for Chiropractic Research, Davenport, IA. Electronic address: Gudavalli_r@palmer.edu.
authors.forename: Maruti Ram
authors.initials: MR
authors.lastname: Gudavalli
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D008348:Manikins; D020393:Manipulation, Spinal / Q000379:methods*; D056888:Patient Positioning; D012984:Software; D013904:Thoracic Vertebrae / Q000502:physiology; D014159:Transducers
keywords: Biomechanics; Chiropractic; Manipulation; Spinal