title: Influence of pain and gender on impact loading during walking: a randomised trial.
abstract: BACKGROUND
  Knee joint osteoarthritis is painful and with an overweight of female incidence. The cardinal symptom is pain, which causes compensatory gait changes, and gender differences in pain sensitivity exist. Impact loadings at heel strike during walking are suspected as a co-factor in development of knee osteoarthritis. Thus the purpose of this study was to investigate the influence of experimental muscle pain and gender on generation and attenuation of impact loading during walking.
  
  
  METHODS
  Ten healthy males and 10 healthy females were recruited. Impact loadings during walking were measured using force platforms and accelerometers attached to the tibia and sacrum. Impact ground reaction force peaks and loading rates, and peak accelerations were used to quantify impact loadings. Attenuation was quantified by means of a transfer function between the tibial and sacral accelerometer signals, and the relative peak acceleration reduction. Knee joint kinematics were collected using a three-dimensional movement analysis system. The study was a cross-over study and data were collected before, during, and after experimental vastus medialis pain and a control situation.
  
  
  RESULTS
  Experimental muscle pain did not affect generation or attenuation of impact loading in either gender. While the impact loading magnitude was similar across genders, lower loading rates and more efficient attenuation were observed in females.
  
  
  CONCLUSIONS
  It is concluded that generation and attenuation of impact loadings during walking are independent of quadriceps pain in both genders. The present study does not provide any evidence of the tested variables to address the gender differences in loading rates and attenuation.
authors.affiliation: The Parker Institute: Clinical Motor Function Laboratory, Frederiksberg Hospital, Ndr. Fasanvej 57, DK-2000 Frederiksberg, Denmark. marius.henriksen@frh.regionh.dk
authors.forename: Marius
authors.initials: M
authors.lastname: Henriksen
authors.forename: Robin
authors.initials: R
authors.lastname: Christensen
authors.forename: Tine
authors.initials: T
authors.lastname: Alkjaer
authors.forename: Hans
authors.initials: H
authors.lastname: Lund
authors.forename: Erik B
authors.initials: EB
authors.lastname: Simonsen
authors.forename: Henning
authors.initials: H
authors.lastname: Bliddal
mesh_terms: D000054:Acceleration; D001696:Biomechanical Phenomena; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D010147:Pain Measurement; D016059:Range of Motion, Articular / Q000502:physiology; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage; D012737:Sex Factors; D016138:Walking / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*
chemical_list: D012462:Saline Solution, Hypertonic