title: Muscle oxygenation and intramuscular pressure related to posture and load in back muscles.
abstract: BACKGROUND
  There is little information about the simultaneous changes of intramuscular pressure (IMP) and oxygen saturation (StO(2)) of the paraspinal muscle under various conditions of posture and load.
  
  
  OBJECTIVE
  To measure simultaneously and compare IMP and StO(2) across a range of static trunk postures commonly observed during normal work tasks.
  
  
  METHODS
  A prospective study using a repeated-measure design in clinical setting.
  
  
  METHODS
  Sixteen healthy young men with no history of back pain.
  
  
  METHODS
  Simultaneous measurements of IMP by a flexible slit catheter and StO(2) by near infrared spectroscopy of the multifidus muscle were performed.
  
  
  METHODS
  The two measures were taken in six static posture tasks: standing upright and bending forward with and without load (20kg), bending backward and during a sustained isometric contraction (ie, Sorensen test). To compare the influence of the tasks on IMP and StO(2) variables, a one-way variance analysis with repeated measures was used. Spearman's rank correlation coefficient (rho) was determined between the two variables for each posture task.
  
  
  RESULTS
  We observed only a moderate but significant correlation between IMP and StO(2) values in upright standing and a trend in bending forward positions with load (p<.05). IMP increased in the bending backward position and showed the greatest increase during the Sorensen test. StO(2) decreased significantly during the Sorensen test, in the bending forward position with and without load bearing but did not in bending backward.
  
  
  CONCLUSIONS
  The simultaneous recording of IMP and StO(2) of the multifidus muscle allows a deeper insight of physiological events during various trunk postures. In the mutifidus muscle, there is no evident linear relationship between IMP and StO(2) values in various static postures of the trunk in young males. This preliminary study shows that IMP may play a role on StO(2) only in some circumstances, such as a prolonged endurance test or in a bending forward position with a significant load bearing.
authors.affiliation: Département de Médecine Physique & Réadaptation, CHU Carémeau, Place du Pr Robert Debré, 30 029 Nîmes, Cedex 09, France. arnaud.dupeyron@chu-nimes.fr
authors.forename: Arnaud
authors.initials: A
authors.lastname: Dupeyron
authors.forename: Jehan
authors.initials: J
authors.lastname: Lecocq
authors.forename: Philippe
authors.initials: P
authors.lastname: Vautravers
authors.forename: Jacques
authors.initials: J
authors.lastname: Pélissier
authors.forename: Stéphane
authors.initials: S
authors.lastname: Perrey
mesh_terms: D001415:Back / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared