title: Effect of two consecutive spinal manipulations in a single session on myofascial pain pressure sensitivity: a randomized controlled trial.
abstract: OBJECTIVE
  To investigate the summative effect of two consecutive spinal manipulative therapy (SMT) interventions within the same session on the pain pressure sensitivity of neurosegmentally linked myofascial tissues.
  
  
  METHODS
  26 participants were recruited and assessed for the presence of a clinically identifiable myofascial trigger point in the right infraspinatus muscle. Participants were randomly assigned to test or control group. Test group received two consecutive real cervical SMT interventions to C5-C6 segment while controls received one real SMT followed by one validated sham SMT intervention to C5-C6 segment. Participants received the two consecutive SMT interventions 30 minutes apart. Pain pressure threshold (PPT) readings were recorded at pre-SMT1 and 5, 10, 15, 20 and 25 minutes post-SMT1 and post-SMT2. PPT readings were normalized to pre-SMT1 values and averaged.
  
  
  RESULTS
  Repeated measures ANOVA demonstrated a significant main effect of SMT intervention [F(1,24)=8.60, p<0.05] but not group [F(1.24)=0.01] (p=0.91). Post-hoc comparisons demonstrated a statistically significant (p<0.05) increase in SMT2 versus SMT1 (18%) in the test group but not in controls (4%) (p=0.82).
  
  
  CONCLUSIONS
  Two consecutive SMT interventions evoke significant decreases in mechanical pressure sensitivity (increased PPT) within neurosegmentally linked myofascial tissues. The antinociceptive effects of SMT may be summative and governed by a dose-response relationship in myofascial tissues.
authors.affiliation: Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, Canada; Division of Graduate Studies, Sports Sciences, Canadian Memorial Chiropractic College.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Laframboise
authors.affiliation: Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, Canada; Professor, Graduate Education and Research, Canadian Memorial Chiropractic College.
authors.forename: Howard
authors.initials: H
authors.lastname: Vernon
authors.affiliation: Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, Canada; Assistant Professor, Department Human Health and Nutritional Science, University of Guelph, Guelph, Ontario, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Srbely
keywords: chiropractic; myofascial pain; pressure thresholds; spinal manipulation