Related Experiment Video
Updated: Mar 18, 2026
Back Mechanical Sensitivity Assessment in the Rat for Mechanistic Investigation of Chronic Back Pain
Published on: August 30, 2022
Effect of two consecutive spinal manipulations in a single session on myofascial pain pressure sensitivity: a
Michelle A Laframboise1, Howard Vernon2, John Srbely3
1Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, Canada; Division of Graduate Studies, Sports Sciences, Canadian Memorial Chiropractic College.
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.
