Central Mechanisms of Intervention for Low Back Pain

• Immediate change in temporal sensory summation [ Time Frame: 10 minutes post-intervention ] [ Designated as safety issue: No ]
  We will use both behavioral (ratings) and cortical (using fMRI) measures of temporal sensory summation.
• Change in temporal sensory summation [ Time Frame: 48 hours post-intervention ] [ Designated as safety issue: No ]
  The change temporal sensory summation (determined using quantitative sensory testing and fMRI) will be calculated from pre-intervention to 48 hours post-intervention

Body-based interventions have consistently shown clinical effectiveness in patients with back pain. The primary objective for this study is to compare the effect of body-based interventions commonly used in the management of low back pain on behavioral and cortical measures of pain sensitivity and central sensitization of pain. Participants will be randomly assigned to receive one of the interventions or be in a control group. The central hypothesis for this proposal is that spinal manipulation, a specific form of body-based intervention, inhibits central sensitization of pain normalizing pain sensitivity more rapidly than other interventions. The completion of the proposed study will elucidate underpinning mechanisms of body-based interventions. Identification of these mechanisms will improve the clinical application and utilization of these interventions in the management of musculoskeletal pain conditions, especially back pain.

170 participants will be randomly assigned to receive one of the interventions or be in a control group. The investigators will use of a model of experimentally induced low back pain to investigate the effects of manipulative and body-based interventions in acute onset low back pain without some of the clinical confounds. The investigators will collect fMRI and psychophysical data about pain sensitivity before and after the induction of pain, and before and after interventions for that pain.

• Other: Spinal Manipulation
  High velocity low amplitude joint-biased intervention
  Other Name: SMT
• Other: Spinal Mobilization
  Low velocity, large amplitude oscillating joint biased technique
  Other Names:

  • Mobilization
  • Mobs
• Other: Static Touch
  The investigators maintains hand contact with both hands over the lumbar area of the participant

• Experimental: Spinal Manipulation
  High-velocity manual technique applied to the pelvis with the participant in supine
  Intervention: Other: Spinal Manipulation
• Sham Comparator: Static Touch
  Practitioner hands are placed on the lumbar spine with the participant in prone.
  Intervention: Other: Static Touch
• Active Comparator: Spinal Mobilization
  Oscillation of the third lumbar level performed with the participant in prone
  Intervention: Other: Spinal Mobilization

Inclusion Criteria:

• aged 18 to 40 years
• able to read and understand spoken English

Exclusion Criteria:

• Previous participation in a conditioning program specific to trunk extensors in the past 6 months
• Any report of back or leg pain in the past 3 months
• Any chronic medical conditions that may affect pain perception (e.g., diabetes, high blood pressure, fibromyalgia, headaches), kidney dysfunction, muscle damage, or major psychiatric disorder
• History of previous injury including surgery to the lumbar spine, renal malfunction, cardiac condition, high blood pressure, osteoporosis, or liver dysfunction
• Consumption of any drugs (e.g., caffeine, alcohol, theophyline, tranquilizers, antidepressants) that may affect pain perception or hydration status from 24 hr. before participation until completion of the investigation
• Performance of any intervention for symptoms induced by exercise and before the termination of their participation or the protocol
• Recent illness
• Any contraindication to MRI e.g.: pacemakers, metal implants which are not MRI compatible (e.g. aneurysm clip), pregnancy and severe claustrophobia.