Muscle testing response to provocative vertebral challenge and spinal manipulation: a randomized controlled trial of construct validity

J Manipulative Physiol Ther. 1994 Mar-Apr;17(3):141-8.


Objective: To evaluate the relationship of muscle strength response to a provocative vertebral challenge and to spinal manipulation.

Design: Prospective double-blind randomized controlled trial: crossover and between subjects designs.

Setting: Laboratory: Center for Technique Research.

Participants: Sixty-eight naive volunteers from the student body, staff and faculty of the college.

Interventions: Provocative vertebral challenge: standardized 4-5 kg force applied with a pressure algometer to the lateral aspects of the T3-12 spinous processes.

Intervention: manual high velocity low amplitude adjustment or switched-off activator sham.

Main outcome measures: Piriformis muscle response was defined in two ways: reactivity (a decrease in muscle resistance, yes or nor, following a vertebral challenge); responsiveness (the cessation of reactivity following spinal manipulation). Relative response attributable to the maneuver (RRAM): the percent of an outcome attributable to the challenge or adjustment itself.

Results: Average RRAM = 16% reactivity to vertebral challenge; average RRAM = 0% responsiveness to spinal manipulation. Six to 10% of muscle tests were positive regardless of examiner, previous finding or intervention.

Conclusions: For the population under investigation, muscle response appeared to be a random phenomenon unrelated to manipulable subluxation. In and of itself, muscle testing appears to be of questionable use for spinal screening and post-adjustive evaluation. Further research is indicated in more symptomatic populations, different regions of the spine, and using different indicator muscles.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bias
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Manipulation, Orthopedic / methods*
  • Muscle Contraction*
  • Reproducibility of Results
  • Spinal Diseases / physiopathology
  • Spine / physiology*