FROM:     
Clinical Chiropractic 2012 (Dec); 15 (3-4): 147–157
John Ward, Ken Tyer, Jesse Coats, Gabbrielle Williams, 
Shauna Weigand, Danielle Cockburn
  Objective       The aims of this study were (1) to determine if there were any statistically significant immediate effects of atlas Chiropractic Manipulative Therapy (CMT) on cardiovascular physiology among normotensive individuals and (2) to quantify those responses if they were found.
  Design       A single-blind, randomized controlled trial.
  Setting       Human physiology lab.
  Subjects       Forty-eight college students (age = 25.9 ± 3.4 years, height = 1.70 ± 0.10 m, body mass = 76.2 ± 20.1 kg: mean ± SD) were sampled in this study.
   Methods      Participants were equally randomized into four study groups: left head-turn control, no contact control, left atlas manipulation, and right atlas manipulation. The CMT provided was a cervical break. Electrocardiogram (ECG), bilateral pulse oximetry, and bilateral blood pressure measurement were performed at baseline, post 1-min intervention, post 10-min intervention, and approximately post 24-h (±1 h) intervention. Between-group dependent variables were analyzed through one-way analysis of variance (ANOVA) at each time point.
  Results       No statistically significant difference was shown among any between-group cardiovascular dependent variables in this study.
   Conclusions      The results of this research suggest cardiovascular physiology is not affected by CMT of the atlas in normotensive individuals. These findings in relation to existing research suggest future cervical spine CMT studies should be performed focusing on hypertensive patients.