ORIGINAL ARTICLES CHANGES IN PRESSURE PAIN THRESHOLDS OVER C5-C6 ZYGAPOPHYSEAL JOINT AFTER A CERVICOTHORACIC JUNCTION MANIPULATION IN HEALTHY SUBJECTS César Fernández-de-las-Peñas, PT, PhD, a,b,h Cristina Alonso-Blanco, PT, a Joshua A. Cleland, PT, PhD, c,d,e Cleofás Rodri ́ guez-Blanco, PT, DO, f,h and Francisco Alburquerque-Sendi ́ n, PT, DO g,h ABSTRACT Objective: This study examines if C7-T1 manipulation results in changes in pressure pain thresholds (PPT) over bilateral C5-C6 zygapophyseal joints in asymptomatic subjects. Methods: Thirty subjects, 13 men and 17 women, without a current history of neck, shoulder, or upper extremity pain participated. Participants were randomly divided into 3 groups: experimental dominant group, subjects who received the manipulative thrust directed at the right side of the C7-T1 joint; experimental nondominant group, those who received the thrust on the left side of the C7-T1 joint; and a placebo group, those who received a sham-manual procedure. The outcome measure was the PPT on both right and left C5-C5 zygapophyseal joints, which was assessed at preintervention and 5 minutes postintervention by an assessor blinded to the treatment allocation of the subject. A 3-way repeated measures analysis of covariance was used to evaluate changes in PPT. Results: The analysis of covariance revealed time × group (F = 32.3; P b .001), time × side (F = 4.9; P b .05), time × sex (F = 7.93; P b .01), and time × group × sex (F = 7.606; P b .001) interactions. Post hoc analyses found that (a) both experimental groups showed greater improvements in PPT than the placebo group (P b .05), without significant differences between them (P N .6); (b) the right side had greater increases in PPT in both experimental groups (P b .05), but not within the placebo group (P N .8); (c) men experienced greater increases in PPT levels than women, particularly in the experimental nondominant group (P b .01). Within-group effect sizes were large for both experimental groups (d N 1), but small for the placebo condition (d b 0.2). Conclusions: These results suggest that a C7-T1 manipulation induced changes in PPT in both right and left C5-C6 zygapophyseal joints in healthy subjects. (J Manipulative Physiol Ther 2008;31:332-337) Key Indexing Terms: Pain Threshold; Manipulation; Spinal; Manipulation; Orthopedic T he effectiveness of manual therapy techniques directed at the cervical spine in patients with neck pain or cervicogenic headache has been supported by an increasing number of high-quality randomized clinical trials 1-3 and systematic reviews. 4,5 However, the potential risks associated with upper cervical spine manipulations have limited the use of techniques in physical therapy practice. Recent evidence has begun to suggest that spinal manipulation directed at the thoracic region may have a Professor, Department of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation, Universidad Rey Juan Carlos, Alcorcón, Spain. b Clinical Researcher, Esthesiology Laboratory, Universidad Rey Juan Carlos, Alcorcón, Spain. c Professor, Department of Physical Therapy, Franklin Pierce College, Concord, NH. d Clinician, Physical Therapist, Rehabilitation Services, Concord Hospital, NH. e Manual Therapy Fellowship Program, Regis University, Denver, Colo. f Professor, Department of Physical Therapy, Universidad de Sevilla, Sevilla, Spain. g Professor, Department of Physical Therapy, Universidad de Salamanca, Salamanca, Spain. h Escuela de Osteopatía de Madrid, Spain. Submit requests for reprints to: César Fernández-de-las-Peñas, PT, PhD, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avenida de Atenas s/n, 28922 Alcorcón, Madrid, Spain (e-mail: cesar.fernandez@urjc.es). Paper submitted September 25, 2007; in revised form December 4, 2007; accepted January 8, 2008. 0161-4754/$34.00 Copyright © 2008 by National University Health Sciences. doi:10.1016/j.jmpt.2008.04.006 332