The effect of chiropractic manipulation on salivary cortisol levels.

BACKGROUND: The stress response in humans is a healthy response and is necessary for life. The effects of chiropractic manipulation (CM), if any, on stress are ill-defined. Cortisol has been used as an accurate measure of the stress response system in humans. Salivary cortisol is a noninvasive technique to accurately quantify biologically active cortisol. OBJECTIVE: To determine whether basal salivary cortisol levels can be properly detected and whether CM has any direct effect on basal salivary cortisol levels in humans. METHODS: Subjects were adult male students attending a chiropractic college. Salivary samples were collected for 5 weeks. During Week 1, samples were collected by the students at home upon waking. During Weeks 2 through 5, home samples were collected upon waking and were followed by an additional time course of samples collected in a laboratory setting before and after CM. Salivary cortisol was measured by enzyme-linked immunoassay. RESULTS: Chiropractic manipulative therapy did not significantly change basal salivary cortisol levels. The time course of acute changes to cortisol levels was independent of testing week and group. A decrease in salivary cortisol was detected over time on each trial testing day. Overall, cortisol levels significantly decreased from the time of the home samples until the pretreatment laboratory measurement (P <.05). Cortisol levels subsequently decreased from pretreatment to 15 minutes after treatment (P <.05). After treatment, there were progressive decreases in cortisol levels from the 15- and 30-minute time points to the 60-minute time point (P <.05). CONCLUSION: The results of this pilot study suggest that there is no effect of CM on salivary cortisol levels in asymptomatic subjects. As such, we conclude that neither the anticipation of CM nor the spinal manipulative procedure itself induces a state of stress or anxiety.

Clinical precision of myofascial trigger point location in the trapezius muscle.

Myofascial trigger points (TrPs) have been clinically described as discrete areas of muscle tenderness presenting in taut bands of skeletal muscle. Using well-defined clinical criteria, prior investigations have demonstrated interrater reliability in the diagnosis of TrPs within a given muscle. No reports exist, however, with respect to the precision with which experienced clinicians can determine the anatomic locations of TrPs within a muscle. This paper details a study wherein four trained clinicians achieved statistically significant reliability (see below) in estimating the precise locations of latent TrPs in the trapezius muscle of volunteer subjects (n=20). To do so, the clinicians trained extensively together prior to the study. The precise anatomic location of each subject's primary TrP was measured in a blinded fashion using a 3 dimensional (3-D) camera system. Use of this measurement system permitted the anatomic co-ordinates of each TrP to be located without providing feedback to subsequent clinicians. The clinicians each used a pressure algometer along with patient feedback to document the sensitivity of each suspected TrP site, however unlike routine clinical practice, the algometry was performed with a double-blinded approach hence the results were only examined post-hoc. At the time of data collection (algometry readings unknown), 16 of the 20 subjects were judged to present with a latent TrP. Subsequently, when subjected to a criterion pressure threshold value of <3.0 kg.cm(-2), 12 of these TrPs were classified as being clinically sensitive. To assess the 3-D measurement precision, and the reliability of the TrP estimates, statistical measures of the SEM and the Generalizability coefficient (G-coeff) were determined for all suspected TrP sites in the superior-inferior, medial-lateral and anterior-posterior directions. The best results were determined by pooling the measurements of all 4 clinicians, however, based upon exceeding a criterion reliability threshold of 80%, the use of just two testers was found to produce reliable results. The two-tester condition yielded a precision of 7.5, 7.6 and 6.5 mm (SEM) with reliability (G-coeff) of 0.92, 0.86 and 0.83, respectively. Given the double-blinded methodology, the use of pressure algometry was also found to demonstrate internal validity. The algometer responses associated with TrP estimates varied inversely with respect to the clinical group's reliability in identify the TrP locations. To summarize, for the trapezius muscle, this study demonstrates that two trained examiners can reliably localize latent TrPs with a precision that essentially approaches the physical dimensions of the clinician's own fingertips. Finally, it should be recognized that the ability to precisely document TrP location appears critical to the success of future studies that may be designed to investigate the etiology and pathogenesis of this commonly diagnosed clinical disorder.