Effects of rib raising on the autonomic nervous system: a pilot study using noninvasive biomarkers.

CONTEXT Rib raising is an osteopathic manipulative treatment technique used to address restricted excursion of the rib cage and modulate sympathetic nervous system (SNS) activity. However, the physiologic effects of this technique have not been well documented. OBJECTIVE To investigate the effects of rib raising on the autonomic nervous system and the hypothalamic-pituitary-adrenal axis using noninvasive biomarkers. METHODS Changes in salivary biomarkers after rib raising were investigated using a pretest-posttest, placebo-controlled design. Healthy adult participants were recruited and randomly assigned to rib raising or placebo (light touch) groups. All participants provided baseline saliva samples and samples immediately and 10 minutes after receiving the rib raising or placebo procedure. Salivary flow rate, alpha-amylase activity, and cortisol levels were measured for each sample. RESULTS Twenty-three participants were recruited, of whom 14 completed the study (7 in each group). Subjects who received rib raising had a statistically significant decrease in alpha-amylase activity both immediately after (P=.014) and 10 minutes after (P=.008) the procedure. A statistically significant change in alpha-amylase activity was not seen in the placebo group at either time point. Changes in salivary cortisol levels and flow rate were not statistically significant in either group. CONCLUSIONS The results of the present pilot study suggest that SNS activity may decrease immediately after rib raising, but the hypothalamic-pituitary-adrenal axis and parasympathetic activity are not altered by this technique. Salivary alpha-amylase may be a useful biomarker for investigating manipulative treatments targeting the SNS. Additional studies with a greater number of subjects are needed to expand on these results.