Effects of a 10-minute back rub on cardiovascular responses in healthy subjects

This study determined the cardiovascular responses to a 10-minute back rub. Twelve healthy, college-age males and females (mean age = 22 years) volunteered to participate as subjects. Using an ABA design, the subjects tested for 10 minutes (Control #1) on a padded plinth lying on one side. During the Treatment period, the back rub was administered, which was followed by Control #2. Oxygen consumption (VO2) was determined via the Medical Graphics CPX/D metabolic analyzer, which also estimated cardiac output (Q) using the CO2 rebreathing (equilibrium) method. A repeated measures ANOVA was performed to statistically compare the cardiovascular responses across the three periods. The back rub, when compared to Control #1, had no significant effect on VO2, but the central and peripheral components of VO2 were changed. Cardiac output was decreased as a result of the decreased stroke volume (SV), as a function of the increased peripheral vascular resistance (PVR). We also found an increase in the extraction of oxygen (a-vO2 diff) in the peripheral tissues. These results indicate that the VO2 response during the back rub was achieved by reciprocal central (SV,Q) and peripheral (a-vO2 diff) adjustments. Following the back rub, (i.e., Control #2 vs. Treatment), the decrease in VO2, VCO2, Ve, and a-vO2 diff appears to indicate that it was effective in inducing relaxation. Since HR, SV, and Q were unchanged, the VO2 response was a result of the decreased a-vO2 diff. Hence, the findings suggest certain positive implications for the health care industry.