Effects of Inversion Table Postural Positions on Cardiovascular Hemodynamics in Apparently Healthy Young Adults

Treatment of low back pain by inverting one’s body on a tilt table permits unloading of bones, joints and discs of the low back. This traction force through the spine has been theorized to decrease low back pain. Randomized controlled studies to evaluate the efficacy of this practice for low back pain are limited. Although the gravitational traction is short lived, patients with hypertension, glaucoma, or cardiovascular disease are cautioned to avoid the inversion treatment because of excessive elevations in blood pressure, heart rate and intraocular pressure. PURPOSE: To evaluate the influence of postural change on cardiovascular hemodynamics, 12 subjects (age 22.6 ± 1.8 yrs, ht 170.4 ± 9.2 cm, body mass 74.0 ± 13.0 kg, 7 ♀) volunteered to participate in 6 assessments in the following positions: seated (S), 45° head up (45H1), horizontal [H], modified Trendelenburg (-30° head down) [T], -60° head down [60HD], and -90° inversion [I]). METHODS: Baseline measures of hemodynamic function (cardiac output [Q], stroke volume [SV], heart rate [HR], systemic vascular resistance[SVR] and cardiac index[CI]) were obtained with an impedance cardiography system, and blood pressure [BP] by auscultation in a seated position [S], followed by a 5 minute assessment in each of the 6 aforementioned positions. Reliability was ensured with repeat trials separated by 48 hours. ANOVA with repeated measures (p<.05) was applied to the data. RESULTS: Total mean BP (mmHg), EDV (mL) & SVR I(dyn.s/cm) were 114.6/70.5, 129.7 & 1164.6, respectively, with NSD among trials. Q (L/min) of 6.6, 6.9, 6.1, 5.9, 5.8, & 6.2; SV [mL/b] of 87.7, 87.9, 88.1, 86.2, 85.1, & 83.8; HR [b/min] of 75.5, 78.8, 68.6, 65.9, 68.3, & 74.7; SVR [dyn.s/cm] of 1030, 986, 1248, 1280, 1288, & 1212; and CI (L/m2] of 3.5, 3.7, 3.2, 3.1, 3.1, & 3.3 were obtained for S, 45H1, H, T, 60HD, and I, respectively. Although statistical analysis revealed differences among several conditions (p<.05), they do not appear clinically significant. CONCLUSION: Postural changes induced by acute exposure to tilt table inversion did not provide clinically significant changes in measures of cardiovascular hemodynamics in a healthy population and thus appears relatively safe.