Cardioperipheral vascular effects of inversion on humans

The purpose of this study was to identify the cardioperipheral vascular effects of inversion on humans. Twenty healthy volunteer subjects (10 men, 10 women), aged 20 to 40 years, participated in this study. Variables of heart rate, blood pressure, and intraocular pressure were measured in four positions: sitting, standing, bent knee inversion, and straight leg inversion. Three trials were recorded in each of the four positions. Data were analyzed by two-way analyses of variance for repeated measures. The results indicated that heart rate increased significantly from the sitting position to the bent-knee-inversion position (p less than .05). Systolic and diastolic blood pressure (observed and corrected) and intraocular pressure (left and right) increased significantly from the sitting and standing positions to the bent-knee-inverted and straight-leg-inverted positions (p less than .01). Intraocular pressure also was significantly higher during straight leg inversion as compared with bent knee inversion (p less than .01). These findings reflect the need for additional research to establish better safety standards for the use of inversion devices.