Changes in cardiovascular function during inversion.

Although inversion therapy is used increasingly as a therapy for musculoskeletal back disorders, its effects on cardiovascular function have not been systematically determined. Heart rate, blood pressure and echocardiographic measurements were performed in 20 normal male volunteers before, during and after bent-knee inversion. Compared to control measurements in the supine position, inversion significantly increased heart rate, systolic and diastolic blood pressure, rate-pressure product, systemic vascular resistance and left ventricular (LV) wall stress. Inversion also resulted in a significant decrease in LV diastolic volume, cardiac output and ejection fraction. Thus inversion produces an increase in LV afterload and myocardial oxygen demand concomitantly with a decrease in LV preload and global systolic function, and may be contraindicated in patients with cardiovascular disease.