The effect of crossing legs on blood pressure

To determine whether crossing of the legs at the knee or at the ankles during blood pressure measurement in sitting position has an effect on blood pressure.

One hundred and eleven patients, 60 women, mean age 52+/-17 years (19-80): 49 chronically treated hypertensives, 28 treated diabetics and 34 normotensives were measured by one trained investigator, with an oscillometric device (Omron 705CP) on the left arm. We looked for the difference of blood pressure with the ankle or the knee crossed versus the uncrossed position.

Leg crossing at the knee during blood pressure measurement increased systolic blood pressure significantly by 6.7 (95% confidence interval 5.0-8.4) mmHg in the hypertensives and 7.9 (4.0-11.8) mmHg in the treated diabetics. Diastolic blood pressure increased by 2.3 (0.8-3.8) mmHg in the hypertensives and 1.7 (0.1-3.4) mmHg for the treated diabetics. Normotensive participants showed a smaller, though significant, increase of systolic blood pressure 2.7 (1.2-4.2) mmHg, but not significant for diastolic blood pressure, -0.1 (-1.5-1.3) mmHg, respectively. In all groups there was no effect of crossing the ankles on blood pressure. No differences were found between men and women. No significant correlation between the increase of the blood pressure when the knees were crossed and BMI, age or baseline blood pressure was present.

Blood pressure increased when legs were crossed at the knee in the sitting position. No significant increase of blood pressure was found when crossing the legs at the ankles. Leg position during measurement of blood pressure should be standardized and mentioned in publications.