Can crossing your legs raise your blood pressure?  

At the Irish Heart Foundation, we aim to provide accurate and evidence-based information on heart health to help you make informed decisions about your health. One of the questions we get asked a lot is, can crossing your legs raise your blood pressure?

We put this question to our helpline nurse Bernadette Bergin who said that while some studies have shown that crossing your legs at the knees can cause a temporary rise in blood pressure; one study found it made no difference. Another study showed that the greatest rise in blood pressure when legs were crossed, occurred in people who were already diagnosed with high blood pressure, or hypertension, and were on medication.

It is also important to note that in some studies, where the blood pressure was checked more than once, the repeated check indicated blood pressure was back to the baseline normal, she added.

Therefore, while crossing your legs at the knees can increase your blood pressure, the good news is that it doesn’t cause any long-term harm except for people at risk of developing blood clots.

How does it work? Why does crossing your legs increase your BP?

Bernadette said that research has shown that there were two possible explanations as to why crossing our legs may affect blood pressure.

“One explanation is that crossing the knees results in more blood being pumped up to the chest, which results in more blood being pumped out of the heart, which raises blood pressure. Another explanation is that when the knees are crossed the leg muscles increase the resistance to the blood passing through the blood vessels, thereby increasing blood pressure,” she explained.

Interestingly your blood pressure does not increase if you cross your legs at the ankles, just the knees.

“An analogy I use to understand how the pressure increases, is to visualise having a garden hose turned on, but keeping my thumb blocking the end. The pressure builds up behind my thumb until I release it. You can literally feel the pressure behind your thumb. This is like having your knees crossed, which contributes to building up the blood pressure in your body,” Bernadette explained.

Does crossing your legs increase your BP by a significant amount?

Bernadette said that while the results varied in different studies, overall there was an increase of between 8 – 14 mmHg in systolic readings, and between 2 – 8 mmHg in diastolic readings. In some studies, there was a difference in the systolic reading, but not in the diastolic reading. This could be significant over a period of time. However, most studies indicated that it was a temporary rise, only while the knees were crossed.

Bernadette warned that this temporary rise in blood rise could lead to the misdiagnosis of high blood pressure, or the over estimation of the seriousness and could result in inappropriate prescribing.

“Therefore, it appears the best practice when having your blood pressure measured is to have your feet flat on the floor,” she advised.

Is it dangerous to cross your legs for a long period of time?

According to Bernadette, most of the studies indicated a rise in blood pressure when the knees were crossed, which returned to normal a few minutes after they were uncrossed. Therefore, she said if we keep our knees crossed for long periods of time, we will be keeping our blood pressure up. However, the good news is that there is no evidence of any long-term consequences, with one exception- people at risk of developing blood clots.

Bernadette advised that those at risk of blood clots, such as deep vein thrombosis in the legs should avoid crossing their legs for long periods. Crossing the knees for a long period of time can block the flow of blood leading to the thrombosis.

Finally, Bernadette said that many people think crossing your legs at the knees can cause varicose veins however there is no evidence of this. She said instead that there was evidence to suggest that those who stand for long periods are at more risk of developing varicose veins.

“However, most evidence would suggest, who gets varicose veins is in part down to our genetics,” she added.

If you have any questions you can contact the free Irish Heart Foundation’s National Heart and Stroke Nurse helpline for more information.