A new study from Johns Hopkins Medicine has shown that something as simple as where you rest your arm during a blood pressure test can make a big difference in the results.
This small detail might even lead to a wrong diagnosis of high blood pressure, also known as hypertension.
Blood pressure readings include two numbers. The top number, called systolic pressure, shows how hard your heart pumps blood.
If this number is 130 or higher, it could mean you have high blood pressure, which can increase the risk of heart attacks, strokes, and other serious health problems.
In this study, researchers looked at how different arm positions changed blood pressure readings. They tested three positions: with the arm supported on a desk, on the lap, or left hanging down without support.
They found that unsupported arms, especially arms hanging by the side, caused higher blood pressure readings than normal.
The most surprising result was that when the arm was left hanging, systolic pressure was 6.5 points higher and diastolic pressure was 4.4 points higher than it should be.
Even when the arm was resting on the lap, the readings were still too high—3.9 points higher for systolic and 4.0 for diastolic—compared to when the arm was supported at heart level.
This matters a lot. For example, a reading of 130 could lead to a diagnosis of stage 1 hypertension, while a more accurate reading of 123 would be considered normal. Getting the wrong number could mean extra worry, taking medicine you don’t need, or other treatments.
Experts say the best way to check blood pressure is with the arm supported at the same level as the heart. Usually, this means resting it on a desk or table. However, in many doctor’s offices, especially when using machines where patients check their own blood pressure, this rule is not always followed.
Dr. Tammy Brady, who led the study, explained that arm position is a major factor in getting the right number. Sherry Liu, another researcher, said that people with no symptoms might get a wrong diagnosis just because their arm was in the wrong place during the test.
The study included 133 adults between the ages of 18 and 80. They were randomly assigned different arm positions and had their blood pressure checked several times, just like during a regular doctor visit.
To make the results fair, everyone followed the same steps before the test, such as using the bathroom and resting quietly.
The study focused on automatic blood pressure machines, like the ones used in clinics or at home. While the results may not apply to manual checks done with a stethoscope, the researchers still recommend that everyone follow the proper method—always support the arm at heart level.
Dr. Brady also said that patients should take charge. If you’re getting your blood pressure checked, ask for a table or surface to rest your arm on. If you’re doing it at home, make sure your arm is supported and level with your heart.
Blood pressure can change based on stress, movement, caffeine, smoking, or even what time of day it is. That’s why it’s important to measure it the same way each time.
This study is a good reminder that small details matter when it comes to health. Simply supporting your arm the right way can help get the most accurate reading, so you and your doctor can make better choices for your care.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more health information, please see recent studies about added sugar in your diet linked to higher blood pressure, and results showing vitamin D could improve blood pressure in people with diabetes.
Copyright © 2025 Knowridge Science Report. All rights reserved.
