Ask the doctors: Study shows isometric exercise can lower blood pressure

Dear Doctors: My blood pressure is just a tiny bit high. Does that really matter? My doctor said I should think about taking a blood pressure drug, but I’d rather try to bring it down naturally. I just read that doing isometric exercises can help. Do you know if that’s true?

Dear Reader: A blood pressure reading measures the force exerted on the artery walls as the heart pumps blood through the body. It is composed of two different numbers that are displayed in the form of a fraction. The top number is a measurement known as systolic pressure: the force that blood exerts on the arteries at the peak of a heartbeat. The bottom number is diastolic pressure: how much pressure the blood vessels are absorbing while the heart is at rest. At this time, blood pressure readings under 120/80 are generally considered to fall into the normal range. Blood pressure higher than 130/80 enters the category of hypertension.

It’s natural for blood pressure to rise and fall throughout the day. But chronic high blood pressure poses a significant health threat. It can force your heart to constantly work harder than necessary to send blood throughout the body. Relentless pressure on the walls of the blood vessels can cause them to lose elasticity. If left untreated, high blood pressure can cause damage to the heart, kidneys, eyes and brain. For these reasons, blood pressure that is chronically high, even a little bit high, should not be ignored.

When it comes to improving blood pressure, the benefit of regular exercise has been clear for some time. Now, a new study has put an intriguing spin on it. Researchers in England analyzed health data that had been collected in 270 studies over the course of 13 years. This gave them a robust participant pool of more than 15,000 adults. When they looked at which form of physical activity had the most favorable effect on blood pressure, the surprising answer was isometric exercise. This when muscles are contracted but the surrounding joints remain stationary.

The trio of the exercises highlighted in the studies were pressing the legs against fixed resistance, squeezing a spring-loaded handgrip and maintaining a squat while pressing the back against a wall. The theory is that while a muscle remains contracted, blood flow naturally decreases. When that contraction is released, the return of blood flow sends metabolic signals that tell the blood vessels to relax. The net result is lower blood pressure.

Adding isometric exercise to your daily routine can be helpful. However, there is an important caveat: When a prolonged muscle contraction impedes blood flow, it results in a rise in blood pressure. Although this lasts for only the time the muscle is contracted, it may not be safe for someone with cardiovascular problems or uncontrolled high blood pressure. Always check with your doctor.

Send your questions to askthedoctors@mednet.ucla.edu.